Accuracy of Controlled Attenuation Parameter for Liver Steatosis in High-Risk Patients for MASLD Using MRI-Proton Density Fat Fraction as Reference Standard

Aim: Controlled attenuation parameter (CAP) enables the noninvasive diagnosis of liver steatosis. Magnetic resonance imaging proton density fat fraction (MRI-PDFF) is increasingly used over biopsy for the assessment of steatosis in patients at risk for metabolic dysfunction-associated steatotic liver disease (MASLD). We assessed the accuracy of CAP for liver steatosis defined as MRI-PDFF ≥ 5%.

Methods: We performed a cross-sectional, diagnostic accuracy study. We prospectively recruited consecutive adult participants with type 2 diabetes and body mass index (BMI) ≥ 25 kg/m², who underwent CAP and MRI-PDFF within two weeks.

Results: We included 113 participants. The area under the receiver operating characteristic (AUROC) of CAP for MRI-PDFF ≥ 5% was 0.82 [95% confidence interval (CI) 0.74-0.89]. CAP thresholds for ruling-out (sensitivity > 90%) and ruling-in (specificity > 90%) liver steatosis were below 249 and over 328 dB/m respectively. The AUROC of CAP for the detection of MRI-PDFF ≥ 10% was 0.81 (0.73-0.88). CAP thresholds for ruling-out and ruling-in MRI-PDFF ≥ 10% were below 271 and over 345 dB/m respectively. CAP measurements with an interquartile range (IQR) < 30 dB/m improved the detection of higher steatosis grades.

Conclusion: CAP has acceptable accuracy for diagnosing MRI-PDFF defined steatosis. Values below 249 dB/m can be used to rule-out liver steatosis, while values over 328 dB/m can set the diagnosis. An IQR < 30 dB/m might improve the accuracy of CAP for higher steatosis grades.

Clinical trial registration: Not applicable.