Influence of age and sex on the longitudinal relaxation time, T1, of the lung in healthy never‐smokers

Kindvall, Simon; Diaz, Sandra; Svensson, Jonas; Wollmer, Per; Slusarczyk, Dariusz; Olsson, Lars

doi:10.1002/jmri.25085

Cited by 10 publications

(15 citation statements)

References 38 publications

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“…One of the limitations of this study is a small sample size of healthy adult subjects. It is well‐known that lung parenchyma density as well as T 1 relaxation time is age‐dependent . Consequently, the feasibility of tSPGR imaging should be tested in a wider age range, including pediatric and elderly subjects.…”

Section: Discussionmentioning

confidence: 99%

Functional lung imaging with transient spoiled gradient echo

Bauman

Pusterla

Bieri

2018

Magnetic Resonance in Med

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Purpose To introduce an alternative framework for perfusion and ventilation lung imaging at 3 T using transient spoiled gradient echo (tSPGR) acquisitions. Methods Sets of coronal 2D time‐resolved lung image series were acquired in 5 healthy volunteers using tSPGR and compared with contemporary SPGR and ultrafast balanced SSFP (uf‐bSSFP) implementations at 1.5 T and 3 T. Sequence parameters and view ordering were optimized for tSPGR to yield maximum signal intensity in the lung tissue. Signal‐to‐noise ratio and contrast‐to‐noise ratio analyses were performed in all acquired tSPGR, SPGR, and uf‐bSSFP data sets. Matrix pencil decomposition was applied to generate functional parameter maps, including fractional ventilation, relative perfusion, and blood arrival time. Results For the lung, the signal intensity of tSPGR imaging was maximal for minimal TR and TE settings of 0.99 ms and 0.43 ms, respectively. Moreover, low RF spoiling increments in combination with a centric view ordering resulted in a further signal‐to‐noise ratio increase of about 30% to 40%. The average signal‐to‐noise ratio in the lung parenchyma was 73.3 for uf‐bSSFP, 38.1 for tSPGR, 20.7 for SPGR at 1.5 T, and 31.2 for uf‐bSSFP, 35.6 for tSPGR, and 21.3 for SPGR at 3 T. The average ventilation and perfusion contrast‐to‐noise ratio was 33.2 and 36.2 for uf‐bSSFP, 15.4 and 12.5 for tSPGR, 13.5 and 4.1 for SPGR at 1.5 T, and 16.5 and 11.3 for uf‐bSSFP, 29.7 and 50.8 for tSPGR, and 22.4 and 16.5 for SPGR at 3 T, respectively. Conclusion At 3 T, application of balanced SSFP is limited, so tSPGR offers an alternative framework for successful lung function assessment using matrix pencil MRI.

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Section: Discussionmentioning

confidence: 99%

Functional lung imaging with transient spoiled gradient echo

Bauman

Pusterla

Bieri

2018

Magnetic Resonance in Med

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“…A few examples for T1: there is a small difference between the T1 measured at end-expiration and end-inspiration [4]. T1 of the lung depends on both sex and age [5], and it was recently found that T1 relaxation time was shortened in lung for COPD patients [6]. …”

Section: Introductionmentioning

confidence: 99%

In Vivo Measurements of T2 Relaxation Time of Mouse Lungs during Inspiration and Expiration

