Hypoperfusion in frontotemporal dementia and Alzheimer disease by arterial spin labeling MRI

Abstract

Objectives-To test if arterial spin labeling (ASL) MRI could detect a pattern of hypoperfusion in frontotemporal dementia (FTD) vs cognitively normal (CN) control subjects; to determine the regional difference of perfusion between FTD and Alzheimer disease (AD); and to determine whether hypoperfusion in FTD correlates with cognitive impairment.Methods-We included 21 patients with FTD, 24 patients with AD, and 25 CN subjects in this cross-sectional MRI study. All subjects had MRI scans including T1-weighted structural images and ASL-MR images.Results-ASL-MRI detected a pattern of hypoperfusion in right frontal regions in patients with FTD vs CN subjects, similar to PET and SPECT. FTD had higher perfusion than AD in the parietal regions and posterior cingulate. Frontal hypoperfusion in FTD correlated with deficits in judgment and problem solving. Adding frontal perfusion to gray matter (GM) atrophy significantly improved the classification of FTD from normal aging to 74%, and adding parietal perfusion to GM atrophy significantly improved the classification of FTD from AD to 75%. Combining frontal and parietal lobe perfusion further improved the classification of FTD from AD to 87%. Conclusion-Frontotemporal dementia andAlzheimer disease display different spatial distributions of hypoperfusion on arterial spin labeling MRI. With further development and evaluation, arterial spin labeling MRI could contribute to the differential diagnosis between frontotemporal dementia and Alzheimer disease.Frontotemporal dementia (FTD) and Alzheimer disease (AD) can be difficult to clinically differentiate because of overlapping symptoms. 1-3 Structural MRI can assess regional patterns of brain pathology and may aid a differential diagnosis between FTD and AD. 4-10 However, overlapping of brain tissue loss limits structural MRI to achieve complete separation between FTD and AD. Functional neuroimaging, yielding complementary information to tissue loss, may help the differentiation between FTD and AD. Previous PET and SPECT studies have shown different patterns of metabolism and perfusion reduction in FTD and AD. 11-26 However, PET and SPECT have several disadvantages, including injection of radioactive tracers and limited availability in comparison with MRI scanners. Arterial spin labeled

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

“…These patterns are similar to those observed with SPECT perfusion and FDG‐PET 21, 22, 23, 24. 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.…”

“…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. The fact that two separate studies have now concluded that ASL‐MRI has comparable diagnostic value to FDG‐PET strengthens the argument that it should be a focus for continued development.…”

“…Recent studies have indicated that measurement of CBF using arterial spin labeling (ASL) MRI is also abnormal in neurodegenerative disease, and can improve differential diagnosis of bvFTD 18, 19, 20. BvFTD shows frontal patterns of hypoperfusion, even after controlling for loss of brain volume, as compared with AD, which is associated with relative hypoperfusion in the parietal regions.…”

Multivariate and Univariate Analysis of Continuous Arterial Spin Labeling Perfusion MRI in Alzheimer's Disease

“…Most AD imaging studies have relied on PET and SPECT and have shown a marked decrease in metabolism and/or regional blood flow in the AD population (Herholz et al, 2002;Johnson et al, 1998;Scarmeas et al, 2004;Silverman et al, 2001). Results from several ASL studies have shown good agreement across techniques (Alsop et al, 2000;Du et al, 2006;Johnson et al, 2005;Sandson et al, 1996). Regardless of the particular imaging technique employed, the general conclusion from these studies is that a quantitative measurement of CBF has the potential of being the imperative biomarker for early detection and diagnosis of AD.…”

“…The other three studies have reported data from PASL, which, in addition to lower SNR, has the disadvantage of being restricted only to a slab commonly placed in the superior cerebral cortex, thus excluding major portions of the temporal and inferior frontal lobes (Du et al, 2006;Johnson et al, 2005;Sandson et al, 1996). Furthermore, a nonquantitative version of PASL was used and therefore only relative measurements (in percent change) of CBF were reported.…”