Fatty liver in obesity: relation to Doppler perfusion index measurement of the liver.

Background: The correlation of clinical and laboratory findings with various imaging techniques in obese patients is difficult. Colour duplex Doppler is of particularly limited value in fat individuals. The Doppler Perfusion Index (DPI) measures the ratio of hepatic arterial to total liver blood flow and seems to be more accurate in the study of hepatic hemodynamics. The aim of the present study was to investigate the clinical use of DPI measurement of the liver in obesity.

Methods: In the present prospective, open study we evaluated the DPI in 41 obese patients (body mass index (BMI) > 30 kg/m2) and 18 volunteers with normal or slightly increased weight. Thirty patients of the study group underwent liver biopsy during bariatric surgery. In these patients liver histology was assessed and age, BMI, waist to hip ratio (WHR), DPI, liver function tests and serum triglycerides were measured.

Results: Obese patients had significantly (P = 0.0036) higher DPI values (0.25 +/- 0.138) than the healthy volunteers (0.15 +/- 0.04). Multivariate analysis revealed that grade of fatty liver in the study group was inversely associated with DPI and positively depended on serum triglyceride and aspartate aminotransferase (ASAT) levels (fatty liver index = 1.03 x ASAT (IU/l) + 0.152 x triglyceride (mg%) - 49.75*DPI, with P < 0.0001 and r2 = 0.80).

Conclusion: Grade of fatty liver in obese patients may be predicted from DPI, serum triglyceride and AST levels. The proposed index may be useful as a non-invasive diagnostic tool during the follow-up of patients with obesity-related fatty liver.