Olsson

Hockings

2016

PLoS ONE

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PurposeThe interest in measurements of magnetic resonance imaging relaxation times, T1, T2, T2*, with intention to characterize healthy and diseased lungs has increased recently. Animal studies play an important role in this context providing models for understanding and linking the measured relaxation time changes to the underlying physiology or disease. The aim of this work was to study how the measured transversal relaxation time (T2) in healthy lungs is affected by normal respiration in mouse.MethodT2 of lung was measured in anaesthetized freely breathing mice. Image acquisition was performed on a 4.7 T, Bruker BioSpec with a multi spin-echo sequence (Car-Purcell-Meiboom-Gill) in both end-expiration and end-inspiration. The echo trains consisted of ten echoes of inter echo time 3.5 ms or 4.0 ms. The proton density, T2 and noise floor were fitted to the measured signals of the lung parenchyma with a Levenberg-Marquardt least-squares three-parameter fit.ResultsT2 in the lungs was longer (p<0.01) at end-expiration (9.7±0.7 ms) than at end-inspiration (9.0±0.8 ms) measured with inter-echo time 3.5 ms. The corresponding relative proton density (lung/muscle tissue) was higher (p<0.001) during end-expiration, (0.61±0.06) than during end-inspiration (0.48±0.05). The ratio of relative proton density at end-inspiration to that at end-expiration was 0.78±0.09. Similar results were found for inter-echo time 4.0 ms and there was no significant difference between the T2 values or proton densities acquired with different interecho times. The T2 value increased linearly (p< 0.001) with proton density.ConclusionThe measured T2 in-vivo is affected by diffusion across internal magnetic susceptibility gradients. In the lungs these gradients are modulated by respiration, as verified by calculations. In conclusion the measured T2 was found to be dependent on the size of the alveoli.

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“…However, since we required subjects to fill out a questionnaire about smoking, as outlined in the methods section, very few prospective volunteers born before the 70’s identified themselves as never-smokers. The lung function as quantified by PFT is normal for all volunteers; residual volume increases with age (ρ = 0.7 at p<0.01); and k CO decreases with age (ρ = -0.4 at p = 0.015) [22]. The error bars represent the CV of the T1-measurement, which mostly depend on the subject’s breathing technique.…”

Section: Discussionmentioning

confidence: 99%

“…Segmentations were considered successful when each slice clearly included the signal magnitude gradient representing the border of the lung. The T 1 -value of the entire lung volume is defined as the center of a Gaussian curve, fitted to the histogram of all voxel values in the lung segmentation after a histogram thresholding [17,22]. Using the T 1 -values at baseline and after 5 min oxygen inhalation, the global difference in relaxation rate, ΔR 1 , was calculated for each subject.…”

Section: Methodsmentioning

confidence: 99%

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The change of longitudinal relaxation rate in oxygen enhanced pulmonary MRI depends on age and BMI but not diffusing capacity of carbon monoxide in healthy never-smokers

et al. 2017

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ObjectiveOxygen enhanced pulmonary MRI is a promising modality for functional lung studies and has been applied to a wide range of pulmonary conditions. The purpose of this study was to characterize the oxygen enhancement effect in the lungs of healthy, never-smokers, in light of a previously established relationship between oxygen enhancement and diffusing capacity of carbon monoxide in the lung (DL,CO) in patients with lung disease.MethodsIn 30 healthy never-smoking volunteers, an inversion recovery with gradient echo read-out (Snapshot-FLASH) was used to quantify the difference in longitudinal relaxation rate, while breathing air and 100% oxygen, ΔR1, at 1.5 Tesla. Measurements were performed under multiple tidal inspiration breath-holds.ResultsIn single parameter linear models, ΔR1 exhibit a significant correlation with age (p = 0.003) and BMI (p = 0.0004), but not DL,CO (p = 0.33). Stepwise linear regression of ΔR1 yields an optimized model including an age-BMI interaction term.ConclusionIn this healthy, never-smoking cohort, age and BMI are both predictors of the change in MRI longitudinal relaxation rate when breathing oxygen. However, DL,CO does not show a significant correlation with the oxygen enhancement. This is possibly because oxygen transfer in the lung is not diffusion limited at rest in healthy individuals. This work stresses the importance of using a physiological model to understand results from oxygen enhanced MRI.

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Influence of age and sex on the longitudinal relaxation time, T1, of the lung in healthy never‐smokers

Cited by 10 publications

References 38 publications

Functional lung imaging with transient spoiled gradient echo

Functional lung imaging with transient spoiled gradient echo

In Vivo Measurements of T2 Relaxation Time of Mouse Lungs during Inspiration and Expiration

The change of longitudinal relaxation rate in oxygen enhanced pulmonary MRI depends on age and BMI but not diffusing capacity of carbon monoxide in healthy never-smokers

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