Diagnostic Performance of<sup>124</sup>I-Metaiodobenzylguanidine PET/CT in Patients with Pheochromocytoma
Manuel Weber, Jochen Schmitz, Ines Maríc, Kim M. Pabst, Lale Umutlu, Martin K. Walz, Ken Herrmann, Christoph Rischpler, Frank Weber, Walter Jentzen, Sarah Theurer, Thorsten D. Poeppel, Nicole Unger, Wolfgang P. Fendler
Abstract
<sup>123/131</sup>I-MIBG scintigraphy has shown a high specificity for imaging pheochromocytoma and paraganglioma however with low sensitivity due to low spatial resolution. <sup>124</sup>I-MIBG PET may overcome this limitation to improve the staging of patients with (suspected) pheochromocytoma. <b>Methods:</b> We analyzed the sensitivity, specificity, positive and negative predictive values (PPV, NPV) of <sup>124</sup>I-MIBG PET in 43 consecutive patients with suspected (recurrence of) pheochromocytoma using histopathological (<i>n</i> = 25) and clinical validation (<i>n</i> = 18) as standard of truth. Furthermore, we compared <sup>124</sup>I-MIBG PET versus contrast enhanced CT (CE-CT) per-patient and per-lesion detection rate of <sup>124</sup>I-MIBG PET in 13 additional patients with known metastatic malignant pheochromocytoma (MMP). <b>Results:</b><sup>124</sup>I-MIBG PET/CT was positive in 19/43 (44%) patients with suspected pheochromocytoma. Presence of pheochromocytoma was confirmed in 22/43 (51%). <sup>124</sup>I-MIBG PET/CT sensitivity, specificity, PPV, NPV were 86%, 100%, 100%, 88%, respectively. <sup>124</sup>I-MIBG PET was positive in 11/13 (85%) MMP patients. Combined <sup>124</sup>I-MIBG PET and CE-CT detected 173 lesions, of which 166 (96%) and 118 (68%) were visible on <sup>124</sup>I-MIBG PET and CE-CT, respectively. <b>Discussion:</b><sup>124</sup>I-MIBG PET detects pheochromocytoma with high accuracy at initial staging and high detection rate at re-staging. Superior diagnostic performance aids guidance of surgical and medical management including personalized <sup>131</sup>I-MIBG therapy.