SPECT with HMPAO compared to PET with FDG in Huntington disease

It is the aim of this study to compare the performance of 99mTc-d,l-hexamethylpropyleneamine oxime (HMPAO) SPECT with that of [18F]fluorodeoxyglucose (FDG) PET in detecting striatal dysfunction as it occurs in Huntington disease (HD).

For the determination of regional cerebral glucose consumption, the PET camera PC-4096 was used; the cerebral uptake of HMPAO was measured using the three-head SPECT camera TRIAD. Eight patients with manifest HD, seven subjects at risk for HD, and nine normal individuals were included in the study. In both modalities data evaluation was performed using caudate-to-whole-slice (C/S) ratios. The patients' data were compared to 95% confidence intervals determined in the nine controls.

The PET and SPECT C/S values correlated significantly (n = 24; r = 0.87; p < 0.0001). The C/S values were significantly reduced in PET in all eight and in SPECT in seven of the eight HD patients studied. Five of the seven at-risk subjects had normal C/S values in PET and SPECT, one showed reduced C/S values in both diagnostic methods, and the remaining at-risk individual showed a reduced C/S value in PET only. Thus, concordant results between PET and SPECT were obtained in seven of eight patients and six of seven at-risk subjects studied, corresponding to an 87% accuracy of SPECT in the detection of striatal dysfunction as compared to the "gold standard" PET.

With use of a multidetector camera, HMPAO-SPECT comes near the performance of FDG-PET in the diagnosis of striatal dysfunction as it occurs in HD.