1. Field of the Invention
The present invention relates to the field of medical imaging, particularly, multimodality imaging, and robotics. Specifically, the present invention relates to a method, device and system for performing multimodality imaging and/or biosensing for assessing the pathophysiology of tissue in situ for diagnostic, therapeutic, and interventional, including surgical, procedures, by means of an actuated or robotic device that mechanically scans the area of interest by carrying one or multiple Limited-FOV sensors.
2. Description of the Related Art
Recent advances in understanding the molecular features of lesions in vivo and the rapid evolution of the associated molecular imaging modalities offer new opportunities in patient care (1-14, 32-36). A wide range of modalities have been introduced, or traditional ones adopted, to assess regional biochemistry and morphology, including radionuclide imaging, magnetic resonance imaging (MRI) and spectroscopy (MRS), optical imaging and contrast enhanced ultrasound (11-12, 15, 33-34, 37). Endowed with the capability of those modalities to assay biochemical processes at the molecular level and assess morphology at the cellular level, the emerging “molecular medicine” may produce new in situ diagnostic and therapeutic approaches (1-36).
The biomolecular or functional processes and structural features associated with the healthy and diseased tissue are complex and occur, or their consequences manifested, at different levels of the living matter. Traditionally, patient management entails the assessment of pathophysiology at several such levels. An example is the combination of laboratory tests, histology of biopsy samples, and imaging. If, hypothetically, that multi-level information can be collected in situ and interpreted accurately and rapidly, then patient management may improve by reducing time, cost and the consequences to the patients, their families, the health care system and the society. It becomes evident from the literature (1-36) that the advent of the aforementioned molecular/cellular modalities, combined with traditional ones, may enhance our ability to probe at three levels: molecular, cellular or near-cellular, and tissue (macroscopic). Until recently, the majority of such approaches were primarily used to study cultures, extracted tissue or small animal models. A bench-to-bedside translation of such assaying methods is an active field of research and development.
Multimodality approaches have been and are pursued for the collection of complementary information that assay different aspects of pathophysiology (46-52). Among those multimodal approaches, characteristic examples are the combination of contrast enhanced MRI with localized proton MRS (53-59), MRI with whole-breast diffuse optical tomography (DOT) (2, 38-40, 60-69) [2, 38-40, 60-69], and endoscope-based OCT and fluorescence in the assessment of oral (70), ovarian (71) and colon (72-73) cancers.
To probe at the molecular level, and assess non-destructively biochemical processes, in this invention it is disclosed the use of modalities that sense tissue in the molecular level such as MR spectroscopy (MRS), light induced fluorescence (LIF), confocal microscopy (CoM) and the same. It should be emphasized that, while MRS probes molecular species and events, its spatial resolution is not at the molecular level. MRS has the ability to characterize the biochemical contents of tissue in vivo (37, 51, 74-99), by sensing a wide range of biologically relevant nuclei, such as hydrogen (1H), phosphorous (31P) and carbon (13C). In many cases, MRS can measure the local concentration of biochemical species allowing the assessment of metabolic and cellular processes. In breast cancer, in vivo 1H-MRS studies have shown that a resonance at a chemical shift of 3.2 ppm is observed in malignant but not in benign or normal tissue (53-59, 91-106) [53-59, 91-105]. This resonance is primarily attributed to Choline-containing compounds and is a superposition of resonances from several species including free Choline, phosphocholine, and Choline head groups on lipids (106-109).
In vivo these resonances are broadened and indistinguishable, even at 4 Tesla, and this peak is referred to as the “total Choline” (tCho) (56, 110). The exact mechanism(s) that elevate tCho are not fully identified; a hypothesis is that elevated tCho is related to increased cellular proliferation and membrane turnover, although tCho may also increase due to changes in biosynthesis and/or catabolism. Nevertheless, studies have shown that tCho is an indicator of malignancy, as well as that tCho decreases or disappears in response to chemotherapy (94). Although MRS can sense those species non-invasively and without contrast agents, it has limited spatial resolution (order of 1 cm) primarily due to the inherent low sensitivity of the nuclear magnetic resonance (NMR).
To probe at the cellular or near-cellular level and assess microscopic morphology in vivo, in this invention we disclose the use of Optical Coherence Tomography (OCT) and the same. Optical methods have demonstrated ability for assessing morphological and biochemical processes (22, 111-117), using the inherent optical properties of the tissue, as well as optical contrast agents (43, 45). Among those optical methods, OCT, which detects near-infrared (NIR) reflections on large and undifferentiated cells, offers near-cellular level resolution at the range of <20 μm (5, 73, 118-123), while modern OCT scanners used in ophthalmology have resolution <2 μm. OCT has demonstrated a high correlation with tissue histopathology (e.g. in breast cancer (5, 73, 118-120) and its capabilities may be further enhanced with the use of exogenous optical contrast agent (11, 14, 43, 45). However, a major drawback of OCT, common to the high resolution or high sensitivity optical methods, is limited tissue penetration to about 2 mm. To address this limitation in situ practice of OCT requires (73, 118-120, 124-131): an invasive fiberoptic or endoscopic approach, i.e. trans-cannula, to reach a targeted lesion, and guidance with a tissue level modality, e.g. x-ray based, ultrasound or MRI) to detect the lesion and guide the OCT probe.
To probe at the tissue at the macroscopic level, this invention discloses the use of magnetic resonance imaging (MRI). While this choice is dictated by the selection of MRS, MRI offers certain benefits: a) Plethora of contrast mechanisms to assess the physiology of the lesion(s) and the surrounding tissue, such as perfusion (16, 132-145) and angiography (48, 50, 147-148), b) High spatial resolution, c) true three-dimensional (3D) or multislice imaging, d) Operator independent performance (vs. ultrasound), and e) lack of ionizing radiation vs. CT or mammography. With its 3D acquisition the modality is ideal for guiding an interventional tool such as the OCT probe. Alternatively, this invention discloses the use of computed tomography (CT), or 2D or 3D ultrasound (US).
Therefore, there is a recognized need in the art for improved in situ diagnostic and therapeutic approaches even with the current advances in understanding the molecular features of lesions in vivo that may lead to assessing the malignancy of a tumor in situ. Thus, the prior art is deficient the methods, device and system for multimodality and multi-level imaging, image-guided scanning and spectroscopy in situ. The present invention fulfills this longstanding need and desire in the art.
The present invention is directed to an automated system for multimodality imaging of a tissue in a subject. The system comprises a robotic delivery device configured for mechanically scanning the area of interest, a computational core comprising a plurality of software modules electronically interlinked with the delivery device, one or more interfaces between one or both of the computational core and the delivery device, at least one limited field of view sensor modality mechanically linked to or carried on the robotic delivery device and electronically linked to the computational core, and an operator thereof, and at least one wide field of view imaging modality electronically linked to the computational core. In a related automated systems, the robotic delivery device may further comprise a medium for coupling the one or more sensor modalities to the tissue and/or means for image-guided tissue sampling mechanically linked to or carried on the robotic delivery device and electronically linked to the computational core. In another related automated system the robotic delivery device may further comprise one or more channels configured to accommodate means for delivery associated with a type of the device, to deliver locally one or more therapeutic agents, one or more diagnostic agents or a combination thereof, or to deliver locally one or more contrast agents compatible with the sensor modality, the imaging modality, or to remove one or more fluids obstructing the link between the sensor modality and the tissue.
