Diagnostic Performance of ¹²⁴I-Metaiodobenzylguanidine PET/CT in Patients with Pheochromocytoma

Abstract

Introduction: 123/131 I-MIBG scintigraphy has shown a high specificity for imaging pheochromocytoma and paraganglioma however with low sensitivity due to low spatial resolution. 124 I-MIBG PET may overcome this limitation to improve the staging of patients with (suspected) pheochromocytoma. Methods: We analyzed the sensitivity, specificity, positive and negative predictive values (PPV, NPV) of 124 I-MIBG PET in 43 consecutive patients with suspected (recurrence of) pheochromocytoma using histopathological (n=25) and clinical validation (n=18) as standard of truth. Furthermore, we compared 124 I-MIBG PET versus contrast enhanced CT (CE-CT) per-patient and per-lesion detection rate of 124 I-MIBG PET in 13 additional patients with known metastatic malignant pheochromocytoma (MMP). Results: 124 I-MIBG PET/CT was positive in 19/43 (44%) patients with suspected pheochromocytoma. Presence of pheochromocytoma was confirmed in 22/43 (51%). 124 I-MIBG PET/CT sensitivity, specificity, PPV, NPV were 86%, 100%, 100%, 88%, respectively. 124 I-MIBG PET was positive in 11/13 (85%) MMP patients. Combined 124 I-MIBG PET and CE-CT detected 173 lesions, of which 166 (96%) and 118 (68%) were visible on 124 I-MIBG PET and CE-CT, respectively. Discussion: 124 I-MIBG PET detects pheochromocytoma with high accuracy at initial staging and high detection rate at re-staging. Future assessment of 124 I-MIBG PET for treatment guidance including personalized 131 I-MIBG therapy is warranted.

Imaging of Pheochromocytomas and Paragangliomas

“…New theranostic pairs may also emerge as new opportunities for TRT such as prostate-specific membrane antigen, which is expressed in the tumor vasculature of some PPGLs ( 135 ). New PET tracers that target NETs 124 I-MIBG can detect PCC with a high accuracy and can be used as a companion agent for selecting candidates for 131 I-MIBG ( 136 ). 18 F-meta-Fluorobenzylguanidine is also a promising alternative PET tracer to 123 I-MIBG ( 137 ).…”

Adrenal functional imaging – which marker for which indication?

“…The first results of [ 124 I]mIBG-PET/computed tomography were recently published. In 43 patients with suspected malignant pheochromocytoma or with known metastases, PET/computed tomography showed sensitivity, specificity, and positive and negative predictive value of 86%, 100%, 100%, and 88%, respectively [58 ▪▪ ].…”

Biodistribution and radiation dosimetry of 124I-mIBG in adult patients with neural crest tumours and extrapolation to paediatric models

“…Meta-iodobenzylguanidine (mIBG) is a synthetic analogue of the adrenergic neurotransmitter norepinephrine and is accumulated and retained in sympathicomimetic cells [ 1 ]. Tumours deriving from neuronal crests such as malignant pheochromocytoma, neuroblastoma, paraganglioma and some neuroendocrine tumours from the midgut have shown to accumulate mIBG with reported sensitivities up to 88% and specificities ranging from 80 to 100% [ 2 , 3 ].…”