Direct visualisation of collateral ventilation in COPD with hyperpolarised gas MRI

Marshall, Helen; Deppe, Martin H.; Parra‐Robles, Juan; Hillis, Susan D.; Billings, Catherine; Rajaram, Smitha; Swift, Andrew J.; Miller, Sam; Watson, Joanna H; Wolber, Jan; Lipson, David A.; Lawson, Rod; Wild, Jim M.

doi:10.1136/thoraxjnl-2011-200864

Cited by 78 publications

(67 citation statements)

References 21 publications

(17 reference statements)

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“…We believe that lung pO 2 mapping with 3 He T 1 measurement is unreliable in patients with moderate to severe COPD in regions of lung showing delayed ventilation (19) or unrestricted diffusion (bullous emphysema), where inter-pixel gas movement within the lungs is significant on the time-scale of the experiment. Accurate separation and quantification of the effects of gas movement and oxygen concentration on the signal is highly challenging because the regional oxygen concentrations experienced by the gas are dependent on its pathway of movement through the lungs.…”

Section: Discussionmentioning

confidence: 99%

“…The mean negative pO 2 value was compared with the time to signal onset parameter used in (19) to assess the influence of the temporal aspect of delayed ventilation. The effect of breath-hold time on the measured pO 2 values was assessed by generating pO 2 maps using all 6 time points (21 second acquisition) and comparing them to those made using only the first 4 time points (12 second acquisition).…”

Section: Methodsmentioning

confidence: 99%

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³He pO₂ mapping is limited by delayed‐ventilation and diffusion in chronic obstructive pulmonary disease

Marshall

Parra‐Robles

Deppe

et al. 2013

Magnetic Resonance in Med

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Purpose: Lung pO 2 mapping with 3 He MRI assumes that the sources of signal decay with time during a breath-hold are radiofrequency depolarization and oxygen-dependent T 1 relaxation, but the method is sensitive to other sources of spatiotemporal signal change such as diffusion. The purpose of this work was to assess the use of 3 He pO 2 mapping in patients with chronic obstructive pulmonary disease. Methods: Ten patients with moderate to severe chronic obstructive pulmonary disease were scanned with a 3D single breath-hold pO 2 mapping sequence. Results: Images showed signal increasing over time in some lung regions due to delayed ventilation during breath-hold. Regions of physically unrealistic negative pO 2 values were seen in all patients, and regional mean pO 2 values of À0.3 bar were measured in the two patients most affected by delayed ventilation (where mean time to signal onset was 3-4 s). Conclusions: Movement of gas within the lungs during breath-hold causes regional changes in signal over time that are not related to oxygen concentration, leading to erroneous pO 2 measurements using the linear oxygen-dependent signal decay model. These spatio-temporal sources of signal change cannot be reliably separated at present, making pO 2 mapping using this methodology unreliable in chronic obstructive pulmonary disease patients with significant bullous emphysema or delayed ventilation. Magn Reson Med 71:1172-1178, 2014. V C 2013 Wiley Periodicals, Inc.Key words: hyperpolarized 3 He; partial pressure of oxygen; chronic obstructive pulmonary disease; delayed-ventilation; diffusionThe partial pressure of oxygen (pO 2 ) in the lung airspaces depends on ventilation and perfusion matching and is a regional indicator of gas exchange. Hyperpolarized 3 He MRI pO 2 mapping has been shown to provide quantitative, regional measures of pO 2 in healthy volunteers (HVs) (1-4), which are physiologically plausible. The method assumes that all signal depletion during a breath-hold is due to radiofrequency (RF) depolarization and oxygen-dependent T 1 effects (5) and these effects can be separated to calculate the regional pO 2 using typically a linear (1), or exponential (6), oxygen-dependent signal decay model.The method is, however, also sensitive to other sources of temporal signal change during the breath-hold acquisition time. pO 2 mapping methods by definition require time resolved images to be separated by a delay time Dt, which is of the same order of magnitude as the 3 He T 1 in air % 20 s (1,5). Hence, inter-frame delays of 2-5 s are typically used to measure the pO 2 with 3 He. On this time scale, inter-slice diffusion of gas with different polarization has been shown to be a source of significant error in slice selective 2D pO 2 acquisitions leading to an underestimation of pO 2 values (4). This can be mitigated by using a 3D sequence (4) where the whole lung experiences the same RF history. Nevertheless, inter-pixel diffusion is still a source of error in 3D pO 2 mapping if the pixel size Dz, is such that, where D i...

