Keywords:
Pathology, Physics, Imaging sequences, MR, MR physics, Musculoskeletal joint
Authors:
Z. tbini1, H. Riahi2, M. Mars1, I. BOUGAMRA2, M. Bouaziz2, M. F. Ladeb2; 1Tunisia/TN, 2Ksar Said/TN
DOI:
10.26044/essr2019/P-0046
Purpose
Introduction
Injuries of the Achilles tendon (AT) are painful and can seriously hamper the activities of daily living. They may arise because of a variety of degenerative changes in the tendon composition including an increase in stiffness of the inter fascicular matrix,
an increase in collagen cross-linking and a reduction in collagen fibril crimp angle [1,
2,
3]. In the early stages of AT degeneration,
it is difficult to detect the small morphological changes using ultrasound or conventional magnetic resonance imaging (MRI). Relaxations Times such as T1 and T2* are sensitive to alteration or disruption of the extracellular matrix (ECM).
Recently introduced quantitative assessment of AT injuries using biochemical sensitive MRI techniques offers the best opportunity to diagnose early microscopic degenerative changes of AT and follow-up of patients after treatment. In the present work,
we studied the biochemical changes in the components of AT with parametric MRI techniques.
Purpose
The aim of this study is to :
- measure and compare T1 and T2* relaxation times in normal and patient with tendinosis
- evaluate the ability of T1 and T2* in the early diagnosis of AT tendinosis
T1 and T2* mapping
The T1 longitudinal relaxation time is the energy transfer between the excited spins and the tissue (spin-lattice relaxation). T1 is the time required for the longitudinal component of M0 to return to 63% of its initial value.
T1 is tissue-specific,
strongly dependent on B0,
and depending on the micro-viscosity of the medium.
The T2 transverse relaxation time is a phase shift of the individual magnetic moments of the proton due to the spin-spin coupling,
no energy is lost in the system. T2 is the time after which the transverse magnetization is decayed to 37% of its starting amplitude.
It is a fundamental property of a tissue at specific conditions such as field strength and temperature.
Achilles tendinosis is associated with inflammation and degeneration of the tendon as result of micro tears from increased stress,
chronic overuse and lack of adequate healing time.
Biochemical and degenerative changes in Achilles tendon are related to proteoglycan loss and disorganization of the collagen matrix,
which becomes less elastic allowing increased mobility of water and consequentially increased levels of H2O proton content which leads to an increased T1 and T2 relaxation values compared to normal levels.
T1 longitudinal relaxation time is a quantitative biomarker of proteoglycan and glycosaminoglycan .
It was reported that depletion of proteoglycan causes increased T1 values.
T2 transverse relaxation time is sensitive to the changes in collagen matrix integrity and water content.
It can also monitor the levels of injuries to improve MRI diagnosis for treatment planning.