Patent Application
20230380921
The present invention relates to a method and a system for manipulating a magnetic instrument within a lumen of a body, for example under radiological guidance.
The gold-standard for treating some neurovascular diseases such as ischemic stroke is an effective and minimal invasive endovascular technique. The primary instruments used are catheters and guidewires that are inserted into the vasculature through a small incision at the groin. Some instruments have a curved tip allowing for easier access of different vessels as they bifurcate and are navigated by pushing, pulling, and rotating. In cerebrovascular interventions, interventional neuroradiologists are often faced with tortuous and complex anatomies that can be challenging to navigate and require a high level of skill and expertise.
An alternative to manual catheter and guidewires is a robotic approach using robotic magnetic navigation (RMN). In RMN, magnetic instruments composed of a flexible magnetic distal portion are redirected by the external magnetic field generated by a magnetic navigation system (MNS). In neurovascular radiology, where the instruments are navigated under radiological guidance, x-ray images of the patient anatomy and the instruments are displayed on a monitor. Under these circumstances, the steering of magnetic catheters and guidewires can be challenging, because they are 3D objects in a 3D environment, whereas the operator is provided a 2D image on a 2D display.
It is known to make use of graphical representations of the magnetic field, the magnetic instrument, and the patient anatomy to help the operator in making mental transformations.
Adding visual cues such as graphical overlays or a separate monitor have the potential to divert an operator's gaze away from the x-ray image. This can lead to loss of focus and potentially increase risk. Consequently, there is a need to further improve the interface used by the operator used to steer a magnetic instrument under radiological guidance.
It is an object of the present invention to propose a method and a system that allows for steering of a magnetic instrument within a lumen of a body without the need of additional visual feedback other than the already available 2D representation of the body or portion of the body, for example a 2D fluoroscope image.
One aspect of the disclosure is directed to a method for manipulating a magnetic instrument within a lumen of a body, the method comprising the step of providing a system for manipulating the magnetic instrument.
The system comprises an imaging instrument for imaging a portion of the body comprising the lumen. The imaging instrument can be for example a x-ray fluoroscope, a camera imaging system, an ultrasound imaging system, or a computed tomography system. Any device providing visual feedback on the position of the magnetic instrument is appropriate as imaging instrument. A 3D cartesian coordinate system {X_xray, Y_xray, Z_xray} can be associated in a fixed manner with respect to the imaging instrument and moving with the imaging instrument.
Further, the system comprises a magnetic navigation system designed to generate a magnetic field to allow the navigation of the magnetic instrument in the lumen. The magnetic navigation system can comprise multiple electromagnets or permanent magnets located and movable around the patient providing a magnetic field at predetermined positions in the space, in which the magnetic instrument is moved. A 3D coordinate system {X_mns, Y_mns, Z_mns} may be associated in a fixed manner with respect to the magnetic navigation system and moving with the magnetic navigation system.
In addition, the system comprises a display device capable of producing a 2D representation of the body or portion of the body imaged by the imaging instrument. The display device may be a device or system capable of producing 2D (two dimensional) or 3D (three dimensional) images or other representations of a point-of-interest, for example the position of the magnetic instrument, in a 2D display image.
The system for manipulating the magnetic instrument can also comprise an advancer designed to apply a force on a proximal portion of the magnetic instrument. Alternatively, the force to advance the magnetic instrument can be applied manually.
Further, the system comprises an interface designed to steer the magnetic instrument and a controller designed to control the system. The controller can be a system usable by an operator to control the system for displaying and manipulating the magnetic instrument, including but not limited to controlling the imaging instrument, the magnetic navigation system, the interface, the magnetic instrument, and, if applicable, the advancer. For this purpose, the controller may comprise a central processing unit and a computer readable media operably connected to a processor capable of carrying out operations or steps according to the method and/or as specified by the operator.
Further, the method comprises the step of providing the magnetic instrument comprising a magnetic distal portion and the step of displaying an image of at least the magnetic distal portion on the display device.
The magnetic instrument is designed for use in a mammalian body during an intra-body medical procedure.
The magnetic instrument can be a steerable device comprising an elongated element in the form of a needle, guidewire, catheter, endoscope, or the like that is used inside of the mammalian body, in particular of a human. The magnetic instrument may be used for inspecting and/or operating inside of organs (e.g. liver, lungs, kidney, brain, etc.), inside of a body cavity (e.g. abdomen, spinal cord, sinuses etc.), or in the vasculature. The magnetic distal portion, preferably a magnetic tip arranged at a distal end of the magnetic instrument, can correspond to a distal end portion of the elongated element and is configured for allowing steering of the magnetic instrument by way of an external magnetic field. In a preferred embodiment, the magnetic distal portion forms the foremost end of the steerable device to allow for an optimal steering. Preferably, the magnetic distal portion comprises a permanent magnetic element.
