Evaluation of a motion‐robust 2D chemical shift‐encoded technique for R2* and field map quantification in ferumoxytol‐enhanced MRI of the placenta in pregnant rhesus macaques. Issue 2 (5th July 2019)

• Record Type: Journal Article
• Authors: Zhu, Ante; Reeder, Scott B.; Johnson, Kevin M.; Nguyen, Sydney M.; Golos, Thaddeus G.; Shimakawa, Ann; Muehler, Matthias R.; Francois, Christopher J.; Bird, Ian M.; Fain, Sean B.; Shah, Dinesh M.; Wieben, Oliver; Hernando, Diego
• Is Part Of: Journal of magnetic resonance imaging. Volume 51:Issue 2(2020)
• Page Start: 580
• Page End: 592
• Publication Date: 2019-07-05
• Subjects: placenta -- ferumoxytol -- chemical shift‐encoded -- R2* -- B0 field -- motion‐robust; Magnetic resonance imaging -- Periodicals; 616
• DOI: 10.1002/jmri.26849
• Languages: English
• ISSNs: 1053-1807

Abstract

Abstract : Background: 3D chemical shift‐encoded (CSE)‐MRI techniques enable assessment of ferumoxytol concentration but are unreliable in the presence of motion. Purpose: To evaluate a motion‐robust 2D‐sequential CSE‐MRI for R2* and B0 mapping in ferumoxytol‐enhanced MRI of the placenta. Study Type: Prospective. Animal Model: Pregnant rhesus macaques. Field Strength/Sequence: 3.0T/CSE‐MRI. Assessment: 2D‐sequential CSE‐MRI was compared with 3D respiratory‐gated CSE‐MRI in placental imaging of 11 anesthetized animals at multiple timepoints before and after ferumoxytol administration, and in ferumoxytol phantoms (0 μg/mL–440 μg/mL). Motion artifacts of CSE‐MRI in 10 pregnant women without ferumoxytol administration were assessed retrospectively by three blinded readers (4‐point Likert scale). The repeatability of CSE‐MRI in seven pregnant women was also prospectively studied. Statistical Tests: Placental R2* and boundary B0 field measurements (ΔB0) were compared between 2D‐sequential and 3D respiratory‐gated CSE‐MRI using linear regression and Bland–Altman analysis. Results: In phantoms, a slope of 0.94 (r 2 = 0.99, concordance correlation coefficient ρ = 0.99), and bias of –4.8 s ‐1 (limit of agreement [LOA], –41.4 s ‐1, +31.8 s ‐1 ) in R2*, and a slope of 1.07 (r 2 = 1.00, ρ = 0.99) and bias of 11.4 Hz (LOA –12.0 Hz, +34.8 Hz) in ΔB0 were obtained in 2D CSE‐MRI compared with 3D CSE‐MRI for reference R2* ≤390 s ‐1 . In animals, a slope of 0.92 (r 2 = 0.97, ρ = 0.98) and bias of –2.2 s ‐1 (LOA –55.6 s ‐1, +51.3 s ‐1 ) in R2*, and a slope of 1.05 (r 2 = 0.95, ρ = 0.97) and bias of 0.4 Hz (LOA –9.0 Hz, +9.7 Hz) in ΔB0 were obtained. In humans, motion‐impaired R2* maps in 3D CSE‐MRI (Reader 1: 1.8 ± 0.6, Reader 2: 1.3 ± 0.7, Reader 3: 1.9 ± 0.6), while 2D CSE‐MRI was motion‐free (Reader 1: 2.9 ± 0.3, Reader 2: 3.0 ± 0, Reader 3: 3.0 ± 0). A mean difference of 0.66 s ‐1 and coefficient of repeatability of 9.48 s ‐1 for placental R2* were observed in the repeated 2D CSE‐MRI. Data Conclusion: 2D‐sequential CSE‐MRI provides accurate R2* and B0 measurements in ferumoxytol‐enhanced placental MRI of animals in the presence of respiratory motion, and motion‐robustness in human placental imaging. Level of Evidence: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2020;51:580–592.