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Applying Contrast Injection Principles for CTA (Case Study)

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Applying the knowledge that you

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learned, let's analyze this case.

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This case was a patient who had

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pain, belly pain and chest pain.

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So they did a CT angiogram of the

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chest to look for aortic pathology.

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And they also did a routine belly

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to look for an acute abdomen.

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This is an image from the routine belly.

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And this is an image from the

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CT angiogram of the chest.

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So what do you think?

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went wrong here.

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Take a look at the images.

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Here's what I asked the tech.

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I said, I asked the tech, where did you trigger from?

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And he sent me those trigger images.

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And these are the images that they sent me.

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So what was the issue?

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We have a few options.

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Region of interest was placed in the false lumen.

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Patient had low cardiac output.

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Tech was incompetent and the patient moved.

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The answer is low cardiac output.

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Be very careful in blaming the tech because

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it's often factors that are very technical.

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Patient moving is always a problem, but

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the region of interest didn't show that.

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And yes, the ROI could have been in

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the false lumen, but the problem wasn't

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that the ROI was in the false lumen.

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If the ROI is in the false lumen, the scan starts late.

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Here, the scan started early.

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See the chest scan started early.

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I mean, in a sense, it didn't start early.

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It started early only in relation to

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the contrast because see that the

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pulmonary artery is nicely pacified.

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Aorta is not touched.

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When we do the routine belly, which was done with

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a 70-second delay from the time of injection,

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you have almost perfect arterial pacification.

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So the issue was low cardiac output.

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This patient actually had a type A dissection,

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which also led to a myocardial infarction,

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which also led to a low cardiac output, which

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is responsible for the problem that we see.

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Okay, so let's.

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Continue applying principles, and although

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this is not cardiac, I think, um, we should

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think of the principles that we've learned.

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To evaluate distal renal arteries for medium

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vessel vasculitis, we must increase contrast

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volume, increase injection rate, use saline

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bolus, lower KVP, and all of the above.

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So, what am I asking?

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I'm asking if you have a protocol that you've set

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up for a CT angiogram and you want to now vary that

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protocol to look for medium vessel vasculitis

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in the renal arteries, which has second-order

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arteries, that you want to look for abnormalities.

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What are you going to do differently?

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And the answer is you're going to do all of the above.

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You're going to increase the contrast volume.

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Because by increasing the contrast volume, you're

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going to increase the peak maximum enhancement

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and also the plateau along which it would apply.

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You'll increase the injection rate, which

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will reduce the time to peak, whilst

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also increasing the peak maximum enhancement.

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The saline bolus will tighten the

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bolus and push things together.

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Lower KVP will give you more iodinated bang for

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your buck, so you would do all of the above.

Report

Faculty

Saurabh Jha, MD

Co-Program Director, Cardiothoracic Imaging Fellowship, Associate Professor of Radiology

University of Pennsylvania

Tags

Vascular

Coronary arteries

Cardiac

CTA

CT

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