Noninvasive evaluation of nonalcoholic fatty liver disease: Current evidence and practice

Table 1 Imaging modalities for diagnosing nonalcoholic fatty liver disease

Test	Description	Accuracy	Advantages	Disadvantages	Guideline recommendation
Ultrasound	Hyperechoic texture or a bright liver	AUROC 0.93, Sn 85%, Sp 94% for diagnosis of steatosis[33]	Cheap; No radiation; Available; Easy to perform	Low sensitivity in individuals with steatosis < 20% or BMI > 40 kg/m2; Observer-dependency; Influenced by fibrosis or iron overload	The first-line diagnostic test for diagnosing moderate and severe steatosis[32]
Computed tomography	Measurement of liver steatosis with attenuation values of liver and spleen	AUROC 0.99, Sn 100%, Sp 82% for diagnosis of steatosis > 30%[29]	Visualize the whole liver; Higher applicability; Quantify moderate-severe steatosis	Low sensitivity for light-moderate steatosis; Radiation exposure	NA
CAP	Measurement of liver steatosis with ultrasound attenuation by Fibroscan	AUROC 0.82, Sn 69%, Sp 82% for diagnosis of any steatosis[44]	Immediate assessment; Can be used in ambulatory clinic setting; Measure LSM simultaneously	Operator-dependency; Limited sensitivity; High failure rates in obesity patient; Low accuracy for quantifying steatosis; Uncertain cut-off values	The role of CAP for steatosis assessment is inclusive, more future studies are needed to define the role of CAP[32]
Magnetic resonance based techniques	Quantitative measurement of steatosis over the entire liver by adding parameter to MRI scanners	MRI-PDFF: AUROC 0.99, Sn 96%, Sp 100% for diagnosis of any steatosis[49] MRS: Sn 80%, Sp 80% for diagnosing steatosis ≥ 5%[58]	Not affected by obesity; Quantify assess steatosis over the entire liver; Lower sampling variability	Expensive; Time consuming; Device- and operator-dependency; Not suitable for patients with implantable devices	It is excellent to quantify steatosis, but the high price limits its application[32]

AUROC: Area under the receiver operating characteristic curve; Sn: Sensitivity; Sp: Specificity; BMI: Body mass index; CAP: Controlled attenuation parameter; NA: Not applicable; MRI: Magnetic resonance imaging; MRI-PDFF: Magnetic resonance imaging-derived proton density fat fraction; MRS: Magnetic resonance spectroscopy; LSM: Liver stiffness measurement.