LAUSR

As the safety and efficacy of fetal magnetic resonance imaging (MRI) at 3 tesla (T) continues to evolve, understanding its potential benefits and limitations is becoming increasingly important. We aim to compare the image quality of fetal MRI between 1.5 T and 3 T in routine clinical practice. Fetal MRIs performed at 3 T between Jan. 1, 2019, and Dec. 31, 2019, at our institution were retrospectively reviewed by four fellowship-trained subspecialty radiologists. Imaging quality by system, sequence and artifacts were compared with matched controls at 1.5 T and rated using a modified Likert scale. Thirty-three fetal MRIs at 3 T were reviewed, and a control group of studies for the same clinical indication and equivalent gestational age were selected for comparison. Two of the four radiologists preferred 3-T image quality of the brain with slight agreement among the four reviewers (k=0.19, P=0.01). Three of the four radiologists had no preference for 1.5 T vs. 3 T in the majority of cases in evaluating the chest and abdomen. In the overall assessment, 3 T was preferred in less than half of cases by all four radiologists (k=0.07, P=0.26). In the evaluation of standing wave, moire fringe and magnetic susceptibility artifacts, 3 T was not preferred in the majority of studies by all four radiologists. Total exam time was significantly longer in the 3-T fetal MRIs (75.0±15.1 min) compared to the 1.5-T fetal MRIs (55.5±13.3 min, P<0.001). While 3 T is a feasible alternative to 1.5 T for fetal MRI, the increased artifacts and longer exam times observed at 3 T without clear improvement in overall image quality make 1.5 T preferable for fetal MRI in routine clinical practice.