Estimation of T2* Values in Healthy and Pathologic Achilles Tendon: Mono and Bi Exponential Analysis

Abstract

Quantitative magnetic resonance imaging (MRI) techniques have been used to analyze significant changes in the structural integrity of tendon. The goals of this study were to compare T2* values calculated using mono and bi exponential methods in healthy and pathologic Achilles tendon and to search for correlation between T2* values and clinical score. Twenty healthy volunteers and twenty patients with tendinopathy were examined for ankle at 3T MRI system. T2* mapping was acquired using Multi Echo Gradient Echo sequence (MEGE) in the sagittal plane. T2* values were measured in three regions of interest in the Achilles tendon (AT) by fitting the signal decay to mono and bi exponential function. P values less than 0.005 were considered statistically significant. Mean mono exponentially calculated T2* (T2*m), short T2* component (T2*s) and long T2* component (T2*1) were 3.79±1.25 ms, 0.85±0.34 ms and 18.06±1.82 ms for asymptomatic volunteers and 7.16±2.37 ms, 1.69±0.40 ms and 20.77±5.24 ms for symptomatic patients respectively. There was a significant difference between the three regions in patients and volunteers (p = 0.001). Mean VISA-A was 24.90±4.53 for patients and 96.85±4.74 for volunteers. Bicomponent T2* relaxation time measurements in vivo using variable echo time (TE) sequence in AT suggest that T2*s could be used to discriminate between healthy and pathologic tendon in acceptable scan times. There was no correlation between T2* relaxation time and VISA-A clinical score for symptomatic and asymptomatic subjects.