Diagnostic Accuracy of Hounsfield Unit Value and Hounsfield Unit to Hematocrit Ratio in Predicting Cerebral Venous Sinus Thrombosis: A Retrospective Case-Control Study.

OBJECTIVE: Non-contrast computed tomography (CT) of the brain is a primary neuroimaging modality in emergency patients suspected of having cerebral venous sinus thrombosis (CVST). The objective of the study was to determine the diagnostic accuracy of Hounsfield unit (HU) values and the ratio of HU to hematocrit value (HU/Htc) in predicting CVST in suspected patients.

MATERIAL AND METHODS: A retrospective, case-control study was done in a tertiary care institute which included 35 patients with CVST constituted as cases and 41 patients without CVST as controls on the basis of magnetic resonance venography (MRV). Non-contrast CT brain of all 76 subjects were assessed by two experienced radiologists independently. HU values of dural venous sinuses were calculated in both groups, and HU/Htc ratio was also determined. Statistical Package for Social Sciences (SPSS) version 25.0 (SPSS© for Windows, IBM© Corp.) was used for statistical analysis. Independent samples t-test was applied to compare the means of continuous variables. The diagnostic values were computed using the Calculator 1 tool on clinical research calculators tab on vassarstats.net. The predictive values of HU and HU/Htc ratio were estimated by the receiver operating characteristic (ROC) curve analysis.

RESULTS: In CVST group, the mean Hounsfield Unit (HU) value was "75.9±3.9 (mean±SD)", while in control group, it was 57.78±4.65 (mean±SD), p < 0.001. The mean HU/Htc ratio was 1.98±0.42 (mean±SD) in the CVST group and 1.51±0.12 (mean±SD) in the control group (p < 0.001). Optimum cut-off HU value was calculated as 68, with 97% sensitivity and 100% specificity. For HU/Htc ratio, optimum cut-off was calculated as 1.69, yielding 71.4% sensitivity and 100% specificity on the basis of ROC curves. The difference was not statistically significant in hemoglobin and hematocrit (Htc) values between the cases and controls.

CONCLUSION: The quantitative measurements like HU value and HU/Htc ratio provide an easily obtainable metric in patients with suspected CVST on non-contrast CT brain, thus enhancing the role of non-contrast CT brain in diagnosing CVST.