Comparison of [111In]pentetreotide-SPECT and [18F]FDOPA-PET in the localization of extra-adrenal paragangliomas: the case for a patient-tailored use of nuclear imaging modalities

Aims and methods The aim of this prospective study was to compare the diagnostic value of [F-18]FDOPA-PET and [In-111]pentetreotide-SPECT somatostatin receptor scintigraphy (SRS) in patients with nonmetastatic extra-adrenal paragangliomas (PGLs). Twenty-five consecutive unrelated patients who were known or suspected of having nonmetastatic extra-adrenal PGLs were prospectively evaluated with SRS and [F-18]FDOPA-PET. I-131-MIBG and [F-18]FDG-PET were added to the work-up in patients with a personal or familial history of PGL, predisposing mutations, abdominal PGLs, metanephrine hypersecretion and abdominal foci on SRS and/or [F-18]FDOPA-PET. Results SRS correctly detected 23/45 lesions of which 20 were head or neck lesions (H&N) and 3 were abdominal lesions. [F-18]FDOPA-PET detected significantly more lesions than SRS (39/45, P < 0 001). Both SRS and F-18-DOPA-PET detected significantly more H&N than abdominal lesions (66.7% vs 20%, P = 0 003 and 96.7% vs 67%, P = 0 012, respectively). In two patients with the succinate dehydrogenase D (SDHD) mutation, [F-18]FDOPA-PET missed five abdominal PGLs which were detected by the combination of SRS, [I-131]MIBG and [F-18]FDG-PET. A lesion-based analysis using a forward stepwise logistic regression model demonstrates that size <= 10 mm (P = 0.002) and abdominal lesions (P = 0.031) were independently associated with "[F-18]FDOPA-PET diagnosis only''. In turn, a previous history of surgery and/or the presence of germline mutation was associated with lower lesion size (P = 0.001). Conclusions The sensitivity of SRS for localizing parasympathetic PGLs is lower than originally reported, and [F-18]FDOPA-PET is better than SRS for localizing small lesions. SRS should be replaced by [F-18]FDOPA-PET as the first-line imaging procedure in H&N PGL, especially in patients at risk of multifocal disease (predisposing mutations and or previous history of surgery).