Diagnostic imaging and therapy of neuroectodermal neoplasms

Computed tomography (CT) and 123I- or 131I-meta-iodo-benzyl-guanidine (MIBG) scintigraphy were compared for accuracy in tumor detection in 47 patients with neuroectodermal neoplasms. MIBG concentration was found in 12 of 13 pheochromocytomas, 12 of 12 neuroblastomas, 5 of 9 carcinoids, and 1 of 4 glomus tumors. MIBG uptake was not observed in medullary thyroid carcinomas, oat-cell carcinomas, Merkel tumors, 1 gastrinoma, and 2 unclassified neuroectodermal neoplasms. With regard to the different tumor manifestations, the sensitivity in detecting pheochromocytomas, neuroblastomas, and carcinoids was 87%, 77%, and 100% for CT, and 83%, 100% and 71% for MIBG scintigraphy. MIBG scintiscan was superior in the detection of small adrenal pheochromocytomas (< 1 cm diameter) and in the depiction of small bone metastases and bone marrow infiltration from neuroblastoma. In all, 25 cycles of high-dose MIBG therapy were performed in eight patients with surgically incurable tumors (4 malignant pheochromocytomas, 1 neuroblastoma, 3 carcinoids). The total therapeutic activity applied was 3.55-43.29 GBq 131I-MIBG. Tumor kinetics of MIBG were investigated before and during treatment. One patient with metastatic pheochromocytoma has been in complete remission for a follow-up period of 36 months since completion of treatment, and another patient is in partial remission. Tumor reduction or no change was observed in four patients. Two patients died of nonconcentrating recurrence and metastases. (orig.)