Diagnosing Cerebral Venous Sinus Thrombosis on Unenhanced Computed Tomography -Measuring the Hounsfield Unit. Does it Add to the Confirmation of Diagnosis?

Background: Over past decade, epidemiology of cerebral venous sinus thrombosis (CVST) has significantly changed. CVST is being diagnosed clinically and by non- invasive imaging techniques early in its course and has better prognosis and non-fatal outcomes.

Methods: Institutional ethical review committee approval was obtained prior to start of this retrospective study. All Magnetic resonance venogram (MRV) performed between January 2007 and December, 2016 were reviewed retrospectively. Only positive cases were included which show thrombosis on MRV. We calculated sensitivity, specificity, positive predictive value and negative predictive value on the basis of CT density taking post contrast MRV as gold standard.

Results: Total 554 positive venous sinuses in 350 patients were included. 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. 554 positive venous sinuses were analyzed as well as 2246 negative sinuses were analyzed in the same cohort. The average (Hounsfield unit) HU 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 is highly sensitive and specific for CVST and can be used as a good screening tool.