Altered probe pressure and body position increase diagnostic accuracy for men and women in detecting hepatic steatosis using quantitative ultrasound

Abstract

Objectives: To evaluate the diagnostic performance of ultrasound guided attenuation parameter (UGAP) for evaluating liver fat content with different probe forces and body positions, in relation to sex, and compared with proton density fat fraction (PDFF).

Methods: We prospectively enrolled a metabolic dysfunction-associated steatotic liver disease (MASLD) cohort that underwent UGAP and PDFF in the autumn of 2022. Mean UGAP values were obtained in supine and 30° left decubitus body position with normal 4 N and increased 30 N probe force. The diagnostic performance was evaluated by the area under the receiver operating characteristic curve (AUC).

Results: Among 60 individuals (mean age 52.9 years, SD 12.9; 30 men), we found the best diagnostic performance with increased probe force in 30° left decubitus position (AUC 0.90; 95% CI 0.82-0.98) with a cut-off of 0.58 dB/cm/MHz. For men, the best performance was in supine (AUC 0.91; 95% CI 0.81-1.00) with a cut-off of 0.60 dB/cm/MHz, and for women, 30° left decubitus position (AUC 0.93; 95% CI 0.83-1.00), with a cut-off 0.56 dB/cm/MHz, and increased 30 N probe force for both genders. No difference was in the mean UGAP value when altering body position. UGAP showed good to excellent intra-reproducibility (Intra-class correlation 0.872; 95% CI 0.794-0.921).

Conclusion: UGAP provides excellent diagnostic performance to detect liver fat content in metabolic dysfunction-associated steatotic liver diseases, with good to excellent intra-reproducibility. Regardless of sex, the highest diagnostic accuracy is achieved with increased probe force with men in supine and women in 30° left decubitus position, yielding different cut-offs.

Clinical relevance statement: The ultrasound method ultrasound-guided attenuation parameter shows excellent diagnostic accuracy and performs with good to excellent reproducibility. There is a possibility to alter body position and increase probe pressure, and different performances for men and women should be considered for the highest accuracy.

Key points: • There is a possibility to alter body position when performing the ultrasound method ultrasound-guided attenuation parameter. • Increase probe pressure for the highest accuracy. • Different performances for men and women should be considered.

Keywords: Fatty liver; Magnetic resonance imaging; Patient positioning; Sex factors; Ultrasonography.

Fig. 1

Flowchart of study population selection and distribution according to liver fat content measured by PDFF

Fig. 2

UGAP diagnostic performance for staging hepatic steatosis in MASLD. There was a significant difference between hepatic steatosis stages S0-S3 in the supine position with normal 4 N probe force. S0, n = 20; S1, n = 18; S2, n = 8; S3, n = 14. Differences in the mean UGAP values: S0 0.53 vs. S1 0.61 dB/cm/MHz (p = 0.027), S1 0.61 vs. S2 0.71 dB/cm/MHz (p = 0.025), S2 0.71 vs. S3 0.84 dB/cm/MHz (p = 0.003). MASLD= metabolic dysfunction-associated steatotic liver disease (defined as ≥ 5% MRI-PDFF), UGAP = ultrasound-guided attenuation parameter, MRI = magnetic resonance imaging, PDFF = proton density fat fraction. PDFF defined cut-offs for steatosis grade 1 (S1) = 5.0–11.2%, S2 = 11.3–17.0%, and S3 ≥ 17.1%

Fig. 3

AUC plots illustrating the diagnostic performance of the ultrasound-guided attenuation parameter (UGAP) for the body in a supine position with normal 4 N probe force, yielding an AUC of 0.87 (95% CI 0.77–0.97), and with increased 30 N probe force (AUC 0.90, 95% CI 0.82–0.98). Body in 30° left decubitus body position with normal 4 N probe force yielded an AUC of 0.87 (95% CI 0.76–0.98), and with increased 30 N probe force an AUC of 0.90 (95% CI 0.82–0.98). MRI-PDFF ≥ 5% was defined as the cut-off for steatosis grade S1. CI = confidence interval, AUC = area under the curve, MASLD= metabolic dysfunction-associated steatotic liver disease (defined as ≥ 5% MRI-PDFF), MRI = magnetic resonance imaging, PDFF = proton density fat fraction

Fig. 4

AUC plots illustrating the diagnostic performance of ultrasound-guided attenuation parameter (UGAP) for men (n = 30). UGAP was performed with normal 4 N force, increased 30 N probe force, and with the body in the supine or 30° left decubitus position. MRI-PDFF < 5% was the cut-off for steatosis grade S0 (n = 11) and ≥ S1 (n = 19). With the body in the supine position and with normal 4 N probe force had an AUC of 0.83 (95% CI 0.67–0.99), and with increased 30 N probe force an AUC of 0.91 (95% CI 0.81–1.00). With the body in 30° left decubitus position and with normal 4 N probe force, the AUC was 0.85 (95% CI 0.68–1.00), and with increased 30 N probe force 0.89 (95% CI 0.77–1.00). AUC = area under the curve, CI = confidence interval, MASLD= metabolic dysfunction-associated steatotic liver disease (defined as ≥ 5% MRI-PDFF), MRI = magnetic resonance imaging, PDFF = proton density fat fraction

Fig. 5

AUC plots illustrating the diagnostic performance of ultrasound-guided attenuation parameter (UGAP) for women (n = 30). UGAP was performed with normal 4 N probe force, increased 30 N probe force, and with the body in the supine or 30° left decubitus position. MRI-PDFF < 5% was the cut-off for steatosis grade S0 (n = 11) and ≥ S1 (n = 19). The supine position with normal 4 N probe force had an AUC of 0.93 (95% CI 0.82–1.00) and with increased 30 N probe force 0.90 (95% CI 0.79–1.00). With the body in 30° left decubitus position with normal 4 N probe force, the AUC was 0.88 (95% CI 0.76–1.00), and with increased 30 N probe force 0.93 (95% CI 0.83–1.00). AUC = area under the curve, CI = confidence interval, MASLD= metabolic dysfunction-associated steatotic liver disease (defined as ≥ 5% MRI-PDFF), MRI = magnetic resonance imaging, PDFF = proton density fat fraction