Table 1.

Noninvasive Modalities for Assessment of Fatty Liver Disease

Modality	Technique	Advantages	Shortcomings
US	Increased echogenicity makes steatotic livers appear brighter than spleen and kidney	Low cost; widely available; reasonable sensitivity/specificity	Lower performance with steatosis <30% and in morbidly obese patients; operator dependent
US-CAP	Measures the degree of ultrasound attenuation by hepatic fat using vibration control transient elastography	Can roughly distinguish steatosis categories	Overlap between stages; not validated in large patient cohorts
CT	Decreased attenuation of fatty liver (10 HU less than spleen, or liver attenuation <40 HU)	Widely available	Not sensitive for detecting mild steatosis (5%–30%); radiation exposure
MRS	Protons in triglycerides resonate with specific spectral peaks	High sensitivity; correlates strongly with the histological fat percentage	Not widely available; increased cost, cannot be used as a screening tool
MRE	Contrast MRI with a low frequency vibration source to assess stiffness	High sensitivity for fibrosis; differentiates between steatosis and NASH	Not widely available; long procedural time; low image resolution
Transient elastography	Velocity of electric shear indicates liver stiffness	Short procedure time; can be done at bedside; immediate results	Mainly looks at fibrosis; operator dependent; difficult to get accurate and valid results (requires at least 10 measurements)

US, ultrasound; US-CAP, ultrasound with controlled attenuation parameter; CT, computed tomography; MRS, magnetic resonance spectroscopy; MRE, magnetic resonance elastography.