The present invention also is directed to a method for multimodal image scanning of a tissue. The method comprises the steps of selecting at least two modalities and co-registering the same and selecting an area of interest on or in the tissue. The area of interest is scanned via the co-registered modalities and the multimodal data collected during scanning is analyzed. A related method further comprises obtaining a tissue sample at the area of interest for analysis. Another related method further comprises delivering locally one or more of a therapeutic, diagnostic or contrast agent prior to or during scanning. Another related method further comprises visually displaying the analyzed data as one or more spatial maps. Yet another related method further comprises diagnosing a pathophysiological condition based on the analyzed multimodal data.
The present invention is directed further to a multimodal tissue scanning system. The system comprises a robotic delivery device configured to deliver a scanning signal from at least one sensor modality to one or more scanning zones on or in the tissue and to collect data during scanning where the one or more scanning zones are determined from one or more selected imaging modalities. The robotic delivery device is electronically linked to a planning module configured to plan collection of multimodal data during scanning, a processing module configured to analyze the collected data, a visualization module configured to graphically output the analyzed data, a fusion module configured to co-register all the modalities and co-visualize the analyzed scanning data, and a control module configured to link the delivery device to the modules. A related system further comprises means for image-guided tissue sampling mechanically linked to or carried on the robotic delivery device and electronically linked to a tissue sampling module configured to enable sampling or biopsy of the tissue at the one or more scanning zones. Another related system further comprises a medium for coupling the scanning signal to the tissue, a channel to deliver locally to the tissue one or more therapeutic agents, one or more diagnostic agents or a combination thereof or a channel to locally deliver to the tissue one or more contrast agents compatible with the one or more modalities.
Other and further aspects, features, benefits, and advantages of the present invention will be apparent from the following description of the presently preferred embodiments of the invention given for the purpose of disclosure.
So that the matter in which the above-recited features, advantages and objects of the invention, as well as others which will become clear, are attained and can be understood in detail, more particular descriptions and certain embodiments of the invention briefly summarized above are illustrated in the appended drawings. These drawings form a part of the specification. It is to be noted, however, that the appended drawings illustrate preferred embodiments of the invention and therefore are not to be considered limiting in their scope.
As used herein, the following terms and phrases shall have the meanings set forth below. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art.
As used herein, the term, “a” or “an” may mean one or more. As used herein in the claim(s), when used in conjunction with the word “comprising”, the words “a” or “an” may mean one or more than one. As used herein “another” or “other” may mean at least a second or more of the same or different claim element or components thereof. The terms “comprise” and “comprising” are used in the inclusive, open sense, meaning that additional elements may be included.
As used herein, the term “or” in the claims refers to “and/or” unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and/or”.
As used herein, the term “about” refers to a numeric value, including, for example, whole numbers, fractions, and percentages, whether or not explicitly indicated. The term “about” generally refers to a range of numerical values (e.g., +/−5-10% of the recited value) that one of ordinary skill in the art would consider equivalent to the recited value, e.g., having the same function or result. In some instances, the term “about” may include numerical values that are rounded to the nearest significant figure.
As used herein, the term “subject” refers to any recipient of in situ, ex vivo or in vivo multimodal scanning, imaging and/or biosensing as described herein.
In one embodiment of the invention there is provided an automated system for multimodality imaging of a tissue in a subject, comprising a robotic delivery device configured for mechanically scanning the area of interest; a computational core comprising a plurality of software modules electronically interlinked with the delivery device; one or more interfaces between one or both of the computational core, the delivery device and an operator thereof; at least one limited field of view sensor modality mechanically linked to or carried on the robotic delivery device and electronically linked to the computational core; and at least one wide field of view imaging modality electronically linked to the computational core.
In this embodiment the robotic delivery device may comprise one or more probes configured to link one or more limited field of view sensor modalities to the area of interest, means for dimensionally translating the one or more sensors along one or more axes of the delivery device and an acquisition unit for acquiring sensor data during translation thereof. Further to this embodiment the robotic delivery device may comprise a medium for coupling the one or more sensor modalities to the tissue and/or means for image-guided tissue sampling mechanically linked to or carried on the robotic delivery device and electronically linked to the computational core. In another further embodiment the robotic delivery device may comprise one or more channels configured to accommodate means for delivery associated with a type of the device, to deliver locally one or more therapeutic agents, one or more diagnostic agents, a combination thereof or to locally deliver one or more contrast agents compatible with the sensor modality or the imaging modality, or remove one or more fluids obstructing the link between the sensor modality and the tissue.
In these further embodiments the robotic delivery device may be a needle, a catheter or an add-on component to another interventional or surgical device. Also, the contrast agent may be activatable and/or targetable. Particularly, if the contrast agent is activatable, the channel associated therewith is electronically linked to a means for activating the contrast agent disposed on the delivery device or external thereto. In addition, the limited field of view sensor modality comprises one or more of optical coherence tomography, light induced fluorescence, confocal microscopy, high-resolution ultrasound, or MR spectroscopy or imaging with miniature radiofrequency coils tuned to appropriate nuclei. The wide field of view imaging modality may comprise magnetic resonance imaging (MRI), non-digital or digital x-ray, mammography, computer tomography (CT), and 2D or 3D ultrasound.
Also in this embodiment the plurality of software modules comprise in electronic communication a planning module configured for planning a collecting of multimodal data, a processing module configured for analyzing the collected data, a tissue sampling module configured for sampling at one or more sites of interest on or in the tissue, a visualization module configured for graphically outputting the analyzed data, a fusion module configured for co-registering and co-visualizing of the one or more sensor modalities and the one or more imaging modalities, and a control module configured for linking the delivery device to the computational core.
In one aspect the planning module is configured to execute tasks to process the one or more imaging modalities, to determine scanning zones for the one or more sensor modalities based on the one or more processed imaging modalities, to determine a trajectory vector R for the scanning zones, and to implement a sensor modality data acquisition. In another aspect the processing module is configured to execute tasks to order the data collected from the one or more sensing modalities, to process the ordered data and to implement analysis of multimodal data. In yet another aspect, the tissue-sampling module is configured to execute tasks to determine one or more signal values received at one or more positions in one or more scanning zones during scanning of the sensor modality and to enable sampling or biopsy of the tissue at the one or more positions based on the signal values. In yet another aspect the fusion module is configured to execute tasks to generate voxels or tissue volumes from data collected from the one or more sensor and imaging modalities, to produce spatial maps of the collected data and to present the mapped spatial data to the visualization module. In yet another aspect the control module is configured to execute tasks to control scanning, to actuate the collection of data with the wide field of view imaging modality and the limited field of view sensor modality according to the collection plan, to actuate tissue sampling and manage the tissue samples, and to deliver one or more of a contrast agent, therapeutic agent or diagnostic agent. Particularly in this aspect, if the contrast agent is activatable, the control module is further configured to execute the task to engage means for activation of the contrast agent.
In another embodiment of the invention there is provided a method for multimodal image scanning of a tissue, comprising the steps of selecting at least two modalities and co-registering the same; selecting an area of interest on or in the tissue; scanning the area of interest via the co-registered modalities; and analyzing multimodal data collected during scanning.
Further to this embodiment the method may comprise obtaining a tissue sample at the area of interest for analysis. In another further embodiment, the method may comprise delivering locally one or more of a therapeutic, diagnostic or contrast agent prior to or during scanning. In yet another further embodiment, the method may comprise visually displaying the analyzed data as one or more spatial maps. In yet another further embodiment the method may comprise diagnosing a pathophysiological condition based on the analyzed multimodal data. An example of a pathophysiological condition is a cancer.
