title: Fast T2 mapping of the patellar articular cartilage with gradient and spin-echo magnetic resonance imaging at 1.5 T: validation and initial clinical experience in patients with osteoarthritis.
abstract: OBJECTIVE
  To evaluate the T2 mapping of patellar articular cartilage in patients with osteoarthritis using gradient and spin-echo (GRASE) magnetic resonance (MR) imaging.
  
  
  METHODS
  After the imaging of a phantom consisting of two sealed 50-ml test objects with different concentrations (30% and 90% weight/volume) of copper sulphate, the T2 mapping of patellar articular cartilage was performed in 35 patients (21 male and 14 female; mean age +/- SD 42+/-17 years) with moderate degree of patellar osteoarthritis. Turbo-spin-echo (TSE) (TR milliseconds/ minimum-maximum TE milliseconds 3,000/15-120; total acquisition time 5 min 52 s) and GRASE (TR milliseconds/ minimum-maximum TE milliseconds 3,000/15-120; total acquisition time 1 min 51 s) were employed. In each patient patellar cartilage was segmented at nine locations (three superior, three central, and three inferior) by manually defined regions of interest. T2 relaxation times were calculated using a linear fit applied to the logarithm of signal intensity decay.
  
  
  RESULTS
  In the phantom the T2 values measured by GRASE were similar to those measured by MR spectroscopy (test object 1: 48.1 ms vs 51 ms; test object 2: 66.8 ms vs 71 ms; P>0.05, Wilcoxon test). In patients GRASE and TSE-derived T2 values demonstrated good agreement (mean difference +/- SD, 1.81+/-3.63 ms). The within-patient coefficient of variation was 22% for TSE and 23% for GRASE.
  
  
  CONCLUSIONS
  Fast T2 mapping of the patellar articular cartilage can be performed with GRASE within a third of the time of that of standard sequences.
authors.affiliation: Department of Radiology, Cattinara Hospital, University of Trieste, Trieste, Italy. equaia@yahoo.com
authors.forename: Emilio
authors.initials: E
authors.lastname: Quaia
authors.forename: Renato
authors.initials: R
authors.lastname: Toffanin
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Guglielmi
authors.forename: Maja
authors.initials: M
authors.lastname: Ukmar
authors.forename: Alexia
authors.initials: A
authors.lastname: Rossi
authors.forename: Bruno
authors.initials: B
authors.lastname: Martinelli
authors.forename: Maria Assunta
authors.initials: MA
authors.lastname: Cova
mesh_terms: D000328:Adult; D002358:Cartilage, Articular / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology*; D010329:Patella / Q000473:pathology*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012720:Severity of Illness Index