Normal variations in cerebral venous anatomy and their potential pitfalls on 2D TOF MRV examination: Results from a private tertiary care hospital in Karachi

Objective: To assess normal venous anatomy of the cranium and its anatomical variants. Methods: This retrospective study was conducted at Radiology Department of Dr. Ziauddin Hospital, Karachi, and comprised data of patients aged 2-75 years and having undergone magnetic resonance imaging of brain from April 2015 to April 2016. Magnetic resonance venography was reviewed to evaluate the cerebral venous system. All magnetic resonance venography examinations were performed using a contiguous two-dimensional time-of-flight venography technique, and were reviewed by two consultant radiologists. Results: Out of 204 patients, 96(47.05%) were males and 108(52.94%) were females. Overall Magnetic Resonance Venography examinations were found to be normal in 94(46.07%), patients, while 110(53.92%) had some of the normal anatomical variants. There was presence of superior sagittal sinus and straight sinus in 204(100%) cases. Inferior sagittal sinus was seen in 179(86.05%). Transverse sinus was hypoplastic in 8(3.92%) on the right and 80(39.2%) on the left side. Hypoplastic sigmoid sinus was present in 51(25%) patients and aplastic sigmoid sinus in 2(0.98%) patients. Flow gaps were also observed in 22(10.78%) patients. Occipital sinus was identified in 17(8.3%), vein of Trolard in 98(48.03%) and vein of Labbe in 105(51.47%). Conclusion: Two-dimensional time-of-flight magnetic resonance venography examination was found to be a useful imaging tool showing great sensitivity in determining the normal cerebral venous anatomy.