In one aspect of all embodiments, prior to the scanning step the method comprises selecting at least one imaging modality as the two or more modalities; determining one or more zones for scanning based on the at least one selected imaging modality; determining a trajectory vector R for each of the at least one scanning zones; selecting at least one sensor modality as the two or more modalities; and implementing acquisition of sensor modality data. In another aspect, the step of analyzing the multimodal data comprises generating voxels or tissue volumes from the multimodal data; and producing spatial maps of the collected data representing each scanned position comprising the one or more scanning zones.
In certain embodiments the at least two modalities comprise at least one wide field of view imaging modality and at least one limited field of view sensor modality. Examples of these modalities are as described supra. Also in all embodiments the tissue may be imaged in situ, in vivo or ex vivo. In addition, imaging the tissue comprises imaging a tumor or imaging a biochemical comprising the tissue.
In yet another embodiment of the invention there is provided a multimodal tissue scanning system, comprising a robotic delivery device configured to deliver a scanning signal from at least one sensor modality to one or more scanning zones on or in the tissue and to collect data during scanning, where the one or more scanning zones are determined from one or more selected imaging modalities; and where the robotic delivery device is electronically linked to a planning module configured to plan collection of multimodal data during scanning; a processing module configured to analyze the collected data; a visualization module configured to graphically output the analyzed data; a fusion module configured to co-register all the modalities and co-visualize the analyzed scanning data; and a control module configured to link the delivery device to the modules.
Further to this embodiment the multimodal tissue scanning system comprises means for image-guided tissue sampling mechanically linked to or carried on the robotic delivery device and electronically linked to a tissue sampling module configured to enable sampling or biopsy of the tissue at the one or more scanning zones. In another further embodiment the multimodal tissue scanning system comprises medium for coupling the scanning signal to the tissue; a channel to deliver locally to the tissue one or more therapeutic agents, one or more diagnostic agents or a combination thereof; or a channel to locally deliver to the tissue one or more contrast agents compatible with the one or more modalities.
In both embodiments the system may be configured to dimensionally translate the one or more sensor modalities along one or more axes of the delivery device. Also, the system may be configured to image tissue in situ, in vivo or ex vivo. Furthermore, the one or more sensor and imaging modalities are as described supra.
Provided herein are methods, devices and systems for performing multimodality imaging and/or biosensing that incorporate one or more modalities or sensors that have limited tissue penetration, herein referred to as Limited Field-of-View or equally Limited-FOV modalities or sensors, and another modality that does not have a particular field-of-view limitation, herein referred to as Wide-FOV modality. Multimodal imaging as described herein is useful for macroscopic or tissue level imaging of the area of interest, and in particular for guiding the scanning of the Limited-FOV modality. The system may utilize at least one Wide-FOV imaging modality and at least one imaging and/or spectroscopy and/or non-imaging Limited-FOV modality or biosensing. Moreover, the image-guided scanning described herein is performed by means of an actuated or robotic device that mechanically scans the area of interest by carrying one or more of the Limited-FOV sensors. The actuated or robotic device is referred to herein as a RoboScanner and the image-guided scanning is referred to as RoboScan or RoboScanning.
The methods, devices and systems described herein are enabling technologies designed to combine with current or future imaging systems and/or modalities and/or sensors to facilitate the placement and scanning using sensors with limited tissue penetration. Particularly, the system is useful for performing multimodality imaging and/or spectroscopy of tissue in situ, in vivo or ex vivo in a subject. The system may be adapted to or configured for in situ therapy planning, therapy monitoring by multi-modality and multi-level characterization of tissue. As a non-limiting example, the microscopic RF antenna may be utilized to access the content of a biochemical or other element, such as choline in breast tumors, or image and characterize other tumors or cancers, such as, but not limited to, prostate cancer. The system may perform in vivo experimental studies on animal models, for example, but not limited to, the experimental study of diseases, pharmaceutical agents, therapy methods, etc. It is contemplated that such applications may require an appropriate frame for combining the delivery device described herein and the animal. The system may perform ex vivo studies of tissue specimens for clinical use, i.e. characterization of patient specimens, or experimental use. As with in vivo experimental studies, ex vivo studies may require an appropriate frame and sample holders for combining the delivery device and the specimen.
Moreover, the system can be adapted to further guide and refine biopsy procedures with third-party biopsy systems and in situ ablation of tissue, e.g., tumors. In addition, the system may function as a generic platform for carrying any sensor. Furthermore, the system may be utilized as a research and development tool for biosensors.
A delivery device with actuators and position encoders may be computer- or manually-controlled or can alternate operation between computer- and manually-control, depending on the specific use. The delivery device is configured to mechanically couple all modalities, both Wide- and Limited-FOV, for their co-registration, fusion and cross-modality interpretation for the diagnosis of lesions in situ, from modalities that may probe the tissue at different levels. The delivery device is configured to mechanically co-register all modalities at the same spatial coordinate system, based on the known position and/or controlled motion of the delivery device relative to the Wide-FOV modality and the known position and/or controlled motion of the different “Limited-FOV” modality sensors relative to the thereto.
Particularly, the delivery device is an actuated implement/device, i.e. a robotic device, that mechanically scans the area of the tissue of interest by carrying one or multiple Limited-FOV sensors or any sensor of limited tissue penetration. This mechanical implement addresses and facilitates several aspects of the multimodality imaging/spectroscopy, including, but not limited to:
The delivery device incorporates an appropriate mechanical implement or stage or base that carries one or more Limited-FOV sensors at well defined positions relative to a known point. The sensors may preferentially be carried inside the hollow part of the delivery device or externally to it. Moreover, the “delivery device” has appropriate access windows on its body allowing access of the Limited-FOV sensors to the tissue, for example, a quartz window for optical sensors, such as OCT or LIF. An additional mechanism may be embedded into the delivery device for extending and retracting a Limited-FOV sensor beyond its distal end as means of exposing the sensor to the tissue for data collection, such as when utilizing a miniature RF coil for the collection of MR spectra. Furthermore, a suction implement may be incorporated such that a small portion of the tissue inside the hollow portion of the delivery device to improve proximity of the Limited-FOV sensors to the tissue and/or facilitate fine-needle aspiration tissue biopsy.
Generally, the delivery device can be adjusted to accommodate and scan via the methods disclosed herein with any optical imaging and/or spectroscopy method that operates with endogenous or exogenous agents. Thus, the delivery device can accommodate sensors of different modalities. The delivery device is designed for the appropriate accommodation into the hollow channel of the delivery device of all links needed for the operation of the Limited-FOV sensors, for example, but not limited to, wires, coaxial cables, optical fibers, etc. The hollow portion of the delivery device also may be filled with appropriate material or medium, for example, saline or a fluid with appropriate optical properties, for the better operation of the Limited-FOV sensors, i.e. for better coupling of the sensor to the interrogated tissue.
