From the Guidelines
Ultrasound is the preferred initial imaging modality for liver characterization, particularly for cystic liver lesions, due to its high sensitivity and specificity, lack of radiation exposure, and cost-effectiveness. According to the EASL clinical practice guidelines on the management of cystic liver diseases 1, ultrasound and MRI are the best imaging modalities to characterize cystic liver lesions, with ultrasound exploring content and wall thickness, and MRI identifying hemorrhagic or proteinaceous contents and wall enhancement. The sensitivity and specificity of ultrasound for the diagnosis of cystic liver lesions is about 90% 1.
Some key advantages of ultrasound include:
- Wide availability
- Inexpensive
- Lack of radiation exposure
- Ability to guide biopsies
- Effective for distinguishing simple cysts from solid lesions
However, CT may be useful in certain situations, such as detecting gas or calcification, but it is less accurate for assessing cyst contents 1. Additionally, in patients with impaired renal function, the administration of contrast agents may play a role in selecting the appropriate imaging modality 1.
In terms of comprehensive liver characterization, while CT provides detailed cross-sectional images and excellent spatial resolution, ultrasound is a valuable initial screening tool, and the optimal choice between the two ultimately depends on the specific clinical question, patient factors, and availability of expertise. Contrast-enhanced ultrasound is also indicated for complex cysts and can help identify malignant cystic lesions by demonstrating vascularized septation or wall enhancement 1.
From the Research
Liver Characterization using Ultrasound or CT
- Both ultrasound and CT are commonly used for liver characterization, but they have limitations in terms of accuracy and detail 2.
- Ultrasound is a non-invasive, real-time, and inexpensive method for liver imaging, and recent advancements in techniques such as contrast-enhanced ultrasound and elastography have improved its diagnostic capabilities 3, 4, 5.
- Contrast-enhanced ultrasound (CEUS) has been shown to be superior to color Doppler and power Doppler ultrasound in detecting tumor vascularity and characterizing focal liver lesions 4.
- Endoscopic ultrasound examination can provide complementary information to cross-sectional imaging and is a powerful tool for diagnosing focal liver lesions, especially when combined with fine needle aspiration 6.
- While CT is not explicitly mentioned as a preferred method for liver characterization in the provided studies, MRI is noted as the preferred radiological investigation for liver lesion characterization due to its ability to demonstrate tissue-specific physiological information 2.
Comparison of Ultrasound and CT
- There is no direct comparison between ultrasound and CT in the provided studies, but it is mentioned that both techniques are suboptimal for liver lesion characterization compared to MRI 2.
- Ultrasound, particularly with contrast-enhanced techniques, has been shown to be effective in characterizing benign and malignant liver lesions, and elastography has enabled reliable assessment of liver fibrosis 3, 4, 5.
- The choice between ultrasound and CT may depend on the specific clinical situation and the availability of equipment and expertise.