EVALUATION OF MAGNETIC RESONANCE IMAGING (MRI) IN DIAGNOSIS OF ACOUSTIC NEUROMA-COMPARATIVE STUDY WITH PLAIN X-RAY AND CTS- KIMIHISA NOMURA, M.D., MAKOTO SAKAI, M.D., ATSUSHI SHINKAWA, M.D. and HIROSATO MIYAKE, M.D. Department of Otolaryngology, Tokai University School of Medicine, Isehara JUNICHI MATSUKAWA, M.D. Department of Otolaryngology, Nihonkokan Hospital, Kawasaki In order to find an approach to earlier and more acurate diagnosis of acoustic neuroma, a comparative evaluation of MRI, plain X-ray (Stenvers'projection), high resolution CT with or without Metrizamide enhancement and air-ct has been made in five clinical cases of acoustic neuroma. A paramagnetic contrast agent, Gadolinium-diethylenetriamine pentaacetic acid (Gd- DTPA), was used to enhance images resolution in two cases of acoustic neuroma. In MRI, the high MRI revealed enlargement of the neurovascular bundle around the VII and VIII cranial nerves compatible with a diagnosis of acoustic neuroma in all 5 cases, and masses within the cerebellopontine angle were also disclosed. In 2 cases the image of equivocal acoustic neuromas was well enhanced, and these lesions were visualized after intravenous administration of Gd-DTPA. In one of the cases the acoustic neuroma was satisfactorily differentiated from the surrounding cystic lesion with the aid of a contrast medium. Magnetic resonance which uses no ionizing radiation seems to be innocuous and offers several advantages over other imaging methods and CT, which may produce an adverse reaction when a contrast medium is used in CT-cisternography. Further advancement of MR technology will offer greater assistance in differential diagnosis of lesions such as acoustic tumors or other cerebellopontine angle tumors.
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