Systematic Review of CT and MR Perfusion Imaging for Assessment of Acute Cerebrovascular Disease

Provenzale, James M.; Shah, Komal; Patel, Uthsavi N; McCrory, Douglas C

doi:10.3174/ajnr.a1161

Cited by 43 publications

(31 citation statements)

References 54 publications

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“…Second, the ischemic penumbra evidenced by perfusion-diffusion mismatch (not evaluated in the current study) can produce symptoms that are clinically indistinguishable from those produced by the infarct core. 36 The ischemic penumbra represents severely hypoperfused tissue around an infarct core; the neurons in the penumbra are supposedly structurally intact but functionally inactive, so penumbral areas are potentially salvageable. 37 In our sample, the ischemic penumbra could explain why some patients without CST involvement by infarct presented motor deficits in the acute stage and why the initial motor deficit did not correlate with motor outcome, though the effects of the ischemic penumbra are limited to the acute phase and have no direct effect on the long-term outcome.…”

Section: Discussionmentioning

confidence: 99%

Acute Damage to the Posterior Limb of the Internal Capsule on Diffusion Tensor Tractography as an Early Imaging Predictor of Motor Outcome after Stroke

Puig¹,

Pedraza²,

Blasco³

et al. 2011

AJNR Am J Neuroradiol

152

124

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Section: Discussionmentioning

confidence: 99%

Acute Damage to the Posterior Limb of the Internal Capsule on Diffusion Tensor Tractography as an Early Imaging Predictor of Motor Outcome after Stroke

Puig¹,

Pedraza²,

Blasco³

et al. 2011

AJNR Am J Neuroradiol

152

124

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“…Few studies have directly examined how CT perfusion affects clinical decision-making or influences patient outcomes, 18 and the clinically acceptable limits of variability in CT perfusion results are unknown. These gaps in the medical literature call attention to the need for future studies to define the role of CT perfusion in acute stroke management.…”

Section: Discussionmentioning

confidence: 99%

Sources of variability in computed tomography perfusion: implications for acute stroke management

Zussman

Jabbour²,

Talekar

et al. 2011

FOC

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Object Although dynamic, first-pass cerebral CT perfusion is used in the evaluation of acute ischemic stroke, a lack of standardization restricts the value of this imaging modality in clinical decision-making. The purpose of this study was to comprehensively review the reported sources of variability and error in cerebral CT perfusion results. Methods A systematic literature review was conducted, 120 articles were reviewed, and 23 published original research articles were included. Sources of variability and error were thematically categorized and presented within the context of the 3 stages of a typical CT perfusion study: data acquisition, postprocessing, and results interpretation. Results Seven factors that caused variability were identified and described in detail: 1) contrast media, the iodinated compound injected intravascularly to permit imaging of the cerebral vessels; 2) data acquisition rate, the number of images obtained by CT scan per unit time; 3) user inputs, the subjective selections that operators make; 4) observer variation, the failure of operators to repeatedly measure a perfusion parameter with precision; 5) software operational mode, manual, semiautomatic, or automatic; 6) software design, the mathematical algorithms used to perform postprocessing; and 7) value type, absolute versus relative values. Conclusions Standardization at all 3 stages of the CT perfusion study cycle is warranted. At present, caution should be exercised when interpreting CT perfusion results as these values may vary considerably depending on a variety of factors. Future research is needed to define the role of CT perfusion in clinical decision-making for acute stroke patients and to determine the clinically acceptable limits of variability in CT perfusion results.

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“…injection of MR contrast agent had been available for MR imaging (MRI) for about 10 years, and became available for CT about 6 years prior to the start of the IST-3 substudy. 20,21 However, a consensus on how the perfusion data should be processed, [22][23][24] or which thresholds distinguish tissue at risk, 25 was still to be established. Thus, it had long been considered that advanced imaging methods with CT perfusion (CTP) or MR DWI and perfusion-weighted imaging (PWI) could help focus use of rt-PA on patients with large amounts of tissue at risk and avoid exposing those with little at-risk tissue to the risk of rt-PA.…”

Section: Fundingmentioning

confidence: 99%

Imaging perfusion deficits, arterial patency and thrombolysis safety and efficacy in acute ischaemic stroke. Anobservational study of the effect of advanced imaging methods in The Third International Stroke Trial (IST-3), arandomised controlled trial

