Liver-spleen attenuation ratio in unenhanced and contrast enhanced computerized tomography in different grades of hepatic steatosis

Abstract

Objective: To assess the average liver-spleen attenuation ratio on both plain and contrast-enhanced computed tomography (CECT) scan in various stages of hepatic steatosis. Method: The descriptive, cross-sectional study was conducted at the Department of Radiology, Dow University of Health Sciences/Dr Ruth K.M. Pfau Civil Hospital, Karachi, from February 1, 2017, to July 31, 2024, and comprised patients aged 15-85 years of either gender who underwent abdominal computed tomography scans for various non-hepatic indications. The liver-spleen attenuation ratio was measured as the ratio of Hounsfield unit values of the hepatic and splenic parenchyma before and after administering contrast for computed tomography scanning, with simultaneous recording of the hepatic steatosis grade via abdominal sonography. The mean liver-spleen attenuation ratios for different stages of hepatic steatosis severity were analysed for both pre- and post-contrast computed tomography scans. Data was analysed using SPSS 21. Result: Of the 334 patients, 206(61.7%) were females and 128(38.3%) were males. The overall mean age was 45.26±11.61 (30-70) years. The mean liver-spleen attenuation ratio values on pre- and post-contrast scans were 0.71±0.08 and 0.72±0.09 for mild, 0.61±0.08 and 0.65±0.13 for moderate, and 0.02±0.72 and 0.36±0.20 for severe steatosis, respectively, as against sonographic hepatic steatosis grading. The overall mean liver-spleen attenuation ratio was 0.49±0.45 for pre- and 0.60±0.20 for post-contrast scans. Complications such as dilated portal vein (p<0.001), dilated splenic vein(p<0.001), splenomegaly (p<0.001), abdominal collaterals (p<0.001), and ascites (p=0.014) were significantly more frequent in those with L/S ratio of 0.7 or less on CECT. Conclusion: The liver-spleen attenuation ratio decreased in fatty liver disease on both pre- and post-contrast computed tomography scans, with a more noticeable reduction seen on the post-contrast images, and with advanced grades of steatosis.

Key Words: Liver-spleen attenuation ratio, Hepatic steatosis, Computerised tomography, CT, Ultrasound, Grades of hepatic steatosis, Unenhanced, Contrast-enhanced CT.