title: Effects of B1 inhomogeneity correction for three-dimensional variable flip angle T1 measurements in hip dGEMRIC at 3 T and 1.5 T.
abstract: Delayed gadolinium-enhanced MRI of cartilage is a technique for studying the development of osteoarthritis using quantitative T(1) measurements. Three-dimensional variable flip angle is a promising method for performing such measurements rapidly, by using two successive spoiled gradient echo sequences with different excitation pulse flip angles. However, the three-dimensional variable flip angle method is very sensitive to inhomogeneities in the transmitted B(1) field in vivo. In this study, a method for correcting for such inhomogeneities, using an additional B(1) mapping spin-echo sequence, was evaluated. Phantom studies concluded that three-dimensional variable flip angle with B(1) correction calculates accurate T(1) values also in areas with high B(1) deviation. Retrospective analysis of in vivo hip delayed gadolinium-enhanced MRI of cartilage data from 40 subjects showed the difference between three-dimensional variable flip angle with and without B(1) correction to be generally two to three times higher at 3 T than at 1.5 T. In conclusion, the B(1) variations should always be taken into account, both at 1.5 T and at 3 T.
authors.affiliation: Department of Medical Radiation Physics, Lund University, Malmö, Sweden. carl.siversson@med.lu.se
authors.forename: Carl
authors.initials: C
authors.lastname: Siversson
authors.forename: Jenny
authors.initials: J
authors.lastname: Chan
authors.forename: Carl-Johan
authors.initials: CJ
authors.lastname: Tiderius
authors.forename: Tallal Charles
authors.initials: TC
authors.lastname: Mamisch
authors.forename: Vladimir
authors.initials: V
authors.lastname: Jellus
authors.forename: Jonas
authors.initials: J
authors.lastname: Svensson
authors.forename: Young-Jo
authors.initials: YJ
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D016477:Artifacts; D002358:Cartilage, Articular / Q000473:pathology*; D002648:Child; D005260:Female; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult