Magnetic resonance imaging in chronic Achilles tendinopathy

Abstract

The main objective of this thesis was to evaluate and monitor the morphological response following treatment interventions in patients with chronic Achilles tendinopathy by using different MRI-techniques. For this purpose. we investigated different types of sequences, including gadolinium contrast medium enhanced T1-WI images (CME T1-WI) and developed a precise method to measure tendon volume and mean intratendinous signal of the Achilles tendon.

Study I aimed at evaluating 15 patients with chronic painful Achilles tendinosis, before and two years after - surgical treatment. There was marked regression of the intratendinous signal postoperatively. The most sensitive sequence for depicting an intratendinous lesion in this study was CME T1-WI images. They showed a regression of the intratendinous signal abnormality from 13/15 patients preoperatively to 4/15 postoperatively. The clinical outcome was excellent in 8. good in 5. fair in I and poor in I patient.

In study II, the early contrast agent enhancement in the dynamically enhanced MRI signal (DEMRI) was correlated to the histopathological findings in 15 patients with chronic Achilles tendinopathy. Early contrast enhancement (within the first 72 seconds) was seen in DEMRI in the symptomatic Achilles tendons with a significant difference compared to the asymptomatic contralateral tendons. Increased severity of tendon changes, including fiber structure abnormality, increased vascularity, rounding of nuclei and increased amount of glycosaminoglycans, correlated to CME.

In study III, we developed a computerized 3-D seed growing MRI-technique to measure tendon volume and mean intratendinous signal. This technique showed an excellent inter- and intraobserver reliability. The technique was also used to prospectively follow tip the tendon adaptation and healing described in studies IV-VI.

In study IV, using serial MRI during a period of one year we evaluated the biological effect of tendon repair following iatrogenic tendon injury by five transversal ultrasoundguided core-biopsies employing a needle technique in patients with chronic Achilles tendinopathy. Alterations found during healing, such as tendon volume and intratendinous reactive changes could be monitored by MR imaging, and subsided as noted in the seven and twelve months follow-tip.

In study V, we evaluated the effect of treatment with three months daily-performed heavy loaded calf muscle strength training program in 25 patients who had been suffering from chronic painful Achilles tendinopathy. The tendon volume decreased with 14%. and the mean intratendinous signal with 23%. The clinical outcome was improved.

In study VI we revealed tendon adaptation immediately following calf muscle strength training. An MRI examination within 30 minutes of the performed exercises resulted in increased total tendon volume (12%) and mean intratendinous signal (3 1%).

In conclusion, MRI-techniques can be used as an adjunct to clinical evaluation by monitoring morphological effects following different treatment interventions, thereby adding evidence in clinical studies on patients with chronic Achilles tendinopathy.