MR DIFFERENTIATION OF PHEOCHROMOCYTOMA FROM OTHER ADRENAL LESIONS BASED ON QUALITATIVE-ANALYSIS OF T2 RELAXATION-TIMES

Aim: To determine the diagnostic accuracy of MR imaging in differentia ting phaeochromocytoma from other adrenal lesions, Materials and metho ds: Sixty-seven adrenal masses (65 patients) including 17 phaeochromoc ytomas were imaged using T2-weighted pulse sequences on 0.6 T and 1.5 T GE MR units, The adrenal lesions mere qualitatively assessed by thre e observers and divided into three categories (benign adenomas, malign ant lesions and phaeochromocytomas) based on lesion signal intensity r elative to liver and cerebrospinal fluid, Results: Eleven phaeochromoc ytomas (65%) were correctly identified while the remaining six (35%) w ere misclassified, five as malignant lesions and one as a benign adeno ma, because of atypical low signal intensity on T2-weighted MR images, Conversely, six non-phaeochromocytomas (three benign adenomas, two ad renal carcinomas and one metastasis) mere wrongly classified as phaeoc hromocytomas because of very high lesion signal intensity, The sensiti vity of MR imaging for diagnosing phaeochromocytoma was 64.7%, specifi city 88.0%, positive predictive value 64.7% and negative predictive va lue 88.0%, Conclusion: There is considerable overlap between the MR ap pearance of phaeochromocytoma and other adrenal lesions, A phaeochromo cytoma cannot be excluded on the basis of a lack of high signal intens ity on T2-weighted MR imaging.