Effect of T<sub>1</sub> relaxation on ventilation mapping using hyperpolarized <sup>129</sup>Xe multiple breath wash‐out imaging

Morgado, Felipe; Couch, Marcus J.; Stirrat, Elaine; Santyr, Giles

doi:10.1002/mrm.27234

Cited by 3 publications

(15 citation statements)

References 34 publications

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“…Figure 4 shows a Bland-Altman analysis of the fractional ventilation results calculated using the 2 T 1 modeling methods. The results in Figure 4A agree with predictions described by Morgado et al, 19 in which the relative bias is In the unpaired t-test, P < .05 was considered to be significant.…”

Section: Resultssupporting

confidence: 89%

“…This study measured fractional ventilation in pediatric CF participants with preserved lung function using a variable T 1 model and a constant T 1 model . As expected, assuming a constant T 1 results in overestimated r values, and the mean relative bias of 18% is in good agreement with a previous preclinical study . This bias may obscure regions of the lung that are underventilated or contain air trapping.…”

Section: Discussionmentioning

confidence: 99%

“…14 As expected, assuming a constant T 1 results in overestimated r values, and the mean relative bias of 18% is in good agreement with a previous preclinical study. 19 This bias may obscure regions of the lung that are underventilated or contain air trapping. Therefore, accounting for the T 1 trajectory should improve the accuracy of r maps; however, neither method produced r maps that could statistically distinguish the healthy and CF groups.…”

Section: Discussionmentioning

confidence: 99%

“…Although 3 He and 129 Xe have substantially different densities and viscosities, fractional ventilation measured using HP 129 Xe has been found to be in good agreement with HP 3 He measurements in healthy adult participants . Although HP gas MBW imaging performed in human lungs to date has assumed a constant T 1 , Morgado et al demonstrated in rats that this assumption leads to a significant bias in fractional ventilation due to expected changes in alveolar oxygenation . Instead of assuming a constant T 1 , Morgado et al proposed modeling T 1 as a function of the HP gas washout.…”

Section: Introductionmentioning

confidence: 99%

“…15 Although HP gas MBW imaging performed in human lungs to date has assumed a constant T 1 , 14 Morgado et al demonstrated in rats that this assumption leads to a significant bias in fractional ventilation due to expected changes in alveolar oxygenation. 19 Instead of assuming a constant T 1 , Morgado et al proposed modeling T 1 as a function of the HP gas washout. To our knowledge, MBW imaging has not yet been demonstrated in a pediatric population using HP 129 Xe.…”

Section: Introductionmentioning

confidence: 99%

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Assessing the feasibility of hyperpolarized ¹²⁹Xe multiple‐breath washout MRI in pediatric cystic fibrosis

Couch

Morgado

Kanhere

et al. 2019

Magnetic Resonance in Med

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Purpose To assess the feasibility of hyperpolarized 129Xe multiple‐breath washout MRI in pediatric cystic fibrosis (CF) participants with preserved lung function. Fractional ventilation (r), defined as the fractional gas replacement per breath, was mapped using 2 signal models: (1) constant T1 and (2) variable T1 as a function of the hyperpolarized gas washout. Methods A total of 17 pediatric participants were recruited (mean age 11.7 ± 2.8 years), including 7 children with clinically stable CF and 10 aged‐matched healthy controls. Pulmonary function tests were performed, including spirometry, to measure the forced expiratory volume in 1 second and nitrogen multiple‐breath washout to measure the lung clearance index. Hyperpolarized 129Xe MRI was performed during consecutive breaths of air following a single 129Xe inhalation, and fractional ventilation maps were calculated. Results The forced expiratory volume in 1 second was similar in both groups (P = .32), but there was a statistically significant difference in lung clearance index between healthy and CF participants (P = .001). With variable T1 modeling, CF participants had a mean r of 0.44 ± 0.08 and healthy participants had a mean r of 0.37 ± 0.12 (P = .20). With constant T1 modeling, CF participants had a mean r′ of 0.48 ± 0.08, and healthy participants had a mean r′ of 0.43 ± 0.12 (P = .32). Therefore, assuming a constant T1 leads to a relative bias in r of 15.1% ± 6.4% and 20.8% ± 7.4% for CF and healthy participants, respectively (P = .12). Conclusion This study demonstrates that hyperpolarized 129Xe multiple‐breath washout imaging is feasible in pediatric participants with CF, and inclusion of variable T1 modeling reduces bias in the fractional ventilation measurements.

