scholarly journals Reliable Estimation of Capillary Transit Time Distributions Using DSC-MRI

2014 ◽  
Vol 34 (9) ◽  
pp. 1511-1521 ◽  
Author(s):  
Kim Mouridsen ◽  
Mikkel Bo Hansen ◽  
Leif Østergaard ◽  
Sune Nørhøj Jespersen
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Transit Time ◽  
Neuronal Response ◽  
Mean Transit Time ◽  
Oxygen Extraction Fraction ◽  
Dynamic Susceptibility ◽  
Arterial Blood ◽  
Dsc Mri ◽  
Wide Range

The regional availability of oxygen in brain tissue is traditionally inferred from the magnitude of cerebral blood flow ( CBF) and the concentration of oxygen in arterial blood. Measurements of CBF are therefore widely used in the localization of neuronal response to stimulation and in the evaluation of patients suspected of acute ischemic stroke or flow-limiting carotid stenosis. It was recently demonstrated that capillary transit time heterogeneity ( CTH) limits maximum oxygen extraction fraction ( OEFmax) that can be achieved for a given CBF. Here we present a statistical approach for determining CTH, mean transit time ( MTT), and CBF using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI). Using numerical simulations, we demonstrate that CTH, MTT, and OEFmax can be estimated with low bias and variance across a wide range of microvascular flow patterns, even at modest signal-to-noise ratios. Mean transit time estimated by singular value decomposition (SVD) deconvolution, however, is confounded by CTH. The proposed technique readily identifies malperfused tissue in acute stroke patients and appears to highlight information not detected by the standard SVD technique. We speculate that this technique permits the non-invasive detection of tissue with impaired oxygen delivery in neurologic disorders such as acute ischemic stroke and Alzheimer's disease during routine diagnostic imaging.

scholarly journals The effect of carotid artery stenting on capillary transit time heterogeneity in patients with carotid artery stenosis

2018 ◽  
Vol 3 (3) ◽  
pp. 263-271 ◽  
Author(s):  
Ethem M Arsava ◽  
Mikkel B Hansen ◽  
Berkan Kaplan ◽  
Ahmet Peker ◽  
Rahsan Gocmen ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Transit Time ◽  
Carotid Artery Stenting ◽  
Cerebral Blood Volume ◽  
Mean Transit Time ◽  
Oxygen Extraction Fraction ◽  
Consecutive Series ◽  
Dynamic Susceptibility ◽  
Dynamic Susceptibility Contrast ◽  
Vascular Events

Introduction Carotid revascularisation improves haemodynamic compromise in cerebral circulation as an additional benefit to the primary goal of reducing future thromboembolic risk. We determined the effect of carotid artery stenting on cerebral perfusion and oxygenation using a perfusion-weighted MRI algorithm that is based on assessment of capillary transit-time heterogeneity together with other perfusion and metabolism-related metrics. Patients and methods A consecutive series of 33 patients were evaluated by dynamic susceptibility contrast perfusion-weighted MRI prior to and within 24 h of the endovascular procedure. The level of relative change induced by stenting, and relationship of these changes with respect to baseline stenosis degree were analysed. Results Stenting led to significant increase in cerebral blood flow ( p < 0.001), and decrease in cerebral blood volume ( p = 0.001) and mean transit time ( p < 0.001); this was accompanied by reduction in oxygen extraction fraction ( p < 0.001) and capillary transit-time heterogeneity ( p < 0.001), but an overall increase in relative capillary transit-time heterogeneity (RTH: CTH divided by MTT; p = 0.008). No significant change was observed with respect to cerebral metabolic rate of oxygen. The median volume of tissue with MTT > 2s decreased from 24 ml to 12 ml ( p = 0.009), with CTH > 2s from 29 ml to 19 ml ( p = 0.041), and with RTH < 0.9 from 61 ml to 39 ml ( p = 0.037) following stenting. These changes were correlated with the baseline degree of stenosis. Discussion: Stenting improved the moderate stage of haemodynamic compromise at baseline in our cohort. The decreased relative transit-time heterogeneity, which increases following stenting, is probably a reflection of decreased functional capillary density secondary to chronic hypoperfusion induced by the proximal stenosis. Conclusion: Carotid artery stenting, is not only important for prophylaxis of future vascular events, but also is critical for restoration of microvascular function in the cerebral tissue.

scholarly journals The relationship between blood flow impairment and oxygen depletion in acute ischemic stroke imaged with magnetic resonance imaging

2017 ◽  
Vol 39 (3) ◽  
pp. 454-465 ◽  
Author(s):  
Alexander Seiler ◽  
Nicholas P Blockley ◽  
Ralf Deichmann ◽  
Ulrike Nöth ◽  
Oliver C Singer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Oxygen Extraction Fraction ◽  
Interventional Treatment ◽  
Dynamic Susceptibility ◽  
Surrogate Markers ◽  
Strong Positive Correlation ◽  
Ischemic Penumbra ◽  
The Relationship

