DIAGNOSTIC-CRITERIA FOR FATTY INFILTRATION OF THE LIVER ON CONTRAST-ENHANCED HELICAL CT

OBJECTIVE, The purpose of the study was to develop quantitative and qu alitative criteria for diagnosing fatty liver on contrast-enhanced hel ical CT. SUBJECTS AND METHODS. Differential liver-spleen attenuation w as evaluated between 80 and 120 sec after injection in 76 patients who underwent contrast-enhanced helical CT. Unenhanced CT images had earl ier established fatty Liver when the liver minus spleen attenuation di fference was less than or equal to -10 H (n = 18), Four observers who had not seen the unenhanced images used contrast-enhanced CT images to assess the presence of fatty liver on a five-point Likert scale, the presence of geographic areas spared from fatty infiltration, and the r elative liver-spleen attenuation. The diagnostic accuracies of various imaging criteria were compared using McNemar's chi-square test (for s ensitivity and specificity) and analysis of receiver operating charact eristic curves. RESULTS. Sensitivity, specificity, and receiver operat ing characteristic curve areas for observers' qualitative judgments we re 54%, 95%, and .91, respectively; for quantitative differential live r-spleen attenuation (80-100 sec; -20.5 H discriminatory value), the v alues were 86%, 87%, and .94, respectively; and for quantitative diffe rential liver-spleen attenuation (101-120 sec; -18.5 H discriminatory value), the values were 93%, 93%, and .98, respectively. Differential liver-spleen attenuation was time-dependent; overlap was noted between healthy subjects and patients with fatty liver. Qualitatively, geogra phic sparing was highly specific (94%) for fatty liver, whereas liver attenuation greater than or equal to spleen attenuatian excluded fatty liver in all but one case. CONCLUSION. Although quantitative and qual itative criteria for diagnosing fatty Liver on helical CT can be deter mined, they are protocol-specific, Limited unenhanced hepatic CT remai ns the optimal technique for detection of fatty infiltration of the li ver.