Background: Circle of Willis is the most important collateral circulation system in brain. Primary goal of imaging is to find out its integrity and hypoplastic for explaining the predisposition / cause of stroke and prior to vascular surgeries and interventional procedures.

Aims & Objectives: To evaluate & describe various patterns of anatomical variations of circle of Willis, elaborate its clinical significance and determine average vessels diameters in general Indian population by using 3D time-of-flight MR angiography.

Methodology: A cross sectional prospective study was undertaken on 200 patients on Philips 1.5T Achieva MR scanner using non-contrast 3DTOF transaxial acquisition. Images were reviewed on the Philips Intellispaceportal workstation.

Results: The prevalence of complete configuration of the circle was 9%. There was significantly higher incidence of complete circle in <40yr age group (24%) than >40yr age group (4%) (p<0.0001). An incomplete circle was noted in 91% subjects (60% males and 40% females). Anterior circulation was complete in 44% and incomplete in 56% whereas posterior circulation was complete in 14% and incomplete in 86%. Posterior circle variations were significantly higher than anterior circle (p<0.0001). Average vessel diameters were slightly higher in male population. Also, average diameters were observed to be greater in anterior circle in below 60age group and in above 60 age group posterior circle diameters were larger.

Conclusion: In today’s scenario, the role of 3D TOF MR angiography in preoperative evaluation of patients undergoing brain, ICA & aortic arch surgeries and advanced interventional procedures cannot be underestimated in order to avoid life-threatening complications.

Keywords: Magnetic Resonance Angiography, 3D TOF MRA, Circle of Willis, Anatomical Variations, Stroke, Impact.

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Dr Sunia Indrajeet Singh

Resident, Department of Radiology,

Dr. SN Medical College, Jodhpur, Rajasthan, India

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