I-131 MIBG SCINTIGRAPHY OF NEUROECTODERMAL TUMORS - COMPARISON BETWEEN I-131 MIBG AND IN-111 DTPA-OCTREOTIDE

An account is given of the results observed with I-131 MIBG scintigrap hy in four patients (1 bladder pheochromocytoma, 3 neuroblastomas) cho sen on account of their particular clinical and diagnostic interest fr om a series of 41 apudoma patients examined by means of this technique . In the first patient, the unusual site of the tumor in the posterior wall of the bladder meant that its detection by I-131 MIBG was only p ossible after catheterization of the bladder. In the second patient, u ptake in the metastasis was only evident after removal of the primary tumor. In the third patient, the scintiscan revealed several metastase s (some in bone) not detected by CT. In the fourth patient (congenital neuroblastoma), enhanced uptake accompanied the appearance of high pl asma catecholamine and urinary vanillylhandelic acid values, suggestin g a functional switch from a nonsecreting to a secreting form. A suppl ementary In-111 DTPA-Octreotide (OCT) scintiscan of this patient demon strated the presence of somatostatin receptors on the neuroblasts. Thu s, this examination would seem particularly useful for the differentia tion of nonsecreting neuroblastomas. Its employment in assessment of t he therapeutic capacity of OCT itself is also suggested.