SENSITIVITY AND SPECIFICITY OF TC(M)-99-HMPAO SINGLE-HEADED SPECT IN DEMENTIA

The sensitivity and specificity of Tc-99m-hexamethylpropyleneamine oxi me (HMPAO) single-headed single photon emission computed tomography (S PECT) in dementia were evaluated in elderly patients with a mean age o f 84 years suffering from dementia (n = 59) and compared to an age- an d sex-matched control group with normal cognitive function (n = 14). T he demented patients were classified as suffering from primary degener ative dementia (PDD, n = 51) based on DSM-III-R criteria. Moreover, PD D patients were divided into three subgroups of severity of cognitive impairment, according to their Folstein score. Multi-infarct dementia (MID, n = 8) was diagnosed based on clinical features, computed tomogr aphic findings and Hachinski ischaemic score. Images were assessed qua litatively by visual interpretation of shades of colour in cortical re gions. A SPECT defect confined to the frontal, parietal, temporal or ( parieto) occipital lobe was defined as one lesion. The mean number of SPECT lesions was 1.4 (range 0-4) in the control group, 2.4 (range 0-8 ) in the PDD group and 2.9 (range 2-5 in the MID group and showed a si gnificant difference (P < 0.02) between groups. To obtain an acceptabl e level of specificity of 64.3%, a cut-off value of three lesions had to be chosen. In the PDD group, sensitivity was then 25% for the mildl y, 43.8% for the moderately and 46.7% for the severely affected PDD su bgroup. In the MID group sensitivity was then 75%. Interestingly, in t his elderly patient population the location of lesions was homogenousl y distributed in all groups, including the control group.