James F Griffith1, Teresa M Hu2, David KW Yeung1, D F Wang1, Fan Xiao1, and Brian Tomlinson2
1Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong SAR, Hong Kong, 2Medicine, The Chinese University of Hong Kong, Hong Kong SAR, Hong Kong
Synopsis
Achilles tendon xanthoma is a key clinical indicator of familial hypercholesteraemia (FH) and associated cardiovascular
disease. Treatment that reduces the size of tendon xanthoma also benefits the arterial
manifestations of FH. Ultrasound and MRI are often used to detect and monitor
treatment response of tendon xanthomas using parameters such as tendon
thickness, width and cross-sectional area. However, MR-based parameters derived from the DIXON technique to determine tendon volume and intratendinous percentage fat fraction may
be more sensitive than traditional US and conventional MRI.Objective
Achilles tendon xanthoma is a key clinical
indicator of familial hypercholesteraemia (FH) and associated cardiovascular
disease. Treatment that reduces the size of tendon xanthoma also benefits the arterial
manifestations of FH. Ultrasound (US) and MRI are used to detect and monitor
treatment response of tendon xanthomas using parameters such as tendon
thickness, width and cross-sectional area (CSA) [1]. MR-based parameters such
as tendon volume and intratendinous percentage fat fraction (Dixon technique) may
be more sensitive to change than these traditional US and conventional MRI. We
compared US and new MR parameters in assessing tendon xanthoma at baseline and
following treatment.
Methods
After ethical approval was obtained, US
(thickness, width, CSA) and MRI (thickness, width, CSA, volume and fat/water
fraction) of the Achilles tendons in 19 FH patients with clinical tendon
xanthomas was performed at baseline and compared to 10 normocholesterolaemic
patients. MR imaging was performed at 3T (Achieva TX, Philips Medical Systems,
Best, the Netherlands) using a 16-channel torso array coil for signal reception. Both
legs were examined while lying in the supine, feet-first position. T1-weighted
axial images were obtained along the length of the Achilles tendon (TR 653ms; TE
20ms; FOV
300mm; NSA
1; slice
thickness 4mm; gap 0.4mm; matrix size 547 × 1200). Fat-water images were
acquired using a
multiecho 3D gradient echo sequence (TR 13 ms; first TE 1.2 ms; echo spacing 1
ms; flip angle 3
o; FOV 300 mm; slice thickness 3 mm; NEX 4). A
relatively short flip angle was employed to minimize T1-related bias between water
and fat. FH patients had follow-up
US and MR assessment at 3 and 6 months following treatment with
probucol, a lipid lowering agent
[2].
Results
At baseline, all US and
MR parameters were significantly increased in FH patients compared to controls
(p< 0.05) (Tables 1a,b). At 6 months, only the newer MR-based parameters,
namely relative water and fat fraction and relative fat-volume product,
relative water volume fraction showed significant change with treatment (p<
0.05 for all) (Tables 2a,b).
Conclusion
This is the first
study to use MR tendon volume and relative fat/water tendon fraction to gauge
and monitor tendon xanthomas. These new parameters seem more sensitive than US or
traditional MR-based parameters at detecting interval change. This study helps
to confirm earlier suggestion that most of the tendon swelling in FH is due to increased
tendon water rather than fat deposition [3].
Acknowledgements
The work described in this paper was fully supported
by a grant from the Research Grants Council of the Hong Kong Special
Administrative Region, China (Project No. SEG CUHK_02).References
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Argyropoulou MI, Mikhailidis DP, Elisaf MS. Pathogenesis,
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life for an old drug? Atherosclerosis 2009;207:16-23.
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