MRI EVALUATION OF EXTREMITY SCHWANNOMA CHARACTERISTICS

Objective: To evaluate signal characteristics, soft tissue signs and contrast enhancement patterns of extremity schwannomas with Magnetic Resonance Imaging (MRI). Material and Methods: The study was comprised of 16 patients with a pathological diagnosis of benign peripheral nerve sheath tumor (schwannoma) originated from different extremity regions. All patients had MRI exams. MRIs were evaluated for the signal characteristics, the presence of special signs described for soft tissue tumors, and contrast enhancement patterns of the lesions. Results: Schwannomas were originated from median nerve (n=7), radial nerve (n=4), femoral nerve (n=2), axillary nerve (n=1), common peroneal nerve (n=1), and posterior tibial nerve (n=1). Four types of signal characteristic were described according to the T1W and T2W MR images. All schwannomas (n=16) had split fat sign,15 of them showed entering-exiting nerve sign, 10 had target sign and 10 had fascicular sign. On contrast enhanced images, 12 of the cases showed peripheral heterogenous enhancement with centrally unenhanced curvilinear areas. Four cases had homogenous contrast enhancement. Conclusion: Most of the extremity schwannomas have diagnostic signal characteristics, soft tissue signs and contrast enhancement patterns on MRI. Preoperative MRI diagnosis of these lesions can reduce the necessity of biopsy and prevent the possibility of nerve fascicle injury