Fetal magnetic resonance imaging: jumping from 1.5 to 3 tesla (preliminary experience)

Abstract

Several attempts have been made at imaging the fetus at 3 T as part of the continuous search for increased image signal and better anatomical delineation of the developing fetus. Until very recently, imaging of the fetus at 3 T has been disappointing, with numerous artifacts impeding image analysis. Better magnets and coils and improved technology now allow imaging of the fetus at greater magnetic strength, some hurdles in the shape of imaging artifacts notwithstanding. In this paper we present the preliminary experience of evaluating the developing fetus at 3 T and discuss several artifacts encountered and techniques to decrease them, as well as safety concerns associated with scanning the fetus at higher magnetic strength.

Fetal MRI at 3T—ready for routine use?

“…Chemical shift artefacts are more prominent at 3.0 T than they are at 1.5 T, but owing to the fact that fetal fat is not present until later in pregnancy, it is not a significant problem in fetal imaging. 3 …”

“…Currently, fetal MRI is performed mainly at 1.5 T, but, recently, a growing interest in 3.0 T examinations has emerged, not only for university and research use. [2][3][4] The wish to perform fetal MR at 3.0 T is due to the increased signal-to-noise ratio (SNR) and probable decreased acquisition time, increased spatial resolution and ultimately a more precise fetal depiction. 5,6 Another point is that some institutions may have access only to a 3.0 T scanner.…”

Fetal Manyetik Rezonans Görüntüleme

“…Bu enerji, SAR (specific absorbtion rate) olarak ölçülmektedir. FDA (Food and Drug Association ) tarafından yapılan, kullanılan magnetin gücünden bağımsız olarak annenin 4 W/kg altında alacağı SAR değerleri kabul edilebilir sınırlardadır [6,7]. The Children's Hospital of Philedelphia'da yapılan çalışmaya göre 3.0 tesla cihazla fetal görüntüleme sırasında alınan SAR değerlerinin FDA tarafından kabul edilen limitlerin altında olduğu gösterilmiştir [7].…”

Fetal magnetic resonance imaging and ultrasound

“…Image construction using 3-Tesla magnetic field strength provides better anatomical delineation of the fetus, which is particularly useful for imaging of fetal brain, as well as functional MRI [8]. The 3-Tesla machine is very sensitive to fetal movement, which results in significant motion artifacts, especially if MRI is performed in the first half of a pregnancy [9]. Other factors that may increase motion artifact include postprandial MRI and polyhydramnios [10].…”

“…For the time being, it may be advisable to be more conservative by starting with magnetic field strength of 1.5 Tesla. If image quality is suboptimal, but not from motion artifacts, then stronger magnetic field strength of 3 Tesla may be offered based on individual cases [9]. With all these concerns, ultrasonography is still the primary method used in prenatal imaging for its safety, low cost, and availability.…”