From the Guidelines
Ultrasound is generally better than CT for the initial evaluation of hepatomegaly. This recommendation is based on the fact that ultrasound is non-invasive, does not use radiation, is widely available, cost-effective, and provides real-time images of the liver 1. It can accurately measure liver size and detect common causes of hepatomegaly such as fatty liver disease, cysts, and many solid lesions. Ultrasound also allows for assessment of liver texture, blood flow using Doppler imaging, and evaluation of surrounding structures.
Some of the key advantages of ultrasound over CT include:
- Non-invasive and no radiation exposure
- Widely available and cost-effective
- Provides real-time images of the liver
- Can accurately measure liver size and detect common causes of hepatomegaly
- Allows for assessment of liver texture, blood flow, and surrounding structures
However, CT may be preferred as a follow-up when ultrasound findings are inconclusive, when there's suspicion of malignancy requiring better characterization of lesions, or when evaluating complications of liver disease 1. The choice between these imaging modalities should consider the clinical context, suspected diagnosis, patient factors, and local expertise and availability. It's also worth noting that contrast-enhanced ultrasound (CEUS) has a complementary role to CT or MRI for lesions that are indeterminate with these modalities, and can be useful for characterization of indeterminate lesions and treatment planning 1.
In terms of specific patient populations, ultrasound may be limited in patients with obesity, nonalcoholic fatty liver disease, and nodular cirrhotic livers, and consideration can be made for screening for hepatocellular carcinoma with either MRI or multiphase CT in these cases 1. Ultimately, the choice of imaging modality should be individualized based on the patient's specific needs and clinical context.
From the Research
Comparison of Ultrasound and CT for Evaluating Hepatomegaly
- Ultrasound is a non-invasive tool that can be used to detect hepatomegaly, with a study finding it to be 100% sensitive and 100% specific in detecting histological nonalcoholic fatty liver disease (NAFLD) 2.
- CT scans can also be used to evaluate hepatomegaly, with a study introducing nomograms for the identification and grading of hepatomegaly from automatic volumetric liver assessment normalized to body surface area (H scores) 3.
- The choice between ultrasound and CT may depend on the specific clinical scenario, with MRI generally considered superior to ultrasound and CT for detection and characterization of focal liver lesions in patients with fatty liver 4.
- Ultrasound has been shown to be accurate in determining the presence or absence of hepatomegaly, with a study finding an 87% accuracy rate using midhepatic line measurements 5.
- Contrast-enhanced ultrasound (CEUS) is a useful tool for evaluating focal liver masses, providing unique advantages over CT and MRI, including dynamic real-time depiction of tumor perfusion and accurate reflection of tumoral and inflammatory blood flow 6.