title: Comparison of 3T and 7T MRI clinical sequences for ankle imaging.
abstract: The purpose of this study was to compare 3T and 7T signal-to-noise and contrast-to noise ratios of clinical sequences for imaging of the ankles with optimized sequences and dedicated coils. Ten healthy volunteers were examined consecutively on both systems with three clinical sequences: (1) 3D gradient-echo, T(1)-weighted; (2) 2D fast spin-echo, PD-weighted; and (3) 2D spin-echo, T(1)-weighted. SNR was calculated for six regions: cartilage; bone; muscle; synovial fluid; Achilles tendon; and Kager's fat-pad. CNR was obtained for cartilage/bone, cartilage/fluid, cartilage/muscle, and muscle/fat-pad, and compared by a one-way ANOVA test for repeated measures. Mean SNR significantly increased at 7T compared to 3T for 3D GRE, and 2D TSE was 60.9% and 86.7%, respectively. In contrast, an average SNR decrease of almost 25% was observed in the 2D SE sequence. A CNR increase was observed in 2D TSE images, and in most 3D GRE images. There was a substantial benefit from ultra high-field MR imaging of ankles with routine clinical sequences at 7T compared to 3T. Higher SNR and CNR at ultra-high field MR scanners may be useful in clinical practice for ankle imaging. However, carefully optimized protocols and dedicated extremity coils are necessary to obtain optimal results.
authors.affiliation: Medical University of Vienna, Department of Radiology, Vienna General Hospital, Waeringer Guertel 18-20, A-1090 Vienna, Austria. vladimir.juras@meduniwien.ac.at
authors.forename: Vladimir
authors.initials: V
authors.lastname: Juras
authors.forename: Goetz
authors.initials: G
authors.lastname: Welsch
authors.forename: Peter
authors.initials: P
authors.lastname: Bär
authors.forename: Claudia
authors.initials: C
authors.lastname: Kronnerwetter
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fujita
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
mesh_terms: D000328:Adult; D000842:Ankle / Q000033:anatomy & histology*; D000843:Ankle Joint / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity