Comparison of In-111 pentetreotide, Tc-99m (V)DMSA and I-123 mIBG scintimaging in neural crest tumors

Three radiolabelled substances In-111-pentetreotide, Tc-99m-(V)DMSA and I-123-mlBG with different kinetics but similar tumor seeking behavior, were i.v. injected to assess and con elate their clinical value in metastatic malignant pheochromocytomas (4 patients), stage III and IV neuroblastomas (7 patients) and medullary thyroid carcinomas (6 patients). All 11 pheochromocytoma/neuroblastoma patients received i.v. a dose of 111 MBq (3 mCi) of I-123-mlBG and 185 MBq (5 mCi) of In-111-pentetreotide, within approximately weeks each other: Furthermore, in 4 of these patients as well as in all medullary thyroid carcinoma patients 111 MBq (3 mCi) of Tc-99m-(V)DMSA were applied i.v. 1 week prior to the pentetreotide/mlBG scans. Foul patients (malignant pheochromocytoma) with a total of 7 foci showing mlBG accumulation had 3 sites with pentetreotide and 1 site with (V)DMSA uptake, while in 7 patients (neuroblastora) with 15 foci showing MIBG accumulation 10 sites had detectable pentetreotide and 3 sites detectable (V)DMSA. Of the three radiotracers, In-111-pentetreotide used for somatostatin receptor identification holds promise mainly in cases where foci imaged with 123I-mIBG negative. In-111-pentetreotide is unlikely to replace 123I-mIBG a first-line routine diagnostic scintigraphic modality; compared to pentetreotide or mlBG, (V)DMSA seems to be highly sensitive only in medullary thyroid carcinomas.