The delivery device may be a needle, a catheter, or an add-on component to an existing, e.g. third-party OEM, interventional or surgical device The delivery device may incorporate one or more of at least one channel for fine needle aspiration (FNA), at least one channel for locally delivering therapeutic agents or at least one channel for locally delivering contrast agents utilizable with the Limited-FOV or the Wide-FOV modality to further enhance contrast and thus the detection and characterization of a pathologic site. Those agents may be, but are not limited to, “smart” agents that target genes, receptors etc. Such agents may be activated as example, but not limited to, the presence of biochemical entities, such as enzymes, that are characteristic of pathology of interest. The critical aspect of utilizing contrast agents is that the contrast agent is preferentially activated and generates a signal that is detectable by the sensors when it interacts or binds to appropriate biochemical entity. This ensures that the sensors are not saturated by the presence of high quantities or concentrations of contrast agent at their vicinity. A clear benefit of localized delivery of contrast agent, as compared to a systemic one, is the far less dose needed; this reduces the cost of the procedure and the potential side effects, e.g. toxicity, to the patient.
The targeted diagnostic and therapeutic agents may be utilized in the system for combined diagnosis and therapy similarly to image-guided tissue sampling. Specifically, as the device scans, depending on the findings from the sensors, the operator may activate the local delivery of a therapeutic agent. Moreover, this procedure can be automated or semi-automated using appropriate algorithms that use criteria for the local release of therapeutic contrast agent either after approval by the operator who becomes aware of this particular finding, i.e., semi-automated or in a fully automated scheme.
The delivery device may incorporate thereon or therein position encoders for determining the length, direction and speed of the motion of the Limited-FOV sensors. Position encoders may be, but are not limited to, linear and/or rotational optical differential encoders. The delivery device may preferentially incorporate optically actuated stop switches to ensure the operation of the scanning portion of the “delivery device” between two positions for safety and kinematic purposes.
The delivery device enables translation of Limited-FOV sensors along its axis for scanning the tissue, thereby generating a one-dimensional scan of the corresponding physical properties of tissue that can be assessed by the particular sensor. This 1-dimensional scan is preferentially herein referred to as Line-Scan or LineScans. Moreover, this translation may occur inside the hollow part of the delivery device, and may be performed manually by the operator, may be actuated by means of actuators, such as motors, pneumatically or hydraulically, and may be controlled by computer software and/or by the operator using manual switches that activate those actuators.
Probes of the delivery device may have appropriate access windows for the Limited-FOV sensors to access the tissue. This access window is covered an appropriate material, e.g. glass, quartz, etc, selected for allowing the appropriate electromagnetic spectrum or ultrasound waves that operate the sensors to pass therethrough. The access window may be an elongated slit along part of or along the entire length of the delivery cannula that allows scanning of the sensors by their mechanical translation inside and along the long axis of the cannula, or may be a small opening, in which case scanning is performed by moving the entire cannula. In the latter case it may be further desirable that the cannula is pulled. Pulling the cannula may be farther suitable for when the probe is for confocal microscopy (CoM).
A plurality of sensors for the Limited-FOV modalities mechanically attached onto and/or coupled to the delivery device. Limited-FOV sensing includes any type of sensing, such as biochemical or physiologic, required for collection of needed information. Limited-FOV sensing can be implemented by means of localized detection of the entities that produce the signal that is detectable by a sensor that is locally placed within the delivery device or can be connected to the site to collect the sensing signal, such as, but not limited to, optical fibers or other type of antennas. Herein, any type of Limited-FOV sensing in general is referred to as Limited-FOV modality. Limited-FOV modality(-ies) are utilized to scan and to collect biologic- and/or patho- or normal-physiologic-relevant information at a localized areas of the tissue of interest and may contribute to the interpretation of the Wide-FOV modality.
Limited-FOV sensor modalities include those for optical imaging and/or optical spectroscopy currently available or that maybe developed in the future that are of limited tissue penetration and require the localized presence of the sensor to alleviate the limited tissue penetration. Limited-FOV modalities are any molecular or cellular level modalities such as, but not limited to, optical coherence tomography (OCT), light induced fluorescence (LIF), confocal micropscopy (CoM) high resolution ultrasound, and MR spectroscopy (MRS) or MR imaging (MRI) with miniature radiofrequency (RF) coils tuned to the appropriate nuclei depending on the sought biochemical information. Moreover, the Limited-FOV modalities may comprise a lab-on-a-chip device.
At least one Wide-FOV imaging modality to image a large area of tissue in vivo or ex vivo, or a sample of material to i) identify a lesion, ii) potentially characterize the tissue, iii) guide the placement of the delivery device or devices that carry and manipulate the sensor(s) of the Limited-FOV modality(-ies), iv) select the mode of scanning of the Limited-FOV modalities, and v) provide information for multi-modal based interpretation of all data for Limited- and Wide-FOV modalities. Wide-FOV modalities are, but not limited to, magnetic resonance imaging (MRI), non-digital or digital x-ray, including specialized imagers such as mammography, computer tomography (CT), and 2D- or 3D-ultrasound. Examples of Wide-FOV modalities are, but not limited to, optical coherence tomography (OCT), light induced fluorescence (LIF), high resolution ultrasound (US), MR spectroscopy (MRS) or high resolution MRI with miniature RF coils.
Generally, as is known in the art, computers, personal computers and other computer devices and computer systems are networkable and comprise memories and processors effective to receive and store data and execute instructions to process data received from the Roboscanner System, monitors, data delivery and processing hardware and software, etc. and may be wired or wireless, hand-held or table top utilizable.
Software modules for, but not limited to, planning the scanning strategy, i.e. use the “Wide-FOV modality” to determine the patterns of scanning for the Limited-FOV, controlling the actuators of the robotic device and performing cross-modal analysis and generation of information-rich, e.g. anatomical and biochemical features, spatial maps of the tissue. The system further may incorporate expert, i.e., machine-learning and or data-mining based, algorithms and software for automated or assistive interpretation of multi-modal data. Moreover, the expert system may include a visualization/graphics output, for example, to a monitor screen of any type, for presenting the results to the operator. The software may enable signal control and co-registration of Limited-FOV and Wide-FOV modalities. In addition, software may incorporate error compensation in the control signals and/or in the co-registration software routine to address non-linearities in the spatial encoding of the Limited-FOV modalities.
The system comprises a human-machine interface to the operator. The system further has interfaces, e.g., cables, optical cables, co-axial cables, etc. to the Wide- and Limited-FOV scanners, electronics, and computer. The system may comprise a PC or dedicated PC board or an embedded PC system to run the software modules. The computational core may reside on a dedicated embedded computing unit, a card, such as a PCI or PCMCIA card, a microprocessor unit and can be a compact hardware piece that can be an add-on component to a desktop or portable computer, including but not limited to a Personal Computer (PC).
The system can operate as a stand-alone unit or as an add-on to a third party original equipment manufacturer (OEM) imaging and diagnosis equipment or products. Examples of such third party products may be, but not limited to, biopsy systems, vacuum assisted devices, biopsy guns, etc. Moreover, Limited-FOV sensor(s) maybe designed and/or constructed by a third party OEM. The system, as a whole or parts thereof, is physically constructed to be compatible with the particular needs of other modalities, for example, MRI, CT, or US compatible. This can be achieved via methods known to those skilled in this art by the appropriate choice of construction material, preparation of different components, such as electrically shielding the cables, software for filtering or compensating for artifactual effects, etc.
The system software comprises a fusion module for performing the co-registration and co-visualization, i.e., fusion, of the different modalities, including the Wide-FOV and the Limited-FOV modalities. The fusion module has, as input, the spatial sensitive area of signal reception for all the employed Limited-FOV sensors. The sensitivity profile may be expressed as a mathematical entity of the type SP(J, P, x, y, z), where J is the index of the specific Limited-FOV sensor, P are the specific parameters of the sensor, (x, y, z) are the coordinates of the position in space, and SP is the detection sensitivity of the sensor that is expressed by any means appropriate for the modality and as is known in the art.
