DOPPLER ULTRASONOGRAPHY AND MAGNETIC RESONANCE IMAGING OF CAROTID PLAQUE IN ISCHEMIC STROKE PATIENTS

Abstract

Background: Stroke is one of the leading causes of morbidity and mortality worldwide with age-adjusted prevalence rate of stroke was between 250-350/100,000 in India accounting for 1.2 % of total deaths. Atherosclerotic plaque at the carotid bifurcation is a major cause of ischemic strokes. Study aimed to evaluate the imaging appearances of atheromatous plaque using Ultrasound and MRI.

Objectives : 1)Characterization of carotid plaque morphology on MRI and Doppler ultrasonography in patients with ischemic stroke and transient ischemic attack 2) Co-relation of plaque morphological features on Doppler ultrasonography and MRI with Ischemic stroke. 3) Plaque enhancement on contrast enhanced MRI and colour Doppler as a surrogate marker for plaque rupture.

Participants: A total of 45 lesions from cases of stroke and TIA who had come to receive treatment in our hospital were taken.

Study Design: It was a prospective hospital based cohort study.

 Material and methods: Sonographic images to be evaluated for Plaque in the carotid artery and was classified as homogenous or heterogeneous with proper surface evaluation for irregularity. MRI of the carotids was done and the visualised plaque were grouped into homogenous and heterogeneous categories which in turn were correlated with ultrasound pictures to characterize the type of plaque. The plaque characteristics were then compared with the clinical condition of the patient to compare its relation with the incidence of stroke or TIA.

 Results: Ultrasound was found to be more sensitive than MRI for plaque size < 1.5mm and to characterize when the area of stenosis was less than 50% and MRI was found to have better discriminatory power  compared with duplex ultrasonography  in detecting 70-90% stenosis.

Conclusion: The study showed that symptomatic individuals had a high degree of correlation with heterogeneous plaques on ultrasound. All heterogeneous lesions on MRI contained intra plaque blood with intracellular methemoglobin and fat. Although MRI gives objectivity to the characterization of the plaque , ultrasound was found to be more sensitive for plaque disease <50% area stenosis and it was found that enhancement of carotid plaque implies vascular wall inflammation which is a marker of vulnerable plaque.