Advanced Hepatic Ultrasound in the MASLD Workup: Steatosis, Fibrosis, Cirrhosis and Nodules

A practical, evidence-based guide to how B-mode ultrasound, quantitative attenuation techniques and elastography have transformed MASLD screening and staging.

Fatty liver disease is now the most prevalent chronic liver disease worldwide, and ultrasound remains the first-line test to screen for it, stage it and follow its complications. But the role of ultrasound has changed substantially in recent years: it is no longer just the exam that tells you the liver looks 'bright' — in many services it now provides quantitative measures of fat content and liver stiffness whose performance rivals biopsy in selected settings. This article reviews what current evidence does — and does not — support in the use of advanced ultrasound for the MASLD workup.

From NAFLD to MASLD: why the name changed in 2023

In June 2023, a multisociety Delphi consensus, published simultaneously in hepatology journals and endorsed by AASLD, EASL and other global societies, replaced 'nonalcoholic fatty liver disease' (NAFLD) with 'metabolic dysfunction-associated steatotic liver disease' (MASLD), and 'nonalcoholic steatohepatitis' (NASH) with MASH. The process involved more than 225 international panelists and achieved 97% approval. The change is not merely semantic: the old term defined the disease by exclusion ('non-alcoholic'), language many patients and clinicians considered stigmatizing and imprecise, since most cases are in fact linked to metabolic dysfunction (obesity, insulin resistance, dyslipidemia, hypertension). The new nomenclature also created an umbrella category, 'steatotic liver disease' (SLD), with subtypes such as MASLD (steatosis plus at least one of five cardiometabolic criteria), MetALD (MASLD with intermediate alcohol intake, between low-risk and alcohol-related liver disease thresholds), and cryptogenic SLD.

For imaging practice, the consequence is direct: the ultrasonographic criteria for steatosis have not changed, but the clinical context in which they are interpreted has — the report and diagnostic suspicion are now expected to be read alongside metabolic risk factors (BMI, glucose, lipid profile, blood pressure), rather than simply the absence of significant alcohol intake.

B-mode ultrasound: useful for screening, limited for grading

The classic B-mode signs of steatosis are well known: diffuse increase in liver echogenicity ('bright liver'), blurring of the portal vein walls, posterior beam attenuation and, arguably the most reproducible finding, the hepatorenal contrast (liver more echogenic than the adjacent renal cortex within the same acoustic window). A 2020 study (Petzold et al.) using high-end equipment and histology as the reference standard found 75.6% sensitivity and 76.0% specificity (AUROC 0.798) for detecting any degree of steatosis (S≥1), with considerably better performance for moderate-to-severe steatosis (S≥2): 90.9% sensitivity, 64.6% specificity and AUROC 0.861. In other words, B-mode is reasonably good at not missing clinically relevant steatosis, but it carries a real false-negative rate for mild fat content, and this performance is heavily dependent on the equipment, the examiner's experience, and the patient's body habitus — signal attenuation in obese patients degrades both sensitivity and the reliability of the visual impression.

The most important limitation, however, is different: B-mode is essentially binary (steatosis is visible or not) and does not reliably quantify fat content. It does not distinguish mild from moderate steatosis well, does not consistently detect mild steatosis, and should not be used in isolation to decide therapeutic or prognostic management for an individual patient — for that, the quantitative techniques described below play an important complementary role.

Fat quantification: CAP, ATI and UGAP

The controlled attenuation parameter (CAP), available on the FibroScan platform (vibration-controlled transient elastography, VCTE), was the first widely validated technology to quantitatively estimate liver fat, measuring ultrasound attenuation at the same site where liver stiffness is measured. A 2019 meta-analysis (7 to 9 studies, over 1,200 patients) showed decreasing performance as the steatosis grade assessed increased: for detecting any steatosis (≥S1), sensitivity was 87% and specificity 91% (AUROC 0.96); for moderate steatosis (≥S2), sensitivity 85% and specificity 74% (AUROC 0.82); and for severe steatosis (S3), sensitivity 76% and specificity only 58% (AUROC 0.70). The authors themselves concluded that CAP should be cautiously considered as a substitute for biopsy, precisely because its discriminative power falls at the more advanced grades — it is a better tool for saying 'there is fat' than for saying 'how much fat'.

