Implantable medical device

Abstract

A method of manufacturing an implantable medical device having reduced MRI image distortion, includes producing an implantable medical device. The implantable medical device has a configuration that comprises a housing and one or more internal components disposed within the housing. The configuration is based upon a design process that includes creating a first prototype, determining the aggregate relative magnetic permeability of the first prototype, and modifying the design of the first prototype by at least one of (a) selecting and adding a diamagnetic shimming material to the first prototype or (b) repositioning one or more internal components of the first prototype. Modifying the design results in a modified design that is the configuration for the implantable medical device.

What is claimed is: 
     
         1 . A method of manufacturing an implantable medical device having reduced MRI image distortion comprising:
 producing an implantable medical device having a configuration that comprises a housing and a plurality internal components disposed within the housing;   wherein the configuration is based upon a design process that includes:
 for at least two internal components, identifying their magnetic permeabilities; and 
 positioning the at least two internal components proximate each other if they have opposite magnetic permeabilities, or spreading apart the at least two internal components from each other within the housing if they are both diamagnetic or both paramagnetic. 
   
     
     
         2 . The method of  claim 1 , wherein the design process further includes:
 creating a first prototype;   determining the aggregate relative magnetic permeability of the first prototype; and   modifying the design of the first prototype by repositioning one or more internal components of the first prototype, wherein said modifying results in a modified design that is the configuration for the implantable medical device.   
     
     
         3 . The method of  claim 2 , wherein the design process further includes:
 creating a first electromagnetic model to determine the aggregate relative magnetic permeability of the first prototype; and   creating a second electromagnetic model of the modified design to determine the aggregate relative magnetic permeability of the modified design.   
     
     
         4 . The method of  claim 2 , wherein the step of modifying the design includes repositioning the one or more internal components according to their magnetic permeabilities. 
     
     
         5 . A method of obtaining an MRI image with reduced distortion caused by an implanted medical device, the method comprising:
 positioning a patient having an implanted medical device in an MRI machine for image acquisition;   prior to imaging, using shim coils to address magnetic field inhomogeneity caused by at least one of the patient or the implantable medical device;   acquiring an image with the MRI machine; and   reconstructing the image using a custom image processing routine that adjusts for known image distortion associated with the implanted medical device of the patent.   
     
     
         6 . The method of  claim 5 , wherein the processing routine executes an image processing algorithm that compensates for known factors of the implanted medical device that cause the known image distortion, the known factors being at least one of material composition, size, and location of the implanted medical device. 
     
     
         7 . The method of  claim 5 , wherein the processing routine executes an image processing algorithm that compensates for image distortion caused by the implanted medical device, the processing algorithm having been determined experimentally according to previously acquired images of the implanted medical device or equivalent. 
     
     
         8 . The method of  claim 5 , wherein the step of using shim coils includes at least one of manually adjusting the shim coils or automatically adjusting the shim coils using software. 
     
     
         9 . The method of  claim 5 , wherein the step of acquiring an image is performed utilizing a spin echo pulse sequence. 
     
     
         10 . The method of  claim 5 , wherein the step of using shim coils is performed to address magnetic field inhomogeneity caused by the implantable medical device. 
     
     
         11 . The method of  claim 10 , wherein the processing routine executes an image processing algorithm that compensates for image distortion caused by the implanted medical device, the processing algorithm having been determined according to at least one of previously acquired images of the implanted medical device or equivalent, or known factors of the implanted medical device that cause the known image distortion. 
     
     
         12 . The method of  claim 11 , wherein the step of using shim coils includes at least one of manually adjusting the shim coils or automatically adjusting the shim coils using software. 
     
     
         13 . The method of  claim 12 , wherein the step of acquiring an image is performed utilizing a spin pulse echo sequence.