Novel magnetic resonance technique for functional imaging of cystic fibrosis lung disease

Nyilas, Sylvia; Bauman, Grzegorz; Sommer, Gregor; Stranzinger, Enno; Pusterla, Orso; Frey, Urs; Korten, Insa; Singer, Florian; Casaulta, Carmen; Bieri, Oliver; Latzin, Philipp

doi:10.1183/13993003.01464-2017

Cited by 66 publications

(101 citation statements)

References 39 publications

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“…Data are presented as median (IQR) unless stated otherwise. FEV 1, forced expiratory volume in 1 s; LCI, lung clearance index; R8 EXP (X8 EXP ), mean expiratory resistance (reactance); R8 INSP (X8 INSP ), mean inspiratory resistance (reactance); R8 TOT (X8 TOT ), mean resistance (reactance) during total breath; RV, residual volume; TLC, total lung capacity; ΔX8, X8 INSP —X8 EXP ; MRI, Magnetic resonance imaging; total MRI morphology score (maximum 60) accounts for bronchiectasis/bronchial wall thickening, mucus plugging, abscesses/sacculations, consolidations, and special findings in the whole lung …”

Section: Resultsmentioning

confidence: 99%

Within‐breath changes in respiratory system impedance in children with cystic fibrosis

Zannin

Nyilas

Ramsey

et al. 2019

Pediatric Pulmonology

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Background The aim of this study was to assess within‐breath respiratory system impedance by the forced oscillation technique (FOT) in children with cystic fibrosis (CF) and relate it to the underlying lung disease. Methods Thirty‐three children with CF (median [range] age 12.0 [6‐17] years) underwent FOT at 8 Hz during tidal breathing, multiple breath nitrogen washout (LCI), spirometry (FEV1), body plethysmography (RV/TLC), and magnetic resonance imaging (MRI). FOT outcomes included: mean inspiratory, expiratory, and whole breath resistance (R8INSP, R8EXP, R8TOT) and reactance (X8INSP, X8EXP, X8TOT), and the differences between X8INSP and X8EXP (ΔX8). Morphological changes were evaluated by MRI using CF‐specific morphological scores. Spearman correlation was performed to examine the correlation between FOT indices and other parameters. Results FEV1 was negatively correlated with R8EXP (r = −0.52, P = 0.002) and ΔX8 (r = −0.55, P = 0.001), and positively correlated with and X8EXP (r = 0.56, P < 0.001). RV/TLC was positively correlated with R8EXP (r = 0.43, P = 0.013), and ΔX8 (r = 0.54, P = 0.001) and negatively correlated with X8EXP (r = −0.54, P = 0.001). We found poor correlation between FOT parameters and LCI and no correlation between FOT parameters and MRI scores. Conclusion In children with CF, changes in within‐breath FOT parameters are consistent with peripheral obstruction and dynamic airway compression, while they are not associated with ventilation heterogeneities and morphological alterations.

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Section: Resultsmentioning

confidence: 99%

Within‐breath changes in respiratory system impedance in children with cystic fibrosis

Zannin

Nyilas

Ramsey

et al. 2019

Pediatric Pulmonology

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“…Alternatively, assuming the MR signal ( S ) is proportional to density ( ρ ), ventilation can be determined from the MR signal as

ventilation = \frac{S_{Ref}}{S_{Insp}} - \frac{S_{Ref}}{S_{Exp}} = \frac{S_{Ref} ((), S_{Exp} - S_{Insp})}{S_{Insp} S_{Exp}} .

Since the assessment of ventilation using PREFUL involves image registration of inspiratory and expiratory lung volumes to an intermediate lung volume, there are three intuitive choices of V Ref to determine ventilation: V Insp , V Exp and the intermediate volume V Mid . Correspondingly, ventilation may be determined by FV,

FV = \frac{V_{Insp} - V_{Exp}}{V_{Insp}} = \frac{S_{Exp} - S_{Insp}}{S_{Exp}},

which is commonly used in FD‐MRI, by SV,

SV = \frac{V_{Insp} - V_{Exp}}{V_{Exp}} = \frac{S_{Exp} - S_{Insp}}{S_{Insp}},

which is primarily used in lung imaging techniques using exogenous contrast agents, eg hyperpolarized 3 He imaging or oxygen‐enhanced imaging, or by the newly introduced regional ventilation ( V R),

V_{R} = \frac{V_{Insp} - V_{Exp}}{V_{Mid}} = \frac{S_{Mid}}{S_{Insp}} - \frac{S_{Mid}}{S_{Exp}} .

Minute ventilation (Δ V VR ) in units of mL/min/mL, which determines the ventilated air volume per voxel volume and per unit time, can be calculated by taking the respiratory frequency into account:

{∆ V}_{VR} ((), x) = V normalR ((), x)

…”

Section: Theorymentioning

confidence: 99%

“…While gas MRI techniques (such as hyperpolarized 129 Xe or 19 F) directly depict the gas distribution typically during breath‐hold, FD MRI uses regional lung motion during normal tidal breathing to calculate regional ventilation. Also, several studies show promising data derived from FD for diseases such as asthma, chronic obstructive pulmonary disease, cystic fibrosis or chronic thromboembolic pulmonary hypertension, which positions FD as a valuable candidate for clinical translation in the near future …”

Section: Introductionmentioning

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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“…Future trials should address efficacy of elastic chest wall restriction in combination with other airway clearance techniques. Promising additional outcomes could be obtained from functional magnetic resonance imaging [39].…”

Section: Strengths and Limitationsmentioning

confidence: 99%

Short-Term Effects of Elastic Chest Wall Restriction on Pulmonary Function in Children with Cystic Fibrosis

et al. 2018

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Background: Elastic chest wall restriction introduced by Chevaillier is thought to reduce existing hyperinflation and improve mucus clearance from peripheral airways. In healthy adults, restriction decreases the functional residual capacity (FRC) and forced vital capacity (FVC), while ventilation inhomogeneity (lung clearance index [LCI]) increases. Pulmonary function response to restriction is unknown in individuals with cystic fibrosis (CF). Objectives: To examine short-term effects of elastic chest wall restriction on pulmonary function in children with CF. Methods: Pulmonary function was first assessed twice 15 min apart at baseline and then again following 15 min of elastic chest wall restriction in 20 school-aged children with CF (12.3 ± 3.4 years). Primary outcomes were LCI from nitrogen multiple-breath washout, residual volume (RV), and FRC from plethysmography. Secondary outcomes were FVC and end-expiratory lung impedance (EELI) from electrical impedance tomography. Endpoints were test-retest reliability at baseline and lung function response to restriction, both on group and individual levels. Results: Test-retest reliability was excellent (intra-class correlation coefficients range 0.84–0.99). Following restriction, FRC significantly declined on average (95% CI) by –0.09 (–0.17 to –0.02) L. Similarly, FVC declined while LCI did not change. RV and EELI declined, but this did not reach statistical significance. On the individuals’ level, heterogeneous changes in pulmonary function occurred following elastic chest wall restriction. Conclusions: These findings indicate that the application of elastic chest wall restriction is safe, induces the intended decline in resting lung volume but does not systematically alter ventilation inhomogeneity in children with CF.

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Novel magnetic resonance technique for functional imaging of cystic fibrosis lung disease

Cited by 66 publications

References 39 publications

Within‐breath changes in respiratory system impedance in children with cystic fibrosis

Within‐breath changes in respiratory system impedance in children with cystic fibrosis

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

Short-Term Effects of Elastic Chest Wall Restriction on Pulmonary Function in Children with Cystic Fibrosis

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