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UBC Theses and Dissertations

Can achilles tendon xanthoma and achilles tendinopathy be distinguished using ultrasonography and MRI? : an exploratory, comparative study Zahradnik, Thomas Michael Lewis


Familial hypercholesterolemia (FH) is a genetic condition characterized by the inability to properly metabolize low-density lipoprotein cholesterol (LDL-C). In addition to serious cardiovascular health complications, FH carriers often develop intratendinous cholesterol deposits, most notably located in the Achilles tendon, known as Achilles tendon xanthoma (ATX). Clinically, physical detection of ATX relies upon visual assessment and palpation. This practice is insensitive and is not capable of distinguishing FH from conditions with similar symptomology, such as Achilles tendinopathy (ATE). Advances in medical imaging, specifically Dixon method for magnetic resonance imaging (MRI) and ultrasound tissue characterization (UTC) for ultrasound (US), may be able to differentiate between ATX and ATE. The Dixon method allows for quantification of relative lipid and water contents within tissue and UTC allows for characterization of tendon structure through echo-type evaluation. We hypothesized that ATX will demonstrate greater relative lipid and water content than ATE or a healthy control population (C), and that ATX and ATE will demonstrate decreased tendon organization compared to C. To test the hypotheses, US and MRI scans of 59 tendons from 30 participants (n=10 ATX, n=10 ATE, n=10 C) were analyzed for relative lipid and water content, UTC echo-type I values, as well as Achilles tendon thickness (ATT). Relative lipid content was not greater in ATX compared to ATE and controls (ATX – ATE, p = 0.23; ATX – Control, p = 0.31; ATE – Control, p = 0.98). Relative water content was greater in ATX compared to controls (p = 0.04) but not compared to ATE (p = 0.16) and did not differ between ATE and control (p = 0.76). ATX tendons were significantly thicker than both ATE and control tendons (p = 0.04 and 0.002, respectively). UTC echo-type I values were significantly lower in ATX than ATE (p = 0.04) and nearly significantly lower in ATX than C (p=0.055), indicating decreased collagen organization in ATX. Results suggest that both US and MRI may serve as viable approaches to aid clinical detection of ATX as well as to differentiate ATX and ATE pathology.

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