Radiology of Liver Circulation (Series in Radiology)

May be seen as areas of parenchymal enhancement usually visible only during the hepatic artery phase that are caused by the dual hepatic blood supply. To quiz yourself on this article, log in to see multiple choice questions. You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Unable to process the form. Check for errors and try again. Thank you for updating your details.

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Pathology Radiographic features Treatment and prognosis References Images: Cavernous transformation of the portal vein: Edit article Share article View revision history. Synonyms or Alternate Spellings: Support Radiopaedia and see fewer ads. Case 1 Case 1. Case 2 Case 2. For Late portal venous phase imaging it is different.

Here you don't want to be too early, because you want to load the liver with contrast and it takes time for contrast to get from the portal vein into the liver parenchyma. Besides you have more time, because the delayed or equilibrium phase starts at about minutes.

So you start at 75 seconds with whatever scanner you have. In some protocols we always want to give the maximum dose of cc, like when you are looking for a pancreatic carcinoma or liver metastases. The upper images are of a patient with liver cirrhosis and multifocal hepatocellular carcinoma examined after contrast injection at 2. There is far better contrast enhancement and better tumor detection.

Some prefer to give positive oral contrast to mark the bowel. This however has some disadvantages:. We use fat containing milk as negative oral contrast or if the patient doesn't drink milk we simply use water. The CT-image shows nice enhancement of the normal bowel wall yellow arrows and no enhancement of the infarcted bowel red arrows. This would not be visible if positive oral contrast was given. We use positive contrast: More information is given in the protocol anastomosis leakage. The conspicuity of a liver lesion depends on the attenuation difference between the lesion and the normal liver.

On a non enhanced CT-scan NECT liver tumors are not visible, because the inherent contrast between tumor tissue and the surrounding liver parenchyma is too low.

References

When we give i. So a hypervascular tumor will be best seen in the late arterial phase. A hypovascular liver tumor however will enhance poorly in the late arterial phase, because it is hypovascular and the surrounding liver does also enhance poorly in that phase. This tumor is best seen when the surrounding tissue enhances, i.

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In the late arterial phase at 35 sec hypervascular lesions like HCC, FNH, adenoma and hemangioma wil enhance optimally, while the normal parenchyma shows only minimal enhancement. Hypovascular lesions like metastases, cysts and abscesses will not enhance and are best seen in the hepatic phase at 70 sec p. Fibrotic lesions like cholangiocarcinoma and fibrotic metastases hold the contrast much longer than normal parenchyma.

They are best seen in the delayed phase at sec p.

Acquired portosystemic collaterals: anatomy and imaging

This late enhancement is comparable to what is seen in cardiac infarcts in MRI of the heart. If you want to characterize a liver lesion, you need maximum contrast at a maximum flow rate, i.



In most cases you also want to scan the whole abdomen. You can do this either at 35 sec or 70 sec p. When you know in advance, that you are dealing with hypovascular metastases, a hepathic phase at 70 sec p. Pancreatic carcinoma is a hypovascular tumor and is best detected in the late arterial phase at sec p.

Metastases in the liver are best detected at sec p. In some cases it can be difficult to differentiate a pancreatic carcinoma from a focal chronic pancreatitis. A NECT can be included in the protocol to detect calcifications in the pancreas, but we do not use that in our standard protocol.



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Imaging in acute pancreatitis is best done after 72 hours of presentation. CT examination of the pancreas should always be done with maximum amount of contrast at a maximum flow rate, because both small pancreatic carcinomas aswell as pancreatic necrosis in pancreatitis are difficult to detect.

Basics of contrast-enhancement

Especially in small bowel obstruction SBO you need to answer the most important question: The coronal reconstruction nicely shows bowel wall enhancement in a patient with ileus due to a small bowel obstruction. Notice the cluster of thick walled loops with poor enhancement and edema of the mesentery red circle. This is a closed loop obstruction with strangulation. This patient needs immediate surgery. If this patient would have been given positive oral contrast, you probably would not have notice the ischemic bowel.

CT contrast injection and protocols

Read more about closed loop obstruction. Leakage after bowel surgery is a great clinical problem. Patients, who are suspected of leakage, need the best CT-protocol they can get and you as a radiologist need the best images to convince the clinician.