Diffusion tensor imaging of human Achilles tendon by stimulated echo readout-segmented EPI (ste-RS-EPI)

Kenneth Wengler, Dharmesh Tank, Takeshi Fukuda, James M. Paci, Mingqian Huang, Mark E. Schweitzer, Xiang He

Research output: Contribution to journalArticle

Abstract

Purpose: Healing, regeneration, and remodeling of the injured Achilles tendon are associated with notable changes in tendon architecture. However, assessing Achilles microstructural properties with conventional diffusion tension imaging (DTI) remains a challenge because of very short T 2 /T 2 * values of the tendon. Hence, the objective of this study was to develop a novel Achilles tendon DTI protocol for a non-invasive investigation of the changes of microstructural integrity in tendinopathy. Methods: A novel stimulated echo readout-segmented EPI (ste-RS-EPI) DTI sequence was proposed to achieve a TE of ∼14–20 ms for typical b-values of 400–800 s/mm 2 on clinical 3T MRI scanners. To further boost tendon MR signal, the Achilles was positioned at the magic angle (∼55 °) with respect to the scanner B 0 field. The sensitivity of the developed protocol was evaluated in 19 healthy participants and 6 patients with clinically confirmed tendinopathy. Results: Compared to spin echo RS-EPI DTI protocol, ste-RS-EPI provided an ∼100–200% increase in Achilles MR signal. Tendinopathic Achilles demonstrated a high degree of microstructural disruption based on DTI tractography analysis, with significantly lower (P < 0.05) axial diffusivity (1.20 ± 0.19 vs. 1.39 ± 0.10 × 10 −3 mm 2 /s), radial diffusivity (0.72 ± 0.11 vs. 0.81 ± 0.08 × 10 −3 mm 2 /s), and mean diffusivity (0.87 ± 0.14 vs. 1.00 ± 0.07 × 10 −3 mm 2 /s), but no significant difference in fractional anisotropy (0.38 ± 0.04 vs. 0.38 ± 0.05; P = 0.86). Conclusion: Achilles tendon ste-RS-EPI DTI can non-invasively detect the tendinopathy-induced changes to microstructural integrity, consistent with the disruption of collagen arrangement and increased cellularity. This study demonstrated the robustness and sensitivity of the proposed protocol in Achilles tendinopathy.

Original languageEnglish (US)
Pages (from-to)2464-2474
Number of pages11
JournalMagnetic resonance in medicine
Volume80
Issue number6
DOIs
StatePublished - Dec 1 2018
Externally publishedYes

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Keywords

  • Achilles tendon
  • diffusion tensor imaging
  • readout-segmented EPI
  • stimulated echo
  • tendinopathy

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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