Clinical implication and prognosis of normal baseline cerebral blood flow with impaired vascular reserve in patients with major cerebral artery occlusive disease

Isozaki, Makoto; Arai, Yoshikazu; Kudo, Takashi; Kiyono, Yasushi; Kobayashi, Masato; Kubota, Toshihiko; Kikuta, Ken-ichiro; Okazawa, Hidehiko

doi:10.1007/s12149-010-0367-9

Cited by 21 publications

(17 citation statements)

References 15 publications

(46 reference statements)

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“…This finding adds to those in previous studies that investigated associations between impaired CVR and increased stroke risk. 4,11,[19][20][21][22][23][24][25][26][27][28][29][30] Nine of 12 studies found a positive association of reduced or exhausted CVR and recurrent risk of future ischemic events or stroke by using a range of vasodilatory stimuli and CVR metrics. The negative findings may be explained by insufficient vasodilatory stimuli because 2 of the studies with negative findings 3,4 used carbogen (typically 5% CO 2 ), whereas Markus and Cullinane 11 showed that exhausted CVR as assessed by hypercapnia transcranial Doppler with 6% or 8% CO 2 independently predicted future stroke and that the prediction was stronger for 8% CO 2 challenges.…”

Section: Discussionmentioning

confidence: 99%

Impaired Cerebrovascular Reactivity Predicts Recurrent Symptoms in Patients with Carotid Artery Occlusion: A Hypercapnia BOLD fMRI Study

Goode

Altaf

Munshi

et al. 2016

American Journal of Neuroradiology

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BACKGROUND AND PURPOSE:A key factor in predicting recurrent ischemic episodes in patients with carotid artery occlusion is the presence of hemodynamic impairment. There is, however, no consensus on how to best assess this risk in terms of imaging modalities or thresholds used. Here we investigated whether a predefined threshold of hemispheric asymmetry in hypercapnia fMRI predicts recurrent symptoms in patients with carotid artery occlusion.

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Section: Discussionmentioning

confidence: 99%

Impaired Cerebrovascular Reactivity Predicts Recurrent Symptoms in Patients with Carotid Artery Occlusion: A Hypercapnia BOLD fMRI Study

Goode

Altaf

Munshi

et al. 2016

American Journal of Neuroradiology

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“…The CVR threshold of 15% between groups B and C was determined based on previous studies, which set thresholds from 10% to 20% [23][24][25] . The CBF b , CBV, OEF, CMRO 2 , and CBF b /CBV ratio were compared between the three groups and evaluated in comparison to the controls.…”

Section: Discussionmentioning

confidence: 99%

Paradoxical reduction of cerebral blood flow after acetazolamide loading: a hemodynamic and metabolic study with 15O PET

et al. 2014

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Paradoxical reduction of cerebral blood flow (CBF) after administration of the vasodilator acetazolamide is the most severe stage of cerebrovascular reactivity failure and is often associated with an increased oxygen extraction fraction (OEF). In this study, we aimed to reveal the mechanism underlying this phenomenon by focusing on the ratio of CBF to cerebral blood volume (CBV) as a marker of regional cerebral perfusion pressure (CPP). In 37 patients with unilateral internal carotid or middle cerebral arterial (MCA) steno-occlusive disease and 8 normal controls, the baseline CBF (CBF b ), CBV, OEF, cerebral oxygen metabolic rate (CMRO 2 ), and CBF after acetazolamide loading in the anterior and posterior MCA territories were measured by 15 O positron emission tomography. Paradoxical CBF reduction was found in 28 of 74 regions (18 of 37 patients) in the ipsilateral hemisphere. High CBF b (>47.6 mL/100 mL/min, n = 7) was associated with normal CBF b /CBV, increased CBV, decreased OEF, and normal CMRO 2 . Low CBF b (<31.8 mL/100 mL/min, n = 9) was associated with decreased CBF b /CBV, increased CBV, increased OEF, and decreased CMRO 2 . These fi ndings demonstrated that paradoxical CBF reduction is not always associated with reduction of CPP, but partly includes high-CBF b regions with normal CPP, which has not been described in previous studies.

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“…This hemodynamic parameter has been called cerebrovascular reserve, and there have been two main approaches to measure this risk factor on imaging studies. One approach involves obtaining direct brain CBF measurements using PET [20], nuclear medicine techniques [21,22], CT perfusion [23], or MR perfusion [24,25] before and after a vasodilatory stimulus. The second approach involves measurement of flow velocities as a surrogate for CBF [26,27,28] (typically in the MCA via transcranial Doppler) distal to a lesion both before and after a vasodilatory stimulus.…”

Section: Hemodynamic Stroke Risk Assessment Strategiesmentioning

confidence: 99%

Moving Beyond Luminal Stenosis: Imaging Strategies for Stroke Prevention in Asymptomatic Carotid Stenosis

Gupta¹,

Marshall

2015

Cerebrovasc Dis

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Background: With progressive improvements in medical therapy and resultant reductions in stroke risk, luminal stenosis criteria are no longer adequate to inform decisions to pursue surgical revascularization in patients with asymptomatic carotid artery stenosis. Summary: In this evidence-based review, we discuss the imaging-based risk stratification strategies that take into account factors beyond luminal stenosis measurements, including cerebral hemodynamics and plaque composition. The existing literature lends support to the use of certain imaging tests in patients with asymptomatic carotid stenosis including cerebrovascular reserve testing, MRI of plaque composition, ultrasound of plaque echolucency, and transcranial Doppler evaluation for microemboli. The highest quality evidence thus far in the literature includes only systematic reviews and meta-analyses of cohort studies with no randomized trials having yet been performed to show how these newer imaging biomarkers could be used to inform treatment decisions in asymptomatic carotid stenosis. Beyond the need for randomized trials, there are additional important steps needed to improve the relevance of evidence supporting risk assessment strategies. Imaging studies evaluating the risk of stroke in carotid disease should clearly define asymptomatic versus symptomatic disease, use uniform definitions of clearly defined outcome measures such as ipsilateral stroke, ensure that imaging interpretations are performed in a manner blinded to treatments and other risk factors, and include cohorts which are on modern intensive medical therapy. Such studies of risk stratification for asymptomatic carotid stenosis will be most valuable if they can integrate multiple high-risk features (including clinical risk factors) into a multi-factorial risk assessment strategy in a manner that is relatively simple to implement and generalizable across a wide range of practice settings. Key Messages: Together, modern imaging strategies allow for a more mechanistic assessment of stroke risk in carotid disease compared to luminal stenosis measurements alone, which, with further validation in randomized controlled trials, may improve current efforts at stroke prevention in asymptomatic carotid stenosis.

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Clinical implication and prognosis of normal baseline cerebral blood flow with impaired vascular reserve in patients with major cerebral artery occlusive disease

Cited by 21 publications

References 15 publications

Impaired Cerebrovascular Reactivity Predicts Recurrent Symptoms in Patients with Carotid Artery Occlusion: A Hypercapnia BOLD fMRI Study

Impaired Cerebrovascular Reactivity Predicts Recurrent Symptoms in Patients with Carotid Artery Occlusion: A Hypercapnia BOLD fMRI Study

Paradoxical reduction of cerebral blood flow after acetazolamide loading: a hemodynamic and metabolic study with 15O PET

Moving Beyond Luminal Stenosis: Imaging Strategies for Stroke Prevention in Asymptomatic Carotid Stenosis

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