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

Summary Aims and methods  The aim of this prospective study was to compare the diagnostic value of [18F]FDOPA-PET and [111In]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 [18F]FDOPA-PET. 131I-MIBG and [18F]FDG-PET were added to the work-up in patients with a personal or familial history of PGL, predisposing mutations, abdominal PGLs, metanephrinehypersecretion and abdominal foci on SRS and/or [18F]FDOPA-PET. Results  SRS correctly detected 23/45 lesions of which 20 were head or neck lesions (H&N) and 3 were abdominal lesions. [18F]FDOPA-PET detected significantly more lesions than SRS (39/45, P < 0·001). Both SRS and 18F-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 dehydrogenaseD ( SDHD) mutation, [18F]FDOPA-PET missed five abdominal PGLs which were detected by the combination of SRS, [131I]MIBG and [18F]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 “[18F]FDOPA-PET diagnosis only”. In turn, a previous historyof surgeryand/or the presence of germline mutationwas associated with lower lesion size (P = 0·001). Conclusions  The sensitivity of SRS for localizing parasympathetic PGLs is lower than originally reported, and [18F]FDOPA-PET is better than SRS for localizing small lesions. SRS should be replaced by [18F]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 historyof surgery).