Dataset Information

Feasibility of dynamic T₂ *-based oxygen-enhanced lung MRI at 3T.

ABSTRACT:

Purpose

To demonstrate proof-of-concept of a T₂ *-sensitized oxygen-enhanced MRI (OE-MRI) method at 3T by assessing signal characteristics, repeatability, and reproducibility of dynamic lung OE-MRI metrics in healthy volunteers.

Methods

We performed sequence-specific simulations for protocol optimisation and acquired free-breathing OE-MRI data from 16 healthy subjects using a dual-echo RF-spoiled gradient echo approach at 3T across two institutions. Non-linear registration and tissue density correction were applied. Derived metrics included percent signal enhancement (PSE), ∆R₂ * and wash-in time normalized for breathing rate (τ-nBR). Inter-scanner reproducibility and intra-scanner repeatability were evaluated using intra-class correlation coefficient (ICC), repeatability coefficient, reproducibility coefficient, and Bland-Altman analysis.

Results

Simulations and experimental data show negative contrast upon oxygen inhalation, due to substantial dominance of ∆R₂ * at TE > 0.2 ms. Density correction improved signal fluctuations. Density-corrected mean PSE values, aligned with simulations, display TE-dependence, and an anterior-to-posterior PSE reduction trend at TE₁ . ∆R₂ * maps exhibit spatial heterogeneity in oxygen delivery, featuring anterior-to-posterior R₂ * increase. Mean T₂ * values across 32 scans were 0.68 and 0.62 ms for pre- and post-O₂ inhalation, respectively. Excellent or good agreement emerged from all intra-, inter-scanner and inter-rater variability tests for PSE and ∆R₂ *. However, ICC values for τ-nBR demonstrated limited agreement between repeated measures.

Conclusion

Our results demonstrate the feasibility of a T₂ *-weighted method utilizing a dual-echo RF-spoiled gradient echo approach, simultaneously capturing PSE, ∆R₂ * changes, and oxygen wash-in during free-breathing. The excellent or good repeatability and reproducibility on intra- and inter-scanner PSE and ∆R₂ * suggest potential utility in multi-center clinical applications.

SUBMITTER: Kim M

PROVIDER: S-EPMC10952203 | biostudies-literature | 2024 Mar

REPOSITORIES: biostudies-literature

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Publications

Feasibility of dynamic T<sub>2</sub> *-based oxygen-enhanced lung MRI at 3T.

Kim Mina M Naish Josephine H JH Needleman Sarah H SH Tibiletti Marta M Taylor Yohn Y O'Connor James P B JPB Parker Geoff J M GJM

Magnetic resonance in medicine 20231127 3

<h4>Purpose</h4>To demonstrate proof-of-concept of a T<sub>2</sub> *-sensitized oxygen-enhanced MRI (OE-MRI) method at 3T by assessing signal characteristics, repeatability, and reproducibility of dynamic lung OE-MRI metrics in healthy volunteers.<h4>Methods</h4>We performed sequence-specific simulations for protocol optimisation and acquired free-breathing OE-MRI data from 16 healthy subjects using a dual-echo RF-spoiled gradient echo approach at 3T across two institutions. Non-linear registrat ...[more]

