Differences in the magnetic resonance imaging parameter T2 may be identified during the course of canine patellar tendon healing: a pilot study

• Published in: Quantitative imaging in medicine and surgery Vol. 11; no. 4; pp. 1234 - 1246
• Main Authors: Pownder, Sarah L, Hayashi, Kei, Lin, Bin Q, Meyers, Kathleen N, Caserto, Brian G, Breighner, Ryan E, Potter, Hollis G, Koff, Matthew F
• Format: Journal Article
• Language: English
• Published: China AME Publishing Company 01.04.2021
• Subjects: Original; Magnetic resonance imaging (MRI); tendon; T2; ultrashort echo (UTE)
• ISSN: 2223-4292; 2223-4306
• DOI: 10.21037/qims-20-684

Previous studies have utilized ultrashort echo (UTE) magnetic resonance imaging (MRI), and derived T2* maps, to evaluate structures with highly ordered collagen structures such as tendon. T2* maps may provide a noninvasive means to assess tendon damage and healing. This pilot study evaluated the longitudinal relationship of an induced mechanical strain on the patellar tendon with corresponding UTE T2* metrics, histologic and biomechanical evaluation at two post-operative time points. A total of 27 patellar tendons in male Beagles were surgically subjected to stretching by a small diameter (SmD) or a large diameter (LgD) diameter rod to induce damage due to strain, and evaluated at 4- and 8-week intervals using quantitative MRI (qMRI), biomechanical testing, and histology. A separate set of 16 limbs were used as controls. The tendons experienced a 67% and 17% prolongation of short T2* values as compared to controls at 4 and 8 weeks post-operatively, respectively. Histologic analysis displayed a trend of increased collagen disruption at 4 weeks followed by presence of greater organization at 8 weeks. Biomechanical evaluation found a reduction of tendon modulus and failure strain at both time points, and an increase in cross-sectional area at 4 weeks as compared to controls. These findings display tendon healing in response to an imposed strain and present the utility of qMRI to evaluate longitudinal differences of patellar tendon T2* values in a model of induced subclinical tendon damage. The qMRI technique of UTE provides a means to non-invasively evaluate the healing process of a mechanically damaged tendon.