Reducing the amount of contrast medium in CTAs of the abdominal aorta using a multiphasic injection technique and a test bolus to reduce the bolus volume

The amount of contrast medium delivered to a patient is of utmost concern due
to the risks of complications, particularly contrast-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. Ways to reduce
the amount of contrast media are therefore highly anticipated.

In literature a multiphasic injection method is described. Here, the rate of
injection exponentially decays, opposed to the current uniphasic technique,
which 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.

This uniform prolonged enhancement can be shortened with reducing the bolus
volume by using the information extracted from the test bolus injection
acquired prior to the multiphasic injection. Patients undergoing an
angiographic CT (CTA) scan of the abdominal aorta at the Jeroen Bosch
Ziekenhuis, receive 100 ml of 350 mg/ml iodine containing contrast medium. With
the multiphasic injection technique and bolus reduction, we will reduce this
amount to 50 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 an exponential decay and
with a bolus reduction, without losing image quality?

Secondary Objectives:
What does the contrast enhancement curve over time looks like using the
multiphasic injection technique with a bolus reduction?

With which protocol a more uniform contrast enhancement is reached?

Intervention study, feasibility study

Randomly, 15 Patients are assigned to undergo standard protocol, and 15
patients are assigned to undergo the multiphasic with bolus reduction protocol.
The multiphasic protocol injects contrast medium with an exponential decay. The
total volume of contrast medium injected is less, 50 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 with
bolus reduction protocol will be of less quality, since less contrast medium is
used. Worst case scenario is that the patient will have to undergo a second
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 with
bolus reduction 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.