The SP(J, P, x, y, z) mathematical entity may be stored in the system's software may include a data-base of library of pre-determined sensitive area of detection of the Limited-FOV sensor(s). In addition, or alternatively, the system may incorporate appropriate methods for determining the sensitive area of detection of the Limited-FOV sensor(s) experimentally in situ and on-the-fly during a diagnostic procedure. In particular, the system's software may include a software module for determining the sensitive area of an RF coil for MR localized biosensing. This module is not limited to, but can be based on the Biot-Savart Law. Also particularly, the system's software may include a software module for determining the sensitive area of detection of an optical sensor.
The system's software includes a software module that orders and places the raw and processed data collected with the different Limited-FOV modalities on the spatial positions that they were collected. This software module further incorporates the sensitivity profile (SA) of detection of the Limited-FOV sensor(s). The fusion module executes a series of tasks including, generating voxels, i.e. tissue volumes from which a particular set of data were collected and producing spatial maps of the data collected with the Limited-FOV modalities for use in clinical diagnosis or analysis of experimental data. Non-limiting examples of such maps are the spatial distribution of metabolites, such as choline, in breast tumors measured with a miniature RF coil, or endogenous or exogenous fluorophores measured with a LIF sensor. The system's software may include a software module for basic processing and loading the multi-modal data and presenting them to a visualization window.
The RoboScanner system comprises a process of tasks for planning, collecting and co-visualizing multimodal information. The selection of the scanning zone may be performed manually or may be semi-automated or automated by the software described herein.
The sensor may be used to guide the localized physical sampling of tissue, i.e. biopsy, for example by means of a fine-needle-aspiration (FNA)-like subassembly or add-on to the scanning device. The tissue sampling subassembly collects multiple samples guided by the multimodality data. Such localized physical sampling of tissue is based on two aspects particular to this intervention the high spatial resolution achieved by the high resolution mechanical scanning of the sensors, and the high specificity of the collected information about the type of tissue that is interrogated. This is due to the inherent particular tissue contrast or biochemical content properties, based on endogenous biochemical entities, and/or the use of suitable exogenous contrast agents delivered systemically, e.g. by means of an intravenous injection or locally by means of a suitable dedicated agent delivery channel, as described herein.
Tissue sampling, for example, but not limited to, fine needle aspiration may be performed in multiple sites along the path of scanning with the sensors. Such multi-site sampling maybe desired to, inter alia, compare healthy to diseased tissue to better identify differences pertinent to diagnosis, to identify the margins of healthy and diseased tissue, to identify inhomogeneities inside the healthy or diseased tissue. When multiple sites are physically sampled or biopsied, e.g. with FNA, then the tissue samples are individually stored and indexed to correlate to the particular signals collected at this site.
Image-guided physical sampling of tissue may be performed manually or may be semi- or fully-automated. In the manual mode of operation, the expert operator is on-line, selects the site and activates the sampling mechanism. The operator is tasked to visualize the data as they are collected by the scanning apparatus at a particular site SJ, where J is the index of scan along the path of scanning, based on this information, and criteria known to those skilled in the art, to decide whether a physical sample must be collected at this particular site SJ and to actuate the sampling mechanism to perform physical sampling, for example, by clicking on a button on the control GUI, or a switch on a joystick or other similar means. This action further activates the mechanism for acquiring the physical sample and creates the appropriate entry to correlate this specific physical sample to the sensor data at this site.
Alternatively, in semi-automated or fully automated multiple physical tissue sampling, a degree of automation of the procedure can be achieved at the level of selection of the site SJ for physical tissue sampling, based on a software module comprising algorithm(s)). This software module accesses the raw or processed data from the sensors, further processes them and, based on certain selection criteria, actuates the tissue sampling subassembly. Examples of criteria for the automated software based actuation of sampling may be based preferentially on, but not limited to, signal properties related to endogenous or exogenous agents. This may include a threshold or a combination of thresholds for one or more values of the signals, the appearance of one or more signals, for example, choline in NMR, that are characteristic of a particular type of tissue or pathologic condition of tissue, a more intelligent algorithm, for example one that uses Boolean operations to combine the changes in multiple signals, and a simple schedule of sampling, as example every certain step in the spatial advancement of the sensors with the mechanical positioned, e.g. every 1 mm.
The device that combines a tissue sampling subassembly is designed and constructed in such a way the sampled tissue spatially coincides with the area probed by the sensors, i.e. SJ. This ensures the direct spatial correlation of the sampled tissue and the signals from the sensors, i.e. the tissue sampled is the exact tissue that has been or is interrogated by the sensors. Thereby, the sampling mechanism can access tissue and sample it forward of the probe at its distal tip, if the sensors are forward looking, on its side, that is, orthogonal to its axis and at a location not at the distal tip of the probe, if the sensors are side-firing or at an angle relative to the tip of the axis of the probe at an angle. Examples of the first type are when the sensor is a forward looking confocal microscope or OCT or LIF. Examples of the second type is when the sensor is a side-looking OCT or LIF. Many different examples and cases can be implemented by the specialists in the field that satisfy the requirement that the sampled tissue is the same with the one interrogated by the sensors.
The delivery device has an appropriate number and type of actuated Degrees of Freedom (DoF) for spatially positioning and scanning with the Limited-FOV sensor(s). These DoF may be, but are not limited to at least one translational DoF along the axis of the delivery device, which is used for the one-dimensional (1D) scanning with the multi-sensor to generate the LineScan according to the scanning pattern. Controlled linear movement of the Limited-FOV sensors generates one or more 1D spatial distributions (LineScan). This translational DoF(s) is used further for 1D scanning of more than one zones in the tissue with the multi-sensor, based on the “scanning pattern”. The translational DoF(s) is further used for positioning the multi-sensor at a specific linear (including initial) position.
Alternatively, DoF may be at least one rotational DoF around the axis of the delivery device. The rotational DoF(s) is/are used to continuously and radially scan the tissue with the multi-sensor around the axis of the delivery device. Controlled rotational movement of the Limited-FOV sensors generates one or more 2D spatial distributions (Planar Scans). The rotational DoF(s) is used further to radially scan one or more arc areas of the tissue with the multi-sensor. The rotational DoF(s) is used further to radially position the multi-sensor at specific angular, including an initial, position.
The scanning of each zone, selected at the Scanning Zones task, with an acquisition strategy that determines the exact way the Limited-FOV sensor data are spatially collected. Different patterns of scanning can be implemented depending of the DoF of the delivery device, such as, but not limited to, multiple planes around the R vector trajectory or a 3D spiral centered on the R-vector trajectory. The operator determines how the zones selected with the acquisition strategy are scanned to better assess the spatial distribution of the interesting moieties. This defines the specific way Limited-FOV sensing can be implemented, i.e. Scanning Modes. Specifically, the Scanning Mode may be, but not limited to, the following:
The delivery device may be maneuvered and placed along the scanning trajectory R as hand-held by the operator, for example, a radiologist, surgeon, technician, or researcher, anchored onto a non-actuated frame/base for positioning relative to the patient or target or attached to another robotic device for positioning relative to the patient.
