An intracerebral sonographic catheter as an adjunct to stereotactic guided endoscopic procedures

To facilitate stereotactic biopsies of intracerebral tumor lesions, to obtain important additional diagnostic information during the procedure and to precisely guide biopsy instrumentation devices to spots of interest, catheter sonography was combined with intracerebral endoscopy intraoperatively in two patients. All catheter instrumentation was performed through the stereotactic puncture channels. A 30 Megahertz ultrasound transducer mounted on the tip of a flexible 5 French catheter is sufficiently penetrating surrounding brain tissue, resulting in high resolution images at a maximum radial penetration depth of 15 mm. Normal brain tissue could be differed from intracerebral tumor tissue in both patients. Smaller tumor lesions within the close surrounding of a solid intracerebral tumor mass clearly appeared in ultrasound. Since diagnostic endoscopy in stereotactic procedures is limited to the surface of a puncture channel, intracerebral ultrasound adds important information about the underlying type of tissue. We found that the combination of both methods facilitates guiding of biopsy instrumentation devices to the spots of interest in stereotactic procedures. In both examined patients all biopsy samples were histologically identified as intracerebral lymphoma. Since ultrasound clearly identified intracerebral blood vessels as tubular hyporeflective structures, the risk of biopsy related hemorrhage could be diminished.