title: MR imaging in chronic Achilles tendon disorder.
abstract: OBJECTIVE
  The primary objective was to compare 4 imaging sequences (T1-weighted, T2-weighted, proton density, and T1-weighted with gadolinium contrast agent enhancement) with regard to intratendinous signal abnormality in patients with achillodynia. The secondary objective was to relate the images to the clinical symptoms and histopathological findings.
  
  
  METHODS
  Twenty patients (16 men, 4 women, median age 40 years) with chronic achillodynia participated in the study. The symptoms prohibited activity and clinical examination revealed swelling and tenderness 1.5-6 cm proximal to the Achilles tendon insertion. Of the 20 patients: 5 had bilateral achillodynia, 4 had had previous contralateral Achilles tendon disorder, and 11 had never had symptoms in the contralateral tendon region. These 11 tendons served as controls for comparison. MR imaging was performed on a superconductive 1.5 T unit. Both Achilles tendons were examined (n = 40) at the same time, and multiple sagittal and transversal images were obtained. The corresponding sections on these images were visually graded according to both extension and level of MR signal intensity. Tissue was obtained for microscopic examination from the most symptomatic side in all patients (n = 20).
  
  
  RESULTS
  T1-weighted images following gadolinium contrast medium enhancement proved to be the best method by which to visualize intratendinous signal abnormality. This sequence revealed signal abnormality in 24/25 symptomatic tendons and in 1/11 control tendons (p < 0.001). Histopathological examination showed an increased noncollagenous extracellular matrix and altered fiber structure in the lesions corresponding to the contrast-enhanced areas.
  
  
  CONCLUSIONS
  Gadolinium enhancement improved the imaging of intratendinous signal abnormality on T1-weighted images. There was a high level of extracellular glycosaminoglycans, which are highly-fixed negatively-charged macromolecules with extreme water-retaining capacity and which may have contributed to the enhancement by the gadolinium contrast agent.
authors.affiliation: Department of Orthopedic Surgery, Karolinska Institute, Huddinge University Hospital, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Movin
authors.forename: M
authors.initials: M
authors.lastname: Kristoffersen-Wiberg
authors.forename: C
authors.initials: C
authors.lastname: Rolf
authors.forename: P
authors.initials: P
authors.lastname: Aspelin
mesh_terms: D000125:Achilles Tendon / Q000737:chemistry / Q000293:injuries / Q000473:pathology*; D000328:Adult; D000368:Aged; D001707:Biopsy, Needle; D002908:Chronic Disease; D003094:Collagen / Q000032:analysis; D003287:Contrast Media; D005260:Female; D005682:Gadolinium; D006025:Glycosaminoglycans / Q000032:analysis; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000175:diagnosis / Q000378:metabolism; D010146:Pain / Q000209:etiology; D012421:Rupture / Q000175:diagnosis
chemical_list: D003287:Contrast Media; D006025:Glycosaminoglycans; D003094:Collagen; D005682:Gadolinium