Regional Fractional Ventilation by Using Multibreath Wash-in <sup>3</sup>He MR Imaging

Hamedani, Hooman; Clapp, Justin T.; Kadlecek, Stephen; Emami, Kiarash; Ishii, Masaru; Gefter, Warren B.; Yi, Xin; Cereda, Maurizio; Shaghaghi, Hoora; Siddiqui, S.; Rossman, Milton D.; Rizi, Rahim R.

doi:10.1148/radiol.2017174027

Cited by 15 publications

(37 citation statements)

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“…Such methods were recently used by Horn with 3 He MRI to estimate fractional ventilation distributions in 4 healthy subjects and reported r= 0.25±0.11 (41). Similarly, Hamedani recently reported r =0.24±0.06 for 3 He MRI (42). A closely related measure is specific ventilation (SV), which was measured by Sa, using oxygen-enhanced proton MRI in 8 healthy individuals to have a mean of 0.24–0.42 and an SD of 0.08–0.14 (43).…”

Section: Discussionmentioning

confidence: 54%

Using Hyperpolarized 129Xe MRI to Quantify the Pulmonary Ventilation Distribution

Driehuys

Que

et al. 2016

Academic Radiology

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Background-Ventilation heterogeneity is impossible to detect with spirometry. Alternatively, pulmonary ventilation can be imaged 3-dimensionally using inhaled 129 Xe MRI. To date such images have been quantified primarily based on ventilation defects. Here, we introduce a robust means to transform 129 Xe MRI scans such that the underlying ventilation distribution and its heterogeneity can be quantified.

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Section: Discussionmentioning

confidence: 54%

Using Hyperpolarized 129Xe MRI to Quantify the Pulmonary Ventilation Distribution

Driehuys

Que

et al. 2016

Academic Radiology

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“…Figure shows a schematic of the device and pictures of the prototype successfully tested with HP 3 He MRI. Details of the design have been described by Hamedani et al and Emami et al ; the general concept is to use MRI‐compatible differential pressure pneumotachometers that independently report the flow rate of each gas component, triggering the pneumatic valves and the MRI scanner when the target volume is reached. The subject then commits a voluntary breath‐hold during which images are acquired, exhales freely, and the sequence is repeated as desired.…”

Section: Methodsmentioning

confidence: 99%

“…) was acquired in a voxel‐wise manner. Available magnetization after each inhalation,

{normalM}_{normalA} (normalj)

, is a combination of magnetization in the fresh HP gas reaching the lung (with source magnetization M S ) and magnetization left from the last breath . This can be written as

{normalM}_{normalA} (normalj) = FV . {normalM}_{normalS} + (1 - FV) . {normalM}_{normalA} (j - 1) . \exp ({normalD}_{normalA}), M_{normalA} (0) = 0,

where FV represents fractional ventilation and is related to specific ventilation as SV = FV/(1 − FV) and D A accounts for all localized relaxation mechanisms, including oxygen‐induced relaxation, RF depolarization, and less significant factors such as magnetization decay due to collisions with alveolar surfaces .…”

Section: Methodsmentioning

confidence: 99%

“…While the analysis is performed using a simultaneous fit of all signal intensities from each voxel, imaging conditions were chosen to best separate the effects of RF depolarization (images 7 and 8), P A O 2 (images 9 and 10), and ADC (images 10 and 11). Regional SV, ADC, and P A O 2 were then derived by fitting each voxel's time series to the coupled equations describing magnetization ( M A ) and alveolar oxygen ( P A O 2 ) evolution as

M_{A} (t_{i}) = [\frac{1}{1 + SV} \times M_{A} (t_{i - 1}) \times \cos {(α)}^{nPE} + \frac{SV}{1 + SV} \times M_{S}] \times \exp [- \frac{\overset{true¯}{P_{A} {normalO}_{2} (t_{i - 1}, t_{i})} \times (t_{i} - t_{i - 1})}{ξ}], [3]

P_{A} {normalO}_{2} (t_{i}) = \frac{1}{1 + SV} \times P_{A} {normalO}_{2} (t_{i - 1}) + \frac{SV}{1 + SV} \times F_{I} {normalO}_{2} - R \times (t_{i} - t_{i - 1}),

ADC = \frac{1}{{normalb}_{0}} \times l o g \frac{S_{0}}{S_{1}},

where SV, initial P A O 2 , flip angle α, HP gas magnetization M S , and R are allowed to vary in the fit . The O 2 relaxivity was ξ = 1.95 × 10 3 Torr/s , and the number of phase encodes was nPE = 48.…”

Section: Methodsmentioning

confidence: 99%

“…The

\overset{true¯}{P_{A} {normalO}_{2}}

value used in the exponent of Equation refers to the P A O 2 midway through acquisition of oxygen‐encoding images during the 12‐s breath‐hold (between

t_{i - 1}

and

t_{i}

) as described previously . The SV in Equation and the R and

P_{A} {normalO}_{2} (t_{i})

in Equation are updated iteratively until the change in the average regional values ( P A O 2 , SV, and R ) in consecutive iterations is less than 0.1%.…”

