Andreas Melzer

Computed Tomography- and Magnetic Resonance Imaging: Guided Microtherapy

This report describes techniques of computed tomography (CT) and magnetic resonance imaging (MRI) image-guided diagnosis and therapy. Fine-needle biopsy, interstitial tumor therapy, and chemical sympathectomy, as well as the treatment of chronic spinal diseases, including periradicular infiltration at irritated spinal nerve roots, percutaneous laser decompression of intervertebral disks, and intraspinal microendoscopic scar dissection after failed back surgery are described. To overcome specific drawbacks of CT application, we have evaluated technological prerequisites and feasibility of MRI guidance of interventional procedures, such as biopsy, aspiration of neoplasm, and local interstitial drug instillation. New MR-compatible needles, trocars/ cannulae, endoscopes, and ancillary equipment were developed and evaluated in collaboration with industry. Sequences, study protocols, and the strategies of performing the procedure wirthin the environment of an interventional MRI suite have been formulated. In 168 patients, 204 interventions such as aspiration biopsy, peridural corticoid injection at spinal nerve roots, intratumoral ethanol instillation, chemical sympathectomy, and percutaneous laser decompression of herniated intervertebral disks were performed successfully. CT and MRI guidance of percutaneous and microendoscopic interventions provides a reproducible and precise means of instrument control. Aside from preoperative planning of the access trajectory, instruments can be placed under CT or MRI control and the therapeutic process can be monitored. Although MRI avoids the need for ionizing radiation and provides multiplanar multislice images with excellent soft tissue contrast, the representation of instruments and the resolution is currently inferior to that achieved by CT imaging.