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Hi, everyone. So the purpose of this course is to discuss CT

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angiogram runoff. My name is Anushri Parakh.

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I'm a cardiovascular radiologist, and I work at the Massachusetts General Hospital

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in Boston. So let's get started.

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So why do we do a CT angiogram lower extremity runoff?

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And the purpose of this mastery series is basically to

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discuss the clinical rationale of this scan, the anatomy

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that's included in this scan, the technique

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needed to obtain the right set of data sets and interpret

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for the clinical indication, how to make the image reconstructions

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necessary for diagnosis, provide a reporting template, and then we'll

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go into a case-based discussion of the different

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pathologies for the lower extremity runoff.

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So what is the clinical indication to obtain a CT angiogram of the lower

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extremity? Limb ischemia, evaluation

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of both the native vessels as well as vessels which have been stented

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or have undergone surgery and have been bypassed and have a

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graft in them.

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When there's history of trauma, either penetrating, blunt, or

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iatrogenic, looking for complications of that,

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as well as in non-atherosclerotic conditions such as inflammatory diseases,

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vasospasm, mass lesions, or entrapment

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syndromes.

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The different modalities used to assess lower extremity arteries

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include ultrasound. The pros are having rapid

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access to them; they're relatively inexpensive; they have no

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radiation dose, so they're safe in even the young population;

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no contrast, so no risk of renal toxicity.

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The cons, however, are that in patients who are obese or when there's a lot

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of bowel gas, looking at the aortoiliac segments can be

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difficult. There's also limited sensitivity when the disease is

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multifocal or if there are heavily calcified arteries.

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The next imaging modality to image lower extremity arteries is

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magnetic resonance imaging or MRI.

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The pros here, again, are no radiation.

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These can be done without contrast.

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So this is an example of an MR that was done without administration of any

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contrast, or they can be done with the administration of a

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gadolinium-based contrast. They're also really

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useful in patients who have really heavily calcified vessels

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because of the better soft tissue resolution of an MR.

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The cons, however, include limited sensitivity for stent patency because

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of blooming of the stent construct,

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risk of renal toxicity and NSF because of gadolinium,

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and the longer acquisition time, and that limits access to this

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modality.

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So really, CT is the workhorse for evaluating lower

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extremity arteries and has supplanted catheter angiogram

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in the past few decades. It's rapid.

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It provides high spatial resolution images that provides

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comprehensive method for evaluating peripheral arterial disease in both acute and

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chronic settings. There's several advantages

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over MR in that its access is better, there's a rapid

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acquisition, the speed is better, the images are more interpretable, and

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even other physicians like vascular surgeons have a

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little bit more ease in following along the images compared to

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an MR.

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So the spectrum of peripheral arterial disease is very

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accurately depicted by a CT angiogram, providing

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the emergency physician, the vascular surgeons, and the interventional

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radiologists with a roadmap to guide management.