Variability of cerebral blood flow deficits in 99mTc-HMPAO SPECT in patients with Alzheimer's disease.

The purpose of this study was to analyse the frequency of the different pathological perfusion patterns in SPECT in a clinical, unselected population of patients with Alzheimer's disease. In 91 patients and 16 control subjects regional cerebral blood flow (rCBF) was measured with Single Photon Emission Computed Tomography (SPECT) using 99mTc-hexa-methyl-propyleneamine oxime (HMPAO). 95% confidence intervals obtained from the perfusion values of the control subjects were used to define normal perfusion ranges. The frequency of perfusion deficits in the left frontal, temporal, parietal and occipital lobes were 62.2%, 60.4%. 70.3% and 23.1%, respectively. In the right hemisphere the corresponding values were 60.4%, 58.2%, 63.7% and 9.9%. With the exception of the occipital lobes these frequencies were not significantly different. The analysis of the perfusion pattern of each patient revealed 35 different combinations of lobes with perfusion deficits. The temporo-parietal perfusion deficits were not more frequent than the temporofrontal perfusion deficits. These results suggest that in the clinical routine a high variety of heterogeneous rCBF patterns have to be expected.