Reducing the amount of contrast medium in CTAs of the abdominal aorta using a multiphasic injection technique

The amount of contrast medium delivered to a patient is of utmost concern due
to the risks of complications, particularly contras-induced nephropathy (CIN).
CIN is the third most common cause of hospital-acquired acute renal failure.
CIN leads to prolonged hospitalization and higher medical costs. Therefore,
ways to reduce the amount of contrast media are highly anticipated.

In literature the multiphasic injection method is described, in which the rate
of injection exponentially decays, opposed to the current uniphasic technique
that injects with a constant rate. Multiphasic injection is found to achieve
better uniform prolonged enhancement, which is desirable, and can yield the
same quality scans with a smaller amount of contrast medium.

Patients undergoing an angiographic CT (CTA) scan of the abdominal aorta at the
Jeroen Bosch hospital, receive 100 ml of 350 mg/ml iodine containing contrast
material. Using the multiphasic injection technique we will reduce this amount
to 89 ml.

Primary Objective: Is it possible to reduce the amount of contrast medium used
in CTAs of the abdominal aorta by injecting the contrast medium with a
multiphasic protocol, without losing image quality?
Secondary Objective: What does the contrast enhancement curve over time looks
like using the multiphasic injection technique?
With which protocol a more uniform contrast enhancement is reached?

Intervention study, feasibility study

30 Patients are randomly assigned to either standard or multiphasic protocol.
15 Patients undergo standard protocol, 15 patients undergo the multiphasic
protocol. The multiphasic protocol injects contrast medium with an exponential
decay; the total volume of contrast medium is injected is less (89 ml instead
of 100 ml). For research purposes low-dose scans will be made for an additional
20 seconds after the diagnostic scan is finished, at the position where the
diagnostic scan stopped.

There is a risk that the scans of patients undergoing the multiphasic protocol
will be of less quality, since less contrast medium is used. Worst-case
scenario is that the patient will have to undergo another scan. Immediately
after scanning the patients, the scans will be looked at by a radiologist to
see if the image quality is sufficient. So when image quality is not
sufficient, patients will be scanned again immediately and an additional needle
prick is not necessary. The patients undergoing the multiphasic protocol will
be subjected to a small additional amount of radiation, approximately 1 mSv,
because of the low-dose scans that will be made after finishing the diagnostic
scan.