title: In vivo bone and cartilage MRI using fully-balanced steady-state free-precession at 7 tesla.
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.
authors.affiliation: Department of Radiology, University of California, San Francisco, San Francisco, California, USA. Roland.Krug@radiology.ucsf.edu
authors.forename: Roland
authors.initials: R
authors.lastname: Krug
authors.forename: Julio
authors.initials: J
authors.lastname: Carballido-Gamio
authors.forename: Suchandrima
authors.initials: S
authors.lastname: Banerjee
authors.forename: Robert
authors.initials: R
authors.lastname: Stahl
authors.forename: Lucas
authors.initials: L
authors.lastname: Carvajal
authors.forename: Duan
authors.initials: D
authors.lastname: Xu
authors.forename: Dan
authors.initials: D
authors.lastname: Vigneron
authors.forename: Douglas A C
authors.initials: DA
authors.lastname: Kelley
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Link
authors.forename: Sharmila
authors.initials: S
authors.lastname: Majumdar
mesh_terms: D000465:Algorithms; D001842:Bone and Bones / Q000033:anatomy & histology*; D002356:Cartilage / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity