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Tendon of the normal supraspinatus muscle: correlations between MR imaging and histology
1Service de Radiologie, Hôpital Universitaire de Bicêtre, Le Kremlin Bicêtre, France.
Abstract:
The aim of this study was to attempt to specify the nature of the signal modifications observed in MRI in the supraspinatus tendon apart from any pathology of the shoulder, and due, according to certain authors, to an artefact associated with MRI. Five macroscopically normal supraspinatus tendons were removed from 4 young subjects (14-28 years), 30 min after cardiac arrest, with the authorization of the ethical committee. These tendons were examined by MRI in the frontal oblique plane along the axis of the muscle with a surface coil of 4 cm diameter, using a T2-weighted spin-echo sequence, and then studied histologically using the same plane of section. 22 control subjects (18-24 years) were examined by MRI with the same T2-weighted spin echo sequence. All the tendons examined possessed a dark signal with zones of intermediate signal on the first echo of the sequence. There was a complete correlation between the MRI appearances of the 5 tendons and their histologic description. Three histologic appearances were described : fibrillary degeneration, fibrous dystrophy, and eosinophil transformation of the tendinous collagen. All the tendons examined in healthy volunteers exhibited heterogenic images at the first echo, in the second echo the hyposignal was uniform and obvious. The good correlation obtained suggests that modifications of the tendon signal from the supraspinatus m. are not related to an artefact described in MRI, but are linked with premature degeneration of this tendon, probably associated with the severity of the mechanical constraints to which it is subject.
Insights
Signal changes in the supraspinatus tendon on MRI are not artifacts but indicate early degeneration. This finding in healthy young adults suggests mechanical stress contributes to premature tendon changes.
Area of Science:
- Orthopedics
- Radiology
- Pathology
Background:
- Magnetic Resonance Imaging (MRI) can show signal modifications in the supraspinatus tendon.
- Some researchers attribute these changes to MRI artifacts rather than pathology.
Purpose of the Study:
- To investigate the nature of MRI signal modifications in the supraspinatus tendon in the absence of shoulder pathology.
- To determine if observed signal changes are due to artifacts or intrinsic tendon properties.
Main Methods:
- Macroscopically normal supraspinatus tendons from young, deceased subjects were examined using T2-weighted spin-echo MRI.
- Histological analysis of the same tendons was performed.
- Control group of healthy volunteers underwent identical MRI scans.
Main Results:
- All examined tendons showed a dark signal with intermediate zones on the first echo, correlating with histological findings.
- Histology revealed fibrillary degeneration, fibrous dystrophy, and eosinophilic transformation of collagen.
- Healthy volunteers' tendons displayed heterogeneous MRI signals initially, becoming uniformly dark on the second echo.
Conclusions:
- Supraspinatus tendon signal modifications on MRI are not artifacts but reflect premature degeneration.
- This degeneration is likely linked to mechanical stress on the tendon.
- Findings suggest early degenerative changes can occur even in macroscopically normal tendons in young individuals.