ABSTRACT
Background: The basilar artery is the large median and major artery of the posterior circulation of the brain. Many variations are seen in the basilar artery, majority of them in position, origin and shape of the artery. Many authors have documented various anomalies as well as differences of the anatomy in this area in the Indian population as compared to the Western literature. Context and purpose of study: Many studies are available on the anterior circulation of the brain i.e. on vessels of the circle of Willis but studies on the posterior circulation are very few. And such studies so far had been done mostly in the American and European races and are mostly based on imaging techniques. Studies in the Indian population have been few. Hence the present study is concentrated on the morphological study of the basilar artery of human adult brain, to show the frequency and type of variations in the morphology of the basilar artery. Results: The basilar artery most commonly takes origin from the vertebral artery where left vertebral artery is greater in size than the right vertebral artery (72.5%). Level of formation of the basilar artery is most commonly observed at the ponto-medullary junction (62.5%). Length of the basilar artery varied from minimum 2.4cm to maximum 3.6cm. More commonly artery lies in the range of 2.6-3.0cm (57.5%). Diameter of the basilar artery at origin ranges from 3.2-4.2mm, at mid level from 3-4mm and at termination 3.1-4mm. Level of termination of the basilar artery is more commonly at the mid brain-pons junction (50%). Most of the basilar arteries are of straight type (55%) and next common is bent or curved type (37.5%). Fenestration of 4mm is seen in proximal part of the one basilar artery (2.5%). Conclusion: Variations of the basilar artery are common. Neurosurgical importance of this study lies during the exposure of the region for different purposes. Knowledge of the vascular variations will increase the success of the surgical procedures and radiological procedures used in interventional radiology.
ABSTRACT
OBJECTIVE: Aim of our study was to evaluate the diagnostic accuracy of 64-slice CT coronary angiogram in measuring the percentage diameter stenosis compared to invasive angiography. METHODS AND RESULTS: 100 consecutive patients with more than 50% stenosis in at least one major coronary artery measured by 64-slice CT angiogram were included in the study. Patients with atrial fibrillation, history of allergy to contrast agent, acute coronary syndrome, renal insufficiency, history of previous coronary bypass surgery or percutaneous transluminal coronary stent, heart rate more than 70 per minute at the time of scan in spite of beta-blocker therapy, and calcium score >2000 Agaston units were not included in the study. 15-segment American Heart Association classification was used, and segments were compared using qualitative angiography. 192 segments (12.80%) could not be assessed due to poor image quality. The major cause for poor image quality was dense calcification precluding the luminal assessment (60.42%). Comparing the maximal percentage diameter stenosis by 64-slice CT versus invasive angiogram, the Spearman correlation coefficient between the two modalities was 0.788 and p value was <0.001. Bland-Altman analysis showed a mean difference in percentage stenosis of 2.1 +/- 16.22%. A total of 91.97% (401 of 436) of segments were within 1.96 standard deviations. CONCLUSION: This study shows that 64-slice CT coronary angiogram is accurate in detecting percentage diameter stenosis compared to coronary angiogram if the image quality is good. Calcifications and motion artifacts are the main culprits of poor image quality.