Quantitative cerebral MR perfusion imaging: Preliminary results in stroke

Shah, Maulin; Shin, Wanyong; Parikh, Vishal S.; Ragin, Ann B.; Mouannes, Jessy; Bernstein, Richard A.; Walker, Matthew T.; Bhatt, Hem M.; Carroll, Timothy J.

doi:10.1002/jmri.22302

Cited by 24 publications

(22 citation statements)

References 42 publications

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“…Bookend technique was used to calculate quantitative perfusion parameters including cerebral blood volume (CBV), flow (CBF) and mean transit time (MTT) 11, 14, 15 . Briefly, bookend technique calibrates relative values to quantitative based on parenchymal T1 changes (in ms) in response to the contrast agent injections (pre-contrast vs post-contrast) used as part of a DSC perfusion scan.…”

Section: Methodsmentioning

confidence: 99%

Cortical Perfusion Alteration in Normal-Appearing Gray Matter Is Most Sensitive to Disease Progression in Relapsing-Remitting Multiple Sclerosis

Hojjat

Kincal

Vitorino

et al. 2016

American Journal of Neuroradiology

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Purpose The role of gray matter in Multiple sclerosis (MS) is increasingly evident; however conventional magnetic resonance (MR) images demonstrate limitations in cortical lesion (CL) identification. Perfusion imaging appears sensitive to changes in tissue type and disease severity in MS. We sought to utilize bookend perfusion to quantify parameters in healthy controls (HC), normal appearing and lesional tissue at different RRMS stages. Methods Thirty-nine RRMS patients and 19 age-matched HC were prospectively recruited. MACFIMS battery was used to assess cognitive performance. Perfusion parameters including cerebral blood flow (CBF) and volume (CBV) and mean transit time (MTT) were compared for HC, normal appearing and lesional tissue for all study groups. Dispersion of perfusion measures for white matter lesion (WML) and CLs were assessed. Results Twenty of the 39 RRMS patients were cognitively impaired (RRMS-I). Significant differences were displayed between all RRMS subgroups and HC except for normal appearing gray matter (NAGM) CBV between HC and unimpaired RRMS patients (RRMS-NI) and for all normal appearing white matter (NAWM) perfusion parameters between HC and RRMS-NI. WML but not CL perfusion was significantly reduced in RRMS-I versus RRMS-NI. Perfusion reduction with disease progression was greater in NAGM and NAWM compared to CL and WML. Smaller dispersion was observed for CLs compared to WML for each perfusion parameter. Conclusion Quantitative GM and WM analysis demonstrates significant but disproportionate WML, CL, NAWM and NAGM changes present between healthy controls and RRMS patients with and without cognitive impairment necessitating absolute rather than relative lesion perfusion measurement.

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Section: Methodsmentioning

confidence: 99%

Cortical Perfusion Alteration in Normal-Appearing Gray Matter Is Most Sensitive to Disease Progression in Relapsing-Remitting Multiple Sclerosis

Hojjat

Kincal

Vitorino

et al. 2016

American Journal of Neuroradiology

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“…Based on previous studies, four commonly-used thresholds of “perfusion deficits” were chosen to test a range of varying perfusion deficit severities. [15-17] For MTTp, thresholds of 3, 4, 5, and 6 seconds (s) were tested. For TTP and Tmax, thresholds of 2, 4, 6, and 8s were tested.…”

Section: Methodsmentioning

confidence: 99%

Clinically Relevant Reperfusion in Acute Ischemic Stroke: MTT Performs Better than Tmax and TTP

Ford

Kong

et al. 2014

Transl. Stroke Res.

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Background While several MRI parameters are used to assess tissue perfusion during hyperacute stroke, it is unclear which is optimal for measuring clinically-relevant reperfusion. We directly compared MTT prolongation (MTTp), TTP, and time-to-maximum (Tmax) to determine which best predicted neurological improvement and tissue salvage following early reperfusion. Methods Acute ischemic stroke patients underwent three MRI's: <4.5hr (tp1), at 6hr (tp2), and at 1 month after onset. Perfusion deficits at tp1 and tp2 were defined by MTTp, TTP, or Tmax beyond four commonly-used thresholds. Percent reperfusion (%Reperf) was calculated for each parameter and threshold. Regression analysis was used to fit %Reperf for each parameter and threshold as a predictor of neurological improvement [defined as admission National Institutes of Health Stroke Scale (NIHSS) – 1 month NIHSS (ΔNIHSS)] after adjusting for baseline clinical variables. Volume of reperfusion, for each parameter and threshold, was correlated with tissue salvage, defined as tp1 perfusion deficit volume – final infarct volume. Results 50 patients were scanned at 2.7 hours and 6.2 hours after stroke onset. %Reperf predicted ΔNIHSS for all MTTp thresholds, for Tmax > 6s and > 8s, but for no TTP thresholds. Tissue salvage significantly correlated with reperfusion for all MTTp thresholds and with Tmax > 6s, while there was no correlation with any TTP threshold. Among all parameters, reperfusion defined by MTTp was most strongly associated with ΔNIHSS (MTTp>3s, p=0.0002) and tissue salvage (MTTp> 3s and 4s, P<0.0001). Conclusion MTT-defined reperfusion was the best predictor of neurological improvement and tissue salvage in hyperacute ischemic stroke.