The operator may manually or automatically select a scanning strategy that may entail the combined or independent movement of the Limited-FOV sensors. As example, combination of LineScans and PlaneScans generate 3 dimensional multi-modal images (or scanning patterns). Such 3D images (or scanning patterns) can also be implemented by means of spiral scanning acquisition schemes. The multimodal Limited-FOV data that generates the LineScans may be organized and stored in a LineScan array that parallels the scanning of the delivery device.
Spatial co-registration of the different modalities may be based on the mechanical spatial link of the Limited-FOV sensors relative to the Wide-FOV modality. Fiducial markers may be implemented, for example, when the Wide-FOV modality is MRI and compartments are filled with Gd-based contrast agents. Moreover those compartments may be wrapped into an inductively coupled RF coil for further enhancing their signal.
During scanning, implementing registration comprises determining an initial position of the delivery device from the Wide-FOV images using the fiducial markers. The forward kinematics of the delivery device are continuously solved by the control software. The transient position of the multi-sensor is determined on-the-fly by the initial position and the forward kinematics and furthermore is stored in a computer file managed by the computational core.
Different acquisition strategies can be defined based on the specific properties of the Limited-FOV modalities and the characteristics of their sensors. Scanning strategies correspond to different patterns of actuating the Limited-FOV sensors by means of the appropriate actuators of the RoboScanner by means of control commands generated by the control module of the computation core of the system. For example, control of scanning may be implemented with, but is not limited to, a series of control pulses that are directed to the appropriate motor controller from the control module in the computational core.
Provided herein are methods for collecting and organizing of the Limited-FOV data spatially encoded to the Wide-FOV modality. As a representative example, such methods are applicable to the Limited-FOV modality optical methods spatially encoded to a Wide-FOV modality that is the MR coordinate system. Since spatial registration is achieved via a mechanical link and considering that the only possible motion with a rigid probe is a linear translation along its axis the present invention provides a method for defining an optical voxel attached to the sensing site of the optical probe, or in general of the Limited FOV modality sensor, that can scan the tissue linearly and samples optical data at discrete positions, known relative to the MR coordinate system, thereby defining a spatial dimension of the MR-registered line scan. In a related method, the optical voxels are correlated or registered with the MR coordinate system via an Acquisition Array (AA) of the optical voxels, or in general of the Limited FOV modality voxel. The AA may be a data structure that hierarchically stores optical data together with the coordinates of the position where they were recorded thereby providing a correlation functionality.
The Acquisition Array comprises a data storage structure within the Computational Core and has the following primary features:
For use of an MRI Wide-FOV modality, the delivery device may incorporate one or more MRI fiducial marker(s)) at known location(s). Multiple MR fiducial markers or MR visible markers of appropriate shape may be incorporated at multiple locations to register the delivery device in 3D. The MRI fiducial marker may be based on miniature radiofrequency (RF) coil(s) which miniature coil marker(s) may be connected to the RF interface of the MR scanner via co-axial cable(s) or may operate in an inductively-coupled manner. Particularly, a fiducial marker can be the miniature RF coil used as a Limited-FOV sensor for MR spectroscopy. The MRI fiducial markers may comprise MRI contrast agent filled vials. Furthermore the robot control software enables automated control of a gradient based localized (GradLoc) technique. The software also enables autonomous control of both the MR scanner and the robot in synchronization.
Spatially co-registering modalities includes the determination or definition of a common coordinate system. When the Wide-FOV modality is MRI, the endogenous coordinate system of the MRI scanner may be used. Specifically, using MR visible markers, the initial position of the RoboScanner is determined from MR images and used to calculate the static and transient position of the sensor(s) of the Limited-FOV modalities or, in the case of an optical sensor the optically active and actuated parts of the probe, from its kinematics.
Registration of the delivery device that carries a probe and the Wide-FOV modality of MRI requires knowing the kinematics relative to the MR scanner and initial registration with On-Probe MR markers. The position where the signals of the limited FOV sensors, for example, but not limited to optical signals, are sampled, which is the position of the detecting optical heads, can be calculated from the kinematics of the probe. The kinematics are the formulas that calculate the transient position of any point of the actuating optical probe relative to an initial position, based on its specific geometry, degree-of-freedom and control signals. To determine the initial position of the probe, at the beginning of each study, it is registered to the MR scanner by determining the coordinates of the centers of MR visible markers, for example, but not limited to, cross-shaped markers. The area of the probe is imaged with a heavily T1-weighted fast gradient recalled echo for high contrast visualization of the markers (149). The coordinates of the center of the markers are extracted manually or with an image processing routine and supplied to the kinematics of the control.
Collecting morphologic and functional information may be collected from an organ-level Wide-FOV modality, i.e. MRI, with morphologic information with a Limited-FOV modality at the cellular or near-cellular level, i.e. OCT, and biochemical assaying with another Limited-FOV modality, i.e. MRS. It is contemplated that multimodal and multi-level sensing may eventually offer high sensitivity from MRI and specificity from MRS and OCT in the characterization of lesions in situ.
III. Imaging or Spectroscopy with Specific Sensors
In a particular example, a Limited-FOV sensor may be an OCT probe combined with a LIF probe, herein termed “CT/LIF dual-sensor. The OCT/LIF dual-sensor” can be implemented in different designs of optical probes that share, but are not limited to, the following general design features:
The plurality of DOF on the proposed probe indicates that there can be a large number of potential scanning paths to optically image a tissue of interest. The number of paths can be even higher considering that the number of LIF (NLIF) and OCT lines (NOCT) collected can be different. Since the duration of scan cannot be infinite, such as for clinical studies, and considering the limited duration of signal enhancement for some applications, it is preferable to be able to optimize protocols.
A dedicated software module can preferentially be incorporated into the computational core of the RoboScanner system for generating optimized acquisition protocols to control the scanning with the OCT/LIF dual-sensor. This software module enables algorithms that have as parameters 1) the duration of a single line of data acquisition for OCT (TOCT) and LIF (TLIF), including the time for electronic switching between the two modalities; 2) duration of actuation per DOF, including delays; 3) mechanical errors; 4) relative desired weighting of density of data collection (WDATA) versus volume scanned (WVOLUME)′ and the relative weighting of number of OCT lines (NOCT) and LIF scans (NLIF). Scanning parameters include the number and position of OCT lines, the number and position of LIF acquisition, and the path followed by the actuated probe to acquire those points. Virtual phantoms can be generated with representations of tissues with different optical properties (153-154).
The code comprising the software module enables calculation of Forward and Reverse optimized scanning. To calculate an optimized Forward scanning protocol, for didactic purposes the algorithm simulates the covered area and the TACQ for simple intuitive scans, such as a single continuous line scan, or one that samples two distinct areas, healthy vs. lesion, as well as spirals around the axis of the probe and rectilinear scans. For Reverse scanning, the algorithm, defines the area of the lesion and, optionally, of healthy tissue for reference, which in practice are both provided by MRI, and calculates the scanning parameters for maximum density of data collected and reports the scanned tissue volume, for maximum volume of tissue scanned and reports the density of data collected and for any weighting WDATA and WVOLUME, for a given TACQ. Preferably, the algorithmic code may be implemented in any platform, including, but not limited to, C, C++, C#, Simulink (Mathworks), Matlab (Matworks), as are known in the art.