According to the invention, the method comprises the step of sending via the interface an operator input to the system to change the direction of the magnetic field from a first direction represented by a first magnetic field vector to a second direction represented by a second magnetic field vector to steer the magnetic instrument in an advancement direction, wherein the operator input is made in reference to a coordinate system of the imaging instrument, i.e. an imaging instrument coordinate system, the imaging instrument coordinate system being associated in a fixed manner to the imaging instrument. The operator input is defined as a set of components necessary to steer the magnetic instrument, for example data characterizing the magnetic field or data related to the advancement of the magnetic instrument.
Further, the method comprises the step of applying the magnetic field corresponding to the second magnetic field vector.
In a rest state of the system, the coordinate system {X_xray, Y_xray, Z_xray} associated with the imaging instrument may be aligned with the coordinate system {X_mns, Y_mns, Z_mns} associated with magnetic navigation system. However, during the intra-body medical procedure, the imaging instrument is rotated around the patient to obtain more favorable views around a longitudinal axis by a rotation angle and/or around a tilt axis by a tilt angle. Hence, the imaging instrument coordinate system {X_xray, Y_xray, Z_xray} is not aligned anymore with the magnetic navigation system coordinate system {X_mns, Y_mns, Z_mns}.
The coordinate systems {X_xray, Y_xray, Z_xray} and {X_mns, Y_mns, Z_mns} can be related by retrieving the tilt angle and the rotation angle directly from the imaging instrument, dialing them in manually by hand or by attaching a sensor on the imaging instrument.
However, using the imaging instrument coordinate system as a reference base for the operator inputs related to the magnetic field has the advantage for the operator that he does not have to make mental transformations to switch from the imaging instrument coordinate system to the magnetic navigation system coordinate system. The operator can remain during the medical procedure in his mental representation corresponding to the imaging instrument coordinate system. Therefore, the navigation of the magnetic instrument is simplified.
In addition, the operator inputs are related directly to the magnetic field orientation that then controls the movements of the magnetic instrument, instead of being related to the magnetic instrument itself, in which case the operator inputs must be converted in parameters of the magnetic field by way of calculation of torque and force applied on the magnetic instrument. It follows that the method allows the operator to learn and observe the effect of the magnetic field on the magnetic instrument and optimize his strategy to exploit the effect of the magnetic field on the magnetic instrument.
In a preferred embodiment, the image displayed by the display device is seen in a plane corresponding to or parallel to a fixed reference plane of the imaging instrument coordinate system. Preferably, the reference plane is an imaging plane of the imaging instrument, i.e. a plane that contains the image projected by the imaging instrument of the body. For example, in the case of a x-ray fluoroscope used as an imaging instrument, the reference plane can be parallel to a detector plate of the x-ray fluoroscope. More generally, the reference plane can be perpendicular to the direction of view of the imaging instrument. This embodiment further simplifies the navigation of the magnetic instrument because the operator has the same fixed reference in the imaging instrument coordinate system during the process.
In some embodiments, a step of mapping operator inputs with corresponding magnetic field vectors in reference to the imaging instrument coordinate system is performed as an initialization step of the system. This results in a one-to-one correspondence of one magnetic field vector with one operator input, i.e. an absolute correspondence in the imaging instrument coordinate system of operator inputs with magnetic field vectors that is even more intuitive for the operator. Therefore, it is not necessary to change the magnetic field in relative steps, i.e. starting from a present first orientation to determine the increment in magnetic field necessary to switch from the first orientation to a second orientation at a certain rate.
In a more preferred embodiment, the method comprises further the steps of mapping the operator inputs made via the interface in reference to a magnetic navigation system coordinate system associated in a fixed manner to the magnetic navigation system. After performing a mapping in reference to the imaging instrument coordinate system as described previously, a further mapping in reference to the system coordinate system of the magnetic navigation system avoids calculation to convert data from the imaging instrument coordinate system to the imaging instrument coordinate system.
In some embodiments, the magnetic field vector is defined by its spherical coordinates in the imaging instrument coordinate system, wherein a polar angle φ (phi) is measured from a fixed zenith direction perpendicular to the fixed reference plane, an azimuthal angle θ (theta) of the orthogonal projection of the magnetic field vector on the fixed reference plane is measured from a fixed reference direction on the fixed reference plane, and an intensity of the magnetic field is defined as the radial extension of the magnetic field vector, and the operator input comprises the polar angle and the azimuthal angle of the of magnetic field vector. This coordinate system is well adapted for the characterization of magnetic field. However, other system like cylindrical coordinates or cartesian coordinates are also possible.
