Can superior saggital sinus density predict anemia?

Introduction: Correlation between density of superior saggital sinus (SSS) on CT scan and haemoglobin (Hb) has been described previously. The extent of contribution of leucocytes (TLC) and platelets (PC) to SSS density is not known. With this study we aimed to find the contribution of WBC and Platelets to the SSS density and identify a cut-off value for SSS density to predict anemia. Methods: Data was collected retrospectively from the electronic database for all head injured (TBI) patients operated within a 4 month period (n = 71). Maximum and average SSS density in Hounsefeld units (HU) was calculated in two ways–(i) triangular area outlining the SSS (Tmax/mean) and (ii) circular area of 0.03–0.05 cm² in SSS (Cmax/mean). Concurrent Hb, TLC and PC were noted. Linear regression was used to find independent predictors of Hb among the significant correlations within hematological parameters. ROC curve was used to find a cut-off value for the SSS density to diagnose Hb less than 10 gm/dl. Results: Tmax/Tmean/Cmax/Cmean had significant correlations with Hb (p<0.05) with coefficients of 0.335, 0.349, 0.416 and 0.445 respectively. TLC and PC were not associated with any of the CT scan parameters. Linear regression revealed only Cmean to be independently predictive of Hb (P = 0.017). Regression equation derived was [Hb=9.142+0.89*Cmean]. Area under the ROC curve for Cmean as a predictive test of Hb was 0.791 (P = 0.003) and Cmean of 44.83 HU predicted Hb <10 gm/dl with sensitivity/specificity 80% and 76% respectively. Conclusion: TLC and PC do not appear to influence the density in SSS on CT scan in TBI patients–because of much higher mass of RBCs compared to WBCs and platelets. Cmean of 44.83 HU predicted Hb <10 gm/dl with good sensitivity and specificity and can be used clinically to determine need for blood transfusion if laboratory value of Hb is not available readily.