In recent years, manufacturers of conventional ultrasound equipment (not dedicated to transient elastography) have developed their own attenuation-imaging techniques that can be applied during a routine abdominal ultrasound exam, without additional equipment: Attenuation Imaging (ATI) and Ultrasound-Guided Attenuation Parameter (UGAP), among other equivalent commercial names. These techniques place a region of interest under direct B-mode visualization, avoiding vessels and artifacts, and calculate the attenuation coefficient in dB/cm/MHz. Studies comparing UGAP to MRI proton-density fat fraction (MRI-PDFF), currently considered the most accurate non-invasive reference standard for liver fat, showed AUROCs of 0.91, 0.90 and 0.88 for detecting steatosis ≥S1, ≥S2 and S3 respectively, with good linear correlation to PDFF (r≈0.77) and a high rate of technically valid measurements. In practice, this means a routine abdominal ultrasound exam, on machines equipped with this software, can already generate a quantitative and reproducible estimate of liver fat, without needing to refer the patient to a dedicated transient-elastography service.

Elastography: staging fibrosis without a scalpel

If fat quantification helps confirm the MASLD diagnosis, it is fibrosis assessment that defines the patient's prognosis — it is the degree of fibrosis, not the degree of steatosis, that correlates most strongly with liver-related and overall mortality. Transient elastography (VCTE/FibroScan) and shear-wave elastography (available on many conventional ultrasound machines, as 2D-SWE and point-SWE) measure the propagation speed of a mechanical wave through liver parenchyma, converted into stiffness expressed in kilopascals (kPa) — the stiffer the liver, the greater the fibrosis. A risk-stratification scheme widely used in MASLD clinical practice defines: liver stiffness below 8 kPa as low risk, with advanced fibrosis reasonably excluded; between 8 and 12 kPa as intermediate risk, requiring further evaluation; and above 12 kPa as high risk, consistent with likely advanced fibrosis. This cutoff is usually combined, at initial primary-care triage, with serologic scores such as FIB-4 (values below 1.3 allow safe follow-up without elastography).

A recent meta-analysis (2025) specifically in MASLD patients confirmed that 2D shear-wave elastography on ultrasound platforms has good diagnostic accuracy for staging significant and advanced fibrosis, with performance consistent enough to support its use as a rule-out tool for significant fibrosis in at-risk populations, reducing the need for referral to liver biopsy in that subgroup. This is, in practice, the most relevant change of the past decade: combining a clinical risk score with elastography now allows liver biopsy — invasive, subject to sampling error and interobserver variability — to be reserved for cases of genuine diagnostic uncertainty, suspected mixed etiology, or an indeterminate non-invasive test result, rather than being the first line of investigation.

It is worth reinforcing that liver stiffness can be falsely elevated by non-fibrotic causes — hepatic congestion (right heart failure), acute inflammation (markedly elevated transaminases), extrahepatic cholestasis, and recent food intake — pitfalls that must be kept in mind before assuming advanced fibrosis from an isolated number.

Recognizing cirrhosis on ultrasound

When fibrosis progresses to cirrhosis, B-mode ultrasound regains a central role, now a morphological one. Classic signs include: a nodular or irregular liver contour (best seen with high-frequency linear transducers over the anterior liver surface, rather than with the standard curvilinear probe alone), volumetric redistribution with relative right-lobe atrophy and hypertrophy of the caudate lobe and left lateral segment (an enlarged caudate-to-right-lobe ratio is a classic indirect sign), coarse parenchymal heterogeneity and, often, increased sound attenuation from the associated fibrosis. These morphological signs are highly specific but have variable sensitivity for compensated, early cirrhosis — so when clinical suspicion is high and ultrasound is normal or equivocal, elastography (typically with liver stiffness values well above the advanced-fibrosis threshold) remains the most robust non-invasive method to confirm cirrhosis.

