Difference in the distribution of ¹²³I-IMP and ^99mTc-HMPAO in the striatum - Comparison with ¹⁵O-PET

Brain perfusion SPECT studies of ¹²³I-IMP and ^99mTc-HMPAO were performed in 10 patients with various brain disorders and the difference in the distribution of ¹²³I-IMP and ^99mTc-HMPAO in the cortices and striatum was compared with the cerebral blood flow by ¹⁵O-PET method. The ratios of the radioactivity in 14 ROIs of the cortices, striatum and cerebellum to that of the reference region or the right frontal cortex were compared among the 3 studies. The coefficient variance between ¹²³I-IMP and PET was 0.71 and that between ^99mTc-HMPAO and PET was 0.74 in the regions excluding the striatum. The striatal activity ratio in ¹²³I-IMP was slightly less than those in ^99mTc-HMPAO and PET which were close to each other. The visual activity in the striatum in ¹²³I-IMP was also slightly less than those in ^99mTc-HMPAO and PET. All the striatal lesions of decreased perfusion diagnosed by PET were observed in ¹²³I-IMP, however 2 lesions were missed in ^99mTc-HMPAO. This seems to be relevant to the difference in the distribution of ¹²³I-IMP and ^99mTc-HMPAO.