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

³He pO₂ mapping is limited by delayed‐ventilation and diffusion in chronic obstructive pulmonary disease

Marshall

Parra‐Robles

Deppe

et al. 2013

Magnetic Resonance in Med

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“…[72][73][74][75] On MRI following inhalation of this gas, its diffusivity can be used to estimate measures of the size of lung microstructure including alveolar ducts and alveoli. In cigarette smokers with absent or mild spirometric abnormality, this technique showed significant decrease in alveolar depth and enlargement of alveolar ducts.…”

Section: Mrimentioning

confidence: 99%

Progress in Imaging COPD, 2004 - 2014

Lynch¹

2014

J COPD F

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Abbreviations: computed tomography, CT; magnetic resonance imaging, MRI; positron emission tomography, PET; Global Initiative for chronic Obstructive Lung Disease, GOLD; quantitative CT, QCT; Hounsfield Units, HU; percentage of low attenuation area, %LAA; relative area of lung less than -950 HU, RA950; Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints, ECLIPSE; forced expiratory volume in 1 second, FEV1; forced vital capacity, FVC. Journal of the COPD Foundation(GOLD) stage may have substantial, little, or no emphysema. Discrete subphenotypes of COPD include emphysema of varying morphologic appearance, large airway abnormality and small airway obstruction. Increasing awareness of the heterogeneity of COPD has led to increased use of CT to characterize COPD for purposes of genetic evaluation and identification of specific subgroups which may be amenable to therapeutic trials. 1-3 While visual assessment is important in determining the presence and character of emphysema, the last decade has been characterized by increasing use of quantitative imaging to provide precise estimates of the severity and distribution of emphysema, gas trapping and airway wall thickening. Several large cohorts of cigarette smokers have now been quite extensively characterized by CT, resulting in increased knowledge of the clinical correlates of quantitative CT parameters. [4][5][6] The purpose of this paper is to present the substantial contribution that imaging has made to our understanding of COPD over the past 10 years. AbstractComputed tomography (CT) has contributed substantially to our understanding of COPD over the past decade. Visual and quantitative assessments of CT in COPD are complementary. Visual assessment should provide assessment of centrilobular, panlobular and paraseptal emphysema, airway wall thickening, bronchiectasis, findings of respiratory bronchiolitis, and enlargement of the pulmonary artery. Quantitative CT permits evaluation of severity of emphysema, airway wall thickening, and expiratory air trapping, and is now being used for longitudinal evaluation of the progression of COPD. Innovative techniques are being developed to use CT to characterize the pattern of emphysema and smoking-related respiratory bronchiolitis. Magnetic resonance imaging (MRI) and positron emission tomography PET-CT are useful research tools in the evaluation of COPD.

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“…HORN et al [61] used hyperpolarised 3 He gas ventilation magnetic resonance imaging (MRI) to map bronchodilator treatment response in COPD. This concept is able to regionally resolve changes in lung ventilation in response to therapy in COPD [62]. Oxygen enhancement at MRI is an alternative modality to map bronchodilator treatment response.…”

Section: Morphological and Functional Imagingmentioning

confidence: 99%

Clinical highlights from the 2013 ERS Congress in Barcelona

Spruit¹,

Marvisi

Coolen³

et al. 2014

European Respiratory Journal

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This article reviews a selection of scientific presentations in the area of clinical problems, which were presented at the 2013 European Respiratory Society Annual Congress in Barcelona, Spain. This article discusses the most relevant topics of interest in the field of clinical respiratory medicine, including breakthrough reports and studies of particular interest to the healthcare professionals. Topics are presented and discussed in the context of the most up-to-date literature, including basic science and translational research. In particular, the reviewed topics deal with the areas of complex chronic obstructive pulmonary disease and asthma (even in the primary care setting), idiopathic pulmonary fibrosis (pathogenesis and therapy), advances in functional chest imaging, interventional pulmonology, pulmonary rehabilitation and chronic care.

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Direct visualisation of collateral ventilation in COPD with hyperpolarised gas MRI

Cited by 78 publications

References 21 publications

³He pO₂ mapping is limited by delayed‐ventilation and diffusion in chronic obstructive pulmonary disease

³He pO₂ mapping is limited by delayed‐ventilation and diffusion in chronic obstructive pulmonary disease

Progress in Imaging COPD, 2004 - 2014

Clinical highlights from the 2013 ERS Congress in Barcelona

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Direct visualisation of collateral ventilation in COPD with hyperpolarised gas MRI

Cited by 78 publications

References 21 publications

3He pO2 mapping is limited by delayed‐ventilation and diffusion in chronic obstructive pulmonary disease

3He pO2 mapping is limited by delayed‐ventilation and diffusion in chronic obstructive pulmonary disease

Progress in Imaging COPD, 2004 - 2014

Clinical highlights from the 2013 ERS Congress in Barcelona

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About

³He pO₂ mapping is limited by delayed‐ventilation and diffusion in chronic obstructive pulmonary disease

³He pO₂ mapping is limited by delayed‐ventilation and diffusion in chronic obstructive pulmonary disease