[Plain language title]

Brazzelli M, Sandercock PAG, Chappell FM, Celani MG, Righetti E, Arestis N, Wardlaw JM, Deeks JJ

Published Online:

October 7, 2009

[Summary text]

Abstract (click to read)

Background:

Magnetic resonance imaging (MRI) is increasingly used for the diagnosis of acute ischaemic stroke but its sensitivity for the early detection of intracerebral haemorrhage has been debated. Computed tomography (CT) is extensively used in the clinical management of acute stroke, especially for the rapid exclusion of intracerebral haemorrhage.

Objectives:

To compare the diagnostic accuracy of diffusion-weighted MRI (DWI) and CT for acute ischaemic stroke, and to estimate the diagnostic accuracy of MRI for acute haemorrhagic stroke.

Search strategy:

We searched MEDLINE and EMBASE (January 1995 to March 2009) and perused bibliographies of relevant studies for additional references.

Selection criteria:

We selected studies that either compared DWI and CT in the same patients for detection of ischaemic stroke or examined the utility of MRI for detection of haemorrhagic stroke, had imaging performed within 12 hours of stroke onset, and presented sufficient data to allow construction of contingency tables.

Data collection and analysis:

Three authors independently extracted data on study characteristics and measures of accuracy. We assessed data on ischaemic stroke using random-effects and fixed-effect meta-analyses.

Main results:

Eight studies with a total of 308 participants met our inclusion criteria. Seven studies contributed to the assessment of ischaemic stroke and two studies to the assessment of haemorrhagic stroke. The spectrum of patients was relatively narrow in all studies, sample sizes were small, there was substantial incorporation bias, and blinding procedures were often incomplete. Amongst the patients subsequently confirmed to have acute ischaemic stroke (161/226), the summary estimates for DWI were: sensitivity 0.99 (95% CI 0.23 to 1.00), specificity 0.92 (95% CI 0.83 to 0.97). The summary estimates for CT were: sensitivity 0.39 (95% CI 0.16 to 0.69), specificity 1.00 (95% CI 0.94 to 1.00). The two studies on haemorrhagic stroke reported high estimates for diffusion-weighted and gradient-echo sequences but had inconsistent reference standards. We did not calculate overall estimates for these two studies. We were not able to assess practicality or cost-effectiveness issues.

Authors' conclusions:

DWI appears to be more sensitive than CT for the early detection of ischaemic stroke in highly selected patients. However, the variability in the quality of included studies and the presence of spectrum and incorporation biases render the reliability and generalisability of observed results questionable. Further well-designed studies without methodological biases, in more representative patient samples, with practicality and cost estimates are now needed to determine which patients should undergo MRI and which CT in suspected acute stroke.

This record should be cited as:

Brazzelli M, Sandercock PAG, Chappell FM, Celani MG, Righetti E, Arestis N, Wardlaw JM, Deeks JJ. Magnetic resonance imaging versus computed tomography for detection of acute vascular lesions in patients presenting with stroke symptoms. Cochrane Database of Systematic Reviews 2009, Issue 4. Art. No.: CD007424. DOI: 10.1002/14651858.CD007424.pub2

Assessed as up to date:

May 25, 2009

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Primary Review Group:

Stroke Group

PEARLS - Practical Evidence About Real Life Situations (click to read)

Clinical question:

How effective is the diagnostic accuracy of diffusion-weighted magnetic resonance imaging (DWI) compared to computed tomography (CT) for acute ischaemic stroke, and what is the diagnostic accuracy of DWI for acute haemorrhagic stroke?

Bottom line:

There was some evidence that DWI is more accurate than CT for the detection of mild ischaemic strokes in highly selected patients. The 2 studies on haemorrhagic stroke reported high estimates for diffusion-weighted and gradient-echo sequence MRI but had inconsistent reference standards.

Caveat:

Given the variability in the quality of included studies and the very selected populations studied, the reliability and generalisability of the observed results are questionable. Practicality and costeffectiveness issues were not assessed.

Context:

DWI is increasingly used for the diagnosis of acute ischaemic stroke but its sensitivity for the early detection of haemorrhagic stroke has been debated. CT is extensively used in the clinical management of acute stroke, especially for the rapid exclusion of haemorrhagic stroke.

Cochrane Systematic Review:

Brazzelli M et al. Magnetic resonance imaging versus computed tomography for detection of acute vascular lesions in patients presenting with stroke symptoms. Cochrane Reviews 2009, Issue 4. Article No. CD007424. DOI: 10.1002/14651858. CD007424.pub2. This review contains 8 studies involving 308 participants.

Authored by:

Brian R McAvoy

Cochrane Primary Health Care Field

Health topics:

Heart & circulation > Stroke > Diagnosis

Neurology > Stroke > Diagnosis

Methodological & diagnostic > Diagnostic test accuracy

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