Evaluation of Fractional Regional Ventilation Using 4D-CT and Effects of Breathing Maneuvers on Ventilation

Mistry, N; Diwanji, Tejan; Shi, Xiaoyang; Pokharel, S; Feigenberg, Steven J.; Scharf, Steven M.; D’Souza, W

doi:10.1016/j.ijrobp.2013.07.032

Cited by 18 publications

(18 citation statements)

References 17 publications

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“…There are various definitions of ventilation depending on the reference volume V Ref :

ventilation = \frac{V_{Insp} - V_{Exp}}{V_{Ref}} .

The volume ( V ) in Equation may be substituted with mass ( m ) and density ( ρ ) which results in

ventilation = \frac{\frac{m_{Insp}}{ρ_{Insp}} - \frac{m_{Exp}}{ρ_{Exp}}}{\frac{m_{Ref}}{ρ_{Ref}}} .

Assuming tissue mass to be constant during respiration, ventilation reduces to

ventilation = \frac{ρ_{Ref}}{ρ_{Insp}} - \frac{ρ_{Ref}}{ρ_{Exp}} .

Assuming that every voxel contains air and tissue (ie water molecules), the lung density ρ = S Lung / S Pha may be estimated from the ratio of the MR signal in the lung S Lung and the signal of a dedicated phantom S Pha , which represents a purely water filled voxel …”

Section: Theorymentioning

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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“…There are various definitions of ventilation depending on the reference volume V Ref :

ventilation = \frac{V_{Insp} - V_{Exp}}{V_{Ref}} .

The volume ( V ) in Equation may be substituted with mass ( m ) and density ( ρ ) which results in

ventilation = \frac{\frac{m_{Insp}}{ρ_{Insp}} - \frac{m_{Exp}}{ρ_{Exp}}}{\frac{m_{Ref}}{ρ_{Ref}}} .

Assuming tissue mass to be constant during respiration, ventilation reduces to

ventilation = \frac{ρ_{Ref}}{ρ_{Insp}} - \frac{ρ_{Ref}}{ρ_{Exp}} .

Section: Theorymentioning

confidence: 99%

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

et al. 2019

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“…19,21,22 Du et al relate this to spontaneous changes in breathing amplitude, frequency, and breathing mode (i.e., abdominal or thoracic) that occur during free-breathing that reduce the reproducibility of regional lung expansion estimates between repeat 4D-CT scans. 23 Patient breathing variability may be mitigated by normalization of repeat 4D-CT VIs based on principles of equivalent tidal volume 24 and by maintaining consistent breathing maneuvers, 25 for example, using audiovisual breathing guidance.…”

Section: Introductionmentioning

confidence: 99%

Measuring interfraction and intrafraction lung function changes during radiation therapy using four‐dimensional cone beam CT ventilation imaging

et al. 2015

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The authors' data support the hypothesis that interfraction ventilation changes are larger than intrafraction ventilation changes for LA-NSCLC patients over a course of conventional lung cancer radiation therapy. Longitudinal ventilation changes are observed to be highly patient-dependent, supporting a possible role for adaptive ventilation guidance based on repeat 4D-CBCT VIs. We anticipate that future improvement of 4D-CBCT image reconstruction algorithms will improve the capability of 4D-CBCT VI to resolve interfraction ventilation changes.

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“…Using the 4DCT image dataset, which includes CT images corresponding to ten phases that were equally spaced in time over the full respiratory cycle, a fractional regional ventilation (FRV) image was calculated via a density change-based algorithm with mass correction for each patient. 10 were segmented on the CT images at the inhale and exhale phases of respiration. The images at these two phases were matched to each other on a voxel-by-voxel basis using a "Demons" deformable image registration technique with a multiresolution scheme from ITK (http:// www.itk.org).…”

Section: B Fractional Regional Ventilationmentioning

confidence: 99%

“…7 However, these studies implicitly assume a spatially uniform function within the lung, despite the fact that this assumption may not be valid for patients with lung cancer. 8 Because lung function requires both perfusion and ventilation of alveoli, both single-photon emission computed tomography (SPECT) perfusion imaging and the more recent 4D computed tomography (4DCT)-based ventilation imaging 9,10 have been proposed to quantify functional variation within the lung and have been suggested as independent surrogates for lung function.…”

Section: Introductionmentioning

confidence: 99%

Should regional ventilation function be considered during radiation treatment planning to prevent radiation‐induced complications?

et al. 2016

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Evaluation of Fractional Regional Ventilation Using 4D-CT and Effects of Breathing Maneuvers on Ventilation

Cited by 18 publications

References 17 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

Measuring interfraction and intrafraction lung function changes during radiation therapy using four‐dimensional cone beam CT ventilation imaging

Should regional ventilation function be considered during radiation treatment planning to prevent radiation‐induced complications?

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