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Section: Resultssupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Assessing the feasibility of hyperpolarized ¹²⁹Xe multiple‐breath washout MRI in pediatric cystic fibrosis

Couch

Morgado

Kanhere

et al. 2019

Magnetic Resonance in Med

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Intra‐ and Inter‐visit Repeatability of ¹²⁹Xenon Multiple‐Breath Washout MRI in Children With Stable Cystic Fibrosis Lung Disease

Alam

Zanette

Munidasa

et al. 2023

Magnetic Resonance Imaging

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Background Multiple‐breath washout (MBW) 129Xe MRI (MBW Xe‐MRI) is a promising technique for following pediatric cystic fibrosis (CF) lung disease progression. However, its repeatability in stable CF needs to be established to use it as an outcome measure for novel therapies. Purpose To assess intravisit and intervisit repeatability of MBW Xe‐MRI in healthy and CF children. Study Type Prospective, longitudinal cohort study. Subjects A total of 18 pediatric subjects (7 healthy, 11 CF). Field Strength/Sequence A 3 T/2D coronal hyperpolarized (HP) 129Xe images using GRE sequence. Assessment All subjects completed MBW Xe‐MRI, pulmonary function tests (PFTs) (spirometry, nitrogen [N2] MBW for lung clearance index [LCI]) and ventilation defect percent (VDP) at baseline (visit 1) and 1‐month after. Fractional ventilation (FV), coefficient of variation (CoVFV) maps were calculated from MBW Xe‐MRI data acquired between intervening air washout breaths performed after an initial xenon breath‐hold. Skewness of FV and CoVFV map distributions was also assessed. Statistical Tests Repeatability: intraclass correlation coefficients (ICC), within‐subject coefficient of variation (CV%), repeatability coefficient (CR). Agreement: Bland–Altman. For correlations between MBW Xe‐MRI, VDP and PFTs: Spearman's correlation. Significance threshold: P < 0.05. Results For FV, intravisit median [IQR] ICC was high in both healthy (0.94 [0.48, 0.99]) and CF (0.83 [0.04, 0.97]) subjects. CoVFV also had good intravisit ICC in healthy (0.92 [0.42, 0.99]) and CF (0.79 [0.02, 0.96]) subjects. Similarly, for FV, intervisit ICC was high in health (0.94 [0.68, 0.99]) and CF (0.89 [0.61, 0.97]). CoVFV also had good intervisit ICC in health (0.92 [0.42, 0.99]) and CF (0.78 [0.26, 0.94]). FV had better intervisit repeatability than VDP. CoVFV correlated significantly with LCI (R = 0.56). Skewness of FV distributions significantly distinguished between cohorts at baseline. Data Conclusion MBW Xe‐MRI had high intravisit and intervisit repeatability in healthy and stable CF subjects. CoVFV correlated with LCI, suggesting the importance of ventilation heterogeneity to early CF. Evidence Level 1. Technical Efficacy Stage 2.

