title: Tendinopathy of the achilles tendon: volume assessed by automated contour detection in submillimeter isotropic 3-dimensional magnetic resonance imaging data sets recorded at a field strength of 3 T.
abstract: OBJECTIVE
  This prospective study assesses volume changes of the Achilles tendon in case of chronic tendinopathy (TEN), using an automated contour detection algorithm in submillimeter isotropic 3-dimensional magnetic resonance imaging data sets, recorded at 3 T.
  
  
  METHODS
  Forty-one subjects (median age, 40 years; range, 19-68 years) were included in this prospective study and underwent nonenhanced magnetic resonance imaging of both Achilles tendons at 3 T, deploying a T2-weighted 3-dimensional Fast-Spin-Echo sequence with submillimeter resolution of 0.8 mm. Of the 41 subjects, 13 were classified as patients with TEN and 28 were healthy volunteers and served as control group. Of the 13 patients, 10 had unilateral TEN and 3 had bilateral TEN. Achilles tendons were automatically segmented in the T2-weighted magnetic resonance data sets for the evaluation of the tendon volume (0-3 cm proximal to the cranial border of the calcaneal bone). The total volume (length, 3 cm) was divided in 3 subvolumes of 1 cm length, named volume (0-1 cm), volume (1-2 cm), and volume (2-3 cm). Minimum and maximum tendon cross-sectional area within the total volume was processed. A standardized pain questionnaire was obtained from all patients.
  
  
  RESULTS
  The automated contour detection algorithm worked reliably in all cases. The TEN group showed a significantly increased tendon volume compared to the control group (mean volume, 2.94 vs 2.43 mm; P < 0.05). The difference was most obvious concerning volume (2-3 cm) (P < 0.0001). Evaluation of clinical severity revealed a moderate correlation between VISA-score and tendon volume (2-3 cm) as well as the maximum/minimum tendon area (ρ = -0.44, ρ = -0.48, and ρ = -0.41). In case of unilateral TEN, the symptomatic side showed an increased tendon volume (2-3 cm) and increased minimum area (P < 0.05).
  
  
  CONCLUSIONS
  Tendon volume and size are adequate surrogate parameters to differentiate patients with chronic TEN from healthy subjects, and may discriminate symptomatic TEN from asymptomatic "silent" TEN in patients with unilateral symptoms.
authors.affiliation: From the *Diagnostic and Interventional Radiology, †Section on Experimental Radiology, and ‡Department of Orthopaedic Surgery, Eberhard-Karls-University, Tübingen, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Syha
authors.forename: Fabian
authors.initials: F
authors.lastname: Springer
authors.forename: Christian
authors.initials: C
authors.lastname: Würslin
authors.forename: Ingmar
authors.initials: I
authors.lastname: Ipach
authors.forename: Dominik
authors.initials: D
authors.lastname: Ketelsen
authors.forename: Gerd
authors.initials: G
authors.lastname: Grözinger
authors.forename: Mike
authors.initials: M
authors.lastname: Notohamiprodjo
authors.forename: Konstantin
authors.initials: K
authors.lastname: Nikolaou
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Fritz
authors.initials: F
authors.lastname: Schick
authors.forename: Ulrich
authors.initials: U
authors.lastname: Grosse
mesh_terms: D000125:Achilles Tendon / Q000473:pathology*; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D011446:Prospective Studies; D052256:Tendinopathy / Q000473:pathology*; D055815:Young Adult