99mTc-HYNIC-TOC scintigraphy is superior to 131I-MIGB imaging in the evaluation of extraadrenal pheochromocytoma

Abstract

In this investigation, the efficacy of scintigraphy using 99mTc-labeled hydrazinonicotinyl-Tyr3-octreotide (HYNIC-TOC) in the evaluation of extraadrenal pheochromocytoma was assessed and compared with 131l-labeled metaiodobenzylguanidine (MIBG) imaging. Methods: Ninety-seven patients who were suspected of having pheochromocytoma but showed no definite adrenal abnormalities on CT were evaluated by both 99mTc-HYNIC-TOC scintigraphy and 131I-MIBG imaging. The results were compared with pathology findings or clinical follow-up. Results: Of 58 patients proven to be without pheochromocytoma, 99mTc-HYNIC-TOC and 131I-MIBG imaging excluded 56 and 58 patients, respectively, rendering a specificity of 96.6% for 99mTc-HYNIC-TOC imaging and 100% for 131I-MIBG imaging. In the evaluation of adrenal pheochromocytoma (14 patients), the sensitivity of 99mTc-HYNIC-TOC scintigraphy and 131l-MIBG imaging was 50% and 85.7%, respectively. However, in the evaluation of extraadrenal pheochromocytomas (25 patients), the sensitivity of 99mTc-HYNIC-TOC scintigraphy and 131I-MIBG imaging was 96.0% and 72.0%, respectively. Conclusion: 99mTc-HYNIC-TOC scintigraphy is more sensitive than 131I-MIBG imaging in the detection of extraadrenal pheochromocytomas. COPYRIGHT © 2009 by the Society of Nuclear Medicine, Inc.