Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1998-11-12
2001-03-06
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C324S318000
Reexamination Certificate
active
06198961
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the magnetic resonance (MR) art. It finds particular application in conjunction with an interventional radio frequency (RF) coil assembly for use in magnetic resonance guided neurosurgery, and will be described with particular reference thereto. However, it should be appreciated that the present invention may also find application in conjunction with other types of neurosurgical and diagnostic imaging systems.
When performing surgery on a patient's brain, the patient's head is usually held fixed by a head frame. Known head frames typically include a clamp or frame-like structure with several sharp pins that are anchored in the patient's skull in order to immobilize the frame-like structure relative to the patient's head. The head frame is connected to a surgical table by a series of links and joints that permit the head frame to be positioned with respect to the table with several degrees of freedom. By this means, the head frame can be positioned to hold the patient's head in a range of orientations to present the surgeon with an appropriate approach to the surgical field. However, access to the patient's head is still restricted by the head frame.
Conventional head frames include the designs of Ohio Medical (Cincinnati, Ohio.) and many other companies. The most common model is the Mayfield frame made by Ohio Medical and described in U.S. Pat. Nos. 4,169,478 and 5,269,034. The Mayfield frame is made from cast aluminum and is not MR compatible. In MR guided neurosurgery, the head frame must be made from an MR compatible material. Ohio Medical and Elekta Instruments (Atlanta, Ga.) both make radiolucent head frames for intraoperative x-ray or CT imaging. These products are made from a carbon fiber/epoxy composite and have been used for intraoperative MR imaging. An exemplary radiolucent head frame is described in U.S. Pat. No. 5,537,704.
When performing neurosurgery with MR guidance, a receive surface coil is used for local imaging of a patient's brain because a higher signal-to-noise ratio can be obtained than with a whole body RF coil. The surface coil is designed to be placed as close as possible to the patient's head to increase the signal to noise ratio. The surface coil is typically covered by a sterile bag or placed on the patient prior to applying sterile drapes. As with head frames, surface coils typically restrict access to the patient's head.
Research and development is presently being conducted on specific surface coil designs for use in MR guided neurosurgery. For horizontal field interventional MR, flexible surface coils, either of a single-solenoid or Helmholtz configuration are being contemplated. These coils would generally be used with the loops in the coronal plane, with a non-sterile loop below the patient's head and a sterile or sterile-bagged loop above the patient's head. For vertical field interventional MR, flexible single-solenoid surface coils are contemplated. These coils are oriented in the transverse plane, placed around the patient's head. The known surface coil designs are not easily sterilized.
Thus, in MR guided neurosurgery, both the head frame and the surface coil restrict access to the patient's head. Further, it is often difficult to position both the surface coil and the head frame so as to keep the region of interest in the sensitive volume of the surface coil and to allow sufficient access for surgery. If the surface coil has to be moved away from the anatomy of interest to allow space for the head frame or access for the surgeon, the signal to noise ratio will suffer.
The present invention contemplates a new and improved interventional radio frequency coil assembly for use in magnetic resonance guided neurosurgery that overcomes the above-referenced problems and others.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, there is provided a diagnostic imaging apparatus including a housing defining an examination region, a main field magnet that generates a temporally constant magnetic field through the examination region, a gradient assembly that induces gradient magnetic fields across the temporally constant magnetic field, a patient couch that positions an object to be imaged within the examination region, and an interventional head frame assembly positioned within the examination region. The head frame assembly includes a head frame housing attached to the object and having at least one first conductor therein, a first mount that supports the head frame housing or the patient couch, a bridge housing including at least one second conductor therein, and a second mount that attaches the bridge housing to the head frame housing and electrically couples the at least one first conductor to the at least one second conductor to form a surface coil for use in imaging an object held by the head frame.
In accordance with a second aspect of the present invention, there is provided an interventional head coil assembly. The interventional head coil assembly includes a base, a head frame housing including at least one first conductor associated therewith, a first mount that connects the head frame housing to the base; a bridge housing including at least one second conductor associated therewith, and a second mount that connects the bridge housing to the head frame housing thereby coupling the first conductor to the second conductor to form a surface coil for use in imaging an object attached to the head frame housing.
In accordance with a second aspect of the present invention, there is provided a method of performing neurosurgery with diagnostic imaging guidance. The method includes attaching a head frame housing to a patient's head, the head frame housing having a first conductor associated therewith, inserting a plurality of pins through a sterile drape positioned over the head frame housing and into engagement with a corresponding plurality of electrical connectors associated with the head frame housing; attaching a sterile bridge housing to the contact pins thereby coupling a second conductor associated with the bridge housing to the first conductor to form a surface coil, positioning the patient's head within an examination region of a diagnostic imaging system, and performing a diagnostic imaging procedure utilizing the surface coil.
One advantage of the present invention is the provision of a new and improved interventional head coil for use with a vertical field MR scanner.
Another advantage of the present invention is the provision of a new and improved interventional head coil that combines a split-top linear receive surface coil with an arc-type head frame.
Another advantage of the present invention is the provision of a new and improved interventional head coil that includes passive NMR fiducials for registering the images obtained with the coil to an image guided surgery system.
Another advantage of the present invention is the provision of a new and improved interventional head coil that combines an MR surface coil and a neurosurgical headframe into one device, allowing convenient positioning of the surface coil for MR guided neurosurgery.
Another advantage of the present invention is the provision of a new and improved interventional head coil that increases the access to the patient's head while maintaining proper positioning of a surface coil and therefore high signal-to-noise ratio.
Another advantage of the present invention is the provision of a new and improved interventional head coil that utilizes surface coil conductors to provide a substantial portion of the requisite strength and stiffness of the head frame.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.
REFERENCES:
patent: 4791372 (1988-12-01), Kirk et al.
patent: 4923459 (1990-05-01), Nambu
patent: 4968936 (1990-11-01), Darrasse et al.
patent: 526
Lampman David A.
Schellenberg John D.
Stern Benjamin R.
Fay Sharpe Fagan Minnich & McKee LLP
Lateef Marvin M.
Picker International Inc.
Shaw Shawna J.
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