Ultrasound hepatic/renal ratio and hepatic attenuation rate for quantifying liver fat content

Table 1 General data comparison of the two groups

Classification	Non-fatty liver group (n = 41)	Fatty liver group (n = 129)	P
Age (yr)	54.32 ± 6.24	53.72 ± 5.81	0.182
Gender (male/female)	20/21	67/62	0.613
BMI (kg/m2)	24.11± 0.73	27.38 ± 0.64	0.005
Waist/hip ratio	0.86 ± 0.02	0.93 ± 0.01	0.001
ALT (IU/L)	18 (11-22)	35 (18-41)	0.001
AST (IU/L)	18 (14-25)	24 (18-39)	0.001
TC (mmol/L)	1.03 (0.75-1.22)	1.72 (1.35-2.43)	0.000
TG (mmol/L)	4.87 ± 0.27	5.02 ± 0.18	0.532
HDL-C (mmol/L)	1.42 ± 0.05	1.18 ± 0.04	0.003
LDL-C (mmol/L)	3.01 ± 0.23	2.98 ± 0.15	0.672
Ultrasound hepatic/renal ratio	0.55 ± 0.01	0.80 ± 0.04	0.000
Hepatic echo-intensity attenuation rate (cm-1·MHz-1)	-0.0193 ± 0.0031	0.0027 ± 0.0016	0.000

BMI: Body mass index; TG: Triglyceride; TC: Total cholesterol; HDL-C: High density lipoprotein cholesterol; LDL-C: Low density lipoprotein cholesterol.

Table 2 Quantitative ultrasound index estimation model for liver fat content

	Model	Regression coefficients ± SD				P value	Corrective R2	RMSE
		Ultrasound hepatic/renal ratio	Hepatic echo-intensity attenuation rate	Constant
Liver fat content	1	72.012 ± 3.445	-	-34.704 ± 2.302	-34.704 ± 2.302	0.000	79.0%	6.12
	2	61.519 ± 4.311	167.701 ± 42.115	-26.736 ± 3.012	-26.736 ± 3.012	0.000	80.1%	5.33

Model 1: Ultrasound hepatic/renal ratio model to estimate ¹H-MRS liver fat content. Model 2: Hepatic echo-intensity attenuation rate model to estimate ¹H-MRS liver fat content. RMSE: Root mean square error; ¹H-MRS: ¹H-magnetic resonance spectroscopy.

Table 3 Correlation analysis between metabolic indices and liver fat content determined by the quantitative ultrasound model

	AST	ALT	TC	TG	HDL-C	LDL-C
r	0.301	0.411	0.015	0.512	-0.331	-0.079
P	0.001	0.000	0.721	0.000	0.001	0.332

ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; TG: Triglyceride; TC: Total cholesterol; HDL-C: High density lipoprotein cholesterol; LDL-C: Low density lipoprotein cholesterol.

Table 4 Comparison of fatty liver diagnosis by the ultrasound quantitative model, the ultrasound hepatic/renal ratio, the hepatic echo-intensity attenuation rate, and conventional ultrasound

Group	1H-MRS diagnosis of fatty liver
	Sensitivity (%)	Specificity (%)	Positive predictive value (%)	Negative predictive value (%)
All subjects
Quantitative ultrasound model	94.7	100.0	100.0	82.6
Conventional ultrasound	83.7	70.7	90.0	58.0
Ultrasound hepatic/renal ratio	88.3	84.5	94.2	72.4
Hepatic echo-intensity attenuation rate	86.7	78.7	92.0	67.0
Subjects with fatty content < 15% (1H-MRS)
Quantitative ultrasound model	81.4	100.0	100.0	84.5
Conventional ultrasound	47.6	70.3	73.1	62.7
Ultrasound hepatic/renal ratio	67.5	81.7	87.6	70.3
Hepatic echo-intensity attenuation rate	55.6	74.3	82.1	68.7

¹H-MRS: ¹H-magnetic resonance spectroscopy.