Oxygenation-sensitive spin relaxation time T2′ and relaxation rate R2′ (1/T2′) are presumed to be markers of the cerebral oxygen extraction fraction (OEF) in acute ischemic stroke. In this study, we investigate the relationship of T2′/R2′ with dynamic susceptibility contrast-based relative cerebral blood flow (rCBF) in acute ischemic stroke to assess their plausibility as surrogate markers of the ischemic penumbra. Twenty-one consecutive patients with internal carotid artery and/or middle cerebral artery occlusion were studied at 3.0 T. A physiological model of the cerebral vasculature (VM) was used to process PWI raw data in addition to a conventional deconvolution technique. T2′, R2′, and rCBF values were extracted from the ischemic core and hypoperfused areas. Within hypoperfused tissue, no correlation was found between deconvolved rCBF and T2′ ( r = −0.05, p = 0.788), or R2′ ( r = 0.039, p = 0.836). In contrast, we found a strong positive correlation with T2′ ( r = 0.444, p = 0.006) and negative correlation with R2′ ( r = −0.494, p = 0.0025) for rCBFVM, indicating increasing OEF with decreasing CBF and that rCBF based on the vascular model may be more closely related to metabolic disturbances. Further research to refine and validate these techniques may enable their use as MRI-based surrogate markers of the ischemic penumbra for selecting stroke patients for interventional treatment strategies.

Early evolution of deficits in acute ischemic stroke: Mean transit time, relative blood volume, and relative blood flow

2002 ◽  
Vol 11 (2) ◽  
pp. 66-71 ◽  
Author(s):  
Thanh G. Phan ◽  
John Huston ◽  
Norbert G. Campeau ◽  
Robert D. Brown ◽  
Jimmy R. Fulgham ◽  
...  
Keyword(s):  
Blood Flow ◽  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Blood Volume ◽  
Transit Time ◽  
Mean Transit Time ◽  
Early Evolution ◽  
Relative Blood Volume

Dexamethasone Normalizes Brain Tumor Hemodynamics as Indicated by Dynamic Susceptibility Contrast MRI Perfusion Parameters

2005 ◽  
Vol 4 (3) ◽  
pp. 245-249 ◽  
Author(s):  
Christopher C. Quarles ◽  
Hendrikus G. J. Krouwer ◽  
Scott D. Rand ◽  
Kathleen M. Schmainda
Keyword(s):  
Transit Time ◽  
Spin Echo ◽  
Mean Transit Time ◽  
Normal Brain ◽  
Post Inoculation ◽  
Dynamic Susceptibility ◽  
Dynamic Susceptibility Contrast ◽  
Functional Changes ◽  
Dsc Mri ◽  
Susceptibility Contrast

The purpose of this study is to demonstrate the utility of dynamic susceptibility contrast (DSC) MRI-derived perfusion parameters to characterize the hemodynamic effects of dexamethasone in a 9L gliosarcoma tumor model. Twenty-four rats underwent intracerebral inoculation with 9L tumor cells. Fifteen were treated with a total of 3mg/kg of dexamethasone on days 10–14 post-inoculation, while the remaining 9 rats served as controls. Fourteen days post-inoculation, MRI images, sensitive to total and micro-vascular cerebral blood flow (CBF), mean transit time (MTT), and intravoxel transit time distributions (TTD)s were obtained using a simultaneous gradient-echo(GE)/spin-echo(SE) DSC-MRI method. Dexamethasone-treated animals had a microvascular (SE) tumor CBF that was 45.9% higher ( p = 0.0008) and a MTT that was 47.8% lower ( p = 0.0005) than untreated animals. With treatment, there was a non-significant 91.3% increase in total (GE) vascular CBF ( p = 0.35), and a significant decrease in MTT (49.1%, p = 0.02). The total vascular and microvascular TTDs from the treated tumors were similar to normal brain, unlike the TTDs in the untreated tumors. These findings demonstrate that DSC-MRI perfusion methods can be used to non-invasively detect the morphological and functional changes in tumor vasculature that occur in response to dexamethasone treatment.

