Improved assessment of cartilage repair tissue using fluid-suppressed 23Na inversion recovery MRI at 7 Tesla: Preliminary results

Gregory Chang, Guillaume Madelin, Orrin H. Sherman, Eric J. Strauss, Ding Xia, Michael P. Recht, Alexej Jerschow, Ravinder R. Regatte

Research output: Contribution to journalReview articlepeer-review


Objectives To evaluate cartilage repair and native tissue using a three-dimensional (3D), radial, ultra-short echo time (UTE) 23Na MR sequence without and with an inversion recovery (IR) preparation pulse for fluid suppression at 7 Tesla (T). Methods This study had institutional review board approval. We recruited 11 consecutive patients (41.5±11.8 years) from an orthopaedic surgery practice who had undergone a knee cartilage restoration procedure. The subjects were examined postoperatively (median=26 weeks) with 7-T MRI using: proton-T2 (TR/TE=3,000 ms/60 ms); sodium UTE (TR/TE=100 ms/0.4 ms); fluid-suppressed, sodium UTE adiabatic IR. Cartilage sodium concentrations in repair tissue ([Na +] R), adjacent native cartilage ([Na +] N), and native cartilage within the opposite, non-surgical compartment ([Na +] N2) were calculated using external NaCl phantoms. Results For conventional sodium imaging, mean [Na +] R, [Na +] N, [Na +] N2 were 177.8±54.1 mM, 170.1±40.7 mM, 172.2±30 mM respectively. Differences in [Na +] R versus [Na +] N (P=0.59) and [Na +] N versus [Na +] N2 (P=0.89) were not significant. For sodium IR imaging, mean [Na +] R, [Na +] N, [Na +] N2 were 108.9±29.8 mM, 204.6±34.7 mM, 249.9± 44.6 mM respectively. Decreases in [Na +] R versus [Na +] N (P=0.0.0000035) and [Na +] N versus [Na +] N2 (P=0.015) were significant. Conclusions Sodium IR imaging at 7 T can suppress the signal from free sodium within synovial fluid. This may allow improved assessment of [Na +] within cartilage repair and native tissue. Key Points • NaIR magnetic resonance imaging can suppress signal from sodium within synovial fluid. • NaIR MRI thus allows assessment of sodium concentration within cartilage tissue alone. • This may facilitate more accurate assessment of repair tissue composition and quality.

Original languageEnglish (US)
Pages (from-to)1341-1349
Number of pages9
JournalEuropean Radiology
Issue number6
StatePublished - Jun 2012


  • 7 Tesla
  • Cartilage repair
  • Inversion recovery
  • Sodium MRI
  • Ultra-high field

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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