Does simple estimation of 131I-metaiodobenzylguanidine uptake in patients with neural crest tumours correlate with clinical outcome?

A retrospective study was undertaken in six patients (three male and three female) with neural crest tumours who received therapeutic doses of 131I-meta-iodobenzylguanidine (131I-MIBG) (6.7-10.5 GBq). The age range of the patients was 13-65 years (mean 36 years). Quantification of tumour uptake was obtained from images acquired with a large-field-of-view gamma camera on a single occasion between 2 and 10 days post-treatment. Tumour uptake was calculated to be 0.1% and 3.2% of the administered dose, corresponding to uptakes of 6.7-142.8 MBq. Tumour volume was assessed from computed tomography (CT) or magnetic resonance (MR) images and estimates of tumour dose made from the Medical Internal Radiation Dosimetry scheme (MIRD) tables. Estimated doses were between 7 and 113 Gy. Most significantly, our findings indicate that high tumour uptake did not always correlate with good clinical response.