Assessment of Perfusion Deficits in Ischemic Stroke Using 3D-GRASE Arterial Spin Labeling Magnetic Resonance Imaging with Multiple Inflow Times (original) (raw)
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NeuroImage: Clinical, 2013
The purpose of the present study was to present a multi-delay multi-parametric pseudo-continuous arterial spin labeling (pCASL) protocol with background suppressed 3D GRASE (gradient and spin echo) readout for perfusion imaging in acute ischemic stroke. PCASL data at 4 post-labeling delay times (PLD = 1.5, 2, 2.5, 3 s) were acquired within 4.5 min in 24 patients (mean age 79.7 ± 11.4 years; 11 men) with acute middle cerebral artery (MCA) stroke who also underwent dynamic susceptibility contrast (DSC) enhanced perfusion imaging. Arterial transit times (ATT) were estimated through the calculation of weighted delays across the 4 PLDs, which were included in the calculation of cerebral blood flow (CBF) and arterial cerebral blood volume (CBV). Mean perfusion parameters derived using pCASL and DSC were measured within MCA territories and infarct regions identified on diffusion weighted MRI. The results showed highly significant correlations between pCASL and DSC CBF measurements (r N =0.70, p b =0.0001) and moderately significant correlations between pCASL and DSC CBV measurements (r N =0.45, p b =0.027) in both MCA territories and infarct regions. ASL ATT showed correlations with DSC time to the maximum of tissue residual function (Tmax)(r = 0.66, p = 0.0005) and mean transit time (MTT)(r = 0.59, p = 0.0023) in leptomeningeal MCA territories. The present study demonstrated the feasibility for noninvasive multi-parametric perfusion imaging using ASL for acute stroke imaging.
Frontiers in Biomedical Technologies, 2019
Purpose: Neuroimaging techniques hold many promises to detect Alzheimer Disease (AD) at early stages before clinical symptoms fully develop, suggesting decreased regional Cerebral Blood Flow (CBF). Perfusion deficiencies are present from very early clinical phases of AD, i.e. Mild Cognitive Impairment (MCI) and persist well into the latest stages, demonstrating a pattern of increased hypo-perfusion with the disease development. Accurate quantification such as quantification model and noise reduction method is necessary to achievement of good results in insufficient Post Labeling Delay (PLD) time. Materials and Methods: Arterial Spin Labeling (ASL) is a non-invasive MRI technique to extract brain regional CBF, which in recent years gained wide acceptance for its value in clinical and neuroscience applications. In the present work, 44 participants in 2 groups were imaged (normal control and MCI) using single-Post Label Delay (single-PLD) model-fitting ASL Perfusion at 1.5T. Images wer...
International Congress Series, 2004
The development of arterial spin labeling (ASL) techniques has provided a useful strategy for quantitative measurement of cerebral blood flow (CBF). However, quantification of transit time has historically been difficult to achieve without prolonged scan times, since ASL has suffered from low signal-to-noise ratio (SNR). Continuous ASL (CASL) has recently been implemented on the 3T magnetic resonance (MR) system, which can provide a more favorable perfusion signal SNR because of the higher Lamor frequency and prolonged T1 times. Therefore, the goal of the present study was to determine whether CASL perfusion imaging on the 3T MR system could evaluate transit time within a reasonable scan time. This study describes a theoretical framework for measuring arterial transit time using a two-compartment model, followed by application of the model to CASL perfusion data obtained from six normal subjects. CBF and arterial arrival time maps were successfully created using a two-parameter fitting procedure, and the transit time obtained with this model was consistent with those obtained from previous reports. However, the CBF values calculated with the present model were lower than those reported when using 1.5T. Possible reasons for this discrepancy, including transit time, CBV, label efficiency and MT effect, are discussed. D
Acta Scientific Neurology
Arterial spin labeling (ASL) is an MRI perfusion technique which helps in non-invasive assessment of the cerebral blood flow (CBF). It is a technique that uses the labeled protons in the arterial blood as an endogenous tracer. Assessment of the perfusion plays a vital role in evaluation of various brain pathologies like neoplasms. Various techniques are available for assessment of the perfusion such as DSC MRI, CT perfusion imaging, SPECT, H2[15O] PET etc. which are invasive and require administration of the exogenous contrast media or use of ionizing radiation. In the recent years, ASL has become an easily available imaging technique due to advances in the technology related to image acquisition, post processing software's and therefore with an increasing spectrum of ASL applications in various neurological pathologies such as stroke, transient ischemic attack, seizures, migraine, neoplasm, headaches and neuropsychiatric diseases such as Alzheimer's dementia and Parkinson's disease. ASL can provide important physiological information which cannot be provided by the conventional MRI. Knowledge of the perfusion characteristics of brain and brain lesions is important as it may be helpful in providing a specific diagnosis or important physiological information which can be difficult to interpret on anatomic imaging or can be crucial in-patient management. The absence of irradiation, or the exogenous injection of the contrast media and no need of IV access, as well as its property to quantify CBF and reproduce the findings makes ASL an important noninvasive perfusion technique especially in patients with impaired renal functions where injection of contrast media is contraindicated. Moreover, with advances in imaging techniques and post processing soft wares, the spectrum of ASL applications has been increasing in various neurological disorders.
