Is There a Typical Pattern of Brain SPECT Imaging in Alzheimer’s Disease?

Abstract

The identification of new nosological forms such as Lewy body disease (LBD) requires a re-evaluation of the patterns observed in brain functional imaging in the various forms of dementia. We studied 60 demented patients, divided into three groups and fulfilling the clinical criteria for Alzheimer’s disease (AD), LBD and frontotemporal dementia (FTD), using Tc-HMPAO and a brain-dedicated SPECT system. After normalisation we applied a cut-off at two levels according to previously established criteria. We reaffirmed the already established data concerning FTD (mainly a bilateral frontal decrease) and for LBD (a severe diffuse decrease in the frontal regions and also in the posterior association cortex). In contrast, the decrease in AD was strictly limited to the parieto-occipital cortex, irrespective of the severity of the cognitive decline. We hypothesise that the major simplification concerning the pattern observed in AD can be explained by the fact that patients suffering from LBD have previously been included in the groups of AD patients.

Cerebral Blood Flow in Parkinson’s Disease, Dementia with Lewy Bodies, and Alzheimer’s Disease according to Three-Dimensional Stereotactic Surface Projection Imaging

“…Patients in our study, who were classified according to this criterion, showed a grossly similar rCBF reduction in parietal, occipital, and cingulate regions between PDD and DLB, except for accentuated flow reduction in the frontal (premotor) cortex in DLB. Frontal flow reduction in DLB has also been shown in other studies [25,41]. The present results may be explained in part by findings that impairments in DLB are usually greatest in attentional and executive tasks, suggesting frontal involvement.…”

“…Statistical comparison was made between the patient groups and the control group in normalized patient and control images, in a pixel-by-pixel manner. Activity was normalized to mean activity in the cerebellum, considered the brain region least likely to be affected by PD [5,11,23,24] or dementia [25,26]. This type of intensity normalization was ultimately chosen over the standard method of proportional scaling to the mean global activity, which when initially tried gave clearly erroneous results in patients with dementia.…”

Can neurodegenerative disease be defined by four ‘primary determinants’: anatomy, cells, molecules, and morphology?

“…In FTLD, which accounts for approximately 20% of all pre-senile cases of dementia [159], the pathological changes are usually more circumscribed, affecting primarily frontal and temporal lobes [156]. Nevertheless, there is often selective anatomical degeneration within this group.…”

Neuroimaging as a Diagnostic Tool in Dementia with Lewy Bodies

“…When Steinling et al [20] studied AD, DLB and frontotemporal dementia (FTD) using technetium-99m hexamethylpropylene amine oxime (Tc-HMPAO) SPECT, they confirmed that patients with FTD have smaller bilateral frontal lobes and that patients with DLB have an extreme (yet diffuse) reduction in the size of the frontal lobes and the posterior association cortex. In AD patients, the reduction in brain size was found in the parieto-occipital cortex and was not related to the degree of a patient's cognitive decline.…”