title: Comparison of biochemical cartilage imaging techniques at 3 T MRI.
abstract: OBJECTIVE
  To prospectively compare chemical-exchange saturation-transfer (CEST) with delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) and T2 mapping to assess the biochemical cartilage properties of the knee.
  
  
  METHODS
  Sixty-nine subjects were prospectively included (median age, 42 years; male/female = 32/37) in three cohorts: 10 healthy volunteers, 40 patients with clinically suspected cartilage lesions, and 19 patients about 1 year after microfracture therapy. T2 mapping, dGEMRIC, and CEST were performed at a 3 T MRI unit using a 15-channel knee coil. Parameter maps were evaluated using region-of-interest analysis of healthy cartilage, areas of chondromalacia and repair tissue. Differentiation of damaged from healthy cartilage was assessed using receiver-operating characteristic (ROC) analysis.
  
  
  RESULTS
  Chondromalacia grade 2-3 had significantly higher CEST values (P = 0.001), lower dGEMRIC (T1-) values (P < 0.001) and higher T2 values (P < 0.001) when compared to the normal appearing cartilage. dGEMRIC and T2 mapping correlated moderately negative (Spearman coefficient r = -0.56, P = 0.0018) and T2 mapping and CEST moderately positive (r = 0.5, P = 0.007), while dGEMRIC and CEST did not significantly correlate (r = -0.311, P = 0.07). The repair tissue revealed lower dGEMRIC values (P < 0.001) and higher CEST values (P < 0.001) with a significant negative correlation (r = -0.589, P = 0.01), whereas T2 values were not different (P = 0.54). In healthy volunteers' cartilage, CEST and dGEMRIC showed moderate positive correlation (r = 0.56), however not reaching significance (P = 0.09). ROC-analysis demonstrated non-significant differences of T2 mapping vs CEST (P = 0.14), CEST vs dGEMRIC (P = 0.89), and T2 mapping vs dGEMRIC (P = 0.12).
  
  
  CONCLUSIONS
  CEST is able to detect normal and damaged cartilage and is non-inferior in distinguishing both when compared to dGEMRIC and T2 mapping.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg, Germany. Electronic address: christoph.rehnitz@med.uni-heidelberg.de.
authors.forename: C
authors.initials: C
authors.lastname: Rehnitz
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg, Germany. Electronic address: julia.kupfer@yahoo.de.
authors.forename: J
authors.initials: J
authors.lastname: Kupfer
authors.affiliation: Department of Orthopedics and Trauma Surgery, University Hospital Heidelberg, Germany. Electronic address: Nikolaus.Streich@med.uni-heidelberg.de.
authors.forename: N A
authors.initials: NA
authors.lastname: Streich
authors.affiliation: Department of Nursing and Health, University of Applied Sciences of the Saarland, Saarbruecken, Germany. Electronic address: stabil@burkholder.de.
authors.forename: I
authors.initials: I
authors.lastname: Burkholder
authors.affiliation: Siemens Healthcare, Erlangen, Germany. Electronic address: benjamin_schmitt@siemens.com.
authors.forename: B
authors.initials: B
authors.lastname: Schmitt
authors.affiliation: Siemens Healthcare, Erlangen, Germany. Electronic address: lars.lauer@siemens.com.
authors.forename: L
authors.initials: L
authors.lastname: Lauer
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg, Germany. Electronic address: Hans-Ulrich.Kauczor@med.uni-heidelberg.de.
authors.forename: H-U
authors.initials: HU
authors.lastname: Kauczor
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg, Germany. Electronic address: MarcAndre.Weber@med.uni-heidelberg.de.
authors.forename: M-A
authors.initials: MA
authors.lastname: Weber
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002357:Cartilage Diseases / Q000473:pathology*; D002358:Cartilage, Articular / Q000473:pathology*; D016022:Case-Control Studies; D002648:Child; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D055815:Young Adult
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA
keywords: Cartilage; Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC); Knee joint; T2 mapping; gagCEST (glycosaminoglycan chemical-exchange saturation-transfer)