Functional lung imaging with transient spoiled gradient echo

Bauman, Grzegorz; Pusterla, Orso; Bieri, Oliver

doi:10.1002/mrm.27535

Cited by 22 publications

(38 citation statements)

References 30 publications

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“…Despite further improvements of FD derived methods, current usage on 3T systems is still limited. Recent studies using sequences with similar acquisition parameters to the proposed triple‐echo sequence showed that it is feasible to derive ventilation weighted images with sufficient quality even on 3T systems . However, in order to overcome challenges of pulmonary MRI at higher fields, it would be advantageous to implement UTE sequences with compressed sensing algorithms to preserve current temporal resolution.…”

Section: Discussionmentioning

confidence: 99%

Free‐breathing quantification of regional ventilation derived by phase‐resolved functional lung (PREFUL) MRI

et al. 2019

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Purpose To test the feasibility of regional fully quantitative ventilation measurement in free breathing derived by phase‐resolved functional lung (PREFUL) MRI in the supine and prone positions. In addition, the influence of T2* relaxation time on ventilation quantification is assessed. Methods Twelve healthy volunteers underwent functional MRI at 1.5 T using a 2D triple‐echo spoiled gradient echo sequence allowing for quantitative measurement of T2* relaxation time. Minute ventilation (ΔV) was quantified by conventional fractional ventilation (FV) and the newly introduced regional ventilation (VR), which corrects volume errors due to image registration. ΔVFV versus ΔVVR and ΔVVR versus ΔVVR with T2* correction were compared using Bland–Altman plots and correlation analysis. The repeatability and physiological plausibility of all measurements were tested in the supine and prone positions. Results On global and regional scales a strong correlation was observed between ΔVFV versus ΔVVR and ΔVVR versus ΔVVRT2* (r > 0.93); however, regional Bland–Altman analysis showed systematic differences (p < 0.0001). Unlike ΔVVRT2*, ΔVVR and ΔVFV showed expected physiologic anterior–posterior gradients, which decreased in the supine but not in the prone position at second measurement during 3 min in the same position. For all quantification methods a moderate repeatability (coefficient of variation <20%) of ventilation was found. Conclusion A fully quantified regional ventilation measurement using ΔVVR in free breathing is feasible and shows physiologically plausible results. In contrast to conventional ΔVFV, volume errors due to image registration are eliminated with the ΔVVR approach. However, correction for the T2* effect remains challenging.

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Section: Discussionmentioning

confidence: 99%

Free‐breathing quantification of regional ventilation derived by phase‐resolved functional lung (PREFUL) MRI

et al. 2019

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“…PREFUL MRI offers the possibility to assess phase‐resolved pulmonary perfusion and ventilation without any contrast agent during free breathing. This approach was shown to be feasible with fast imaging sequences such as the steady‐state free precession sequence and the widely available and generic spoiled gradient echo sequence FLASH 2,9,10 . In image acquisitions of a gradient‐echo sequence, multiple RF pulses are delivered within short time intervals.…”

Section: Introductionmentioning

confidence: 99%

“…This approach was shown to be feasible with fast imaging sequences such as the steady-state free precession sequence and the widely available and generic spoiled gradient echo sequence FLASH. 2,9,10 In image acquisitions of a gradient-echo sequence, multiple RF pulses are delivered within short time intervals. By this, the longitudinal magnetization is not able to recover completely between the upcoming pulse repetitions and the signal decreases to a steady state level.…”

Section: Introductionmentioning

confidence: 99%

Perfusion quantification using voxel‐wise proton density and median signal decay in PREFUL MRI

