What is CEUS?

Contrast-Enhanced Ultrasound (CEUS) is an ultrasound scan performed after injecting a special microbubble contrast agent into a vein. These tiny gas-filled bubbles reflect ultrasound strongly, lighting up blood flow in real time. Because a liver lesion’s pattern of blood supply is often the key to what it is, watching how contrast enters and leaves a nodule, second by second, is a powerful way to characterise it. Unlike a CT or MRI, CEUS uses no radiation and no iodine- or gadolinium-based dye, and the microbubble agent is safe even in patients with kidney impairment.

Telling cancer from benign lesions

The great strength of CEUS is its live, dynamic view. The scan follows a lesion through three phases – arterial, portal-venous and late. The behaviour in these phases tells the story:

Liver cancer (HCC) typically takes up contrast briskly in the arterial phase (arterial phase hyperenhancement) and then slowly gives it up later – a mild, late “washout.”
Benign lesions such as haemangiomas and focal nodular hyperplasia have their own characteristic patterns, which CEUS often shows clearly.
Other malignancies (for example cancer that has spread to the liver, or bile-duct cancer) tend to wash out earlier and more markedly, which helps flag that a lesion is not a typical HCC and needs different work-up.

CEUS LI-RADS

To standardise reporting in patients at risk of liver cancer, radiologists use a system called CEUS LI-RADS (Liver Imaging Reporting and Data System). It grades a nodule from LR-1 (definitely benign) up to LR-5 (definitely HCC), based on features such as lesion size, non-rim arterial hyperenhancement, and the timing and degree of washout. An LR-5 pattern in an at-risk patient is reliable enough that HCC can often be diagnosed without a biopsy. A separate category, LR-M, flags features that suggest a malignancy that may not be HCC, prompting further tests.

Where CEUS fits – and where it doesn’t

CEUS is excellent for characterising a single lesion already seen on ultrasound, CT or MRI, especially an indeterminate nodule, or when a patient cannot have CT/MRI contrast because of kidney problems or allergy. It gives a real-time answer, in the clinic, without radiation. Its limitation is that it examines one area at a time, so it is not a whole-liver survey and it does not replace CT or MRI for staging cancer or mapping the whole liver.

Dr Kalal’s role

CEUS is performed in the radiology suite by a radiologist, since it requires contrast injection and specialised scanning. Dr Kalal’s role as the hepatologist is to decide when CEUS is the right test, often for a nodule found on surveillance ultrasound in a patient with cirrhosis, to order it, and then to integrate the result with the LI-RADS category, tumour markers and other imaging to reach a diagnosis and plan treatment.