Journal of Magnetic Resonance Imaging, 2013
Purpose: To evaluate the reproducibility of estimation of cerebral blood flow (CBF), bolus arrival time (BAT), and arterial blood volume (aBV) from arterial spin labeling (ASL) data acquired at multiple postlabeling delays (PLDs). Materials and Methods: CBF, BAT, and aBV parameters were estimated from flow-suppressed and nonflowsuppressed multiple-PDL PICORE-Q2TIPS ASL using model-based Bayesian and least-squares fitting frameworks, and aBV was also obtained from a model-free approach. Reproducibility of these parameters was assessed by computing the within-and between-subject coefficients of variability (CVw and CVb). Results: CVw and CVb were comparable across modelbased approaches, but were greater for the aBV from the model-free approach. Overall, the Bayesian model estimation procedure was found to provide the best compromise between reliability and reproducibility, yielding CVw/CVb values of 21/21, 3/4, and 24/26% for CBF, BAT, and aBV, respectively. Although a CBF range of 45 mL/100g/ min to 59 mL/100g/min was found on average and a BAT of 0.7-1.0 seconds across methods, the corresponding maps were comparable in terms of the parameters' spatial distributions, and in particular in the identification of macrovascular locations, as assessed through comparison with time-of-flight images. Conclusion: Reproducible estimates of CBF, BAT, and aBV values can be obtained from non-macroflowsuppressed ASL using both least-squares and Bayesian model-based methods.
BMC Medical Imaging
Background: In a prospective cohort of patients with transient ischemic attack (TIA), we investigated usefulness and feasibility of arterial spin labeling (ASL) perfusion and susceptibility weighted imaging (SWI) alone and in combination with standard diffusion weighted (DWI) imaging in subacute diagnostic work-up. We investigated rates of ASL and SWI changes and their potential correlation to lasting infarction 8 weeks after ictus. Methods: Patients with TIA underwent 3T-MRI including DWI, ASL and SWI within 72 h of symptom onset. We defined lasting infarction as presence of 8-week MRI T2-fluid attenuated inversion recovery (FLAIR) hyperintensity or atrophy in the area of initial DWI-lesion. Results: We included 116 patients. Diffusion and perfusion together identified more patients with ischemia than either alone (59% vs. 40%, p < 0.0001). The presence of both diffusion and perfusion lesions had the highest rate of 8-week gliosis scars, 65% (p < 0.0001). In white matter, DWI-restriction was the determinant factor for scar development. However, in cortical gray matter half of lesions with perfusion deficit left a scar, while lesions without perfusion change rarely resulted in scars (56% versus 21%, p = 0.03). SWI lesions were rare (6%) and a subset of perfusion lesions. SWI-lesions with DWI-lesions were all located in cortical gray matter and showed high scar rate. Conclusions: ASL perfusion increased ischemia detection in patients with TIA, and was most useful in conjunction with DWI. ASL was fast, robust and useful in a subacute clinical diagnostic setting. SWI had few positive findings and did not add information. Trial Registration.: http://www.clinicaltrials.gov. Unique Identifier NCT01531946, prospectively registered February 9, 2012.
Background and Purpose-Continuous arterial spin-labeled perfusion MRI (CASL-PI) uses electromagnetically labeled arterial blood water as a diffusible tracer to noninvasively measure cerebral blood flow (CBF). We hypothesized that CASL-PI could detect perfusion deficits and perfusion/diffusion mismatches and predict outcome in acute ischemic stroke. Methods-We studied 15 patients with acute ischemic stroke within 24 hours of symptom onset. With the use of a 6-minute imaging protocol, CASL-PI was measured at 1.5 T in 8-mm contiguous supratentorial slices with a 3.75-mm in-plane resolution. Diffusion-weighted images were also obtained. Visual inspection for perfusion deficits, perfusion/diffusion mismatches, and effects of delayed arterial transit was performed. CBF in predetermined vascular territories was quantified by transformation into Talairach space. Regional CBF values were correlated with National Institutes of Health Stroke Scale (NIHSS) score on admission and Rankin Scale (RS) score at 30 days. Results-Interpretable CASL-PI images were obtained in all patients. Perfusion deficits were consistent with symptoms and/or diffusion-weighted imaging abnormalities. Eleven patients had hypoperfusion, 3 had normal perfusion, and 1 had relative hyperperfusion. Perfusion/diffusion mismatches were present in 8 patients. Delayed arterial transit effect was present in 7 patients; serial imaging in 2 of them showed that the delayed arterial transit area did not succumb to infarction. CBF in the affected hemisphere correlated with NIHSS and RS scores (Pϭ0.037 and Pϭ0.003, Spearman rank correlation). The interhemispheric percent difference in middle cerebral artery CBF correlated with NIHSS and RS scores (Pϭ0.007 and Pϭ0.0002, respectively). Conclusions-CASL-PI provides rapid noninvasive multislice imaging in acute ischemic stroke. It depicts perfusion deficits and perfusion/diffusion mismatches and quantifies regional CBF. CASL-PI CBF asymmetries correlate with severity and outcome. Delayed arterial transit effects may indicate collateral flow. (Stroke. 2000;31:680-687.)
Oncotarget, 2016
Multi-delay arterial spin-labeling (ASL) perfusion imaging has been used as a promising modality to evaluate cerebral perfusion. Our aim was to assess the association of leptomeningeal collateral perfusion scores based on ASL parameters with outcome of endovascular treatment in patients with acute ischemic stroke (AIS) in the middle cerebral artery (MCA) territory. ASL data at 4 post-labeling delay (PLD) times (PLD = 1.5, 2, 2.5, 3 s) were acquired during routine clinical magnetic resonance examination on AIS patients prior to endovascular treatment. A 3-point scale of leptomeningeal collateral perfusion grade on 10 anatomic regions was determined based on arterial transit times (ATT), cerebral blood flow (CBF), and arterial cerebral blood volume (CBV), estimated by the multi-delay ASL protocol. Based on a 90-day modified Rankin Scale (mRS), the patients were dichotomized to moderate/good (mRS 0-3) and poor outcome (mRS 4-6) and the regional collateral flow scores were compared. Fif...