Dataset Information

Contrast-to-noise ratios and thickness-normalized, ventilation-dependent signal levels in dark-field and conventional in vivo thorax radiographs of two pigs.

ABSTRACT: Lung tissue causes significant small-angle X-ray scattering, which can be visualized with grating-based X-ray dark-field imaging. Structural lung diseases alter alveolar microstructure, which often causes a dark-field signal decrease. The imaging method provides benefits for diagnosis of such diseases in small-animal models, and was successfully used on porcine and human lungs in a fringe-scanning setup. Micro- and macroscopic changes occur in the lung during breathing, but their individual effects on the dark-field signal are unknown. However, this information is important for quantitative medical evaluation of dark-field thorax radiographs. To estimate the effect of these changes on the dark-field signal during a clinical examination, we acquired in vivo dark-field chest radiographs of two pigs at three ventilation pressures. Pigs were used due to the high degree of similarity between porcine and human lungs. To analyze lung expansion separately, we acquired CT scans of both pigs at comparable posture and ventilation pressures. Segmentation, masking, and forward-projection of the CT datasets yielded maps of lung thickness and logarithmic lung attenuation signal in registration with the dark-field radiographs. Upon correlating this data, we discovered approximately linear relationships between the logarithmic dark-field signal and both projected quantities for all scans. Increasing ventilation pressure strongly decreased dark-field extinction coefficients, whereas the ratio of lung dark-field and attenuation signal changed only slightly. Furthermore, we investigated ratios of dark-field and attenuation noise levels at realistic signal levels via calculations and phantom measurements. Dark-field contrast-to-noise ratio (CNR) per lung height was 5 to 10% of the same quantity in attenuation. We conclude that better CNR performance in the dark-field modality is typically due to greater anatomical noise in the conventional radiograph. Given the high physiological similarity of human and porcine lungs, the presented thickness-normalized, ventilation-dependent values allow estimation of dark-field activity of human lungs of variable size and inspiration, which facilitates the design of suitable clinical imaging setups.

SUBMITTER: De Marco F

PROVIDER: S-EPMC6546243 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Publications

Contrast-to-noise ratios and thickness-normalized, ventilation-dependent signal levels in dark-field and conventional in vivo thorax radiographs of two pigs.

De Marco Fabio F Willer Konstantin K Gromann Lukas B LB Andrejewski Jana J Hellbach Katharina K Bähr Andrea A Dmochewitz Michaela M Koehler Thomas T Maack Hanns-Ingo HI Pfeiffer Franz F Herzen Julia J

PloS one 20190603 6

Lung tissue causes significant small-angle X-ray scattering, which can be visualized with grating-based X-ray dark-field imaging. Structural lung diseases alter alveolar microstructure, which often causes a dark-field signal decrease. The imaging method provides benefits for diagnosis of such diseases in small-animal models, and was successfully used on porcine and human lungs in a fringe-scanning setup. Micro- and macroscopic changes occur in the lung during breathing, but their individual effe ...[more]

PMID: 31158251

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Project description:ImportanceGuidelines from December 2011 recommended against obtaining daily chest radiographs (CXRs) for patients requiring mechanical ventilation (MV). Daily CXR use for patients receiving MV in US hospitals is unknown and, if high, may represent an opportunity to reduce low-value care and unnecessary radiation.ObjectivesTo determine frequency of daily CXR use for US patients receiving MV, assess variability across hospitals, and evaluate whether use has decreased over time.Design, setting, and participantsRetrospective cohort study of hospitalized adults (aged ≥18 years) receiving MV for 3 days or longer. Mechanical ventilation was defined by having an International Classification of Diseases, Ninth Revision, Clinical Modification code of 96.7x and an MV charge on more than 1 hospital day. Hospital discharges in the Premier Perspectives database were examined from July 1, 2008, to December 31, 2014. Data analysis was conducted from July 28, 2017, to December 13, 2017.ExposuresHospital discharge date (quarter of the year) and hospital in which patients received MV.Main outcomes and measuresThe outcome was daily CXR use (up to 7 days) during MV. We used standard statistics to describe CXR use, multilevel multivariable regression modeling with adjusted median odds ratio (OR) to evaluate variability by hospital, and multivariable piecewise regression (breakpoint: fourth quarter of 2011) with adjusted OR to evaluate time trends and response to guideline recommendations.ResultsThe primary cohort included 512 518 patients receiving MV (mean [SD] age, 63.0 [16.1] years; 46% female) in 416 hospitals, of whom 321 093 (63%) received daily CXRs. Wide variability was seen across hospitals; hospitals performed daily CXRs on a median of 66% of patients (interquartile range, 50%-77%; full range, 12%-97%). The adjusted median OR was 2.43 (95% CI, 2.29-2.59), suggesting the same patient had 2.43-fold higher odds of receiving a daily CXR if admitted to a higher- vs lower-use hospital; the odds of receiving daily CXRs were unchanged through quarter 3 of 2011 (adjusted OR, 1.00; 95% CI, 0.99-1.01), after which there was a 3% relative reduction in the odds of daily CXR use per quarter (adjusted OR, 0.97; 95% CI, 0.96-0.98).Conclusions and relevanceThree-fifths of US patients receiving MV also received daily CXRs from 2008 to 2014, although use declined slowly after new guidelines were published. The hospital at which a patient received care was associated with the odds of daily CXR receipt.

Dataset Information

Contrast-to-noise ratios and thickness-normalized, ventilation-dependent signal levels in dark-field and conventional in vivo thorax radiographs of two pigs.

Publications

Contrast-to-noise ratios and thickness-normalized, ventilation-dependent signal levels in dark-field and conventional in vivo thorax radiographs of two pigs.

Similar Datasets

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