131I-meta-iodobenzylguanidine scintigraphy in patients with neuroblastoma

Twenty-six studies by meta-(131I)-iodobenzylguanidine scintigraphy (131I-MIBG), 26 studies by 67Ga-citrate and 33 99mTc-hydorxymethylene diphosphate (99mTc-HMDP) scintigraphic studies were performed for 10 patients with abdominal neuroblastoma. Comparing the 131I-MIBG images obtained at 24, 48 and 72 h, the 48-h image was the most distinctive for the tumor. Intrabdominal primary lesions, which ranged from bean to fist-size, were visualized in 7/7 cases (100%) by 131I-MIBG, 4/7 cases (57%) by 67Ga-citrate and 4/8 cases (50%) by 99mTc-HMDP before surgery and at diagnosis. In serial follow-up of these patients after starting chemotherapy, 131I-MIGB detected 100% of regressing primary tumors. Studies of 5 postoperative patients showed negative images for the primary tumor in all 3 scintigraphies except one in whom 131I-MIBG was positive, but not 67Ga-citrate or 99mTc-HMDP, for an unresectable residual tumor. 131I-MIBG also detected metastatic lesions not predicted by 67Ga-citrate or 99mTc-HMDP and reflected tumor progression more sensitively than known tumor markers such as urinary vanillylmandelic acid (VMA), homovanillic acid (HVA), serum neuron-specific enolase (NSE) and ferritin. These findings indicate that the 48 hr 131I-MIBG scintigraphy is superior to 67Ga-citrate or 99mTc-HMDP images and to other biochemical markers in monitoring the effect of treatment on neuroblastoma.