Dementia with Leukoaraiosis: Clinical Differentiation by Temporoparietal Hypometabolism on ¹⁸FDG-PET Imaging

Abstract

Patients with dementia and leukoaraiosis may have either Alzheimer’s disease (AD) with cerebrovascular changes or a form of vascular dementia (VaD). The presence or absence of the characteristic AD pattern of bilateral temporoparietal hypometabolism on ¹⁸FDG-PET was used to differentiate 30 patients with progressive dementia and severe leukoaraiosis. Compared to 18 patients with the typical AD pattern (group I), the remaining 12 (group II) had better recognition memory, and greater difficulty with sustained attention and serial reversals. Better recognition memory, confluent periventricular leukoaraiosis, and poorer sustained attention distinguished all group II patients from group I. Dementia patients with severe leukoaraiosis and bilateral temporoparietal hypometabolism may have predominant AD; those who lack this pattern and have confluent leukoaraiosis may have a greater contribution from VaD.

Subcortical Vascular versus Amnestic Mild Cognitive Impairment: Comparison of Cerebral Glucose Metabolism

“…Third, our results suggest that the involvement of the insula and superior temporal areas may occur in the earlier stages of the vascular cognitive impairment associated with small vessel pathology. Previous studies using FDG‐PET showed that hypometabolism in the deep structures or frontal region is a sensitive marker of SVaD 22, 24–26 . Because all of the studies, 24–26 except for one, 22 analyzed their data by using region of interest (ROI) or visual inspection, they had difficulty in finding the regional distribution of hypometabolism in the entire brain of patients with SVaD.…”

The Value of Positron Emission Tomography in the Clinical Evaluation of Dementia

“…Mendez et al 17 explored the role that PET may play in differentiating patients with dementia and leukoariosis into those with AD with cerebrovascular changes or those with vascular dementia. Leukoariosis is a common radiological finding that is probably caused by cerebral ischemia.…”

“…The review was focused on those articles describing the use of dedicated PET cameras to aid in the diagnostic evaluation of dementia. The systematic review identified 16 original articles 4,8–22 and seven HTA reports 6,7,23–27 . Papers that exclusively examined modified PET cameras or Single Positron Emission Computed Tomography (SPECT) were excluded because of significant differences in the technologies these techniques employ.…”

“…Table 3 summarizes information on the 16 original investigations 4,8–22 that examined the role of PET imaging in the diagnosis of dementia. No study was grade A, and eight were grade B 8–15 .…”

“…No study was grade A, and eight were grade B 8–15 . One grade C study 17 warranted discussion, because it examined the role of PET in differentiating AD from vascular dementia, and is therefore included in this review. No attempt has been made at a quantitative summary of PET imaging's performance characteristics, given that different PET cameras and widely varying methodologies were used in the individual articles.…”