The value of HMPAO SPECT scanning in the diagnosis of early Alzheimer??s disease in patients attending a memory clinic

Brain SPET perfusion in early Alzheimer’s disease: where to look?

“…Although the predominant pattern of regional functional change with the best positive predictive value for AD is that of bilateral temporo-parietal abnormalities with or without other regional defects [19,36,37], it appears to be neither sensitive nor specific for early AD [17,18]. Based on recent studies, reduced flow and metabolism in brain regions shown to be critical to episodic memory in early AD patients, i.e.…”

“…Several studies, using visual and region of interest analysis, reported on 99m Tc-HMPAO brain SPET perfusion changes in early, mildly demented AD patients and provided conflicting results [15,16,17,18,19]. In general, the validity of these results is questionable as the exact number of patients fulfilling criteria of probable AD in the early stage of the disease often cannot be traced and conclusions are based on simultaneous inclusion of advanced AD patients as well, who are no longer characterized by a specific cognitive impairment but by general cognitive decline.…”

“…Based on poor sensitivity and specificity obtained by semi-quantitative measurements of temporo-parietal perfusion, the authors concluded that brain SPET perfusion has limited value in the evaluation of elderly, mildly demented patients. Similarly, McMurdo et al [18] studied 26 probable AD patients attending a memory clinic. In this series only 15 (58%) of the patients, some of whom were mildly demented, presented perfusion patterns strongly suggestive of AD.…”

Tc-99m HMPAO brain SPECT findings in mild and moderate Alzheimer's disease: Correlation with event related potentials

“…Van Gool et al [18] found high specificity (89%) but low sensitivity (43%) values for distinguishing mild patients with AD from controls. Other studies also have showed that SPECT is not a useful technique as a diagnostic adjunct in patients suspected of having mild AD [19,28]. Claus et al [19] found that the discriminative ability of SPECT improved with increasing dementia severity.…”

An automatic threshold-based scaling method for enhancing the usefulness of Tc-HMPAO SPECT in the diagnosis of Alzheimer’s disease

“…Because of the limited availability and high cost of PET, attention has focused on SPECT to provide a low cost alternative to PET. SPECT provides data on regional blood flow that correlates with the metabolic data provided by PET in patients with AD, such as decreases in blood flow to temporo-parietal areas [3], and is considered a useful tool to aid in the diagnosis of AD [9,10]. Some investigators have found that the degree and extent of decreased cerebral blood flow correlates with severity [12] of AD.…”