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- Hedström, Erik, et al.
(författare)
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Factors affecting performance of fetal blood T2 measurements for noninvasive estimation of oxygen saturation
- 2023
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Ingår i: Magnetic Resonance in Medicine. - 1522-2594. ; 90:6, s. 2472-2485
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Tidskriftsartikel (refereegranskat)abstract
- PurposeTo ultimately make accurate and precise fetal noninvasive oxygen saturation (sO2) measurements by T2-prepared bSSFP more widely available by systematically assessing error sources in order to potentially reduce perinatal mortality in cardiovascular malformations and fetal growth restriction.MethodsT2-prepared bSSFP data were acquired in phantoms; in flowing blood in adults in the superior sagittal sinus, ascending and descending aorta, and main pulmonary artery; and in the fetal descending aorta and umbilical vein. T2 was assessed in relation to T2 two- or three-parameter curve-fitting techniques, SSFP readout, refocusing time delay (τ), constant and pulsatile blood flow, and impact of T1 recovery. Further, fetal T2 and sO2 variability were quantified in the descending aorta and umbilical vein in healthy fetuses and fetuses with cardiovascular malformation (gestational weeks 32–38).ResultsIn phantoms, three-parameter fitting was accurate irrespective of phase FOV (ConclusionsErrors due to T2-fitting techniques, off-resonance, flow velocity, and insufficient T1 recovery between image acquisitions could be mitigated by using three-parameter fitting with included saturation-prepared images approximating infinite T2-preparation time, adequate shimming covering the fetus and placenta, and by modifying acquisition parameters. Variability in fetal blood T2 and sO2, however, indicate that it is currently not feasible to use these methods for prediction of disease.
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| 2. |
- Sjöberg, Pia, et al.
(författare)
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Comparison of 2D and 4D Flow MRI in Neonates Without General Anesthesia
- 2023
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 57:1, s. 71-82
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundNeonates with critical congenital heart disease require early intervention. Four-dimensional (4D) flow may facilitate surgical planning and improve outcome, but accuracy and precision in neonates are unknown.PurposeTo 1) validate two-dimensional (2D) and 4D flow MRI in a phantom and investigate the effect of spatial and temporal resolution; 2) investigate accuracy and precision of 4D flow and internal consistency of 2D and 4D flow in neonates; and 3) compare scan time of 4D flow to multiple 2D flows.Study TypePhantom and prospective patients.PopulationA total of 17 neonates with surgically corrected aortic coarctation (age 18 days [IQR 11–20]) and a three-dimensional printed neonatal aorta phantom.Field Strength/SequenceA 5 T, 2D flow and 4D flow.AssessmentIn the phantom, 2D and 4D flow volumes (ascending and descending aorta, and aortic arch vessels) with different resolutions were compared to high-resolution reference 2D flow. In neonates, 4D flow was compared to 2D flow volumes at each vessel. Internal consistency was computed as the flow volume in the ascending aorta minus the sum of flow volumes in the aortic arch vessels and descending aorta, divided by ascending aortic flow.Statistical testsBland–Altman plots, Pearson correlation coefficient (r), and Student's t-tests.ResultsIn the phantom, 2D flow differed by 0.01 ± 0.02 liter/min with 1.5 mm spatial resolution and −0.01 ± 0.02 liter/min with 0.8 mm resolution; 4D flow differed by −0.05 ± 0.02 liter/min with 2.4 mm spatial and 42 msec temporal resolution, −0.01 ± 0.02 liter/min with 1.5 mm, 42 msec resolution and −0.01 ± 0.02 liter/min with 1.5 mm, 21 msec resolution. In patients, 4D flow and 2D flow differed by −0.06 ± 0.08 liter/min. Internal consistency in patients was −11% ± 17% for 2D flow and 5% ± 13% for 4D flow. Scan time was 17.1 minutes [IQR 15.5–18.5] for 2D flow and 6.2 minutes [IQR 5.3–6.9] for 4D flow, P < 0.0001.Data ConclusionNeonatal 4D flow MRI is time efficient and can be acquired with good internal consistency without contrast agents or general anesthesia, thus potentially expanding 4D flow use to the youngest and smallest patients.Evidence Level1Technical EfficacyStage 2
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