Ultrasound evaluation of cirrhosis should always include an active search for signs of portal hypertension, which reinforce the diagnosis and signal higher risk of decompensation: splenomegaly (the most sensitive indirect finding), portal vein dilation, loss of respiratory variation in portal flow or hepatofugal flow on Doppler, umbilical vein recanalization and collateral circulation (esophagogastric varices, splenorenal shunt), and ascites in more advanced stages.

Nodules in the cirrhotic or steatotic liver: when to investigate further

Every patient with confirmed cirrhosis — regardless of etiology, including MASH-related cirrhosis — enters a hepatocellular carcinoma (HCC) surveillance program, and abdominal ultrasound, combined with serum alpha-fetoprotein (AFP), is the backbone of that surveillance. Practice recommended by societies such as AASLD is to repeat the exam every six months; studies show this interval increases detection of very-early-stage HCC compared with annual surveillance, with no meaningful added benefit from shortening it to three-month intervals. It is important to have realistic expectations about the method's performance: overall ultrasound sensitivity for detecting HCC of any size, in experienced hands, ranges from 60 to 80%, but falls to about 45 to 60% when the target is specifically very-early-stage HCC — and AFP alone has a sensitivity of only 47 to 64%, which is why the two tests are used together rather than as alternatives.

When a nodule is identified on surveillance, the US LI-RADS system (updated in 2024 by the American College of Radiology) standardizes management: exams with no suspicious findings are categorized US-1 (negative, continue six-monthly surveillance); nodules smaller than 10 mm, of any echogenicity, that are not definitely benign, are US-2 (subthreshold) and should be reassessed with short-interval ultrasound at three to six months; and observations of 10 mm or larger, focal parenchymal distortion of 10 mm or larger, or new venous thrombosis are categorized US-3 (positive). A US-3 exam requires further characterization with multiphase CT, multiphase MRI, or contrast-enhanced ultrasound (CEUS), following the respective LI-RADS diagnostic algorithms — a substantial proportion of these patients, particularly those with cirrhosis, will ultimately be diagnosed with HCC or another malignancy. At this point CEUS has a particularly useful role as a complementary, point-of-care characterization method when MRI is not readily available or is contraindicated — a topic covered in more depth in this site's dedicated article on contrast-enhanced ultrasound.

Putting it all together in a practical protocol

In daily practice, a liver ultrasound exam focused on MASLD can today — and, whenever the equipment allows, should — combine four layers of information in the same session: (1) morphological B-mode assessment, including liver contour, echotexture and hepatorenal contrast; (2) when available, a quantitative attenuation measurement (ATI, UGAP or equivalent) to objectively estimate the degree of steatosis; (3) shear-wave elastography or referral for transient elastography, to stratify the risk of advanced fibrosis; and (4) active screening for signs of portal hypertension and focal nodules, applying US LI-RADS whenever cirrhosis is already established. This layered protocol does not eliminate the need for liver biopsy in every case, but it substantially reduces the number of patients who need to undergo it, concentrating the invasive procedure on scenarios of genuine diagnostic uncertainty.

The central point for anyone practicing ultrasonography is to recognize the limits of each layer: B-mode screens but does not grade; CAP and ATI/UGAP quantify fat but lose precision at the extremes; elastography stages fibrosis but can be confounded by congestion or acute inflammation; and nodule surveillance depends on a standardized protocol and a low threshold for referral to cross-sectional characterization. Used together, with careful interpretation, these tools have transformed ultrasound from a qualitative screening exam into a genuine longitudinal staging instrument for MASLD.