Facilitated Diagnosis of Pneumothoraces in Newborn Mice Using X-ray Dark-Field Radiography. Issue 10 (October 2016)

• Record Type: Journal Article
• Authors: Hellbach, Katharina; Yaroshenko, Andre; Willer, Konstantin; Pritzke, Tina; Baumann, Alena; Hesse, Nina; Auweter, Sigrid; Reiser, Maximilian F.; Eickelberg, Oliver; Pfeiffer, Franz; Hilgendorff, Anne; Meinel, Felix G.
• Is Part Of: Investigative radiology. Volume 51:Issue 10(2016:Oct.)
• Publication Date: 2016-10
• Subjects: neonatal lung injury -- mechanical ventilation -- pneumothorax -- disease diagnosis -- x-ray dark-field imaging -- grating-based x-ray imaging -- x-ray phase-contrast imaging; Diagnosis, Radioscopic -- Periodicals; Radiology, Medical -- Periodicals; 616.0757
• DOI: 10.1097/RLI.0000000000000285
• Languages: English
• ISSNs: 0020-9996

Abstract

Abstract : Objective: The aim of this study was to evaluate the diagnostic value of x-ray dark-field imaging in projection radiography-based depiction of pneumothoraces in the neonatal murine lung, a potentially life-threatening medical condition that requires a timely and correct diagnosis. Materials and Methods: By the use of a unique preclinical model, 7-day-old C57Bl/6N mice received mechanical ventilation for 2 or 8 hours with oxygen-rich gas (FIO2 = 0.4; n = 24). Unventilated mice either spontaneously breathed oxygen-rich gas (FIO2 = 0.4) for 2 or 8 hours or room air (n = 22). At the end of the experiment, lungs were inflated with a standardized volume of air after a lethal dose of pentobarbital was administered to the pups. All lungs were imaged with a prototype grating-based small-animal scanner to acquire x-ray transmission and dark-field radiographs. Image contrast between the air-filled pleural space and lung tissue was quantified for both transmission and dark-field radiograms. After the independent expert's assessment, 2 blinded readers evaluated all dark-field and transmission images for the presence or absence of pneumothoraces. Contrast ratios, diagnostic accuracy, as well as reader's confidence and interreader agreement were recorded for both imaging modalities. Results: Evaluation of both x-ray transmission and dark-field radiographs by independent experts revealed the development of a total of 10 pneumothoraces in 8 mice. Here, the contrast ratio between the air-filled pleural space of the pneumothoraces and the lung tissue was significantly higher in the dark field (8.4 ± 3.5) when compared with the transmission images (5.1 ± 2.8; P < 0.05). Accordingly, the readers' diagnostic confidence for the diagnosis of pneumothoraces was significantly higher for dark-field compared with transmission images ( P = 0.001). Interreader agreement improved from moderate for the analysis of transmission images alone (κ = 0.41) to very good when analyzing dark-field images alone (κ = 0.90) or in combination with transmission images (κ = 0.88). Diagnostic accuracy significantly improved for the analysis of dark-field images alone ( P = 0.04) or in combination with transmission images ( P = 0.02), compared with the analysis of transmission radiographs only. Conclusions: The significant improvement in contrast ratios between lung parenchyma and free air in the dark-field images allows the facilitated detection of pneumothoraces in the newborn mouse. These preclinical experiments indicate the potential of the technique for future clinical applications. Abstract : Supplemental digital content is available in the text.