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Multibreath Hyperpolarized 3He Imaging Scheme to Measure Alveolar Oxygen Tension and Apparent Diffusion Coefficient

et al. 2019

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Rationale and Objective: In this study, we compared a newly developed multi-breath simultaneous alveolar oxygen tension and apparent diffusion coefficient (P A O 2-ADC) imaging sequence to a single-breath acquisition, with the aim of mitigating the compromising effects of inter-voxel flow and slow-filling regions on single-breath measurements, especially in COPD subjects. Materials and Methods: Both single-breath and multi-breath simultaneous P A O 2-ADC imaging schemes were performed on a total of ten human subjects (five asymptomatic smokers and five COPD subjects). Estimated P A O 2 and ADC values derived from the different sequences were compared both globally and regionally. The distribution of voxels with non-physiological values was also compared between the two schemes. Results: The multi-breath protocol decreased the ventilation defect volumes by an average of 12.9±6.6%. The multi-breath sequence generated non-physiological P A O 2 values in 11.0±8.5% fewer voxels than the single-breath sequence. Single-breath P A O 2 maps also showed more regions with gas-flow artifacts and general signal heterogeneity. On average, the standard deviation of the P A O 2 distribution was 16.5±7.0% lower using multi-breath P A O 2-ADC imaging, suggesting a more homogeneous gas distribution. Both mean and standard deviation of the ADC increased significantly from single-to multi-breath imaging (P=0.048 and p=0.070, respectively), suggesting more emphysematous regions in the slow-filling lung. Conclusion: Multi-breath P A O 2-ADC imaging provides superior accuracy and efficiency compared to previous imaging protocols. P A O 2 and ADC maps generated by multi-breath imaging allowed for the qualification of various regions as emphysematous or obstructed which singlebreath P A O 2 maps can only identify as defects. The simultaneous P A O 2 and ADC measurements

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Effect of T₁ relaxation on ventilation mapping using hyperpolarized ¹²⁹Xe multiple breath wash‐out imaging

Abstract: Analysis of hyperpolarized Xe MBWO imaging using a model incorporating T (n) corrects for an overestimating bias in the mapping of fractional ventilation in mechanically ventilated rats introduced by assuming a fixed T .

Cited by 3 publications

References 34 publications

Assessing the feasibility of hyperpolarized ¹²⁹Xe multiple‐breath washout MRI in pediatric cystic fibrosis

Assessing the feasibility of hyperpolarized ¹²⁹Xe multiple‐breath washout MRI in pediatric cystic fibrosis

Intra‐ and Inter‐visit Repeatability of ¹²⁹Xenon Multiple‐Breath Washout MRI in Children With Stable Cystic Fibrosis Lung Disease

Multibreath Hyperpolarized 3He Imaging Scheme to Measure Alveolar Oxygen Tension and Apparent Diffusion Coefficient

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Effect of T1 relaxation on ventilation mapping using hyperpolarized 129Xe multiple breath wash‐out imaging

Abstract: Analysis of hyperpolarized Xe MBWO imaging using a model incorporating T (n) corrects for an overestimating bias in the mapping of fractional ventilation in mechanically ventilated rats introduced by assuming a fixed T .

Cited by 3 publications

References 34 publications

Assessing the feasibility of hyperpolarized 129Xe multiple‐breath washout MRI in pediatric cystic fibrosis

Assessing the feasibility of hyperpolarized 129Xe multiple‐breath washout MRI in pediatric cystic fibrosis

Intra‐ and Inter‐visit Repeatability of 129Xenon Multiple‐Breath Washout MRI in Children With Stable Cystic Fibrosis Lung Disease

Multibreath Hyperpolarized 3He Imaging Scheme to Measure Alveolar Oxygen Tension and Apparent Diffusion Coefficient

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Product

Resources

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Effect of T₁ relaxation on ventilation mapping using hyperpolarized ¹²⁹Xe multiple breath wash‐out imaging

Assessing the feasibility of hyperpolarized ¹²⁹Xe multiple‐breath washout MRI in pediatric cystic fibrosis

Assessing the feasibility of hyperpolarized ¹²⁹Xe multiple‐breath washout MRI in pediatric cystic fibrosis

Intra‐ and Inter‐visit Repeatability of ¹²⁹Xenon Multiple‐Breath Washout MRI in Children With Stable Cystic Fibrosis Lung Disease