title: Actual imaging time in fetal MRI.
abstract: OBJECTIVE
  Safety issues in magnetic resonance imaging (MRI) are important, especially in fetal MRI. However, since basic data with respect of the effective exposure time in fetal MRI are not available, this study aimed to determine the actual imaging time during a fetal MRI study.
  
  
  METHODS
  100 fetal MRI studies of singleton pregnancies performed on a 1.5 T system were analysed with respect to study duration (from starting the survey scan until the end of study), the number of sequences acquired, and the actual imaging time, which was calculated by adding up scan time of each sequence. Furthermore, each sequence type was analysed regarding the number of acquisitions, specific absorption rates (SAR), and duration.
  
  
  RESULTS
  Mean study duration was 34.6 min (range: 14-58 min; standard deviation (SD): 9.7 min), the average number of sequences acquired was 26.6 (range: 11-44, SD: 6.6). Actual scan time averaged 11.4 min (range: 4-19 min, SD: 4.0 min). Ultrafast T2-weighted and steady-state free-precession sequences accounted for 62.3% of actual scan time, and were distributed over the whole duration of the study.
  
  
  CONCLUSIONS
  Actual imaging time only accounts for 33% of total study time and is not continuous. The remaining time is consumed by the preparation phases of the scanner, and is spent with planning sequences and the eventual repositioning of the coil and/or pregnant woman. These data may help to more accurately estimate the exposure to radiofrequency deposition and noise during fetal MRI studies.
authors.affiliation: Integrative Morphology Group, Centre for Anatomy and Cell Biology, Department of Radiology, Medical University of Vienna, Waehringerstrasse 13, 1090 Vienna, Austria. peter.brugger@meduniwien.ac.at
authors.forename: Peter C
authors.initials: PC
authors.lastname: Brugger
authors.forename: Daniela
authors.initials: D
authors.lastname: Prayer
mesh_terms: D005260:Female; D005333:Fetus; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging / Q000379:methods*; D061214:Patient Safety; D011247:Pregnancy; D013997:Time Factors