A miniature RF coil may be utilized as a Limited-FOV sensor modality, by itself or combined with other Limited-FOV sensors, for MR spectroscopy at lower magnetic field scanners, where the proximity of the coil substantially improves the sensitivity of the modality. Such a Limited-FOV RF sensor is dedicated to magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). A biosensor for MRI/MRS can be a single or a multi-tuned radiofrequency (RF) coil. This RF coil can be tuned to the proton (1H) resonance, and/or tuned to the phosphorous (31P) resonance, and/or tuned to sodium (23Na) resonance, and/or tuned to multiple nuclei.
A Limited-FOV RF sensor can be used in one or more of both Transmission/Reception (Tx/Rx) mode, for Reception (Rx) with external RF coil(s) for RF transmission or inductively coupled for localized enhancement of the RF signal, using external RF coil(s) for reception/transmission. When the Limited-FOV RF coil is used in Tx/Rx and/or Rx mode, the coil can be interfaced via an ultra-thin co-axial cable to the RF interface of the MR scanner signal reception module. Moreover, as is known in the art, the RF coil sensor may be equipped with an RF tuning/matching circuit for tuning the coil to the desired frequency(-ies). This tuning/matching circuit can be implemented, for example, but not limited to, by locating the circuit at a distance from the RF coil or by locating the circuit in the vicinity of or onto the coil, for example, by placing capacitors onto its wire.
When utilizing a Tx/Rx or Rx RF coil as a Limited-FOV sensor, as is known in the art, means may be taken for addressing potential variable loading of the coil as the assembly of the delivery device plus the miniature Tx/Rx or Rx-only RF coil advances into the tissue, since the co-axial cable is part of the tuning circuit. This can be accomplished by additional and/or improved grounding of the co-axial, by using a miniature tuning and/or matching capacitor on the coil, i.e. at the distal tip of the delivery device or by using an inductive coupling approach.
The excitation/reception profile of the miniature RF coil may be used for determining the size of the sensitive area and the voxel that can be sensed during a scan. This can be, for example, calculated during scanning or it may be stored already in the file libraries of the computational core of the system. Those profiles can be calculated, for example, but not limited to, with the Biot-Savart Law. Particularly MRS can be performed with a single excitation pulse.
A Limited-FOV RF sensor may be utilized to perform single-voxel spectroscopy (SVS) with existing or future developed methods. Accordingly, point-resolved spectroscopy (PRESS) or Stimulated Echo Acquisition Mode (STEAM) with or without water and/or fat suppression or other type of magnetization preparation can be used according to techniques known to those skilled in this art. A Limited-FOV RF sensor with a SVS modality includes the automated, i.e., computer-controlled, relocation of the voxel of the SVS MR technique to match the position of the RF coil as the latter is scanned as described herein. This can be enabled by the actuation control software module of the delivery device that calculates the appropriate coordinates of the single-voxel in such a way that the single-voxel of the SVS technique is at a preferred position relative to the sensitive area of the RF coil on the delivery device and that supplies them to the MR scanner acquisition control software by means known to those skilled in this art. In a non-limiting example the coordinates can be sent via a dedicated Ethernet connection on-the-fly or pre-scanning in the form of an electronic file that is stored locally to the MR scanner and is loaded to the control software accessing the list of the position SVS can be performed.
As described below, the invention provides a number of advantages and uses, however such advantages and uses are not limited by such description. Embodiments of the present invention are better illustrated with reference to the Figure(s), however, such reference is not meant to limit the present invention in any fashion. The embodiments and variations described in detail herein are to be interpreted by the appended claims and equivalents thereof.
With continued reference to
With continued reference to
The probes also include a channel of access 426a,b,c for sampling physical tissue with its associated applicator 427a,b,c, for example, a bendable needle for performing fine needle aspirations. For a side-looking probe, the needle is bendable and its bend shape also may be controlled with a suitable mechanical or piezoelectric or other type of element. The design of the applicator is such that the FNA is performed at a volume of tissue 428a,b,c that is inside the area detected by the sensors, ensuring that there is a spatial coincidence of the area of tissue that gives riose to the signal and the area of tissue sampled.
In a multi-modal guided tissue sampling operation the sampling system is advanced to position Sj at step 432 and multimodal data lj is collected at 434 and, if needed, the raw data Ij is processed at 436. Processing may be automated at 438a or by manual operation at 438b and selection criteria are inputted at step 440. The system is queried at 438c whether to proceed to the site to sample the tissue. If No at 438d, the system moves to the next position Sj+1 at 418. If Yes at 438e, the sampling mechanism is actuated at 442 and the physical sample is collected at 444 and stored and indexed at 446, whereupon the system proceeds to the next position Sj+1 at 448.
An example of a simple code for actuating tissue sampling at 444 uses two criteria in an AND type selection. At 450, the signal from modality “1” is above a threshold and at 452 the signal from modality “2” is within a lower and upper limit. A query is made at 454. When both conditions 450 and 452 are true at 456 then the tissue sampling mechanism is actuated at 442. If one or both of conditions 450 and 452 are not met at 458, the system proceeds to the next position 448. The control code may also incorporate constraints of the minimal step between samples.
The planning module 520 enables the selective processing 521 of the Wide-FOV images to be appropriate for the planning task. The planning module also enables the collection of the Limited-FOV data. This task maybe performed entirely manually at 522 or via computer-assisted planning routines and/or tools at 523 that may be semi-automated 524a or automated 524b. This task entails the processes of setting the trajectory R of scanning 525a, setting the zones for scanning 525b, setting the acquisition strategy 525c, and calculating for the generation of the Acquisition Array (AA) 525d from the Limited-FOV modality or sensor parameters 526. The planning module allows the operator to manually or semi-automatically, or automatically define a trajectory for the insertion of the delivery device. This trajectory, can be configured to pass through the portion of the tissue identified from the Wide-FOV modality for scanning with the Limited-FOV sensor(s), for example, through a lesion, and may be arranged to avoid harming vital structures, for example, blood vessels or nerves, or to minimize the length of the traversed healthy tissue.
The data collection module 530 enables the collection 532 of the LineScan data with the Limited-FOV data based on the acquisition strategy 525c with overall control from the control module 534. The processing module 540 enables multi-modal processing that includes ordering and co-registration of the Limited- and Wide-FOV data 542, processing of the Limited-FOV data for extraction of information 544 and, selectively, additionally analysing for multi-modal interpretation 546, for example, but not limited to, data mining and machine learning processes. The visualization module 650 enables multi-modal visualization for diagnosis 548.
The system provides graphical and visualization tools that facilitates setting scanning zones and setting the acquision strategy. In a preplanned scanning strategy, the operator may select or plan a single continuous scanning or multiple areas to be scanned from the Wide-FOV data or images. The pre-planned scanning strategy can be selected automatically with image analysis software or images or can be selected manually by visual inspection and graphical tools from the Wide-FOV data or images,
Generally,
At the line-scan system site all process and data management are performed by the control core shown in
The manipulator is first designed and its mechanical structure optimized using computer 3D solid modeling (Autodesk Inventor), and then physically prototyped entirely of non-magnetic and non-conductive acrylonitrile butadiene styrene (ABS).
The distal end of the manipulator carries a four turn miniature solenoid RF coil with a diameter of 1.1 mm and length of 1.2 mm, as shown in
The hardware set up is based on a PC that is connected via a serial port to the motor controller (MC-1000, New Scale Technologies Inc., Victor, N.Y.) and via a USB port to a data acquisition unit (DI-148U, DATAQ Instruments Inc., Akron, Ohio) for performing the dual-triggering scheme. The control core software is developed on Matlab (Mathworks, Inc., Natick, Mass.), using the ActiveX library for the motor controller (NstSquiggleCTRL ActiveX by New Scale Technologies) and the ActiveX control interface for communication with the data acquisition unit (UltimaSerial by DATAQ Instruments Inc.). The dual triggering scheme is implemented by running two co-axial cables from the data acquisition unit to the MR scanner controller.
