The present invention relates to systems and methods for imaging and, more particularly, systems and methods for imaging spinal anatomy and blood supply.
Imaging of the spine and its vascular supply allows for monitoring spinal cord anatomical changes in addition to assessing spinal cord blood supply. Recently, transesophageal echocardiography (TEE) has been used to produce two-dimensional (2D) and three-dimensional (3D) images of the spine. For example, a TEE probe is positioned inside an anesthetized patient and spinal structures are identified, enabling real-time monitoring of cord blood flow and anatomical structures.
TEE imaging thus provides a means for observing anatomical structures and physiological events during surgical interventions. However, such a system requires the patient to be anesthetized during the process, in which the TEE probe is inserted through the esophagus and positioned precisely to allow for optimal intervertebral disc alignment. Additionally, the large size of the TEE probe allows for minimal variance when positioning the device. Thus, TEE as a reliable and reproducible monitor of spinal structures has not expanded as a routine clinical monitor. In addition, generally only the thoracic portion of the spine is available for insonation using such procedures.
It is also possible to image the spinal cord vasculature using high-resolution and magnification angiography. For example, by injecting a radio-opaque contrast agent into the blood vessels, the vasculature can be visualized using X-ray imaging. While this technique is successful in imaging vasculature, the process is more invasive than desired and cannot be performed on patients who are critically ill or in the operating room.
Additionally, surface ultrasound systems have been used as an attempt to guide therapies of the spine. However, limitations of the patient's size and off-axis windows make continuous imaging challenging. Generally, this technique has only been demonstrated to see ligaments, tissue layers, and possible nerve roots. More specifically, the spinal cord and the vascular supply have not been effectively seen using this technique, though it may be possible for neonatal patients where imaging through bone is slightly less difficult.
Accordingly, it would be desirable to have a system and method for acquiring information about the spine and the vascular supply to the spinal cord and associated structures without the drawbacks described above.
The present invention overcomes the aforementioned drawbacks by providing a system and method for 2D and 3D spinal imaging that utilizes a device inserted into the epidural or intrathecal space. An ultrasound imaging system, including the device, is provided to obtain real-time images of the spine as well as cord blood flow.
In accordance with one aspect, a device for use with an ultrasound console to image one of spinal anatomy and cord blood flow of a subject is disclosed. The device includes a catheter sized to be positioned within one of epidural and intrathecal space of the subject and a plurality of imaging transducer elements spaced apart along a length of the catheter. The device also includes a tether coupled to a proximal end of the catheter and configured to be coupled to the ultrasound console. The plurality of imaging transducer elements are configured to be controlled by the ultrasound console through the tether.
In a further aspect, a system for imaging spinal anatomy and cord blood flow of a subject is disclosed. The system includes a device comprising a catheter sized to be positioned within one of epidural and intrathecal space of the subject, a plurality of imaging transducer elements spaced along a length of the catheter, and a tether coupled to a proximal end of the catheter. The system also includes an ultrasound console configured to be coupled to the tether and to energize the plurality of transducer elements and receive a set of reflected signals from the plurality of transducer elements. The ultrasound console includes a display system and is configured to produce an image based on the reflected signals on the display system.
In yet a further aspect, a method for spinal imaging of a subject is provided. The method includes introducing a catheter including a plurality of imaging transducer elements spaced along a length of the catheter into one of an epidural and intrathecal space of the subject and positioning the catheter at a target region within one of the epidural and intrathecal space. The method also includes setting one or more parameters of the catheter to capture image data of at least a portion of the target region and acquiring the image data of the at least portion of the target region. The method further includes generating output including one of an image of the at least portion of the target region and an output variable related to the target region.
The foregoing and other aspects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration at least one embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention.
As will be described, systems and methods for two-dimensional (2D) and three-dimensional (3D) imaging of locations along the neuraxis are provided herein using a catheter placed in the epidural space or intrathecal space of a subject. An operator, such as a surgeon or medical professional, can introduce the catheter into the epidural or intrathecal space via needle introduction, and position the catheter so that image data received via the catheter detail desired anatomical features. The catheter includes multiple locations along its length capable of acquiring image data and can be coupled to an imaging console that controls ultrasound output and image generation.
Generally, the plurality of transducer elements 14 of the transducer array 12 can be separately driven. For example, each transducer element 14 can be separately energized by the transmitter 16 to produce a burst of ultrasonic energy (an “echo signal”), which can be directed toward a target region of a subject under study. Some of this emitted ultrasonic energy can reflect off objects within the target region back toward the transducer array 12 and, when received by a transducer element 14, can be converted to an electrical signal. Each converted electrical signal is then applied separately to the receiver 18 through the switch mechanism 20. The transmitter 16, the receiver 18, and the switch mechanism 20 can be controlled by the digital controller 22 responsive to commands or input from a user (for example, from a computer console or other user interface, not shown).
