title: Ultrasound detection of cartilage calcification at knee level in calcium pyrophosphate deposition disease.
abstract: OBJECTIVE
  To determine the sensitivity, specificity, and accuracy of ultrasound (US) in the detection of cartilage calcification at knee level in patients with calcium pyrophosphate deposition disease (CPDD) and to assess the interobserver reliability.
  
  
  METHODS
  Seventy-four CPDD patients and 83 controls with other chronic arthritis were included. All patients underwent a clinical examination, synovial fluid analysis, and radiographic assessment of the knee. US examinations were performed in order to detect hyperechoic spots within the hyaline cartilage layer and hyperechoic areas within the meniscal fibrocartilage. Twenty patients were assessed by 2 operators in order to calculate the interobserver reliability.
  
  
  RESULTS
  A total of 314 knees in 157 patients (74 with CPDD, 19 with rheumatoid arthritis, 17 with spondyloarthritis, 32 with osteoarthritis, and 15 with gout) were assessed. In the 74 patients with CPDD, hyaline cartilage spots were detected by US in at least 1 knee in 44 patients (59.5%), whereas radiography detected hyaline cartilage spots in 34 patients (45.9%) (P < 0.001). Meniscal fibrocartilage calcifications were detected by US in 67 of the 74 CPDD patients (90.5%), whereas conventional radiography detected calcifications in 62 patients (83.7%) (P = 0.011). The criterion validity expressed as percentage of sensitivity, specificity, and accuracy of US in the detection of articular cartilage calcification was high. Both kappa values and overall agreement percentages showed moderate to excellent agreement.
  
  
  CONCLUSIONS
  US is an accurate and reliable imaging technique in the detection of articular cartilage calcification at knee level in patients with CPDD.
authors.affiliation: Università Politecnica delle Marche, Jesi, Ancona, Italy.
authors.forename: Marwin
authors.initials: M
authors.lastname: Gutierrez
authors.forename: Luca
authors.initials: L
authors.lastname: Di Geso
authors.forename: Fausto
authors.initials: F
authors.lastname: Salaffi
authors.forename: Marina
authors.initials: M
authors.lastname: Carotti
authors.forename: Rita
authors.initials: R
authors.lastname: Girolimetti
authors.forename: Rossella
authors.initials: R
authors.lastname: De Angelis
authors.forename: Emilio
authors.initials: E
authors.lastname: Filippucci
authors.forename: Walter
authors.initials: W
authors.lastname: Grassi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging; D002114:Calcinosis / Q000000981:diagnostic imaging*; D002358:Cartilage, Articular / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D002805:Chondrocalcinosis / Q000000981:diagnostic imaging*; D005260:Female; D006073:Gout / Q000000981:diagnostic imaging; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025241:Spondylarthritis / Q000000981:diagnostic imaging; D014463:Ultrasonography / Q000379:methods*