Section: Methodsmentioning

confidence: 99%

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A hybrid multibreath wash-in wash-out lung function quantification scheme in human subjects using hyperpolarized³He MRI for simultaneous assessment of specific ventilation, alveolar oxygen tension, oxygen uptake, and air trapping

et al. 2016

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Purpose To present a method for simultaneous acquisition of alveolar oxygen tension (PAO2), specific ventilation (SV), and apparent diffusion coefficient (ADC) of hyperpolarized (HP) gas in the human lung, allowing reinterpretation of the PAO2 and SV maps to produce a map of oxygen uptake (R). Method An imaging scheme was designed with a series of identical normoxic HP gas wash-in breaths to measure ADC, SV, PAO2 and R in less than 2 minutes. Signal dynamics was fit to an iterative recursive model that regionally solves for these parameters. This measurement was successfully performed in twelve subjects classified in three healthy, smoker and COPD cohorts. Results The overall whole-lung ADC, SV, PAO2 and R were (0.20 ± 0.03cm2/s, 0.39 ± 0.06,113 ± 2Torr and 1.55 ± 0.35Torr/s) and (0.21 ± 0.03 cm2/s, 0.33 ± 0.06, 115.9 ± 4 Torr and 0.97 ± 0.2 Torr/s) and (0.25 ± 0.06cm2/s, 0.23 ± 0.08, 114.8 ± 6.0Torr and 0.94 ± 0.12Torr/s) in healthy, smoker and COPD subjects, respectively. Maps of SV, PAO2 or R are indicators of both smoking-related changes and disease, and the severity of the disease correlated to the degree of this heterogeneity. Subjects with symptoms showed reduced oxygen uptake and specific ventilation. Conclusion High-resolution, nearly coregistered and quantitative measures of lung function and structure were obtained with less than 1 liter of HP. This promising hybrid multi-breath technique produced measures of lung function which revealed clear differences among the cohorts and subjects, and which were confirmed by correlations with global lung measurements.

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¹⁹F MRI of the Lungs Using Inert Fluorinated Gases: Challenges and New Developments

Couch

Ball²,

et al. 2018

Magnetic Resonance Imaging

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Fluorine‐19 (19F) MRI using inhaled inert fluorinated gases is an emerging technique that can provide functional images of the lungs. Inert fluorinated gases are nontoxic, abundant, relatively inexpensive, and the technique can be performed on any MRI scanner with broadband multinuclear imaging capabilities. Pulmonary 19F MRI has been performed in animals, healthy human volunteers, and in patients with lung disease. In this review, the technical requirements of 19F MRI are discussed, along with various imaging approaches used to optimize the image quality. Lung imaging is typically performed in humans using a gas mixture containing 79% perfluoropropane (PFP) or sulphur hexafluoride (SF6) and 21% oxygen. In lung diseases, such as asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF), ventilation defects are apparent in regions that the inhaled gas cannot access. 19F lung images are typically acquired in a single breath‐hold, or in a time‐resolved, multiple breath fashion. The former provides measurements of the ventilation defect percent (VDP), while the latter provides measurements of gas replacement (ie, fractional ventilation). Finally, preliminary comparisons with other functional lung imaging techniques are discussed, such as Fourier decomposition MRI and hyperpolarized gas MRI. Overall, functional 19F lung MRI is expected to complement existing proton‐based structural imaging techniques, and the combination of structural and functional lung MRI will provide useful outcome measures in the future management of pulmonary diseases in the clinic. Level of Evidence: 3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:343–354.

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Regional Fractional Ventilation by Using Multibreath Wash-in ³He MR Imaging

Abstract: Equation E4in Appendix E1 (online) should have appeared as follows:

Cited by 15 publications

References 0 publications

Using Hyperpolarized 129Xe MRI to Quantify the Pulmonary Ventilation Distribution

Using Hyperpolarized 129Xe MRI to Quantify the Pulmonary Ventilation Distribution

A hybrid multibreath wash-in wash-out lung function quantification scheme in human subjects using hyperpolarized³He MRI for simultaneous assessment of specific ventilation, alveolar oxygen tension, oxygen uptake, and air trapping

¹⁹F MRI of the Lungs Using Inert Fluorinated Gases: Challenges and New Developments

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Regional Fractional Ventilation by Using Multibreath Wash-in 3He MR Imaging

Abstract: Equation E4in Appendix E1 (online) should have appeared as follows:

Cited by 15 publications

References 0 publications

Using Hyperpolarized 129Xe MRI to Quantify the Pulmonary Ventilation Distribution

Using Hyperpolarized 129Xe MRI to Quantify the Pulmonary Ventilation Distribution

A hybrid multibreath wash-in wash-out lung function quantification scheme in human subjects using hyperpolarized3He MRI for simultaneous assessment of specific ventilation, alveolar oxygen tension, oxygen uptake, and air trapping

19F MRI of the Lungs Using Inert Fluorinated Gases: Challenges and New Developments

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Regional Fractional Ventilation by Using Multibreath Wash-in ³He MR Imaging

A hybrid multibreath wash-in wash-out lung function quantification scheme in human subjects using hyperpolarized³He MRI for simultaneous assessment of specific ventilation, alveolar oxygen tension, oxygen uptake, and air trapping

¹⁹F MRI of the Lungs Using Inert Fluorinated Gases: Challenges and New Developments