In vivo bone and cartilage MRI using fully-balanced steady-state free-precession at 7 tesla

✍ Scribed by Roland Krug; Julio Carballido-Gamio; Suchandrima Banerjee; Robert Stahl; Lucas Carvajal; Duan Xu; Dan Vigneron; Douglas A.C. Kelley; Thomas M. Link; Sharmila Majumdar

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 445 KB
• Volume: 58
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.21429

✦ Synopsis

Abstract

The purpose of this work was to investigated the feasibility of fully‐balanced steady‐state free‐precession (bSSFP) pulse sequence for trabecular bone and knee cartilage imaging in vivo using ultra‐high‐field (UHF) MRI at 7T in comparison with pulse sequences previously used at 3T. We showed that bSSFP and spin‐echo imaging is possible at higher field strengths within 3.2 W/kg specific absorption rate (SAR) constraints. All pulse sequences were numerically optimized based on measured tissue relaxation parameters from six healthy volunteers (T~1~ = 820 ± 128 ms, T~2~ = 43.5 ± 3 ms for bone marrow and T~1~ = 1745 ± 104 ms and T~2~ = 30 ± 4 ms for cartilage). From simulations of the Bloch equation, a signal‐to‐noise ratio (SNR) increase of more than 1.9 was predicted. Cartilage SNR of bSSFP was 2.4 times higher at 7T (51.3 ± 4.3) compared with 3T (21.3 ± 3.3). Bone SNR increased from 11.8 ± 2.0 to 13.2 ± 2.5 at the higher field strength. We concluded that there is SNR benefit and great potential for bone and cartilage imaging at higher field strength. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.