In Chennai, we have many CT scan centers. It is common for our patients to come and see us with CT scan reports of scans done outside. Sometimes, we are unable to look at the CT films and give a genuine opinion. So we end up asking for a second imaging to the dismay of our patients.
Imaging standards for pancreatic tumour imaging has been standardized by many radiologic societies and only a standardized evaluation will give us appropriate decision making. Using the wrong scans to decide will lead us into confusion.
So what are the established standards for CT scan of the pancreas?
Here we go.
Before we deal with pancreatic CT, I will explain what constitutes a normal CT scan protocol.
Normal CT scans are done in different formats. Plain CT scan refers to CT scan done without giving contrast agents. Plain scan will not show the blood vessels and cannot accurately define the relationship of the lesion or even clearly define the lesion. It is useful to pick up very large lesions, calcium deposits and air related issues.
The volume of contrast required for good pancreatic CT scan is 150 cc and has to be injected at a rate of 5 cc per second.
The next step is taken at 25 s after injection of the contrast. This lights up the arteries (Blood vessels that carry blood away from the heart) and is very useful in planning surgery in complex pancreatic diseases.
The key step is to take the next set of scans 45 - 50 seconds after contrast injection. This is called the pancreatic parenchymal phase. This part of the scan is very helpful to define the tumour and its behavior. This is also the part of the scan where you can guess the type of tumour in the pancreas.
The next set of scans is done 70 seconds after the contrast injection. This is called the portal phase imaging. I take a lot of information from this phase. This is where I learn how the tumour is related to the key blood vessels, and the length of involvement and the degree of involvement. I also use the multiplanar projections (special sections created by the CT software) which gives me detailed map of the lesions.
With appropriately done scans, we will be able to provide good counselling and prepare the patient for safe surgery.
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