Imaging the Liver
The one organ we can’t survive without (apart from the brain)
Disclaimer: This article is for information only and is not intended as medical advice
The Liver:
The liver is supplied by multiple vessels and divided into 8 segments.
In the normal liver most of the blood supply comes from the portal vein which is the blood supply which comes from the gut and back to the heart via the liver. Yes, the liver has 3 different vessels in it!
Regarding imaging. Ultrasound is great but unfortunately the results are not reproducible between different operators. Therefore a lot of the time we rely on CT (doughnut) and MRI (tunnel) scans.
Common benign findings include: Cysts
but sometimes these cysts can actually be something else:
This one above turned out to be a hyatid cyst (Echinococcosis). Complex features in the cyst tend to suggest alternative causes.
Haemangiomas are another liver finding which can be difficult to distinguish from other findings:
They often need MRI with contrast to distinguish them.
Another common benign finding is FNH or focal nodular hyperplasia:
FNH can be distinguished from cancers by using Primavist (a novel contrast agent that came out in 2004). This contrast is taken up avidly by healthy hepatocytes (liver cells) and not by cancerous cells which don’t.
Fatty Liver:
Above is a fatty liver which makes it very difficult to distinguish the liver structure. This is an increasingly common finding and in and of itself it is just a risk factor for developing liver injury. However, further tests have to be done to properly decide on the likelihood of developing a liver problem aka hepatitis:
This is what acute hepatitis looks like on USS. The liver looks ‘brighter’. All hepatitis means is that the liver is inflamed. It doesn’t in and of itself tell you the cause of the inflammation. It is an important finding to recognise as it normally suggests further tests are required.
The radiologist can also see all sorts of other things such as vessels, ascites (fluid in the abdomen) and cirrhosis.
Cirrhosis is ‘hardening’ of the liver and it implies permanent damage. Up until the point the liver becomes fibrosed (scarred) it can heal, but once the liver cells or ‘hepatocytes’ die and are replaced by scar tissue that part of the liver can no longer regenerate. Of CT, USS and MRI — MRI is the best at picking up cirrhosis but it is also the most expensive and difficult to access test.
Hepatocellular Carcinoma
The above conditions are all benign, but what we really want to spot are the cancers. Hepatocellular carcinomas or primary liver cancers normally occur in those with pre-existing cirrhosis.
Diagnosis can be very tricky if the timing of the scan is off. The contrast has to hit the liver at the correct time. This is why you need a skilled radiology team to get good images.
Above are some images of these tumours. They tend to be surrounded by areas of ‘necrosis’ or dead tissue as the tumour develops a rim of dead cells around it.
Treatment options include:
Sorafenib, TACE, transarterial chemoembolization, resection and transplant but these all need to be covered in another article really.
This is where we are now with liver imaging in 2016.
There are many other investigation and treatment options under further investigation but at the present time we can normally identify what is going on without resorting to invasive means which is amazing!
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