Functional respiratory imaging : opening the black box

In respiratory medicine, several quantitative measurement tools exist that assist the clinicians in their diagnosis. The main issue with these traditional techniques is that they lack sensitivity to detect changes and that the variation between different measurements is very high. The result is that the development of respiratory drugs is the most expensive of all drug development. This limits innovation, resulting in an unmet need for sensitive quantifiable outcome parameters in pharmacological development and clinical respiratory practice. In this thesis, functional respiratory imaging (FRI) is proposed as a tool to tackle these issues. FRI is a workflow where patient specific medical images are combined with computational fluid dynamics in order to give patient specific local information of anatomy and functionality in the respiratory system. A robust high throughput automation system is designed in order get a workflow that is of a high quality, consistent and fast. This makes it possible to apply this technology on large datasets as typically seen in clinical trials. FRI is performed on 486 unique geometries of patients with various pathologies such as asthma, chronic obstructive lung disease, sleep apnea and cystic fibrosis. This thesis shows that FRI can have an added value in multiple research domains. The high sensitivity and specificity of FRI make it very well suited as a tool to make decisions early in the development process of a device or drug. Furthermore, FRI also seems to be an interesting technology to gain better insight in rare diseases and can possibly be useful in personalized medicine

Experimental study of the flow field in patient specific lower airways

In this study Particle Image Velocimetry (PIV) is used to visualize and measure airflow in the lower airways. Using Rapid Prototyping Manufacturing (RPM) technology, a hydraulic in vitro model was developed and constructed. Preliminary 2D PIV measurements compared successfully to Computational Fluid Dynamics (CFD) results

Functional imaging on patient-specific lower airways using Computational Fluid Dynamics

Adding functional information to anatomical CT-data by means of Computational Fluid Dynamics (CFD) is a non-invasive method for analyzing patient-specific respiratory dynamics. As CFD is based on numerical models, validation is required to obtain reliable results. For this purpose, 2D PIV measurements are performed and compared to the CFD data

Effect of high-dose N-acetylcysteine on airway geometry, inflammation, and oxidative stress in COPD patients

Background: Previous studies have demonstrated the potential beneficial effect of N-acetylcysteine (NAC) in chronic obstructive pulmonary disease (COPD). However, the required dose and responder phenotype remain unclear. The current study investigated the effect of high-dose NAC on airway geometry, inflammation, and oxidative stress in COPD patients. Novel functional respiratory imaging methods combining multislice computed tomography images and computer-based flow simulations were used with high sensitivity for detecting changes induced by the therapy. Methods: Twelve patients with Global Initiative for Chronic Obstructive Lung Disease stage II COPD were randomized to receive NAC 1800 mg or placebo daily for 3 months and were then crossed over to the alternative treatment for a further 3 months. Results: Significant correlations were found between image-based resistance values and glutathione levels after treatment with NAC (P = 0.011) and glutathione peroxidase at baseline (P = 0.036). Image-based resistance values appeared to be a good predictor for glutathione peroxidase levels after NAC (P = 0.02), changes in glutathione peroxidase levels (P = 0.035), and reduction in lobar functional residual capacity levels (P = 0.00084). In the limited set of responders to NAC therapy, the changes in airway resistance were in the same order as changes induced by budesonide/formoterol. Conclusion: A combination of glutathione, glutathione peroxidase, and imaging parameters could potentially be used to phenotype COPD patients who would benefit from addition of NAC to their current therapy. The findings of this small pilot study need to be confirmed in a larger pivotal trial

Functional respiratory imaging assessment of budesonide/glycopyrrolate/formoterol fumarate and glycopyrrolate/formoterol fumarate metered dose inhalers in patients with COPD:the value of inhaled corticosteroids

