Magnetic resonance imaging in the evaluation of chronic Achilles tendinosis

Abstract

The aim of the thesis was to evaluate magnetic resonance imaging (MRI) as an outcome in the evaluation of treatment in mid-portion Achilles tendinosis. Conventional MRI sequences, dynamic contrast enhanced MRI and measurement of transversal relaxation time, using an ultrashort time to echo sequence, has been evaluated.

In study I intratendinous signal and tendon volume was evaluated in five different MR-sequences, using a computerized data program, in patients with unilateral chronic Achilles tendinopathy. Increased intratendinous signal on MRI correlated to increased severity of pain and functional impairment. A significant difference of intratendinous signal between the symptomatic and the contralateral asymptomatic tendons was found in all sequences except in T2-weighted images. Contrast enhanced T1-WI did not contribute to an improved correlation to clinical score compared to other sequences. The symptomatic Achilles tendons had a higher mean volume compared to the contralateral asymptomatic tendons but the volume did not correlate to clinical scores.

In study II symptoms and MRI findings were evaluated four to five years after eccentric calf-muscle treatment in patients with chronic Achilles tendinosis. Semi-quantitative evaluation showed decreased intratendinous signal in the symptomatic treated tendons after 4.2 years both compared to inclusion and after 3 months of eccentric calf-muscle training. The clinical scores were significantly improved both compared to inclusion and at 3 months. The decrease in tendon volume was not statistically significant.

In study III dynamic contrast-enhancement in tendon and in fat ventrally of the tendon in patients with Achilles tendinosis was evaluated before and after three months of eccentric calf-muscle training. In the fat ventrally of the tendon there was a significantly increased contrast enhancement in the symptomatic side compared to the contralateral non-symptomatic side before treatment that disappeared after three months of training. However there was no significant change of enhancement before compared to after training and there was no correlation of dynamic contrast enhancement to symptoms.

In study IV the short-term repeatability of the UTE sequence was evaluated and T2* in patients with chronic Achilles tendinopathy was compared to healthy controls. There was a significant difference in mean T2* between the 20 symptomatic tendons and the 20 control tendons. In the 13 patients with unilateral symptoms a significant difference in T2* was found between the symptomatic tendons and their contralateral asymptomatic tendon. The short-term repeatability of the UTE-sequence showed a CV of 35% and intra-class correlation with an average consistency of 0.98. The least significant change was 98%. There was no significant correlation between VISA-A and T2*.

Conclusions: Increased intratendinous signal on MRI correlate to clinical scoring in patients with chronic mid-portion Achilles tendinopathy but the arbitrary scaling of intratendinous signal makes the computerized method unreliable as an outcome measure.

The significantly better clinical outcome and decreased intratendinous signal on MRI after four to five years compared to directly after the eccentric training program indicates that thelong-term prognosis in chronic Achilles tendinosis is good. A remaining high volume may be a remnant of a previous disorder.

We could not show any additional value of dynamic contrast enhanced MRI compared to MRI without contrast media.

T2* relaxation obtained with a UTE sequence is able to differentiate between chronic Achilles tendinosis and healthy controls but it was not associated with the clinical index. There was a low reproducibility of the method limiting future evaluation of treatment effect to the group level.