Delayed Gadolinium-enhanced MR Imaging of Articular Cartilage: Three-dimensional T1 Mapping with Variable Flip Angles and B 1 Correction Gustav Andreisek, MD Lawrence M. White, MD Yi Yang, MD Emma Robinson, MD Hai-Ling Margaret Cheng, PhD Marshall S. Sussman, PhD Purpose: To develop and verify the accuracy of a rapid imaging protocol for delayed gadolinium-enhanced magnetic reso- nance (MR) imaging of cartilage that was based on three- dimensional (3D) spoiled gradient-recalled acquisition in the steady state (SPGR) sequences with variable flip angles (FAs) (VFAs) and where a correction method for B 1 field inhomogeneities was applied. Materials and Methods: The institutional research ethics board approved this study. Written informed consent was obtained from all subjects. A B 1 field inhomogeneity correction method was applied to a 3D SPGR pulse sequence with VFAs (repeti- tion time msec/echo time msec, 7.1/3.3; FAs, 2°, 5°, 10°, and 20°) and was used to perform delayed gadolinium- enhanced MR imaging of cartilage 3D T1 measurements at 1.5 T. The 3D T1 measurements were validated with the reference standard (the results of T1 mapping by using a single-section two-dimensional [2D] inversion-recovery [IR] fast spin-echo [SE] pulse sequence in vitro and in vivo) in six healthy volunteers. Results: T1 values calculated from 3D T1 maps were not signifi- cantly different from reference T1 values in vitro (P = .195) and in vivo (P = .52) when a B 1 field inhomogeneity correction method was applied. In vivo T1 mapping of the articular surface of the whole femoropatellar joint, includ- ing data acquisition, was performed in approximately 8 minutes of acquisition time at a spatial resolution of 0.55  0.55  3.00 mm. Conclusion: Rapid T1 mapping by using 3D SPGR acquisitions with a VFA approach and a correction for B 1 field inhomogene- ities can be used for delayed gadolinium-enhanced MR imaging of cartilage. T1 measurements performed in vitro and in vivo by using this approach are highly accurate when compared with those performed by using standard 2D IR fast SE T1 mapping as a reference.  RSNA, 2009 1 From the Department of Medical Imaging, Mount Sinai Hospital and the University Health Network (G.A., L.M.W., E.R.), Research Institute, the Hospital for Sick Children (Y.Y., H.L.M.C.), Department of Medical Biophysics (H.L.M.C.), and Department of Medical Imaging, Toronto General Hospital (M.S.S.), University of Toronto, Toronto, Ontario, Canada; Institute for Diagnostic Radiology, Uni- versity Hospital Zu ¨ rich, Ra ¨ mistrasse 100, CH-8091 Zu ¨ rich, Switzerland (G.A.); and Ultrasound Diagnostic Imaging Department, Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China (Y.Y.). Received June 24, 2008; revision requested August 8; revision received March 1, 2009; accepted March 26; final version ac- cepted April 14. Address correspondence to G.A. (e-mail: gustav@andreisek.de ).  RSNA, 2009 ORIGINAL RESEARCH  TECHNICAL DEVELOPMENTS Radiology: Volume 252: Number 3—September 2009 ▪ radiology.rsnajnls.org 865 Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights.