Direct comparison of fluorodeoxyglucose positron emission tomography and arterial spin labeling magnetic resonance imaging in Alzheimer's disease

Abstract

BACKGROUND The utility flourodeoxyglucose PET (FDG-PET) imaging in Alzheimer’s Disease (AD) diagnosis is well established. Recently, measurement of cerebral blood flow using arterial spin labeling MRI (ASL-MRI) has shown diagnostic potential in AD, though it has never been directly compared to FDG-PET. METHODS We employed a novel imaging protocol to obtain FDG-PET and ASL-MRI images concurrently in 17 AD patients and 19 age-matched controls. Paired FDG-PET and ASL-MRI images from 19 controls and 15 AD patients were included for qualitative analysis, while paired images 18 controls and 13 AD patients were suitable for quantitative analyses. RESULTS The combined imaging protocol was well tolerated. Both modalities revealed very similar regional abnormalities in AD, as well as comparable sensitivity and specificity for the detection of AD following visual review by two expert readers. Interobserver agreement was better for FDG-PET (kappa 0.75, SE 0.12) than ASL-MRI (kappa 0.51, SE 0.15), intermodality agreement was moderate to strong (kappa 0.45-0.61), and readers were more confident of FDG-PET reads. Simple quantitative analysis of global cerebral FDG uptake (FDG-PET) or whole brain cerebral blood flow (ASL-MRI) showed excellent diagnostic accuracy for both modalities, with area under ROC curves of 0.90 for FDG-PET (95% CI 0.79-0.99) and 0.91 for ASL-MRI (95% CI 0.80-1.00). CONCLUSIONS Our results demonstrate that FDG-PET and ASL-MRI identify similar regional abnormalities and have comparable diagnostic accuracy in a small population of AD patients, and support the further study of ASL-MRI in dementia diagnosis.

Diagnostic utility of ASL‐MRI and FDG‐PET in the behavioral variant of FTD and AD

“…Despite these limitations, the practical clinical implications of this report add to other reports25, 26, 27 suggesting that ALS‐MRI has a similar sensitivity and specificity to FDG‐PET for detecting brain changes due to AD and bvFTD. MRI examinations are noninvasive without ionizing radiation.…”

“…In addition, prior studies have indicated that the diagnostic value of ASL‐MRI is similar to that of FDG‐PET in AD 25, 26. Several prior studies have shown that patterns of perfusion are different in AD and bvFTD,18, 19, 20 and one prior study from Europe has supported the idea that diagnostic value of ASL‐MRI is similar to the diagnostic value of FDG‐PET 19.…”

“…Studies have indicated that community radiologists often fail to identify potentially diagnostic findings in structural MRIs 48. While no studies have assessed the diagnostic accuracy of FDG‐PET in FTD in community as opposed to academic settings, prior studies have demonstrated that visual interpretation of FDG‐PET can accurately diagnose FTD,49, 50 and studies of AD have demonstrated that inter‐reader agreement and confidence are higher for visual interpretation of FDG‐PET compared with ASL‐MRI 26. This represents an advantage for FDG‐PET, given current clinical practice.…”

“…One study has demonstrated that ASL‐MRI improves diagnostic classification of bvFTD versus age‐matched controls 19. In AD, studies have demonstrated that patterns of CBF deficits detected with ASL‐MRI are roughly similar to metabolic deficits identified using FDG‐PET,25, 26, 27 and that both imaging modalities have similar diagnostic value in AD 26. Although recent studies have indicated that patterns of CBF abnormalities and patterns of metabolic deficits are also similar in bvFTD,25 no studies have yet compared the diagnostic value of CBF measures from ASL‐MRI with the diagnostic utility of CMRgl measures from FDG‐PET in differentiating bvFTD from other dementias such as AD.…”

P2‐143: Prediction of Alzheimer's disease pathophysiology based on cortical thickness patterns

“…These co-registered images were spatially normalized to a MNI atlas space. The partial volume correction was performed using results with more than 25% of the maximal regional intensity [17]. The mean standard uptake value ratio (SUVr) in the cerebellum GM was used as a reference.…”