Non-invasive staging of hepatic steatosis by Quantification Attenuation Index (QAI).

[BACKGROUND] Metabolic dysfunction-associated steatotic liver disease (MASLD) is a condition that can progress to cirrhosis and hepatocellular carcinoma. Non-invasive techniques are increasingly used to assess hepatic steatosis. This study aimed to evaluate the accuracy of the Quantification Attenuation Index (QAI) and define diagnostic cut-offs by comparing QAI to liver biopsy and controlled attenuation parameter (CAP).

[METHODS] This prospective study included adults with chronic liver disease undergoing B-mode ultrasound, QAI, and vibration-controlled transient elastography with CAP. Liver biopsy, performed when indicated, served as gold standard. Diagnostic performance was assessed by ROC analysis; agreement between QAI and CAP was assessed using Cohen's kappa.

[RESULTS] A total of 209 patients were included (median age 62 years; 57.4% male). MASLD was diagnosed in 63 patients, who showed significantly higher CAP (288 dB/m) and QAI (0.88 dB/cm/MHz) compared to other liver diseases (CAP 235 dB/m; QAI 0.70 dB/cm/MHz; P<0.001). Steatosis was histologically confirmed in 22/40 biopsied patients. ROC analysis using biopsy as reference identified a QAI cut-off of 0.67 dB/cm/MHz for distinguishing absence of steatosis (S0) from any degree of steatosis (≥S1) (AUROC 0.683; sensitivity 63%, specificity 73%) and a cut-off of 0.81 dB/cm/MHz for discriminating severe steatosis (S3) from lower grades (≤S2) (AUROC 0.925; sensitivity 100%, specificity 87%). The overall agreement between QAI and CAP was substantial (κ=0.767 and κ=0.734; P<0.001). QAI correlated better with biopsy (r=0.719, P<0.001) than CAP (r=0.540, P<0.001).

[CONCLUSIONS] QAI is a reliable, non-invasive method for assessing hepatic steatosis, with good agreement with histology and with CAP.