The diagnostic utility of unenhanced computed tomography of the brain and D-dimer levels in acute cerebral venous sinus thrombosis: A quantitative study

Abstract

Objectives: (1) To calculate the sensitivity and specificity of the Hounsfield Unit (HU), the HU to hematocrit (H:H) ratio, and the D-dimer level in the diagnosis of acute CVST. (2) To assess the D-dimer level's linear relationship with the HU and the H:H ratio.

Materials and methods: A single-center retrospective case-control study was conducted from 2005 to 2020. The inclusion criteria for the thrombosed and control groups were specified. A region of interest (ROI) was plotted on the respective sinuses to calculate the HU. The H:H ratio was calculated by dividing the HU value by the hematocrit value. The receiver operating characteristic curve was used to calculate the sensitivity and specificity of the HU and the H:H ratio at different cutoff values. The Pearson correlation was used to assess the linear relationship between the D-dimer level and the HU and H:H ratio.

Results: There were 19 patients in the thrombosed group and 28 patients in the control group. There were significant differences in the mean HU (71 ± 6.3 vs. 45 ± 4.8, P < 0.001) and the mean H:H ratio (2.11 ± 0.38 vs. 1.46 ± 0.63,P < 0.001). An optimal HU value of 56 yielded 100% sensitivity and specificity. An H:H value of 1.48 yielded a sensitivity of 100% and a specificity of 65%, an H:H ratio of 1.77 demonstrated a sensitivity of 85% and a specificity of 90%, and an H:H ratio of 1.88 yielded a sensitivity of 79% and a specificity of 93%. D-dimer levels had a 95% and 71% sensitivity and specificity, respectively. There was a significant moderately positive linear correlation between the D-dimer level and the HU (r = 0.52, P < 0.001) and the H:H ratio (r = 0.61, P < 0.001).

Conclusion: Unenhanced CT of the brain can be a valuable objective diagnostic tool for acute CVST diagnosis. Hounsfield blood density and its normalized ratio with hematocrit are positively correlated with D-dimer levels, which may indicate active blood coagulation in a cerebral venous sinus.

Keywords: Acute cerebral venous sinus thrombosis; D-dimer; Hounsfield unit; Hounsfield:Hematocrit ratio.

Figure 1a:

A 39-year-old woman with antiphospholipid syndrome who presented with a headache. (a) A non enhanced CT image in this control patient shows two ROIs plotted on the sigmoid sinuses at the jugular fossa.

Figure 1b:

A 39-year-old woman with antiphospholipid syndrome who presented with a headache. (b) A non enhanced CR image in the same control patient shows the ROI plotted on the posterior superior sagittal sinus. The average mean HU value of the three ROIs is 42.33. Contrast-enhanced CT brain (not shown) shows no evidence of venous thrombosis.

Figure 2a:

A 37-year-old woman with acute lymphoblastic leukemia who presented with headache and blurry vision. (a) Non-enhanced axial CT image of the brain shows increased attenuation of the superior sagittal sinus (HU = 72).

Figure 2b:

A 37-year-old woman with acute lymphoblastic leukemia who presented with headache and blurry vision. (b) Contrast-enhanced axial image at the same location shows a filling defect of the superior sagittal sinus consistent with thrombosis (arrow).

Figure 3:

Box and whisker plot of the HU values in the thrombosed and control groups.

Figure 4:

Box and whisker plot of the H:H ratio values in the thrombosed and control groups.

Figure 5:

The ROC curves of the HU and the H:H ratio.

Figure 6:

Pearson’s correlation between the HU and the D-dimer (r = 0.52, p < 0.001).

Figure 7:

Pearson’s correlation between the H:H ratio and D-dimer (r = 0.61, P < 0.001).