Fetal skeletal imaging: Radiation dose reduction when performing fetal CT and the possible usefulness of fetal MRI

Abstract

Fetal CT is the next best examination after ultrasonography for the diagnosis of fetal skeletal dysplasia because it can easily visualize the entire skeleton. Advances in CT devices have made it possible to visualize the fetal skeleton, even with considerably reduced radiation doses. However, CT cannot reduce the radiation dose to zero. Therefore, we wondered whether it would be possible to evaluate the fetal skeleton using MRI without radiation exposure, and thus conducted a study to compare the bone depiction between MRI and CT using fetal specimens stored at our facility. Our findings demonstrated that it was difficult to evaluate the entire fetal skeleton using 3D imaging with the current MRI system. However, there are several reports on fetal bone morphology evaluation using the MRI gradient echo (GRE) method. In addition, MR bone images (CT-like images) have also recently been applied in the clinical setting. Depending on further advances in MRI methods, in the future MRI may replace CT in the diagnosis of fetal skeletal dysplasia.