In some embodiments, the operator input comprises an advancement speed of the magnetic instrument with respect to the imaging instrument coordinate system. This feature allows the control of the advancement of the magnetic instrument also via the interface so that the work of the operator is optimized. For the sake of simplicity of operating, it is also possible to provide for preset advancement sequences in the imaging plane, wherein for example an advancement of a predefined length and direction of the magnetic instrument is performed upon actuation.
In some embodiments, the intensity of the magnetic field is preset to a fixed value, for example the maximum magnetic field intensity, before operating the system. However, it is also possible to define the intensity of the magnetic field as a component of the operator input while operating the system.
In the present disclosure, the term proximal is used to specify a side or a direction facing the operator and distal refers to a side or a direction facing away from the operator, i.e. oriented towards the patient.
One aspect of the disclosure is directed to a system for manipulating a magnetic instrument within a lumen of a body.
The magnetic instrument has a magnetic distal portion; further features of the magnetic instrument have been described above in relation to the method and apply likewise in the system disclosed.
The system comprises an imaging instrument for imaging a portion of the body containing the lumen, an imaging instrument coordinate system and a fixed reference plane being associated to the imaging instrument; a magnetic navigation system designed to generate a magnetic field to allow the navigation of the magnetic instrument in the lumen; a display device capable of producing a 2D representation of the portion of the body imaged by the imaging instrument; an interface designed to steer the magnetic instrument; and a controller designed to control the system. The system can also comprise an advancer designed to apply a force on a proximal portion of the magnetic instrument. However, the magnetic instrument can also be advanced by hand. Features of the elements of the system have been discussed above in relation to the method and apply likewise in the system disclosed here.
According to the invention, the interface is a navigation console designed to control the magnetic field in the coordinate system of the imaging instrument.
In a preferred embodiment, a magnetic field vector associated to the magnetic field is defined by its spherical coordinates in the imaging instrument coordinate system, a polar angle φ being measured from a fixed zenith direction perpendicular to the fixed reference plane, an azimuthal angle θ of the orthogonal projection of the magnetic field vector on the fixed reference plane being measured from a fixed reference direction on the fixed reference plane, and an intensity of the magnetic field being defined as the radial extension of the magnetic field vector. In addition, the navigation console having a first steering device designed to input the polar angle φ and a second steering device designed to input the azimuthal angle θ.
In some embodiments, the navigation console has a further steering device designed to input an advancement speed of the magnetic instrument with respect to the imaging instrument coordinate system.
Advantages of these embodiments have been discussed in relation to the method disclosed above and apply equally to the system.
These and other aspects and embodiments are described in further detail below, in reference to the attached drawings.
Referring now to the drawings,
The controller 40 is a system usable by an operator 55 to control the system for manipulating the magnetic instrument 20, including but not limited to controlling the imaging instrument 30, the magnetic navigation system 60, the interface, the advancer, and the magnetic instrument 20. For this purpose, the controller 40 may comprise a computer readable media operably connected to a processor capable of carrying out operations or steps specified by the operator and a central processing unit.
The display device 50 may be a device or system capable of producing 2D (two dimensional) or 3D (three dimensional) images or other representations of the point-of-interest 22 in a 2D display image 52. The display device 50 can also image the magnetic instrument 20 for example by way of an x-ray fluoroscope that provides visual feedback on its position. For example, the display device 50 may include a device for creating images or video using radiography, magnetic resonance imaging, ultrasound, and other sources of imaging.
Referring to the imaging instrument 30, a 3D coordinate system {X_xray, Y_xray, Z_xray} may be associated in a fixed manner with respect to the imaging instrument 30 and moving with the imaging instrument. For example, the coordinate system is set in
Similarly, referring to the magnetic navigation system 60, a 3D coordinate system {X_mns, Y_mns, Z_mns} may be associated in a fixed manner with respect to the magnetic navigation system 60 and moving with the magnetic navigation system 60.
In a rest state of the system, the coordinate system {X_xray, Y_xray, Z_xray} associated with the imaging instrument 30 may be aligned with the coordinate system {X_mns, Y_mns, Z_mns} associated with magnetic navigation system 60. However, during the intra-body medical procedure, the imaging instrument 30, for example an x-ray fluoroscope, is rotated around the patient to obtain more favorable views around a longitudinal axis by a rotation angle β (beta) and/or around a tilt axis by a tilt angle α (alpha). Hence, the coordinate system {X_xray, Y_xray, Z_xray} is not aligned anymore with the coordinate system {X_mns, Y_mns, Z_mns}.
