RESULTS:The superior sagittal, straight sinus and the internal cerebral veins were visualized in all patients. There was hypoplasia of the right transverse sinus in 13 patients, left transverse sinus in 35 patients, right sigmoid sinus in 6 patients and left sigmoid sinus in 19 patients. Absence of transverse sinus on left side was observed in one patient and absence of sigmoid sinus in 2 patients on left side. Flow gaps were observed in non-dominant transverse sinus, sigmoid sinus as well as transverse sigmoid sinus junctions. The occipital sinus was visualized in 17 patients. CONCLUSIONS: MR angiography done at low field strengths is also a reliable method, for assessing cerebral venous sinuses. Awareness of the normal anatomical variations of venous sinuses and apparent MR angiographic flow gaps prevent misdiagnosis of cerebral venous sinus thrombosis.

Objectives : Examinations performed using CT scanners impart high radiation dose to patients and use of this modality is on the increase in the present day scenario. This study was intended to evaluate and optimize radiation dose imparted to patients during CT examination of brain performed using spiral CT scanner. Materials and Methods : One hundred and one patients who underwent CT examination of brain were included in the study. The effective dose to patients was calculated using volume computed tomography dose index (CTDIvol) and dose length product (DLP) values. Patients were categorized according to the type of examination involved. Patients who underwent a complete examination of brain (non-contrast as well as contrast) were categorized in Group A and patients who underwent either a non-contrast or contrast examination were categorized as Group B. Results : The effective dose to patients ranged from 0.65 mSv to 0.93 mSv for Group A patients and 0.28 mSv to 0.53 mSv for Group B patients. Conclusion : There was a reduction of doses imparted to patients undergoing CT examination of the brain using optimized exposure parameters without any loss of diagnostic information.