Importance of Unenhanced CT as a Screening Tool for Cerebral Venous Sinus Thrombosis

Background: Cerebral venous sinus thrombosis (CVST) is being diagnosed clinically and by non- invasive imaging techniques early in its course for better prognosis and non-fatal outcomes. It hinders proper drainage of deoxygenated blood from brain resulting in drastic hemodynamic changes which can be fatal. It is more common in younger age group and women of child bearing age. Over the past decade, epidemiology of CVST has significantly changed and is not a rare disorder anymore.

Methods: After obtaining institutional ethical review committee approval, retrospective data collection of Magnetic resonance venogram (MRV) and CT Brain were performed between January 2007 and December 2016. Hounsfield units were obtained from dural sinuses on CT only in cases that were positive for sinus thrombosis on MRV.

Results: Total 554 positive venous sinuses in 350 patients as well as 2246 negative sinuses were analysed in the same cohort. Mean age was 37.46 ± SD 15.4 years, range: 72 years, minimum 4, and maximum 76 years. Only those cases were included who had MRV and non-contrast CT (NCT) within 24 hours of each other. The average Hounsfield units of vessels containing a thrombus was 60 ± 1.56 which was significantly higher than that of any other normal sinus in same patient  40 ± 0.28 (𝑝 < 0.05). Sensitivity, specificity, positive predictive value and negative predictive value were calculated as 99.6%, 89.05%, 69.17% and 99.9% respectively.

Conclusion: Hounsfield unit can be used as a good screening tool for CVST. CVST is increasingly common and highly treatable cause of stroke. The goal of imaging is to rapidly diagnose sinus thrombosis and provide a ground for early treatment for this condition to produce optimal clinical outcomes. Hounsfield unit is highly sensitive and specific for cerebral venous sinus thrombosis and can be used as a good screening tool in patient suspected of CVST.

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