Date of Award

January 2023

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Raul J. Guzman

Abstract

Objectives: Duplex ultrasound (DUS) of the lower extremities is commonly used to assess patients with lower extremity atherosclerosis. Arterial calcification can often be visualized in these images, however efforts to quantify its extent have been limited. We thus sought to develop a new scoring system to measure calcification on duplex US studies of the femoral artery and correlate it with standard CT-based methods. We then made preliminary attempts to correlate US-based femoral artery calcification scores with limb-specific outcomes in patients with peripheral artery disease. Methods: Patients who underwent CT scan evaluation of the lower extremities and arterial duplex US of either lower extremity within 6 months of one another were included in the study. CT based calcium scores of the femoral artery were generated using calcium scoring software. To determine an ultrasound score, 5 standard arterial segments (common femoral artery, proximal superficial femoral artery (SFA), mid SFA, distal SFA, and above knee popliteal artery) were scored using a scale of 0 – 2 where 0 signified a completely normal vessel segment, 1 was a vessel with hyperechoic irregularities of the vessel wall, and 2 was assigned to images with clear anechoic shadowing. The available scores were then averaged to yield a single femoral calcium score for each leg. Predictors of femoral calcification scores were then assessed and compared with CT-based methods. The correlation between US and CT based femoral calcification was assessed, and then the association between the US-based femoral calcification score and limb outcomes was evaluated. Results: A total of 113 patients met the inclusion criteria and were included in the final analysis. US based calcification scores were increased in patients with diabetes, renal failure, and the present of chronic limb threatening ischemia in a manner that was similar to CT-based femoral calcification. US and CT-based calcification scores showed a moderate-strong correlation (r=.64). An elevated US-based femoral artery calcification score was associated with decreased amputation free survival. Conclusions: A novel US-based methods shows promise as a simple method for quantifying the extent of femoral artery calcification in patients with PAD. It correlates with standard CT-based methods. Preliminary studies show that it may be useful for predicating outcomes in patients with PAD.

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This is an Open Access Thesis.

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