Glandorf

Klimeš

Behrendt

et al. 2021

Magnetic Resonance in Med

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Purpose Contrast‐free lung MRI based on Fourier decomposition is an attractive method to monitor various lung diseases. However, the accuracy of the current perfusion quantification is limited. In this study, a new approach for perfusion quantification based on voxel‐wise proton density and median signal decay toward the steady state for Fourier decomposition‐based techniques is proposed called QQuantified (QQuant). Methods Twenty patients with chronic obstructive pulmonary disease and 18 patients with chronic thromboembolic pulmonary hypertension received phase‐resolved functional lung‐MRI (PREFUL) and dynamic contrast‐enhanced (DCE)‐MRI. Nine healthy participants received phase‐resolved functional lung‐MRI only. Median values of QQuant were compared to a Fourier decomposition perfusion quantification presented by Kjørstad et al (QKjørstad) and validated toward pulmonary blood flow derived by DCE‐MRI (PBFDCE). Blood fraction maps determined by the new approach were calculated. Regional and global correlation coefficients were calculated, and Bland‐Altman plots were created. Histogram analyses of all cohorts were created. Results The introduced parameter QQuant showed only 2 mL/min/100 mL mean deviation to PBFDCE in the patient cohort and showed less bias than QKjørstad. Significant increases of regional correlation with PBFDCE were achieved (r = 0.3 vs. r = 0.2, P < .01*). The trend of global correlation toward PBFDCE is not uniform, showing higher values for QKjørstad in the chronic obstructive pulmonary disease cohort than for QQuant and vice versa in the chronic thromboembolic pulmonary hypertension cohort. In contrast to QKjørstad, QQuant perfusion maps indicate a physiologic dorsoventral gradient in supine position similar to PBFDCE with similar value distribution in the histograms. Conclusion We proposed a new approach for perfusion quantification of phase‐resolved functional lung measurements. The developed parameter QQuant reveals a higher accuracy compared to QKjørstad.

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“…Therefore, the effects of higher field strengths on functional lung parameters need to be examined to guarantee reproducibility between different scanners and scan sites. Bauman et al recently analyzed the impact of higher magnetic field strength on SNR, CNR and relative functional parameters derived by matrix pencil decomposition using steady state free precession and a transient state spoiled gradient echo sequence [24]. The purpose of this study is to evaluate the influence of different field strengths on SNR, CNR and the functional parameters derived by PREFUL MRI in a cohort of healthy participants using a commercially available spoiled gradient echo fast low angle shot (FLASH) sequence.…”

Section: Introductionmentioning

confidence: 99%

Comparison of phase-resolved functional lung (PREFUL) MRI derived perfusion and ventilation parameters at 1.5T and 3T in healthy volunteers

et al. 2020

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Purpose The purpose of this study is to evaluate the influence of different field strengths on perfusion and ventilation parameters, SNR and CNR derived by PREFUL MRI using predefined sequence parameters. Methods Data sets of free breathing 2d FLASH lung MRI were acquired from 15 healthy subjects at 1.5T and 3T (Magnetom Avanto and Skyra, Siemens Healthcare, Erlangen, Germany) with a maximum period of 3 days in between. The processed functional parameters regional ventilation (RVent), perfusion (Q), quantified perfusion (QQuant), perfusion defect percentage (QDP), ventilation defect percentage (VDP) and ventilation-perfusion match (VQM) were compared for systematic differences. Signal- and contrast-to-noise ratio (SNR and CNR) of both acquisitions were analyzed. Results RVent, Q, VDP, SNR and CNR presented no significant differences between 1.5T and 3T. QQuant (1.5T vs. 3T, P = 0.04), and QDP (1.5T vs. 3T, P≤0.01) decreased significantly at 3T. Consequently, VQM increased significantly (1.5T vs. 3T, P≤0.01). Skewness and kurtosis of the Q-values increased significantly at 3T (P≤0.01). The mean Sørensen-Dice coefficients between both series were 0.91 for QDP and 0.94 for VDP. The Bland-Altman analysis of both series showed mean differences of 4.29% for QDP, 1.23% for VDP and -5.15% for VQM. Using the above-mentioned parameters for three-day repeatability at two different scanners and field strengths, the retrospective power calculation showed, that a sample size of 15 can detect differences of 3.7% for QDP, of 2.9% for VDP and differences of 2.6% for VQM. Conclusion Significant differences in QDP may be related to field inhomogeneities, which is expressed by increasing skewness and kurtosis at 3T. QQuant reveals only poor reproducibility between 1.5T and 3T. RVent, Q, VDP, SNR and CNR were not altered significantly at the used sequence parameters. Healthy participants with minimal defects present high spatial agreement of QDP and VDP.

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Functional lung imaging with transient spoiled gradient echo

Cited by 22 publications

References 30 publications

Free‐breathing quantification of regional ventilation derived by phase‐resolved functional lung (PREFUL) MRI

Free‐breathing quantification of regional ventilation derived by phase‐resolved functional lung (PREFUL) MRI

Perfusion quantification using voxel‐wise proton density and median signal decay in PREFUL MRI

Comparison of phase-resolved functional lung (PREFUL) MRI derived perfusion and ventilation parameters at 1.5T and 3T in healthy volunteers

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