Quantitative differences between healthy adults in brain imaging with I-123 iodoamphetamine and TC-99m L,L-ethyl cysteinate dimer

Regional cerebral blood flow quantitation in seven normal adults with I-123 iodoamphetamine (MP) was compared with that in four normal adults studied with TC-99m L,L-ethyl cysteinate dimer (ECD). Subjects studied with IMP underwent SPECT studies with parallel hole collimation, while fanbeam collimation was used for subjects studied with ECD. The caudate and putamen were seen separately only on SPECT/ECD images. Ratios of frontal, temporoparietal, and basal ganglia to cerebellar activity differed significantly (P < 001) from IMP and ECD. IMP and ECD ratios varied in a similar fashion by anatomic location. IMP and ECD differences may be due to acquisition method (parallel hole collimation vs fanbeam collimation) or in biodistribution