title: Feasibility of high-dose dobutamine stress SSFP Cine MRI at 3 Tesla with patient adaptive local RF Shimming using dual-source RF transmission: initial results.
abstract: OBJECTIVE
  To investigate the feasibility of high-dose dobutamine stress (HDDS) imaging using SSFP sequences at 3 T employing patient-adaptive local RF-shimming using a dual-source RF transmission system.
  
  
  METHODS
  13 Patients underwent a HDDS protocol on a 3 T MRI scanner (Achieva 3.0T-TX, Philips Healthcare), equipped with a dual-source RF transmission system. SSFP cine sequences using patient-adaptive local RF-shimming (RF-S) were compared to cine images acquired without additional shimming. Image quality was evaluated on a 4-point grading scale and number of non-diagnostic segments assessed. Contrast (CN) between myocardium (SIM) and blood pool (SIB) was calculated [(SIB-SIM)/(SIB+SIM)].
  
  
  RESULTS
  Image quality both at rest and maximum stress was significantly improved with RF-S (ED:3.56±0.5 vs. 3.23±0.63; ES:3.4±0.5 vs. 3.1±0.7) compared to no RF-S (ED:2.9±0.72 vs. 2.15±0.78; ES:2.64±0.74 vs. 1.95±0.76; p<0.01). The amount of non-diagnostic segments was significantly reduced when using RF-S at rest and stress (3 vs. 39; 19 vs. 78, p<0.05). All HDDS studies were diagnostic if performed with RF-S (n=13/13) in comparison to conventional shimming (n=5/13). Image contrast was improved for SSFP sequences with RF-S (0.53±0.08) compared to conventional images (0.46±0.09, p=0.06).
  
  
  CONCLUSIONS
  Patient-adaptive local RF-shimming using a dual-source RF transmission system allows for reliable SSFP imaging in a clinical high-dose dobutamine stress protocol at 3 T. RF-S significantly improves image quality and reduces the number of non-diagnostic myocardial segments.
authors.affiliation: Radiologische Universitätsklinik, Rheinische Friedrich-Wilhelms Universität Bonn, Sigmund-Freud-Strasse 25, Bonn, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Strach
authors.forename: R
authors.initials: R
authors.lastname: Clauberg
authors.forename: A
authors.initials: A
authors.lastname: Müller
authors.forename: U
authors.initials: U
authors.lastname: Wonneberger
authors.forename: C P
authors.initials: CP
authors.lastname: Naehle
authors.forename: M
authors.initials: M
authors.lastname: Kouwenhoven
authors.forename: J
authors.initials: J
authors.lastname: Gieseke
authors.forename: H H
authors.initials: HH
authors.lastname: Schild
authors.forename: D
authors.initials: D
authors.lastname: Thomas
mesh_terms: D000465:Algorithms; D054059:Coronary Occlusion / Q000473:pathology*; D004280:Dobutamine / Q000008:administration & dosage*; D005080:Exercise Test / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D004280:Dobutamine