How can PAD be diagnosed?
I order to diagnose PAD, it is better to start with noninvasive tests such as Ankle Brachial Index (ABI) and arterial Ultrasound (US)
In ABI, arterial systolic pressures are measured on both ankles and brachial arteries and by dividing the ankle to brachial systolic blood pressures, PAD can be diagnosed. ABI <0.9 is considered abnormal.
Arterial ultrasound is another modality to diagnose PAD. Arterial blood flow speed is measured during the arterial US and based on the blood flow velocity changes, severity and location of the PAD can be determined.
Arterial Computed Tomography Angiography (CTA) and Magnetic Resonance Angiography (MRA) are also great tools to diagnose PAD. They both provided the severity and location of the PAD which are extremely important for invasive procedure planning. When making the decision to order CTA vs MRA, we should consider the risks and benefits in each of these tests. In CT angiogram, patient is exposed to radiation and risk of contrast induce nephropathy and allergic reactions should be considered. On the other hand, MRA will not expose the patient to radiation or contrast induced nephropathy but expense can be an issue. MRA also can result in Gadolinum induced Nephrogenic systemic fibrosis (NSF) in patients with chronic kidney disease.
Finally, the gold standard test to diagnose PAD is invasive aortic angiogram with distal run off which is done in the cath lab under moderate sedation. This test is done by inserting an arterial sheath in the common femoral artery and taking pictures through catheters and using contrast under fluoroscopy. After taking pictures, arterial lesions can be treated using balloons or stents which will be discussed in our next blog post.
