Zain A. Bhutta

Hamad Medical Corporation, Qatar


Dr. Zain A. Bhutta is a Doctoral Research Fellow in the Department of Emergency Medicine at Hamad Medical Corporation and PhD candidate at the University of Helsinki. He completed his medical licentiate degree from Dow University of Health Sciences and proceeded into an Internal Medicine residency training program at Aga Khan University Hospital. He completed a doctoral level post graduate emergency medicine research short course from the Department of Epidemiological and Preventive Medicine, Monash University, Australia before starting his Doctoral studies at the University of Helsinki. He is currently a Clinical Scientist and Research Lead in the Department of Emergency Medicine. His work is centred on evaluating and improving pre-hospital and emergency department delays in stroke management and health programs impact evaluation.


INTRODUCTION: Patients presenting with symptoms of an acute focal neurologic deficits have multiple underlying etiologies where MR imaging may be useful for confirmation the potential cause. The aim of our study was to evaluate the usefulness of MRI in patients presenting with a suspected diagnosis of acute stroke.

METHODS: We admitted 4400 patients with the diagnosis of acute stroke between Jan 2014 and June 2017 at Hamad Medical Corporation. A total of 2880 patients underwent 3T MRI within 48 hours of admission. Patients were assessed for demographics, risk factors, clinical features, severity of stroke and outcome. Multivariate regression analysis done to find out predictors of abnormal MRI and 90-day prognosis.

RESULTS: Mean age was 55.9 (±13.2) and 83.3% were male (1570/1885). Ischemic stroke was diagnosed in 65.4% (1885/2880) including lacunar strokes 44.1% (831), cortical strokes 26.6% (502), and posterior circulation stroke 29.3% (552). Normal MRI was found in 5.4% (n=101) in patients with confirmed ischemic stroke. Normal MRI was more frequent in lacunar strokes compared to posterior circulation or cortical strokes (62.4%, 24.8% and 12.9%, p<0.0001). Abnormal MRI was significantly higher patients with diabetes (55.5% vs 43.6%, p=0.019), dyslipidemia (54.9% vs 43.6%, p= 0.026), higher systolic blood pressure at arrival
(157.8 vs151.7 mmHg, p=0.047), higher admitting NIHSS (5.21 vs 3.43, p<0.0001), higher Hba1c on (7.5% vs 6.9%, p=0.021) and higher serum cholesterol (5.06 vs 4.62, p=0.002). Patients with normal MRI were found to have better 90-day prognosis (mRS 0-2) as compared to patients with abnormal MRI on admission (68.3% vs 53.0%, p=0.003). On multivariate analysis, after adjusting for age and other factors, NIHSS (p=0.011, OR=1.096 [CI 1.021-1.176]) and higher serum cholesterol levels (p0.015, OR 1.340 [CI 1.059-1.696]) were associated with higher frequency of abnormal MRI.

CONCLUSION: After excluding mimics and TIAs, 5.4 % of patients with acute ischemic stroke have normal MRI. These patients have lower NIHSS, are more likely to have lacunar stroke and have a significantly better prognosis.

Take Away Points:

1. Normal MRI should be expected more frequently in lacunar strokes compared to posterior circulation or cortical strokes.
2. Abnormalities in MRI and ischemic injury is more evident in patients with diabetes, dyslipidemia, hypertension and higher NIHSS at admission.
3. Patients with normal MRI after acute ischemic stroke have a possibility of better prognosis as compared to abnormal imaging after stroke.