Delayed gadolinium-enhanced MR to determine glycosaminoglycan concentration in reparative cartilage after autologous chondrocyte implantation: preliminary results.
OBJECTIVE
To prospectively evaluate delayed gadolinium-enhanced magnetic resonance (MR) imaging of cartilage for assessment of glycosaminoglycan (GAG) concentration in reparative cartilage after autologous chondrocyte implantation (ACI).


METHODS
The study was approved by the ethics review committee of the National Institute of Radiological Sciences, and informed consent was obtained from all patients. The study group comprised nine knees of nine patients (six male, three female; mean age at ACI, 21.2 years +/- 7.5 [standard deviation]; age range, 13-35 years) who had undergone ACI and second-look arthroscopy with biopsy. MR imaging was performed at 1.5 T before and after intravenous injection of anionic gadopentetate dimeglumine. The precontrast R1 (R1(pre)), postcontrast R1 (R1(post)), and difference between R1(pre) and R1(post) (DeltaR1) were measured in reparative cartilage and normal cartilage. GAG concentrations in cartilage biopsy specimens were measured by using high-performance liquid chromatography. To evaluate delayed gadolinium-enhanced MR imaging of cartilage for assessment of GAG concentration, the authors defined the relative R1(pre), relative R1(post), and relative DeltaR1 (ie, R1(pre), R1(post), or DeltaR1, respectively, in reparative cartilage divided by that in normal cartilage) and the relative GAG concentration (ie, GAG concentration in reparative cartilage divided by that in normal cartilage). They then examined the relationships between relative R1(pre), relative R1(post), relative DeltaR1, and relative GAG by using correlation analysis.


RESULTS
A significant correlation between relative DeltaR1 and relative GAG concentration (r = 0.818, P < .05) was observed. However, no significant correlation between relative R1(pre) and relative GAG concentration (r = 0.010, P = .983) or between relative R1(post) and relative GAG concentration (r = 0.660, P = .106) was observed.


CONCLUSIONS
Study results indicate that pre- and postcontrast imaging is necessary for delayed gadolinium-enhanced MR imaging evaluation of reparative cartilage after ACI.
Watanabe
Atsuya
A
Departments of Orthopaedic Surgery and Radiology, Graduate School of Medicine, Chiba University, Chiba, Japan.
Wada
Yuichi
Y
Obata
Takayuki
T
Ueda
Takuya
T
Tamura
Mitsuru
M
Ikehira
Hiroo
H
Moriya
Hideshige
H
D000293:Adolescent; D000328:Adult; D002356:Cartilage / Q000033:anatomy & histology* / Q000737:chemistry* / Q000601:surgery; D019902:Chondrocytes / Q000637:transplantation*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006025:Glycosaminoglycans / Q000032:analysis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011446:Prospective Studies; D013997:Time Factors
D003287:Contrast Media; D006025:Glycosaminoglycans; D019786:Gadolinium DTPA