Functional imaging of malignant paragangliomas and carcinoid tumours

Complete staging is mandatory for the management and therapy of neuroendocrine tumours, Various radiotracers are available but the best imaging strategy has yet to be defined. In this study we retrospectively compared I-123-MIBG, In-111-[D-Phe(1)]-DTPA-octreotide and F-18-FDG (PET) imaging in 15 patients with metastatic neuroendocrine tumours (11 carcinoid tumours, 4 paragangliomas). Planar images were acquired 1, 4, 24 and 48 h following the injection of In-111-[D-Phe(1)]-DTPA-octreotide and I-123-MIBG. Whole-body PET scans were performed 45 min after injection of F-18-FDG. In-111-[D-Phe(1)] -DTPA-octreotide was positive in 11/15 patients and identified 44 lesions, F-18-FDG PET was positive in 11/15 patients and identified 107 lesions and I-123-MIBG was positive in 8/15 patients and identified 67 lesions. No single scintigraphic technique identified all metastatic sites. In one patient all studies were negative. F-18-FDG PET identified more abnormal sites than the other two modalities. Combination of all three imaging modalities with X-ray CT helps to provide a more comprehensive map of the disease.