Magnetic resonance brain imaging in patients with acute stroke: feasibility and patient related difficulties

Abstract

Objectives: To assess organisational and patient specific limitations and safety of magnetic resonance imaging (MRI) as the first line investigation for hospital admitted stroke patients. Methods: Consecutive patients admitted with acute stroke were assessed and an attempt was made to perform MRI in all patients. Oxygen saturation and interventions required during scanning were recorded. Results: Among 136 patients recruited over 34 weeks, 85 (62%) underwent MRI. The patients' medical instability (15 of the 53 not scanned), contraindications to MRI (six of the 53 not scanned), and rapid symptom resolution (10 of the 53 not scanned) were the main reasons for not performing MRI. Of the 85 patients who underwent MRI, 26 required physical intervention, 17 did not complete scanning, and 11 of the 61 who had successful oxygen saturation monitoring were hypoxic during MRI. Organisational limitations accounted for only 13% of failures to scan. Conclusions: Up to 85% of hospital admitted acute stroke patients could have MRI as first line imaging investigation, but medical instability is the major limitation. Hypoxia is frequent in MRI. Patients should be monitored carefully, possibly by an experienced clinician, during scanning. M agnetic resonance imaging (MRI) has been advocated as a method of improving the selection of patients with stroke for thrombolysis.1 However, MRI has more contraindications, is more difficult to perform in ill patients, and takes longer than computed tomography scanning.The current issue is to determine the proportion of patients with acute stroke in whom MRI is achievable, and how to identify (in the acute situation) those in whom MRI is unlikely to be successful. Studies of imaging appearances in selected patients, 2 or which were retrospective but gave no indication of the actual number of suspected strokes not referred for MRI in the same time period, 3 4 have not provided such information. One recent prospective study found that 20% of 144 stroke patients recruited ''at the hospital door'' could not have MRI (of whom half had MRI contraindications and half were medically unstable).5 No study has investigated whether MRI is safe in acute stroke.We aimed to determine: (1) whether it was possible to use MRI as the first line assessment for all suspected acute strokes, and (2) the limitations and safety of MRI in acute stroke. METHODSFrom among all consecutive admissions to our hospital (population served, 500 000) with suspected acute stroke, patients were eligible for the MRI feasibility study if they could be assessed by a clinical research fellow and scanned within 24 hours of stroke, and the clinical diagnosis was probable or definite stroke (transient ischaemic attacks and obvious non-strokes were excluded).We recorded time of stroke and assessment, clinical features, neurological deficit (National Institutes of Health Stroke Scale Score (NIHSS): http://www.strokecenter.org/ trials/scales/) and stroke subtype. 6 An experienced neurologist assessed the risk of complications occurring duri...

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