Comparison of PASL, PCASL, and background‐suppressed 3D PCASL in mild cognitive impairment

Abstract

We compared three implementations of single-shot arterial spin labeled (ASL) perfusion magnetic resonance imaging (MRI): two-dimensional (2D) pulsed ASL (PASL), 2D pseudo-continuous ASL (PCASL), and background suppressed (BS) 3D PCASL obtained in a cohort of patients with mild cognitive impairment (MCI) and elderly controls. Study subjects also underwent 18F-flurodeoxyglucose positron emission tomography (18F-FDG PET). While BS 3D PCASL showed the lowest (p<0.001) gray matter-white matter cerebral blood flow (CBF) contrast ratio, it provided the highest (p<0.001) temporal signal-to-noise ratio. Mean relative CBF estimated using the PCASL methods in posterior cingulate cortex (PCC), precuneus and hippocampus showed hypoperfusion in the MCI cohort compared to the controls consistent with hypometabolism measured by 18F-FDG PET. BS 3D PCASL demonstrated the highest discrimination between controls and patients with effect size comparable to that seen with 18F-FDG PET. 2D PASL did not demonstrate group differentiation with relative CBF in any ROI, whereas 2D PCASL demonstrated significant differences only in PCC and hippocampus. Mean global CBF values did not differ across methods and were highly correlated, however the correlations were significantly higher (p<0.001) when either the same labeling (PCASL) or the same acquisition strategy (2D) was used as compared to when both the labeling and readout methods differed. In addition, there were differences in regional distribution of CBF between the three modalities, which can be attributed to differences in sequence parameters. These results demonstrate the superiority of ASL with PCASL as well as BS 3D readout as a biomarker for regional brain function changes in MCI.

Estimating regional cerebral blood flow using resting-state functional MRI via machine learning

“…This approach will be useful especially for studies that have large sample size (Habes et al, 2016), where reacquiring missing imaging modalities from the same subject is not practical. CBF estimation was better at the posterior regions, where many previous studies (Alsop et al, 2008;Dolui et al, 2017;Huang et al, 2018) and our results showed altered CBF in MCI or Alzheimer's pathology, suggesting the potential use of proposed method in those populations.…”

“…The parietal lobe is densely vascularized structure (Clark et al, 2017;Duvernoy et al, 1981;Liebeskind, 2003), which might provide a stronger signal to be estimated. In ASL literature, regions within the parietal lobe are consistently reported to be associated with hypoperfusion in MCI or Alzheimer's disease (Alsop et al, 2010;Dolui et al, 2017). The parietal regions thus might be well-positioned for functional measures captured via fMRI and/or ASL perfusion, which eventually could reflect in our machine learning-based predictions.…”

“…The T1 images were probabilistically segmented into gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) using the SPM12 and they were subsequently used to compute a brain mask containing GM, WM, and ventricular CSF (Dolui et al, 2017). Each subject's T1-weighted images were used to estimate a subject-specific nonlinear warping to the MNI152 template using FMRIB's non-linear image registration tool (FNIRT) (Andersson et al, 2010).…”

Disconnectome Associated with Progressive Ischemic Periventricular White Matter Lesions

“…We complemented our study of the healthy cohort with multimodal MRI data from 46 cognitively normal elderly subjects (31 female, age = 72.30 ± 6.81 years) from a research study of aging and cognitive impairment conducted at the Penn Memory Center (PMC) and the Alzheimer Disease Core Center (ADCC) at the University of Pennsylvania. All participants had an extensive annual evaluation of medical history, physical examination, neurological history and examination, and psychometric assessment; all of these data are collectively used to determine clinical status (64). The study procedures were approved by the IRB of the University of Pennsylvania.…”

Cortical pattern of reduced perfusion in hearing loss revealed by ASL‐MRI

“…At present, due to its higher labeling efficiency, the PCASL is also the recommended ASL implementation for clinical studies (Alsop et al, 2015;Dolui et al, 2017) and can be suitably combined with a 3D readout acquisition scheme (3D-PCASL) to achieve optimal signalto-noise ratio performances (Vidorreta et al, 2013).…”