 I'll be presenting my paper on the study of anatomical variation of circle of willis in brain using 3D time of light magnetic resonance angiography. The introduction to my study, the human brain although small in size receives one fifth of the total cardiac output, it has at least tolerance to vascular insults. Circle of willis forms the major brain vascular supply and is at most important as a source of bilateral vascular supply in the case of need. In a non-variant case bilateral internal carotid arteries distribute flow into their respective anterior cerebral arteries and eventually continue as middle cerebral arteries. Posteriorly the basilar artery distribute flow viposterior cerebral arteries further communicate at the base of the brain forming a ring shaped structure known as the circle of willis. The primary anastomosis of circle of willis are formed by the anterior communicating arteries and posterior communicating arteries. However alternate secondary collaterals can be recruited. The capacity of circle of willis to supply vicolaterals is dependent on the presence distributed morphology and the respective size of its vessels which shows variations amongst the individuals of the population. Hence the presence of anatomical variation may compromise its function to supply collaterals in case of any vascular accidents. The average age of patient which stroke in a developing country like India is significantly earlier increasing than the developed countries. With the advances in neuro-surgical procedures to deal with vascular insults the highly-variating knowledge about anatomical differences of circle of willis holds at most significance. Now we come to the human objectives of our study. The study aims to non-invasively study the prevalence and anatomical patterns of the circle of willis in patients undergoing MR angiography of the brain. The anatomical variation of arteries forming the circle of willis at the base of brain the study any gender-related or age-related differences in the anatomy of the circle of willis to provide a ready reference for any further studies on micro-neovascular interventions of the circle of willis. The study took place at Dr. D. Y. Partil Medical College Hospital and Research Centre Pimpri Pune. The study is of observational types. The period of the study is from September 2019 to August 2021. The sample size is 556. The medical equipment used is Siemens Megaton Veda 3 tesla MRI and 1.5 tesla MRI. Data collection and statistical analysis. Data will be collected from the subjects when anatomical variants in the circle of willis on 3D time of light MR angiography. Statistical variables used will be age, gender, circulation whether it's anterior or posterior, vessels involved. Data will be entered in an Excel sheet. Descriptive statistical analysis will be done on the basis of compiled data. Inclusion criteria. All the patients of age group and gender undergoing 3D time of light MR angiography and subsequently getting detected with anatomical variation on circle of willis. Exclusion criteria. As the aim of the study is to normal anatomical variants, exclusions are history of non-neurosurgical neuro radiological intervention. History of any intracranial mass occupying region in the region of circle of willis. Uncooperative patients or non-willing for consent. All patients with contraindications to MR studies. This is the protocol of our MR angiography used. Now we come to the observation and results part. A total of 556 individuals in our study were taken out of which 337 were males which were roughly about 61% and 219 were females which were 40%. The major age distribution in our study was somewhere around 41 years to 60 years. There are two types of circulation. One is the anterior and the posterior and the anatomical variation to it can be complete or incomplete. Complete variation were about 32%. Incomplete was 62%. 68%. The mean age of our study was 49 to 58 years. It was observed that individuals with age less than mean age of the study had higher probability of having a complete circle of willis. While we use the general linear model of binomial regression model to look for the significance and association between complete circle of willis and gender, it was observed that the p-value was more than 0.05 which suggests no significant association. These are the most common variants according to the decreasing frequencies which brings us to the most common one which is the unilateral absent posterior communication and the least common which is hypoplastic anterior communication. Now to summarize our study, the study was mainly undertaken to evaluate the different anatomic variants of arteries that form the circle of willis using 3D time of flight MR angiography. Males outnumbered females in our study. The mean age of the study group was 49 years ranging from 2 months to 95 years. Nearly 42% of the study individuals belong to 51 to 70 years of age group. A complete circle of willis was seen in 32% of individuals. A complete anterior circulation was seen in more frequently which was 88.4%. The incidence of incomplete circle of willis was more in individuals with age more than the mean age which was 49 years which showed strong statistical significance. In our study, the most common variant of circle of willis was unilateral absent posterior communication followed by bilateral absent posterior communication. Most frequent findings seen in our study matched with the many of the autopsy and MR angiography studies of various ethnicities in the literature. As to conclude our study, knowing the anatomical variants of circle of willis is very important before planning neurosurgical interventions. Recent studies have shown that many of these anatomical variants are associated with the increased risk of stroke. With this study, we conclude that 3D time flight MR angiography is an excellent tool for the investigation of arteries forming the circle of willis. Hence, before any neurosurgical interventions, patients should be evaluated for MR angiography for any anatomical variants. There, where one segment of the arteries might be absent and can cause resultant severe reduced supply of blood in the ethylateral site and can induce stroke. These are the references from the article which were done before. Thank you so much.