BACKGROUND: For patients with chronic obstructive pulmonary disease (COPD), greater improvements in lung function have been demonstrated for triple versus dual inhaled therapies in traditional spirometry studies. This study was the first to use functional respiratory imaging (FRI), known for increased sensitivity to airway changes versus spirometry, to assess the effect of the inhaled corticosteroid (ICS) component (budesonide) on lung function in patients with moderate-to-severe COPD and a blood eosinophil count > 150 cells/mm(3). METHODS: Patients in this Phase IIIb (NCT03836677), randomized, double-blind, crossover study received twice-daily budesonide/glycopyrrolate/formoterol fumarate (BGF) 320/18/9.6 μg fixed-dose triple therapy and glycopyrrolate/formoterol fumarate (GFF) 18/9.6 μg fixed-dose dual therapy over 4 weeks, each delivered via a single metered dose Aerosphere inhaler. Primary endpoints were the improvements from baseline for each treatment in specific (i.e. corrected for lobar volume) image-based airway volume (siVaw) and resistance (siRaw) measured via FRI taken at total lung capacity (Day 29). Secondary outcomes included spirometry and body plethysmography. Adverse events were monitored throughout the study. RESULTS: A total of 23 patients were randomized and included in the intent-to-treat analysis (mean age 64.9 years, 78.3% males, 43.5% current smokers, mean predicted post-bronchodilator forced expiratory volume in 1 s [FEV(1)] 63.6%). BGF and GFF both statistically significantly increased siVaw from baseline at Day 29 (geometric mean ratio [GM], 95% confidence interval [CI]: 1.72 [1.38, 2.13] and 1.53 [1.28, 1.83], respectively, both p < 0.0001), with a greater increase observed for BGF versus GFF (GM, 95% CI 1.09 [1.03, 1.16], p = 0.0061). Statistically significant reductions in siRaw were also observed with both BGF and GFF (GM, 95% CI 0.50 [0.39, 0.63] and 0.52 [0.40, 0.67], respectively, both p < 0.0001). Additionally, significant improvements from baseline in post-dose FEV(1) were observed with BGF and GFF (mean 346 mL, p = 0.0003 and 273 mL, p = 0.0004, respectively). Safety findings were consistent with the known profiles of BGF and GFF. CONCLUSIONS: As observed using FRI, triple therapy with BGF resulted in greater increases in airway volume, and reductions in airway resistance versus long-acting muscarinic antagonist/long-acting β(2)-agonist (LAMA/LABA) dual therapy with GFF, reflecting the ICS component’s contribution in patients with moderate-to-severe COPD. Trial registration: ClinicalTrials.gov, NCT03836677. Registered 11 February 2019, https://clinicaltrials.gov/ct2/show/NCT03836677 SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12931-021-01772-2

The effects of extrafine beclometasone/formoterol (BDP/F) on lung function, dyspnea, hyperinflation, and airway geometry in COPD patients: novel insight using functional respiratory imaging

Background: The efficacy of inhaled corticosteroids (ICS) in moderately severe COPD patients remains unclear. At the same time, the use of extrafine particles in COPD patients is a topic of ongoing research. Objectives: This study assessed the effect of ICS in steroid-naive mild COPD patients and the effect of reducing the ICS dose in more severe COPD patients previously using ICS when switching to an extrafine particle BDP/F formulation (Foster using Modulite technology, Chiesi Pharmaceutici, Parma, Italy). Methods: Novel functional respiratory imaging (FRI) methods, consisting of multi-slice CT scans and Computational Fluid Dynamics, were used in combination with conventional pulmonary function tests and patient reported outcomes. Results: The study showed that the administration of extrafine BDP/F after 4-6 h led to a significant improvement in lung function parameters and hyperinflation as determined by spirometry, body plethysmography, and functional respiratory imaging. After 6 months of treatment, it was observed that, compared to baseline, the hyperinflation on lobar level at total lung capacity was significantly reduced (-1.19 +/- 7.19 %p, p=0.009). In addition, a significant improvement in SGRQ symptom score was noted in the entire patient population. Patients who improved in terms of hyperinflation also improved their MMRC dyspnea score. CFD indicated a difference in regional deposition between extrafine and non-extrafine formulations with -11% extrathoracic deposition and up to +4% lobe deposition for the extrafine formulation. Conclusions: The study showed that the administration of extrafine BDP/F improved lung function parameters and hyperinflation. Patients previously treated with ICS remained stable despite the lower dose, while ICS naive patients improved in terms of lobar hyperinflation. FRI seems to be a sensitive biomarker to detect clinically relevant changes that are not detected by spirometry. The next step is to confirm these findings in a controlled trial

Sediment Hydraulical Studies on the Control of Sediments. XI : Application of Vortex Tube Sand Trap to Storage Dams

The hydraulic problems of vortex tube sand trap with a jet flow gate and with a double-opened slit inlet are examined for its application to a storage dam. The behaviour of spiral flow in a vortex flow tube, inlet velocity to slit, and the efficiency of a linear sand trap in a modelled dam reservoir are tested more than 300 times using vortex flow tube with double-cylinder slit inlet. The grading at sediment terrace in a modelled reservoir is also examined after flushing sand