Quantitative diagnosis at 131-I-MIBG therapy

During whole body scintigraphy to localize and quantify 131I-MIBG accumulation under conditions of treatment we have reduced the initially high count rates to levels acceptable for the gamma camera by providing for additional detector shielding. Activities for the whole body, the liver and the tumor can thus be recorded. Sequential renal scintigrams obtained with the ROI technique explain the rapid elimination of 25% of the initial activity during 131I-MIBG infusion. Our results suggest that activity should be applied for prolonged periods to improve tumor uptake. Splitting the therapeutic dose to administer 2 infusions at an interval of 24 hours currently appears to be the most feasible solution. Research into quantitation and dosimetry are still under way. (Author)