Association between medial temporal lobe atrophy on CT and parietotemporal uptake decrease on SPECT in Alzheimer's disease

The role of brain perfusion SPECT in the diagnosis of frontotemporal dementia: A systematic review

BACKGROUND AND PURPOSE

Frontotemporal dementia (FTD) is the second most common cause of presenile dementia. The clinical distinction between FTD, Alzheimer's disease (AD), and other dementias is a clinical challenge. Brain perfusion SPECT may contribute to the diagnosis of FTD, but its value is unclear.

METHODS

We performed a systematic review to investigate the diagnostic accuracy of the brain SPECT in (1) distinguishing FTD from AD and other dementias and (2) differentiating FTD variants.

RESULTS

Overall, 391 studies were retrieved on the initial search and 35 studies composed the final selection, comprising a total number of 3142 participants of which 1029 had FTD. The sensitivity and the specificity for the differential diagnosis of FTD versus AD ranged from 56% to 88% and from 51% to 93%, respectively. SPECT is not superior to the clinical method of diagnosis, but the combination of SPECT with clinical data seems to improve the diagnostic accuracy.

CONCLUSION

Brain perfusion SPECT has a limited value in the diagnostic framework of FTD. SPECT can be performed when FDG-PET is not available. SPECT is recommended only for selected cases when the diagnosis is challenging using conventional methods.

Is there any role for computed tomography measurements of medial temporal lobe atrophy in dementia? A review of the literature and case series from a memory clinic

Neuroimaging in dementia has focused on documenting any burden of vascular disease or excluding any reversible intracranial pathology. We review the use of computed tomography to examine for medial temporal lobe atrophy in dementia and compare this with a case series of such measurements from our memory clinic. Measures of medial temporal lobe atrophy were used to separate patients with Alzheimer's disease from those with normal cognition, mood disorders or other forms of early dementia.

Evidence-based evaluation of magnetic resonance imaging as a diagnostic tool in dementia workup

BACKGROUND

The diagnostic utility of magnetic resonance imaging in dementia workups has increased recently. The basic use is to exclude space-occupying processes in the brain. However, magnetic resonance imaging offers major opportunities for studying atrophy of specific brain areas. A great interest has been put in whether atrophy in the medial temporal lobe can serve as an early diagnostic marker for Alzheimer disease.

METHODS AND RESULTS

In this evaluation, we used evidence-based techniques and reviewed more than 400 articles that address this issue. Our main finding is that a variety of methods in studying brain areas were used, and this made it difficult to extract conclusive information in a systematic way.

CONCLUSION

However, we were able to conclude that atrophy of the hippocampus can distinguish patients with Alzheimer disease from healthy subjects, but there was a lack of evidence because of insufficient studies concerning the usefulness of medial temporal lobe atrophy as a diagnostic marker in a more general setting.

Cerebral hypoperfusion and clinical onset of dementia: the Rotterdam Study

Cerebral blood flow (CBF) velocity is decreased in patients with Alzheimer's disease. It is being debated whether this reflects diminished demand because of advanced neurodegeneration or that cerebral hypoperfusion contributes to dementia. We examined the relation of CBF velocity as measured with transcranial Doppler with dementia and markers of incipient dementia (ie, cognitive decline and hippocampal and amygdalar atrophy on magnetic resonance imaging) in 1,730 participants of the Rotterdam Study aged 55 years and older. Cognitive decline in the 6.5 years preceding CBF velocity measurement was assessed with repeated Mini-Mental State Examinations in nondemented subjects (n = 1,716). Hippocampal and amygdalar volumes were assessed in a subset of 170 nondemented subjects. Subjects with greater CBF velocity were less likely to have dementia. Furthermore, in nondemented subjects, greater CBF velocity was related to significantly less cognitive decline over the preceding period (odds ratio per standard deviation increase in mean CBF 0.74 [95% confidence interval, 0.58-0.98]) and larger hippocampal and amygdalar volumes. A low CBF is associated with dementia, but also with markers of incipient dementia. Although we cannot exclude that this is caused by preclinical neurodegeneration leading to hypoperfusion, it does suggest that cerebral hypoperfusion precedes and possibly contributes to onset of clinical dementia.

Correlation of neuropsychological evaluation and SPECT imaging in patients with Alzheimer's disease

BACKGROUND

Mini-Mental State Examination (MMSE) is a very useful tool for diagnosing changes in cognitive functions by the general practitioner or other medical staff who is not familiar with neuropsychological tests. On the other hand, HMPAO brain SPECT has been shown to have a high sensitivity to detect neurodegenerative processes, which lead to dementia. The correlation between both methods is unknown. We compared both methods in order to find a rational evaluation tool for the practitioner to obtain a higher efficacy and cost effective way of using both methods.

PATIENTS AND METHODS

Fifty-one patients diagnosed as having Alzheimer's disease (AD) were examined. Each patient underwent MMSE analysis, as well as HMPAO brain SPECT. The severity of SPECT abnormalities was categorized into mild, moderate and severe. Statistical analysis was performed in order to evaluate the correlation between imaging findings and neuropsychological testing.

RESULTS

Marginal inverse correlation was found between global MMSE SPECT imaging on right and left side (p = 0.05) and the left temporal region (p = 0.05). MMSE subgroup component of orientation was highly significantly inversely associated with SPECT imaging of right and left frontal region (p > 0.0001). The MMSE subgroup of immediate memory was significantly correlated to left and right temporal regions (p = 0.001 and p = 0.002 respectively). Age was not significantly correlated to global MMSE or any of its subtest components.

CONCLUSION

MMSE score has no linear correlation to SPECT perfusion findings. In cases of abnormal orientation score subgroup SPECT imaging is not recommended. In most instances, a combination of both methods should be employed by the general practitioner for further evaluation of dementia.

Neuroimaging in dementia

Positron emission tomography, single photon emission computed tomography, and MR imaging are brain imaging techniques that have been applied widely to the study of patients with dementia. This article reviews current data on the clinical use of these techniques in the differential diagnosis of dementia and the prediction of dementia in those at risk.