Wardlaw

Carpenter

Sakka

et al. 2014

Efficacy and Mechanism Evaluation

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BackgroundIntravenous thrombolysis with recombinant tissue plasminogen activator (rt-PA) improves outcome after an ischaemic stroke but increases the risk of intracranial haemorrhage. Restricting rt-PA to patients with salvageable tissue, or arterial occlusion, might reduce risk, increase benefit and enable treatment at late time windows.ObjectivesTo determine if computed tomography (CT) or magnetic resonance (MR) perfusion or angiography (CTP/CTA; MRP/MRA) imaging provide important information to guide the use of rt-PA up to 6 hours after a stroke.DesignProspective, multicentre, randomised, open, blinded, end-point trial of rt-PA.SettingForty-eight centres (eight countries) performed CTP/CTA; 37 centres (11 countries) performed MRP/MRA.ParticipantsPatients aged over 18 years in whom brain scanning excluded intracranial haemorrhage, with known time of stroke onset and no clear indication for or contraindication to rt-PA, in whom treatment can start within 6 hours of a stroke.Interventionsrt-PA (0.9 mg/kg, maximum dose 90 mg) intravenously (10% bolus, the rest infused over 1 hour) compared with best medical care.Main outcome measuresPrimary – alive and independent (Oxford Handicap Score 0–2) at 6 months; secondary – symptomatic and fatal intracranial haemorrhage, early and late death. All imaging assessed centrally, blind to other data. Perfusion lesion sizes [cerebral blood volume (CBV); cerebral blood flow; mean transit time (MTT); time to maximum flow], angiographic occlusion, associations with plain scan findings, clinical baseline and outcomes, and the interaction with rt-PA were assessed with dichotomous and ordinal analyses.ResultsBaseline characteristics of patients in the Third International Stroke Trial (IST-3) with perfusion and angiography imaging did not differ from those without (95% did not meet the prevailing licence criteria for rt-PA): 151 patients had perfusion imaging and 423 had angiography (141 and 307 obtained at randomisation respectively). Most randomisation imaging was with CT (n = 125/141, 89% perfusion;n = 277/307, 90% angiography) with little MR (n = 16/141, 11% perfusion;n = 39/307, 10% angiography). The median patient age was 81 (interquartile range 71–86) years; perfusion imaging or angiography imaging was performed at median of 3.9 hours after stroke. Perfusion lesion size differed significantly between parameters (MTT lesions largest, CBV lesions smallest;p < 0.0000; 46% had mismatch). Patients scanned earlier, who were older, or with more severe stroke, had larger perfusion lesions. Larger perfusion lesions were associated with poor outcome. Neither perfusion lesion size nor mismatch modified rt-PA effect on haemorrhage or 6-month outcome. Randomisation CTA (n = 253) showed arterial stenosis/occlusion in 42% (95% confidence interval 34% to 47%). Abnormal plain CT and plain CT + CTA were equally associated with worse baseline stroke severity, imaging and functional outcomes. rt-PA accelerated dissolution of arterial thrombus and reduced thrombus extension, but rt-PA effects did not differ between patients with angiographic occlusion compared with those without.ConclusionLarger perfusion lesions and arterial occlusion are associated with severe stroke and worse outcomes. However, patients with perfusion lesions, mismatch or angiographic occlusion had similar benefit and no worse hazard from rt-PA compared with those without. Visual assessment is an effective classification method. Perfusion or angiography imaging may improve diagnostic confidence in acute stroke but this does not improve prediction of prognosis or identify patients who respond differently to rt-PA. Although this trial is larger than others, the conclusion regarding perfusion imaging is limited by the sample size.Trial registrationCurrent Controlled Trials ISRCTN25765518.FundingThis project was funded by the NIHR Efficacy and Mechanism Evaluation programme and the Medical Research Council, and will be published in full inEfficacy and Mechanism Evaluation; Vol. 1, No. 1. See the NIHR Journals Library website for further project information.

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Systematic Review of CT and MR Perfusion Imaging for Assessment of Acute Cerebrovascular Disease

Cited by 43 publications

References 54 publications

Acute Damage to the Posterior Limb of the Internal Capsule on Diffusion Tensor Tractography as an Early Imaging Predictor of Motor Outcome after Stroke

Acute Damage to the Posterior Limb of the Internal Capsule on Diffusion Tensor Tractography as an Early Imaging Predictor of Motor Outcome after Stroke

Sources of variability in computed tomography perfusion: implications for acute stroke management

Imaging perfusion deficits, arterial patency and thrombolysis safety and efficacy in acute ischaemic stroke. Anobservational study of the effect of advanced imaging methods in The Third International Stroke Trial (IST-3), arandomised controlled trial

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