To facilitate closed loop control, the manipulator is equipped with in-house developed MR-compatible optical sensors. A quadrature linear optical encoder assesses the translation of the probe, as
The quadrature linear optical encoder in
The following examples are given for the purpose of illustrating various embodiments of the invention and are not meant to limit the present invention in any fashion. One skilled in the art will appreciate readily that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those objects, ends and advantages inherent herein. Changes therein and other uses which are encompassed within the spirit of the invention as defined by the scope of the claims will occur to those skilled in the art.
The essence of the proposed approach is the use of the actuated manipulator to mechanically couple and co-register the guiding, i.e., MRI, and the Limited-FOV, i.e., MRS, modalities. The adopted approach is based on the facts that the MR scanner has its inherent coordinate system defined by the resident magnetic field gradient coils and any MR signal generating entity can be imaged relative to this coordinate system.
Specifically, this is performed by registering an initial position of the probe to the MR coordinate system and then by calculating its transient position based on the known motion steps from the optical encoder.
This approach has been successfully used before in MR-guided robot control (155), with the difference that instead of the optical encoder signals used herein, in that work it is used the outcome of the forward kinematics. Practically, this is implemented with a straightforward process: (a) the exact initial position (Z0) of the probe relative to the coordinate system of the MR scanner is measured, (b) during line-scanning, the transient position (ZN) of the probe is calculated based on the optical encoder signal counts (±N; including direction relative to the MR coordinate system) and the pre-set step of motion (DZ); i.e. ZN=Z0+N·DZ. It should be noted that due to the specific experimental set up, the probe is translated only along the Z axis of the magnet; in the general case the above approach can be used for translation, i.e. scanning, along an arbitrary vector.
The initial registration of the manipulator is performed using the miniature RF probe as a fiducial marker (
Herein, instead of a separate dedicated marker, the miniature RF coil. i.e. the Limited-FOV modality sensor, is employed to collect a GRE sagittal image to image along the Z-axis with a Wide-FOV. The projection of the image is then calculated and the center of the RF coil profile is selected as the Z0. Instead of a complete image, the projection along any axis of translation can be collected with the appropriate MR pulse sequence. The full image is preferred for better visualization of the probe in those preliminary studies. Alternative to this process would be the collection of an image or a projection after any translation to calculate the transient sensor position.
All MR studies are performed on a UNITY/NOVA (Varian, Palo Alto, Calif.) spectrometer imager system. The sample holder, that carries the phantom, is secured onto a custom-made base, the probe is inserted into the scanning channel, and the assembly is then inserted into the volume RF coil and secured onto the scanner's cradle. The cradle is positioned so the centre of the volume coil corresponded to the isocenter of the scanner, and then both the volume and the miniature RF coils are fine tuned and matched with the cradle in place. This or a similar set-up can be used in phantom, excised tissue and animal studies.
Studies are performed using two-compartment rectangular phantoms (39.6×44.6×89 mm3), one filled with a gelatin matrix and the other with commercially available vegetable oil. The sample holder, that carries the phantom, is secured onto the custom-made base, the probe is inserted into the scanning channel, and the assembly is then inserted into the volume RF coil and secured onto the scanner's cradle. The cradle is positioned so the center of the volume coil corresponded to the isocenter of the scanner, and then both the volume and the miniature RF coils were fine tuned and matched with the cradle in place.
MR compatibility studies evaluated the effect of the presence and operation of the manipulator on 1H spectra, collected after a single excitation pulse, i.e. the free induction decay (FID), and on gradient recalled echo (GRE) images. To better appreciate the effect of motor operation, dynamic acquisition studies were performed. At these studies GRE images and spectra were continuously collected. After a period of motor idling, to collect baseline data, the manipulator is actuated. The specific acquisition parameters for the GRE and the FID were the same with those used in the line-scans, reported in the following paragraph. Those studies were performed with both the volume and the miniature RF coils.
Line-scan MR data collection studies were performed with the following protocol. Scout and multislice imaging with a gradient recalled echo (GRE) sequence (TR/TE/a; matrix, FOV), shimming on a 5 cm wide slab along the axis of the scanning and localized scout spectroscopy with point resolved spectroscopy (PRESS) (bandwidth=4006.4 Hz number of points=8000 and voxel size=64 mm3). The device is registered by collecting an appropriate slice orientation, for example, a sagittal image using the miniature coil with a GRE (same parameters as above). The initial position of the translating element is calculated as discussed in this invention. Subsequently a scanning protocol is prescribed and the Line-scan is performed with the automated procedure described in section A by repeated translation-spectra collection steps. Usually eighty to ninety steps of 0.5 mm were performed. After each translation has been completed, the control software triggered the spectrometer that collected the free induction decay (FID) after a single excitation pulse (with a flip angle=45°; bandwidth=5000 Hz and number of points=2048).
All data processing is performed off-line with in-house developed software on Matlab. For each set of experimental data, the initial position of the miniature RF coil, for example, as shown in the
The spectra are Fourier transformed and the zero ppm frequency is assigned at the water peak from the gelatin compartment. Resonances are first identified on the PRESS spectra collected with the volume coil and then on representative SMIN spectra collected at center of the phantom compartments prescribing the bands of each resonance. For each identified peak, the software extracted the following: center resonance in ppm and difference in Hz from the water peak, integrated intensity, SNR and reported them as value±standard deviation. Additional outputs included stacked plots of the spectra and graphs of parameter vs. position on the Z axis. The latter are further processed to identify the position ZSP as mid-way of the transition zone. Images collected with the volume coil were also loaded and the position (ZIM) of the boundary between the two compartments is extracted and compared to this calculated from the spectra, i.e. ZSP.
The device demonstrated sufficient MR compatibility with insignificant effect on the SNR of the images, and the SNR and line width of the spectra. Specifically, with the motor idling the gradient recalled echo images manifested a SNR for the gelatin compartment of 7.08±0.10 and vegetable oil of 5.72±0.07. When the motor is operating at its set speed, the SNR of the gelatin is 6.79±0.11 and of the oil compartment is 5.62±0.06. The SNR of spectra is measured to be 2260±36 for the water and 1076±28, for the most explicit oil resonance, for the motor idling. When the motor is actuated the SNR of those resonances is measured 579±26 for the gelatin and 830±31 for the most explicit oil resonance.
To further appreciate the spatial localization using the miniature coil with a single pulse sequence,
The following references are cited herein.
The present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present invention. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.
One of ordinary skills in the art, with the benefit of this disclosure, would recognize the extension of the approach to other fields of medical imaging and in particular in the field of multimodality imaging for assessing the pathophysiology of tissue in situ for diagnostic, therapeutic, and interventional, including surgical, procedures.
This non-provisional application claims benefit of provisional application U.S. Ser. No. 61/402,941, filed Sep. 8, 2010, now abandoned, the entirety of which is hereby incorporated by reference.
The U.S. Government has a paid-up license in this invention and the rights in limited circumstances to require the patent owners to license others on reasonable terms as provided for by the terms of grant No. CNS-0932272 awarded by the National Science Foundation.
Number | Date | Country | |
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61402941 | Sep 2010 | US |