The coordinate systems {X_xray, Y_xray, Z_xray} and {X_mns, Y_mns, Z_mns} can be related by retrieving the tilt angle α and the rotation angle β directly from the x-ray fluoroscope, dialing them in manually by hand or by attaching a sensor on the x-ray fluoroscope.
In the present embodiment, the magnetic instrument 30 is steered with the magnetic field generated by the magnetic navigation system 60, represented by the vector b_xray in
Based on the visual feedback provided by the display device, the operator can steer the magnetic instrument 20 with a navigation console by changing the magnetic field and the advancement speed v.
For an intuitive navigation of the catheter, it is preferable that the magnetic field is defined in the coordinate system {X_xray, Y_xray, Z_xray} associated with the imaging instrument 30. This allows the operator to steer the magnetic instrument in the display image 52 without having to maintain a mental model of all the necessary geometric transformations.
One solution is to update the orientation of the imaging instrument constantly to keep the coordinate system {X_xray, Y_xray, Z_xray} aligned with the coordinate system {X_mns, Y_mns, Z_mns} associated with the magnetic navigation system 60 by accessing the rotation angle β, and the tilt angle α. However, this solution requires multiple driving devices that must be coordinated to execute movements necessary to keep both coordinate systems aligned. It is complex and expensive.
In the present embodiment, steering is made more intuitive by controlling the magnetic field in the coordinate system {X_xray, Y_xray, Z_xray} associated with the imaging instrument 30. For this purpose, the magnetic field represented by the vector b_xray is defined by its spherical coordinates in the coordinate system {X_xray, Y_xray, Z_xray}, wherein the polar angle φ (phi) is measured from the fixed zenith direction Z_xray, and the azimuthal angle θ (theta) of its orthogonal projection on the plane defined by the axis X_xray and Y_xray, is measured from a fixed reference direction, here X_xray, on that plane. The intensity of the magnetic field is defined as the radial extension of the magnetic field vector b_xray.
For the operator, the navigation of the magnetic instrument in the display image 52 can be executed without having to maintain a complex mental model of geometric transformations. Steering the magnetic instrument over the display image 52 is limited to the operator input of the polar angle φ and the azimuthal angle θ to the controller 40 as well as the advancement speed v. The polar angle φ is in the plane of the display image by construction, corresponding to a movement of the magnetic distal portion in a clockwise or counterclockwise direction with respect to X_xray. The azimuthal angle θ extends above or below the display image 52, corresponding to a movement of the magnetic distal portion in the upwards direction or in the downwards direction with respect to the display image 52.
In the present embodiment, the interface is embodied in the form of a navigation console 80 represented in
The method for manipulating the magnetic instrument within a lumen of the body, for example a vessel, comprises the step of providing a system 10 for manipulating the magnetic instrument 20 as described above above and the step of providing the magnetic instrument 20 having the magnetic distal portion 25.
Further, the method comprises the step of displaying an image of at least the magnetic distal portion 25 on the display device 50.
Further, the method comprises the step of sending via the interface the operator input to the system to change the direction of the magnetic field from a first direction represented by a first magnetic field vector to a second direction represented by a second magnetic field vector to steer the magnetic instrument 20 in an advancement direction, wherein the operator input is made in reference to the imaging instrument coordinate system associated in a fixed manner to the imaging instrument 30. Then, the method comprises the step of applying the magnetic field corresponding to the second magnetic field vector to advance the magnetic instrument 20.
The method is further described in relation to
The navigation console 80 was tested in the setup disclosed schematically in
The magnetic instruments are inserted and retracted by an advancer designed in the form of a remote-controlled robotic advancer unit. The magnetic instruments are imaged by an imaging instrument 30 in the form of a C-arm fluoroscope (Ziehm Imaging Inc.).
During the navigation of the magnetic instruments, the operator is provided with display images as illustrated in
The navigation console 80 illustrated in
In addition, the navigation console 80 has programmable buttons 86 and a linear joystick 88 to control the catheter advancement speed v.
A 4 Fr magnetic catheter and 2 Fr guidewire were successfully navigated in the aortic arch
The navigation console 80 and control strategy were demonstrated to be effective in steering the magnetic instrument without the need of additional visual cues other than the already available x-ray image. The interface is intuitive and shows a shallow learning curve for new adopters, good catheter and guidewire control, improving patient safety, and simple integration in the operating room infrastructure.