PMID: 38013206

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Project description:BackgroundOxygen-enhanced magnetic resonance imaging (OE-MRI) can be used to assess regional lung function without ionizing radiation. Inhaled oxygen acts as a T1-shortening contrast agent to increase signal in T1-weighted (T1w) images. However, increase in proton density from pulmonary hyperoxic vasodilation may also contribute to the measured signal enhancement. Our aim was to quantify the relative contributions of the T1-shortening and vasodilatory effects of oxygen to signal enhancement in OE-MRI in both swine and healthy volunteers.MethodsWe imaged 14 anesthetized female swine (47 ± 8 kg) using a prototype 0.55 T high-performance MRI system while experimentally manipulating oxygenation and blood volume independently through oxygen titration, partial occlusion of the vena cava for volume reduction, and infusion of colloid fluid (6% hydroxyethyl starch) for volume increase. Ten healthy volunteers were imaged before, during, and after hyperoxia. Two proton density-weighted (PDw) and 2 T1w ultrashort echo time images were acquired per experimental state. The median PDw and T1w percent signal enhancement (PSE), compared with baseline room air, was calculated after image registration and correction for lung volume changes. Differences in median PSE were compared using Wilcoxon signed rank test.ResultsThe PSE in PDw images after 100% oxygen was similar in swine (1.66% ± 1.41%, P = 0.01) and in healthy volunteers (1.99% ± 1.79%, P = 0.02), indicating that oxygen-induced pulmonary vasodilation causes ~2% lung proton density increase. The PSE in T1w images after 100% oxygen was also similar (swine, 9.20% ± 1.68%, P < 0.001; healthy volunteers, 10.10% ± 3.05%, P < 0.001). The PSE in T1w enhancement was oxygen dose-dependent in anesthetized swine, and we measured a dose-dependent PDw image signal increase from infused fluids.ConclusionsThe contribution of oxygen-induced vasodilation to T1w OE-MRI signal was measurable using PDw imaging and was found to be ~2% in both anesthetized swine and in healthy volunteers. This finding may have implications for patients with regional or global hypoxia or vascular dysfunction undergoing OE-MRI and suggest that PDw imaging may be useful to account for oxygen-induced vasodilation in OE-MRI.

Project description:PurposeWe aimed to compare arterial spin labeling (ASL) with dynamic susceptibility contrast (DSC) enhanced perfusion MRI for the surveillance of primary and metastatic brain tumors at 3T, both in terms of lesion perfusion metrics and diagnostic accuracy.MethodsIn this retrospective study, we included 115 patients, who underwent both ASL and DSC perfusion in the same 3T MRI scanning session between 1 January and 31 December 2019. ASL-derived cerebral blood flow (CBF) maps and DSC-derived relative cerebral blood volume (rCBV) maps, both uncorrected and corrected for leakage, were created with commercially available software. Lesions were identified as T2-/T2-FLAIR hyperintensity with or without contrast enhancement. Measurements were done by placing a region of interest in the visually determined area of highest perfusion, copying to the contralateral normal appearing white matter (NAWM), and then propagating to the other perfusion maps. Pearson's correlation coefficients were calculated between the CBF and rCBV ratios of tumor versus NAWM. Accuracy for diagnosing tumor progression was calculated as the area under the receiver operating characteristics (ROC) curve (AUC) for the ASL-CBF and leakage corrected DSC-rCBV ratios.ResultsWe identified 178 lesions, 119 with and 59 without contrast enhancement. Correlation coefficients between ASL-derived CBF versus DSC-derived rCBV ratios were 0.60-0.67 without and 0.72-0.78 with leakage correction in all lesions (n = 178); these were 0.65-0.80 in enhancing glioma (n = 80), 0.58-0.73 in non-enhancing glioma, and 0.14-0.40 in enhancing metastasis (n = 31). No significant correlation was found in enhancing (n = 8) or non-enhancing (n = 7) lymphomas. The areas under the ROC curves (AUCs) for all patients were similar for ASL and DSC (0.73-0.78), and were higher for enhancing glioma (AUC = 0.78-0.80) than for non-enhancing glioma (AUC = 0.56-0.62). In brain metastasis, the AUC was lower for ASL-derived CBF (AUC = 0.72) than for DSC-derived rCBV ratios (AUC = 0.87-0.93).ConclusionWe found that ASL and DSC have more or less the same diagnostic accuracy. Our findings suggest that ASL can be used as an alternative to DSC to measure perfusion in enhancing and non-enhancing gliomas and brain metastasis at 3T. For lymphoma, this should be further investigated in a larger population.

Dataset Information

Feasibility of dynamic T₂ *-based oxygen-enhanced lung MRI at 3T.

Purpose

Methods

Results

Conclusion

Publications

Feasibility of dynamic T<sub>2</sub> *-based oxygen-enhanced lung MRI at 3T.

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Methods

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Publications

Feasibility of dynamic T<sub>2</sub> *-based oxygen-enhanced lung MRI at 3T.

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OmicsDI is part of the ELIXIR infrastructure

Tweets

Feasibility of dynamic T₂ *-based oxygen-enhanced lung MRI at 3T.