The association between neurological deficit in acute ischemic stroke and mean transit time

2005 ◽  
Vol 48 (2) ◽  
pp. 69-77 ◽  
Author(s):  
Peter D. Schellinger ◽  
Lawrence L. Latour ◽  
Chen-Sen Wu ◽  
Julio A. Chalela ◽  
Steven Warach
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Transit Time ◽  
Neurological Deficit ◽  
Mean Transit Time

scholarly journals Elevated brain oxygen extraction fraction measured by MRI susceptibility relates to perfusion status in acute ischemic stroke

2019 ◽  
Vol 40 (3) ◽  
pp. 539-551 ◽  
Author(s):  
Audrey P Fan ◽  
Ahmed A Khalil ◽  
Jochen B Fiebach ◽  
Greg Zaharchuk ◽  
Arno Villringer ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Venous Blood ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Cerebral Veins ◽  
Dynamic Susceptibility ◽  
Longitudinal Assessment ◽  
Stroke Patients ◽  
Extraction Fraction

Recent clinical trials of new revascularization therapies in acute ischemic stroke have highlighted the importance of physiological imaging to identify optimal treatments for patients. Oxygen extraction fraction (OEF) is a hallmark of at-risk tissue in stroke, and can be quantified from the susceptibility effect of deoxyhemoglobin molecules in venous blood on MRI phase scans. We measured OEF within cerebral veins using advanced quantitative susceptibility mapping (QSM) MRI reconstructions in 20 acute stroke patients. Absolute OEF was elevated in the affected (29.3 ± 3.4%) versus the contralateral hemisphere (25.5 ± 3.1%) of patients with large diffusion–perfusion lesion mismatch ( P = 0.032). In these patients, OEF negatively correlated with relative CBF measured by dynamic susceptibility contrast MRI ( P = 0.004), suggesting compensation for reduced flow. Patients with perfusion–diffusion match or no hypo-perfusion showed less OEF difference between hemispheres. Nine patients received longitudinal assessment and showed OEF ratio (affected to contralateral) of 1.2 ± 0.1 at baseline that normalized (decreased) to 1.0 ± 0.1 at follow-up three days later ( P = 0.03). Our feasibility study demonstrates that QSM MRI can non-invasively quantify OEF in stroke patients, relates to perfusion status, and is sensitive to OEF changes over time. Clinical trial registration: Longitudinal MRI examinations of patients with brain ischemia and blood brain barrier permeability; clinicaltrials.org : NCT02077582

Prolonged Mean Transit Time Detected by Dynamic Susceptibility Contrast Magnetic Resonance Imaging Predicts Cerebrovascular Reserve Impairment in Patients with Moyamoya Disease

2016 ◽  
Vol 42 (1-2) ◽  
pp. 131-138 ◽  
Author(s):  
Takayuki Kawano ◽  
Yuki Ohmori ◽  
Yasuyuki Kaku ◽  
Daisuke Muta ◽  
Ken Uekawa ◽  
...  
Keyword(s):  
Transit Time ◽  
Moyamoya Disease ◽  
Cerebral Artery ◽  
Mean Transit Time ◽  
Photon Emission ◽  
Dynamic Susceptibility ◽  
Dynamic Susceptibility Contrast ◽  
Cerebrovascular Reserve ◽  
Dsc Mri ◽  
Susceptibility Contrast

Background: Evaluating cerebrovascular reserve (CVR) is important for patients with moyamoya disease (MMD). 123I-iodoamphetamine single-photon emission CT (SPECT) with acetazolamide (ACZ) challenge is widely carried out, but using ACZ becomes problematic owing to its off-label use and its adverse effects. Here, we report the efficacy of dynamic susceptibility contrast MRI (DSC-MRI) for the evaluation of CVR in MMD patients. Methods: All 33 MMD patients underwent both SPECT and DSC-MRI at an interval of <10 days from each other (mean age 38.3 years). The region of interest (ROI) was the anterior cerebral artery (ACA) territory, middle cerebral artery (MCA) territory, basal ganglia and cerebellum hemisphere for cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) images. The ratios of the ROIs to the ipsilateral cerebellum were calculated for each parameter and evaluated. The CVR was calculated using images acquired by SPECT before and after ACZ administration. The ratios of DSC-MRI parameters and CVR were compared and evaluated for each ROI. Results: The MTT of the ACA and MCA territories significantly correlated with CVR (p < 0.0001). However, CBF and CBV had no correlation with CVR. The MTT ratio had a threshold of 1.966, with a sensitivity of 68.4% and a specificity of 91.5% for predicting decreased CVR (<10%). Conclusion: MTT had a negative correlation with CVR. DSC-MRI is easy, safe and useful for detecting decreased CVR and can be used as a standard examination in MMD patient's care.

Cerebral vascular mean transit time determined by PET and DSC-MRI

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S676-S676
Author(s):  
Masanobu Ibaraki ◽  
Hiroshi Ito ◽  
Eku Shimosegawa ◽  
Hideto Toyoshima ◽  
Keiichi Ishigame ◽  
...  
Keyword(s):  
Transit Time ◽  
Mean Transit Time ◽  
Dsc Mri ◽  
Cerebral Vascular
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