Extending slice coverage for breathhold fat-suppressed T2-weighted fast spin-echo of the liver at 3.0T: application of variable-rate selective-excitation (VERSE) RF pulses.
OBJECTIVE
To determine the benefits of variable-rate selective-excitation (VERSE) radio frequency (RF) pulses for increased slice coverage in breathhold (BH) fat-suppressed T2-weighted fast spin-echo (FS-T2W-FSE) liver imaging at 3.0T.


METHODS
A total of 12 healthy volunteers were imaged on 3.0T, using FS-T2W-FSE. Slice coverage and specific absorption rate (SAR) levels were monitored for VERSE-RF and standard-RF (sRF), respectively. BH time was 25 seconds; slice thickness 3.5 mm. Maximum coverage was recorded for interactive variation of repetition time (TR), bandwidth (BW), and echo-train length (ETL). Image quality was assessed qualitatively and quantitatively.


RESULTS
Total slice coverage was always higher using VERSE-RF, but varied depending on the selected parameters. For BW > or = 62.5 kHz, slice coverage using VERSE increased between 38% (TR = 8200 msec) and 58% (TR = 2500 msec). Maximum coverage was obtained for TR = 5000 msec, ETL = 12, and BW > or = 62.5 kHz; with a mean of 31.8 slices for VERSE-RF and 22.5 slices for sRF, respectively (P < 0.005, 41% increased coverage). SAR was lower for VERSE-RF using BW < 41.67 kHz (P < 0.05), and equal to sRF for higher BW. Image quality was best for TR < or = 5000 msec (P < 0.05). FS was more homogeneous for lower ETL (P < 0.05). Blood suppression was best for TR < or = 5000 msec (P < 0.05).


CONCLUSIONS
VERSE-RF pulses can be applied for thin-slice BH FS-T2W liver imaging at 3.0T, with significantly improved slice coverage.
Department of Radiology, Erasmus Medical Center, The Netherlands. vandenbos.ic@gmail.com
Indra C
IC
van den Bos
Shahid M
SM
Hussain
Gabriel P
GP
Krestin
Piotr A
PA
Wielopolski
D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D008099:Liver / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018709:Statistics, Nonparametric