More specifically, to acquire a series of echo signals, a plurality of switches in the switch mechanism 20 are first set to their transmit position, directing the transmitter 16 to momentarily energize each transducer element 14 to output an echo signal. The switches 20 are then set to their receive position and reflected echo signals received by each transducer element 14 are applied to the receiver 18. The separate echo signals from each transducer element 14 are combined in the receiver 18 to produce a single echo signal that is employed by the controller 22 to produce a line in an image, for example, displayed on the display system 24.
In some embodiments, the above-described echo console 26 (that is, the transmitter 16, the receiver 18, the switch mechanism 20, the controller 22, and/or the display system 24) can be integrated with or coupled to a device 30, as shown in
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Additionally, the microcrystals 32 can be biologically safe when used within the human body. As such, the microcrystals 32 can be selected and/or operated in a way so that the heat generated by the microcrystals 32 during use of the device 30 can be below a predetermined threshold. For example, this threshold can correlate to a level that ensures that the clinical viability of the neural and spinal tissues surrounding the catheter 34 are not afflicted during use of the device 30.
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Additionally, in some embodiments, the device 30 can be electrically grounded (that is, can include an electrical ground connection, not shown) to protect it from micro currents and electrical leakage during use. By insuring the electrical stability of the device 30, the safety and signal fidelity associated with the device 30 are inherently improved. Additionally, grounding the device 30 allows for insulation from commonly used devices in an operating room or surrounding area, such as Bovie electrosurgery devices, electrocardiographs, twitch monitors, and the like. More specifically, grounding the device 30 reduces the risk of such devices interfering with the signals from both the transmitters and the microcrystals 32.
Referring to step 52, initially setting the device 30 to capture a target region can include positioning the device 30 as well as setting echo signal parameters to create an imaging region. Notably, the imaging region can include part of or the entire target region. For example, at this step, the catheter 34 can be inserted along the neuraxial space (such as the epidural space or the intrathecal space) near or at the target region. In some cases, the catheter 34 can be threaded upward from a lower site to the target region.
More specifically, the catheter 34 can be inserted at a desired location by a surgeon, anesthesiologist, or medical professional under direct guidance (e.g., direct placement adjacent to the target region during an open operation or surgical field) or through needle introduction (e.g., similar to that of an epidural procedure). As a non-limiting example, an 18 gauge needle system may be used; however a 14 gauge system or other sizes may also be desirable in certain applications. As such, the diameter and length of the catheter 32 may be small enough to allow for insertion through clinically used needle systems.
While the above example describes catheter insertion and placement along a length of the neuraxis, it should be noted that step 52 can further include rotating the catheter 34 to ensure the microcrystals 32 are properly positioned relative to the target region (or a portion thereof). Furthermore, with respect to step 52, echo signal parameters can be set to create an imaging region that matches the target region (or a portion thereof). More specifically, echo signal parameters, such as output frequency, power output, focusing, gain, time-gain compensation (TGC), and/or other parameters, can be selected based on the target region to be imaged (e.g., depth, area, etc.) and the desired output. For example, echo parameters can be set for direct imaging of vascular structures, such as anterior and posterior spinal arteries, as well as imaging characteristics of the cord and cerebral spinal fluid. In addition, echo parameters can be set to obtain color images for determining Doppler measurements of the vessels (e.g., color flow, continuous wave Doppler, and pulsed wave Doppler modalities can be used to measure blood flow). Additionally, echo parameters may be selected based on a desired object to be imaged within the target region, such as spinal vasculature, tumors, spinal cord tissue, blood clots, echo-visible agents, or others. In some embodiments, catheter rotation and echo parameters can be set and/or adjusted by the controller 22 of the echo console 26 (e.g., via user inputs to the echo console 26).
Furthermore, generally, the number and placement of microcrystal transducer elements 32 along the catheter 34 can be selected, prior to placement, based on a length and/or a region to be imaged. For example, the microcrystals 32 can be arranged for imaging one or more anatomical regions within the spine, such as one or more of the cervical, thoracic, and lumbar regions. As a result, due to the multiple transducer elements 32, the device 30 can be configured to visualize some or all regions of the neuraxis without requiring repositioning of the device 30. Accordingly, the plurality of spaced-apart microcrystal transducer elements 32 provides for a greater imaging area than what has been previously instituted, as imaging information can be received along a length of the catheter 34 (or the entirety of the catheter 34), rather than being focused primarily at a distal tip of the device 30.
Referring now to step 54, image data is acquired using the positioned catheter 34. More specifically, using an imaging system or echo console 26 coupled to the catheter 34, the plurality of spaced-apart microcrystal transducer elements 32 are controlled to insonate the local anatomy around the catheter 34 (that is, transmit ultrasound energy and receive subsequent reflected signals) based on the set echo parameters. As such, the image data may be considered ultrasound image data.
At step 56, the acquired image data may be processed to generate 2D images, 3D images, and/or one or more output variables (such as, but not limited to, measurements of blood flow, Doppler signals, color flow Doppler, tissue motion, cell viability, post-surgical changes, and/or cell deposition). For example, these images or output variables can be displayed to an operator via the display system 24 of the echo console 26. Additionally, in some applications, such images and/or output variables can be generated in real time or near real time. For example, the device 30 can be used for direct observation of the target region during surgical procedures by generating real-time Doppler measurements of blood flow. Such real-time imaging during a surgical procedure cannot be done using previous techniques (e.g., due to challenges presented by anatomical variability of spinal vasculature or challenges of being in a surgical suite or ICU and not a dedicated imaging room). In a further example, the above-described Doppler capabilities can be used to detect low-flow in spinal arteries that run perpendicular to the imaging beams. In some embodiments, image processing can be executed by the controller 22 of the echo console 26, for example, in response to user inputs.
Additionally or alternatively, in some applications, a report, including images, output variables, and/or other data, may be generated and/or saved for later display. For example, in some applications, imaging can be done through the perioperative period (e.g., in the ICU) and such images viewed later during surgery. Furthermore, imaging can be done post-operatively and compared to pre-operative or surgical images or data.
With respect to step 58, optionally, the imaging region can be modified, for example to capture other portions of the target region or a new target region. For example, in some applications, the geometry of the image beam produced by the microcrystal transducer elements 32 can be modified remotely by a user at the echo console 26 or other user interface. For example, in some embodiments, the image beam can be rotated by adjusting the echo parameters (and/or rotating the catheter 34). In another example, in some embodiments, a depth of the image beam can be modified by adjusting a frequency parameter of the echo signal. Additionally, other types of modifications are contemplated within the scope of this disclosure. Accordingly, the device 30, connected to a console 26, is capable of producing an imaging set with alternative anatomical features without repositioning the device 30 superiorly or inferiorly within the dural space.
In light of the above, some embodiments provide a device 30 including an ultrasound catheter 34 to be used in the epidural or intrathecal space of a subject and having multiple transducer elements 32 positioned along its length. The device 30 may be used with an imaging console 26 to obtain 2D or 3D images of a surrounding target region and/or one or more output variables related to the target region.
Furthermore, the present device 30 can additionally or alternatively be used for other types of monitoring or therapeutic uses. For example, in some embodiments, a sheath of the catheter 34 can be hollow and can include one or more therapeutic channels or ports. More specifically, the sheath can include one or more inlets at or adjacent the proximal end 40 and one or more outlets at or adjacent the distal end 44. As such, the catheter 34 can include one or more channels through the hollow sheath configured to accommodate one or more tools or to deliver one or more agents from the proximal end 40 to the distal end 42. Such tools can be used with the device 30 for, for example, microsurgery and/or endoscopic procedures. Another example tool includes an optical fiber capable of acquiring video images from the distal end 42. Further example tools can include sensors, for example, to enable oximetry monitoring or neural signal monitoring via the device 30. The channels can also be used to introduce therapeutic modalities, such as stem cell introduction, echo visible agents, chemotherapy agents, regenerative therapy agents, or other agents.
Accordingly, the device 30 may be used in the epidural or intrathecal space of a subject to obtain real-time images of the spine (e.g., spinal ultrasound) and/or cord blood flow, for example, before, during, or after surgery. The device 30 may also be used, for example, to monitor spinal regions (e.g., post-operatively and/or in an ICU setting for subjects with paraplegia concerns). Also, the device 30 may be used to image and/or treat spinal masses, infarcts, arteriovenous malformations (AVMs), hematomas, ailments of the brainstem, high cervical lesions or other structures or ailments. Additionally, the device 30 may assist with procedures of the aorta (such as by helping visualize anatomy and monitor blood flow to nerves and cord during dissections, thoracic aneurysm procedures, endovascular aneurysm repair (EVAR) procedures, etc.). Furthermore, the device 30 can be used to administer medications and/or stem cells in the epidural or intrathecal space, or for intrathecal draining, monitoring, or administrations, or for monitoring neural cell viability, stem cell administration, spinal medication treatments, metastasis to the spine and neural structures, and/or degenerative changes in the spine. Additionally, the device 30 may be used at any location along the neuraxis, and may further be used intracranially (e.g., in the ventricular system).
While the invention is described through the above-described exemplary embodiments, it will be understood by those of ordinary skill in the art that modifications to, and variations of, the illustrated embodiments may be made without departing from the inventive concepts disclosed herein. Moreover, while the preferred embodiments are described in connection with various illustrative data structures, one skilled in the art will recognize that the system may be embodied using a variety of data structures. Furthermore, disclosed aspects, or portions of these aspects, may be combined in ways not specifically listed above. Accordingly, it is felt therefore that the scope of protection provided by this patent should not be viewed as limited by the above description, but rather should only be limited by the scope of the below claims.
This application is based on, claims priority to, and incorporates herein by reference in its entirety, U.S. Provisional Patent Application Ser. No. 62/419,545, filed on Nov. 9, 2016.
Filing Document | Filing Date | Country | Kind |
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PCT/US2017/060909 | 11/9/2017 | WO | 00 |
Number | Date | Country | |
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62419545 | Nov 2016 | US |