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“…Recently, several methods for improving the reliability of the assessment of perfusion with MRI methods were proposed (38)(39)(40), but they all need to be validated by quantitative measures. Therefore, PET-validated and -calibrated thresholds of the most predictive MRI perfusion maps must be implemented for optimal mismatch detection.…”

Section: Pwi Of Penumbramentioning

confidence: 99%

Validation of MRI Determination of the Penumbra by PET Measurements in Ischemic Stroke

Heiss

Weber

2016

J Nucl Med

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The concept of the ischemic penumbra was formulated on the basis of animal experiments showing functional impairment and electrophysiologic disturbances with decreasing flow to the brain below defined values (the threshold for function) and irreversible tissue damage with blood supply further decreased (the threshold for infarction). The perfusion range between these thresholds was termed the "penumbra," and restitution of flow above the functional threshold was able to reverse the deficits without permanent damage. In further experiments, the dependency of the development of irreversible lesions on the interaction of the severity and the duration of critically reduced blood flow was established, proving that the lower the flow, the shorter the time for efficient reperfusion. As a consequence, infarction develops from the core of ischemia to the areas of less severe hypoperfusion. The translation of this experimental concept as the basis for the efficient treatment of stroke requires noninvasive methods with which regional flow and energy metabolism can be repeatedly investigated to demonstrate penumbra tissue, which can benefit from therapeutic interventions. PET allows the quantification of regional cerebral blood flow, the regional oxygen extraction fraction, and the regional metabolic rate for oxygen. With these variables, clear definitions of irreversible tissue damage and of critically hypoperfused but potentially salvageable tissue (i.e., the penumbra) in stroke patients can be achieved. However, PET is a research tool, and its complex logistics limit clinical routine applications. Perfusion-weighted or diffusion-weighted MRI is a widely applicable clinical tool, and the "mismatch" between perfusion-weighted and diffusion-weighted abnormalities serves as an indicator of the penumbra. However, comparative studies of perfusion-weighted or diffusionweighted MRI and PET have indicated overestimation of the core of irreversible infarction as well as of the penumbra by the MRI modalities. Some of these discrepancies can be explained by the nonselective application of relative perfusion thresholds, which might be improved by more complex analytic procedures. The heterogeneity of the MRI signatures used for the definition of the mismatch are also responsible for disappointing results in the application of perfusion-weighted or diffusion-weighted MRI to the selection of patients for clinical trials. As long as validation of the mismatch selection paradigm is lacking, the use of this paradigm as a surrogate marker of outcome is limited. ENERGY REQUIREMENTS OF BRAIN TISSUEBecause the energy demand of nervous tissue is very high, sufficient blood supply to the brain must be maintained consistently. The oxygen consumption of the brain is involved almost entirely in the oxidative metabolism of glucose which, in normal physiologic conditions, is the almost exclusive substrate for the energy metabolism of the brain (1). The glucose metabolized in neuronal cell bodies is used mainly to support cellular vegetative and hou...

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Quantitative cerebral MR perfusion imaging: Preliminary results in stroke

Cited by 24 publications

References 42 publications

Cortical Perfusion Alteration in Normal-Appearing Gray Matter Is Most Sensitive to Disease Progression in Relapsing-Remitting Multiple Sclerosis

Cortical Perfusion Alteration in Normal-Appearing Gray Matter Is Most Sensitive to Disease Progression in Relapsing-Remitting Multiple Sclerosis

Clinically Relevant Reperfusion in Acute Ischemic Stroke: MTT Performs Better than Tmax and TTP

Validation of MRI Determination of the Penumbra by PET Measurements in Ischemic Stroke

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