From the Guidelines
Hepatomegaly on CT or MRI is defined as an enlarged liver, typically when the liver span exceeds 15-16 cm in the midclavicular line, and is diagnosed by evaluating the liver's craniocaudal length, anteroposterior diameter, and overall volume compared to established normal ranges.
Definition and Diagnosis
Hepatomegaly can be accurately assessed using MRI, which is more accurate than US for evaluating cirrhosis in obese patients and patients with NAFLD 1. MRI can assess morphologic features of cirrhosis, and fibrosis can be evaluated on dynamic contrast-enhanced sequences with extracellular gadolinium contrast agents.
Key Features
Some key features of hepatomegaly on CT or MRI include:
- An increased liver span, typically greater than 15-16 cm in the midclavicular line
- An increased craniocaudal length, anteroposterior diameter, and overall volume compared to established normal ranges
- Characteristic patterns and density changes within the liver tissue, which can indicate the underlying cause of hepatomegaly ### Causes and Management Hepatomegaly can result from various conditions, including fatty liver disease, hepatitis, cirrhosis, infiltrative disorders, congestion from heart failure, or space-occupying lesions like tumors or cysts. When hepatomegaly is identified on imaging, further clinical correlation and potentially additional tests are typically needed to determine the specific etiology and appropriate management, as recommended by the American Association for the Study of Liver Diseases 1.
Imaging Modalities
Multiphase CT or MRI is necessary for accurate diagnosis, and biopsy is reserved for indeterminate nodules on CT or MRI, particularly with gadoxetate disodium for staging hepatic nodules 1 to 2 cm in size 1. Hepatobiliary MRI contrast agents such as gadoxetate disodium and gadobenate dimeglumine are not as widely used as extracellular agents, but research is ongoing regarding their use in diagnosing fibrosis 1.
From the Research
Definition of Hepatomegaly on CT or MRI
Hepatomegaly refers to the enlargement of the liver, which can be detected on imaging studies such as CT or MRI scans.
- The study 2 defines hepatomegaly as a liver volume that exceeds the normal range, with H-score cutoffs of 0.92 and 1.08 L/m2 used to define mild and massive hepatomegaly, respectively.
- The average volumes of normal and enlarged livers were found to be 1.51 ± 0.25 and 2.32 ± 0.75 L, respectively, in the same study 2.
- Hepatomegaly can be caused by various liver diseases, including fatty liver disease, viral hepatitis, and autoimmune hepatitis, as discussed in studies 3, 4, 5, and 6.
Detection of Hepatomegaly on CT or MRI
- The study 2 introduces nomograms for the identification and grading of hepatomegaly from automatic volumetric liver assessment normalized to body surface area (H scores).
- The use of H scores was found to match well with clinical interpretations for hepatomegaly and may improve hepatomegaly detection compared with height measurements or visual inspection, commonly used in current clinical practice 2.
- The sensitivity of radiologists in detecting all, mild, and massive hepatomegaly was found to be 84.4%, 56.7%, and 100.0% at 90.1% specificity, respectively, using the H score as the reference standard 2.