Estimation of Splenic Volume: Prolate Ellipsoid Method Correlated with 3-D Helical CT Determination

Abstract

To establish the correlation between two methods of volume estimation of spleen, e.g., prolate ellipsoid formula and 3-D reconstruction of abdominal helical CT-image. Settings and Design: One hundred twenty-six patients were selected aged between 20 and 80 years in which male and female were 72 and 54 respectively for cross-sectional study. Patients who had underlying malignancy, infections, hematological disorders and other conditions that could alter splenic size were excluded. Methods and Material: Total volume of spleen in each patient was obtained by summation of stacks of images with the help of volume and surface rendering technique of Able 3-D doctor software. Other dimensions, e.g., length, width, and thickness were also obtained. Then volume of spleen was calculated by prolate ellipsoid method of each patient by using length, width and thickness. Then two methods were correlated by application of linear regression model. Results: The mean volume calculated by prolate ellipsoid formula was 288 ± 142.6 cm³. Splenic volume measured by prolate ellipsoid formula well correlated with volume measured by 3-D reconstruction of abdominal CT images (161.57 ± 90.2 cm³). We had developed the regression formula of ellipsoid splenic volume (cm³) = 1.224 × true splenic volume (cm³) + 61.49 (r = 0.929, p < 0.001). Conclusions: By CT-scan or sonographic measurements, prolate ellipsoid formula 0.524 × length × width × thickness provides best accuracy with helical CT determination of splenic volume. Above regression formula would be used to calculate the volume of spleen if helical CT is not used and would help in predicting diagnosis of splenomegaly in suspected clinical conditions.