¹⁸F-FDG PET and Perfusion SPECT in the Diagnosis of Alzheimer and Lewy Body Dementias

Abstract

Brain imaging with glucose ( 18 F-FDG) PET or blood flow (hexamethylpropyleneamine oxime) SPECT is widely used for the differential diagnosis of dementia, though direct comparisons to clearly establish superiority of one method have not been undertaken. Methods: Subjects with Alzheimer disease (AD; n 5 38) and dementia with Lewy bodies (DLB; n 5 30) and controls (n 5 30) underwent 18 F-FDG PET and SPECT in balanced order. The main outcome measure was area under the curve (AUC) of receiver-operating-characteristic analysis of visual scan rating. Results: Consensus diagnosis with 18 F-FDG PET was superior to SPECT for both dementia vs. no-dementia (AUC 5 0.93 vs. 0.72, P 5 0.001) and AD vs. DLB (AUC 5 0.80 vs. 0.58, P 5 0.005) comparisons. The sensitivity and specificity for dementia/no-dementia was 85% and 90%, respectively, for 18 F-FDG PET and 71% and 70%, respectively, for SPECT. Conclusion: 18 F-FDG PET was significantly superior to blood flow SPECT. We recommend 18 F-FDG PET be performed instead of perfusion SPECT for the differential diagnosis of degenerative dementia if functional imaging is indicated.

The relationship between hallucinations and FDG-PET in dementia with Lewy bodies

“…Main results from the study have been reported elsewhere (O'Brien et al 2014). The study subjects were recruited prospectively from people aged over 60 with mild to moderate dementia (MMSE > 12) referred to clinical services in North-East England.…”

“…As described in more detail elsewhere, (O'Brien et al 2014) the PET scans were non-linearly spatially normalised to a study specific template. Scans were intensity normalised to the mean within a cerebellar region-of-interest (ROI) and smoothed with a 8 mm Gaussian.…”

“…Although reduced occipital and parietal perfusion, and glucose metabolism, are well documented in DLB compared to healthy subjects, (Colloby et al 2002;Ishii et al 1999;O'Brien et al 2014) few studies have investigated the relationship with hallucinations within DLB subjects, and results have been mixed. We investigated the relationship between hallucinations as measured by the neuropsychiatric inventory, and FDG-PET brain imaging in a cohort of patients with DLB.…”

Neuroimaging in dementia: an update for the general clinician

“…A recent comparison demonstrated that FDG-PET had superior sensitivity and specificity than HMPAO-SPECT in the diagnosis of dementia. 11 Both HMPAO-SPECT and FDG-PET involve the administration of an intravenous tracer, a waiting period prior to the scan, and lying still on a flat surface. The level of radioactivity received is similar in both tests and comparable to CT scans.…”

Diagnosing dementia

“…5 Amyloid deposition may be detected with PET using fluorine-18-labelled florbetapir, flutemetamol or florbetaben. Recently, PET has also been used to identify the presence of tau protein.…”