Marius Erik Mayerhoefer, Presenter: Nothing to Disclose

Stefan Zbyn, Abstract Co-Author: Nothing to Disclose

David Stelzeneder MD, Abstract Co-Author: Nothing to Disclose

Goetz Hannes Welsch MD, Abstract Co-Author: Nothing to Disclose

Lukas Negrin, Abstract Co-Author: Nothing to Disclose

Siegfried Trattnig MD, Abstract Co-Author: Nothing to Disclose

To evaluate the sodium signal-to-noise ratio (SNR), suggestive of glycosaminoglycan (GAG) content, in native cartilage and cartilage repair tissue, and to compare the SNR between patients treated by bone marrow stimulation (BMS) and patients treated by matrix-associated autologous chondrocyte transplantation (MACT) in the knee.

Institutional Review Board approval and written, informed consent from each patient were obtained. 18 patients (9 BMS and 9 MACT patients) were included. Each BMS patient was matched with one MACT patient according to age (BMS, 36.7±10.7 years; MACT, 36.9±10.0 years), postoperative interval (BMS, 33.5±25.3 months; MACT, 33.2±25.7 months), and cartilage defect location. Magnetic resonance imaging (MRI) was performed at 7T. For morphological evaluation of repair tissue based on proton density- and T1-weighted images, the MR observation of cartilage repair tissue (MOCART) scoring system was used. Sodium images were acquired with an optimized 3D gradient echo sequence. Regions-of-interest covering the repair tissue and morphologically normal appearing reference cartilage tissue were defined (Figure 1). Statistical analysis comprised analysis of covariance, t-tests, and Pearson correlation coefficients.

Sodium SNR was significantly lower in BMS (p<.001) and MACT (p=.002) repair tissue than in the reference cartilage. These differences were influenced by surgery type (p=.027), but not by age (p=.075) and follow-up interval (p=.154). Sodium SNR was significantly higher in MACT than in BMS repair tissue (p=.002). Sodium SNR did not differ significantly between the reference cartilage in MACT and BMS patients (p=.528). There was no significant difference between MOCART scores of MACT and BMS patients (p=.889). No significant correlation was observed between the MOCART score and sodium repair tissue SNR (r=.111; p=.662), or between patient age and sodium reference cartilage SNR (r=-.329; p=.182).

MACT provides higher GAG content, and thus, higher-quality repair tissue than the BMS technique. Sodium MRI at 7T might be useful in the non-invasive evaluation of cartilage repair procedure efficacy in the knee.

Sodium imaging at 7T enables an in vivo evaluation of cartilage repair tissue quality in the knee, and shows that in terms of cartilage quality, MACT seems to provide better results than BMS.

Mayerhoefer, M, Zbyn, S, Stelzeneder, D, Welsch, G, Negrin, L, Trattnig, S, Evaluation of 23Na (Sodium) Content in Native Hyaline Cartilage and Repair Tissue after Two Cartilage Repair Techniques in the Knee with 7 T MR Imaging.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11007050.html