Type Scientific Poster Presentation Topic Pediatric RadiologyPurpose Cystic fibrosis (CF) is characterized by chronic respiratory infections and functional impairment of the lung. Lung function tests such as nitrogen multiple breath washout (N2-MBW), are sensitive in detecting ventilation inhomogeneity, but cannot determine its exact origin. Novel magnetic resonance imaging (MRI) methods such as matrix pencil decomposition MRI can visualize functional changes in the lung without the administration of contrast agents and the need for breathing maneuvers.Objectives: To examine the correlation between novel functional MRI and lung function tests in patients with CF. Methods and MaterialsMethods: Forty patients with CF (mean age 11.7 years, range 6-18) underwent MRI and lung function tests on the same day. Functional MRI provided semiquantitative measures of the perfusion (RQ) and ventilation (RFV) impairment as percentages of the affected lung volume. Morphological MRI was evaluated using a CF-specific score. N2-MBW provided information about global (lung clearance index, LCI) ventilation inhomogeneity. ResultsResults: MRI detected functional impairment in all patients with CF: RFV ranged from 19% to 38% and RQ ranged from 16% to 35%. RFV and RQ were strongly correlated with LCI (r=0.76, p<0.001; r=0.85, p<0.001, respectively), as well as total morphology scores and sub-scores. ConclusionConclusions: Non-invasive functional MRI is a promising method to detect and visualize perfusion and ventilation impairment in CF without the need of contrast agents or breath holding maneuvers. AffirmationsAuthors agreement: I confirm that all authors indicated within the author block of this abstract have been informed about this abstract submission and agreed to the same. (I confirm) Mandatory presenter registration: I understand that if the presenting author has not paid his registration fee by April 24, 2017, he will not be permitted to display the poster or hold the presentation and the abstract will not be published. (I agree)Copyright: I affirm that if my poster contains any material that has been previously published, I was entitled to use this material by applicable law or have obtained a transferable license from the copyright holder. (I confirm) Seite

Bronchiolitis obliterans (BO) is a rare, chronic form of obstructive lung disease, often initiated with injury of the bronchiolar epithelium followed by an inflammatory response and progressive fibrosis of small airways resulting in nonuniform luminal obliteration or narrowing. The term BO comprises a group of diseases with different underlying etiologies, courses, and characteristics. Among the better recognized inciting stimuli leading to BO are airway pathogens such as adenovirus and mycoplasma, which, in a small percentage of infected children, will result in progressive fixed airflow obstruction, an entity referred to as postinfectious bronchiolitis obliterans (PIBO). The present knowledge on BO in general is reasonably well developed, in part because of the relatively high incidence in patients who have undergone lung transplantation or bone marrow transplant recipients who have had graft-versus-host disease in the posttransplant period. The cellular and molecular pathways involved in PIBO, while assumed to be similar, have not been adequately elucidated. Since 2016, an international consortium of experts with an interest in PIBO assembles on a regular basis in Geisenheim, Germany, to discuss key areas in PIBO which include diagnostic workup, treatment strategies, and research fields.

Background: Chronic lung diseases such as cystic fibrosis (CF) can be monitored by imaging and lung function modalities. Magnetic resonance imaging (MRI) techniques such as matrix pencil (MP) decomposition allows for evaluation of regional impairment of fractional ventilation (R FV ) and relative perfusion (R Q ). However, reproducibility of MP MRI outcomes in children with CF is unknown. We examined short-term variability of ventilation and perfusion impairment from MP MRI and compared this to lung function outcomes. Method: Twenty-threeCF and 12 healthy school-aged children underwent MRI and lung function tests on the same day on two occasions 24 h apart. Global ventilation inhomogeneity was assessed by the lung clearance index (LCI) from nitrogen-multiple breath washout (N 2 -MBW) technique. Intra-class-coefficient (ICC), percentage change, and Bland-Altman limits of agreement were evaluated to assess reproducibility. Results: Sixty-nine measurements from MP MRI and N 2 -MBW were performed. The ICC between two visits for R FV , R Q and LCI ranged between 0.60 and 0.90 in individuals with CF and healthy controls. In individuals with CF, percentage of change between the visits was 0.02% for R FV , −1.11% for R Q and 2.91% for LCI and limits of agreement between visits were − 4.3% and 3.9% for R FV , −4.4% and 3.7% for R Q , and −2.6 and 3.0 for LCI. Conclusions: Functional imaging is reproducible and short-term changes in R FV and R Q greater than ±4.4% can be considered clinical meaningful. Very good short-term reproducibility, and easy application without the need for breathing maneuvers or contrast agent, makes MP MRI a promising surveillance method for CF.

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Rationale: Primary ciliary dyskinesia (PCD) is an inherited disorder characterized by heterogeneous airway disease. Traditional lung function techniques (e.g. spirometry) may underestimate severity and complexity of PCD. Objectives: We assessed lung impairment in individuals with PCD using structural and functional magnetic resonance imaging (MRI) and different lung function techniques. Methods: Thirty study participants with PCD (median 13.4 years, range 5-28) underwent structural and functional MRI, spirometry, and multiple breath washout (MBW) on the same day. Primary endpoints included structural MRI morphology scores, relative ventilation and perfusion impairment from functional MRI, FEV 1 from spirometry, and lung clearance index (LCI) from MBW. Results: Severity and complexity of PCD lung disease varied significantly between individuals. Structural lung disease was detected in all subjects with a median (IQR) extent score of 10.3 (7 to 19; maximum score = 60). Functional MRI ventilation impairment was present in 52% of subjects affecting 24.2% (21.1 to 25.2%) of the lung. Relative perfusion impairment was detected in 78% of individuals affecting 21.1% (19.4 to 25.9%) of the lung. LCI was abnormal in 83% (median 8.3 (2.6 to 13.2) z-scores) and FEV 1 was abnormal in 27% (-0.5 (-1.6 to 0.3) zscores) of individuals. Concordance between spirometry and imaging outcomes was poor, with 52% of patients showing both abnormal MRI and LCI values, but normal FEV 1. Conclusions: Discordance between lung function and imaging outcomes in patients with PCD supports the use of both imaging and lung function, such as MBW, for surveillance of this heterogeneous disease.

The multiple-breath washout (MBW) is a lung function test that measures the degree of ventilation inhomogeneity (VI). The test is used to identify small airway impairment in patients with lung diseases like cystic fibrosis. However, the physical and physiological factors that influence the test outcomes and differentiate health from disease are not well understood. Computational models have been used to better understand the interaction between anatomical structure and physiological properties of the lung, but none of them has dealt in depth with the tracer gas washout test in a whole. Thus, our aim was to create a lung model that simulates the entire MBW and investigate the role of lung morphology and tissue mechanics on the tracer gas washout procedure. To this end, we developed a multi-scale lung model to simulate the inert gas transport in airways of all size. We then applied systematically different modifications to geometrical and mechanical properties of the lung model (compliance, residual airway volume and flow resistance) which have been associated with VI. The modifications were applied to distinct parts of the model, and their effects on the gas distribution within the lung and on the gas concentration profile were assessed. We found that variability in compliance and residual volume of the airways, as well as the spatial distribution of this variability in the lung had a direct influence on gas distribution among airways and on the MBW pattern (washout duration, characteristic concentration profile during each expiration), while the effects of variable flow resistance were negligible. Based on these findings, it is possible to classify different types of inhomogeneities in the lung and relate them to specific features of the MBW pattern, which builds the basis for a more detailed association of lung function and structure.

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