Low-field-strength MRI is reliable and feasible for fetal imaging: Study
UK: A 20-minute low-field-strength fetal MRI protocol was capable of producing reliable functional and structural measures of the placenta and fetus in pregnancy, a recent study published in Radiology has suggested.
"The low-flow-field-strength protocol showed significant correlations with MRI measures found in control groups, indicating that the abbreviated protocol may perform as well as protocols using 1.5-tesla (1.5T) and 3-tesla (3T) MRI," Jordina Verdera, King’s College London, London, United Kingdom, and colleagues reported.
The results offer potential for increased patient accessibility owing to a larger bore and shorter time requirements and allowed for wider use by removing the need for specialist techniques and reducing costs.
Previous studies have shown the benefits of low-field-strength fetal MRI for analyzing fetal development. These include larger bore size, reduced image artifacts, increased comfort, and potentially reduced costs. However, there is a lack of data in this area. Therefore, Verdera and the team sought to evaluate the feasibility and reliability of low-field-strength fetal MRI to assess functional and anatomic measures in pregnant women using a commercially available 0.55-T MRI scanner and a comprehensive 20-minute protocol.
For this purpose, the resarchers performed a prospective study at a large teaching hospital in UK from May to November 2022 in healthy pregnant participants with pregnancy-related abnormalities using a commercially available 0.55-T MRI scanner.
It used a commercially available 0.55-tesla MRI scanner and a comprehensive 20-minute protocol. The protocol included anatomic T2-weighted fast-spin-echo, quantitative T2, and diffusion sequences.
Data was taken from 79 fetal MRI exams, with an average gestational age of 29.4 and an average maternal age of 34.4 years in 47 healthy pregnant women (control group), and 32 participants with pregnancy-related abnormalities. The key anatomic 2D measures for the 47 healthy women agreed with large cross-sectional 1.5T and 3T control studies.
The study led to the following findings:
- The key anatomic two-dimensional measures for the 47 healthy participants agreed with large cross-sectional 1.5-T and 3-T control studies.
- The interobserver correlations for the biparietal diameter in the first 40 consecutive scans were 0.96 for abnormalities and 0.93 for control participants.
- Functional features, including placental and brain T2* and placental apparent diffusion coefficient values, strongly correlated with gestational age (mean placental T2* in the control participants: 5.2 msec of decay per week; R2 = 0.66; mean T2* at 30 weeks, 176.6 msec).
The researchers called for future studies to have a dedicated high-risk study sample and additional fetal body anomalies, have paired participants who undergo both high- and low-field-strength exams on the same day, and analyze myelination.
“In addition, future work could focus on possible tissue contrast enhancement, noncontrast-enhanced angiography, and perfusion techniques and may explore techniques and sequences exploiting the longer T2 and ability for longer readouts,” they wrote.
Reference:
Reliability and Feasibility of Low-Field-Strength Fetal MRI at 0.55 T during Pregnancy. Jordina Aviles Verdera, Lisa Story, Megan Hall, Tom Finck, Alexia Egloff, Paul T. Seed, Shaihan J. Malik, Mary A. Rutherford, Joseph V. Hajnal, Raphaël Tomi-Tricot, and Jana Hutter. Radiology 2023 309:1
