Jin Yamamura MD, Presenter: Nothing to Disclose

Michael Ulrich Frisch, Abstract Co-Author: Nothing to Disclose

Joachim Graessner MS, Abstract Co-Author: Nothing to Disclose

Jan-Hendrik Buhk MD, Abstract Co-Author: Nothing to Disclose

Gerhard B. Adam MD, Abstract Co-Author: Nothing to Disclose

Ulrike Wedegaertner MD, Abstract Co-Author: Nothing to Disclose

The aim of this study was to perform fetal cardiac MR imaging using the self-gating MRI technique and to compare it with MR imaging with triggering of the fetal heart beat in utero in a sheep model.

Images of the fetal sheep heart were performed on 3 pregnant ewes at a 1.5 T scanner (Siemens, Erlangen, Germany). The fetuses were chronically instrumented with a carotid catheter to measure the fetal heart frequency for cardiac triggering. Self-gating MRI and pulse wave triggered, breath-hold cine MRI with steady-state free precession (SSFP) of the fetal heart were achieved simultaneously in short axis view, two, four and three chamber view. From the short-axis, the left and right ventricular volume and thus the function was measured and compared.

The fetal heart frequencies were between 130 and 160 beats per minute. It was possible to perform both self gated and triggered fetal cardiac MRI in all fetuses. In cine sequences the contraction was shown. The average blood volumes could be measured in both techniques: at end systole 3.1 ml (SD±0.2), at end diastole 4.9 ml (±0.2); with ejection fractions between 38.6% and 39%, respectively. Although the mitral, the tricuspid, aortic and the pulmonary valves as well as the foramen ovale were clearly observed with the pulse wave triggering technique, the images with the self-gating techniques were slightly inferior due to blurry artifacts. Especially the atrial septum was not clearly depicted with the latter technique.

Both self-gating and pulse-wave triggered cardiac MRI allowed an evaluation of anatomical structures and functional information, although the images obtained with self-gating technique was slightly inferior than the pulse-wave triggered MRI.

In the future, fetal cardiac MRI might be of great impact in the evaluation of fetuses with complex congenital heart defects and might help the surgery in utero.

Yamamura, J, Frisch, M, Graessner, J, Buhk, J, Adam, G, Wedegaertner, U, Self-gating MR Imaging of the Fetal Heart in Comparison with MR Imaging with Cardiac Triggering: A Feasibility Study in the Sheep Fetus.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8015895.html