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3D‐T 1ρ prepared zero echo time‐based PETRA sequence for in vivo biexponential relaxation mapping of semisolid short‐T 2 tissues at 3 T
Author(s) -
Sharafi Azadeh,
Baboli Rahman,
Chang Gregory,
Regatte Ravinder R.
Publication year - 2019
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.26664
Subject(s) - ankle , achilles tendon , anterior cruciate ligament , ligament , medicine , osteoarthritis , imaging phantom , in vivo , nuclear medicine , population , cartilage , anatomy , tendon , biomedical engineering , materials science , pathology , biology , alternative medicine , microbiology and biotechnology , environmental health
Background In addition to the articular cartilage, osteoarthritis (OA) affects several other tissues such as tendons, ligaments, and subchondral bone. T1 ρ relaxation study of these short T 2 tissues may provide a more comprehensive evaluation of OA. Purpose To develop a 3D spin‐lattice relaxation in the rotating frame (T 1ρ ) prepared zero echo time (ZTE)‐based pointwise encoding time reduction with radial acquisition (3D‐T 1ρ ‐PETRA) sequence for relaxation mapping of semisolid short‐T 2 tissues on a clinical 3 T scanner. Study Type Prospective. Population Phantom, two bovine whole knee joint and Achilles tendon specimens, 10 healthy volunteers with no known inflammation, trauma or pain in the knee or ankle. Field Strength/Sequence A customized PETRA sequence to acquire fat‐suppressed 3D T 1ρ ‐weighted images tissues with semisolid short T 2 / T 2 * relaxation times in the knee and ankle joints at 3 T. Assessment Mono‐ and biexponential T 1ρ relaxation components were assessed in the patellar tendon (PT), anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and Achilles tendon (AT). Statistical Tests Kruskal–Wallis with post‐hoc Dunn's test for multiple pairwise comparisons. Results Phantom and ex vivo studies showed the feasibility of T 1ρ relaxation mapping using the proposed 3D‐T 1ρ ‐PETRA sequence. The in vivo study demonstrated an averaged mono‐T 1ρ relaxation of (median [IQR]) 15.9 [14.5] msec, 23.6 [9.4] msec, 17.4 [7.4] msec, and 5.8 [10.2] msec in the PT, ACL, PCL, and AT, respectively. The bicomponent analysis showed the short and long components (with their relative fractions) of 0.65 [1.0] msec (46.9 [15.3]%) and 37.3 [18.4] msec (53.1 [15.3]%) for PT, 1.7 [2.1] msec (42.5 [12.5]%) and 43.7 [17.8] msec (57.5 [12.5]%) for ACL, and 1.2 [1.9] msec (42.6 [14.0]%) and 27.7 [14.7] msec (57.3 [14.0]%) for PCL and 0.4 [0.02] msec (58.8 [13.3]%/) and 31.3 [10.8] msec (41.2 [13.3]%) for AT. Statistically significant ( P ≤ 0.05) differences were observed in the mono‐ and biexponential relaxation between several regions. Data Conclusion The 3D‐T 1ρ ‐PETRA sequence allows volumetric, isotropic (0.78 × 0.78 × 0.78 mm), biexponential T 1ρ assessment with corresponding fractions of the tissues with semisolid short T 2 / T 2 * . Level of Evidence: 2 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:1207–1218.