Comparison of magnetic resonance angiography(MRA) as diagnostic tool for carotid artery stenosis with carotid doppler in cerebral ischemic patients

Stroke is defined as rapid onset of focal neurological deficit resulting from diseases of cerebral vasculature and its contents. Carotid artery stenosis is a common condition encountered in general practice. It represents one of the major causes of acute ischemic stroke. Carotid artery stenosis can be classified as symptomatic or asymptomatic disease with the distinction between the two significantly altering the management pathway.

Community surveys in India have shown a crude prevalence rate for hemiplegia in the range of 200 per 100,000 persons, nearly 1.5% of all urban hospital admission, 4.5% of all medical and around 20% of neurological cases.

Stroke is one of the leading causes of mortality and morbidity. Ischemic infarcts account for 80-85% of all strokes. Stroke related neurological disability has a major impact on the patient, family members and caretakers. 17% will remain institutionalized and 25-30% will need moderate to total assistance for activities of daily living.

Carotid atherosclerosis is one of the main risk factor for ischemic stroke which accounts for 5-10% of all ischemic stroke. The widely used TOAST (Trial of Org 10172 in Acute Stroke Treatment) classification of ischemic stroke distinguishes 5 major categories of stroke : Large artery atherosclerosis, Cardioembolism, Small vessel occlusion, Other determined etiology and Undetermined etiology. Carotid plague progression contributes to increasing stroke risk.

Carotid endarterectomy has been shown to effectively reduce the risk of developing stroke in patients with significant stenosis i.e. 70% or more.

Various noninvasive vascular techniques can now be used to evaluate Carotid atherosclerosis which includes Carotid Doppler Ultrasonography,  transcranial Doppler, CT angiography, Magnetic Resonance angiography, contrast enhanced Magnetic Resonance angiography.

Among the tests Carotid Doppler ultrasound is a noninvasive, cost effective and easy available mode of investigation to identify the patients with significant stenosis and other changes due to atherosclerosis.

Since the noninvasive tests are used for preliminary screening before doing Carotid endarterectomy the value of the tests lie in their ability to accurately identify patients with significant stenosis. However newer studies of older technologies and the emergence of new noninvasive tests justify a revaluation of published data about noninvasive testing of Carotid arteries.

The purpose of this study is to estimate retrospectively the various changes in Carotid arteries by Magnetic resonance angiography in patients who had already suffered a stroke, which in turn determine the value of using Magnetic resonance angiography as a modality of test to screen for atherosclerosis and the risk of developing stroke in people with risk factors for stroke.

A reproducible 3D image of carotid bifurcation with improved sensitivity for high grade stenosis is provided by MRA. The value is that it is possible to test further ICA, aortic arch and proximal broad arteries, Circle of Willis, and the posterior circulation, and it is not operator dependent.