RPS 504 - Imaging of diffuse lung diseases: old and new

Author Block: T. Schnitzler, J. H. Sohn; San Francisco, CA/US
Purpose: Interstitial lung abnormality (ILA) is often an incidental imaging finding, representing early or mild fibrosis. While most cases do not progress, some advance to idiopathic pulmonary fibrosis (IPF), leading to severe outcomes. Accurate risk stratification of ILA on non-contrast chest CT is crucial for guiding follow-up and early treatment. This study aims to improve stratification by identifying imaging and clinical features that predict progression from ILA to IPF.
Methods or Background: This retrospective case-control study included patients from a longitudinal ILD database: a low-risk ILA cohort (n = 525) and a high-risk ILA cohort (n = 221). Imaging features analyzed included subpleural fibrotic reticulation, cranial extent of fibrosis, anterior lung involvement, and emphysema severity. Clinical variables included age and gender. Statistical analyses were conducted using chi-square tests for categorical variables and independent t-tests for continuous variables.
Results or Findings: The high-risk ILA cohort had significantly higher rates of subpleural fibrotic changes (78% vs. 36%, p < 0.001), cranial extent of fibrosis (61% vs. 14%, p < 0.001), anterior lung involvement (86% vs. 37%, p < 0.001), and severe emphysema (48% vs. 39%, p < 0.001) compared to the low-risk cohort. The high-risk cohort was also older (mean age 72.64 years vs. 70.65 years, p = 0.020), with no significant gender difference.
Conclusion: This study identifies key imaging and clinical predictors of ILA progression to IPF, such as subpleural fibrotic changes, cranial extent of fibrosis, and older age. These findings could improve risk stratification, guiding timely monitoring and interventions to enhance patient outcomes. Future research should validate these findings in larger, multi-center cohorts.
Limitations: The main limitation is the retrospective single-center design.
Funding for this study: RSNA Research Fellow Grant 2024
Swiss Society for Radiology Research Grant 2023
Bangerter-Rhyner Foundation, Basel, Switzerland
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study is IRB approved (17-22317).

Author Block: L. Sun¹, M. A. Mestas Nuñez², J. Jacob¹, S. Piciucchi³, L. Calandriello⁴, A. Carvalho⁵, R. E. Ledda⁶, M. Chen¹, A. Devaraj¹; ¹London/UK, ²Barcelona/ES, ³Forlì/IT, ⁴Rome/IT, ⁵Porto/PT, ⁶Parma/IT
Purpose: To evaluate the performance and agreement of thoracic radiologists and interstitial lung disease (ILD) physicians in identifying progressive pulmonary fibrosis on serial CT scans in patients without idiopathic pulmonary fibrosis (IPF).
Methods or Background: 100 patients with various non-IPF fibrotic lung diseases (median age, 64 years [range, 36 to 85]; male, n=40) had serial CTs obtained 6 to 24 months apart, which were reviewed independently by 12 ILD physician and thoracic radiologist readers blinded to clinical data. CTs were reviewed side-by-side and categorised as one of two groups: Stable Disease or Progressive Fibrosis. Groups were compared using contemporary relative change in percentage predicted forced vital capacity (FVC), per reader and across the cohort, and analysed by Mann-Whitney U test and mixed-effects modelling. Interobserver agreement was assessed using intraclass correlation coefficient (ICC).
Results or Findings: Preliminary data are presented. Mean FVC change for all patients was -6.28% (SD, 14.9). For individual readers, there was a significant difference in median FVC decline between corresponding Progressive Fibrosis versus Stable Disease CT groups (range, -6.84% to -11.44%, p=<0.001–0.015). For the whole reader cohort, mean FVC decline was significantly greater in Progressive Fibrosis versus Stable Disease on CT (-10.70%, 95% CI [-11.89%, -9.50%] versus -1.47%, 95% CI [-2.78%, -0.15%]). Interobserver agreement was moderate (ICC = 0.501, 95% CI [0.420, 0.588]).
Conclusion: Among specialist thoracic radiologists and ILD physicians, visual evaluation of serial CT scans is a valuable method for determining progressive fibrosis in non-IPF fibrotic lung diseases, judged against contemporary FVC decline, though interobserver agreement remains moderate.
Limitations: Single-centre retrospective study
Funding for this study: Nil sought
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: Prior IRAS approval for retrospective research within the Royal Brompton Hospital radiology department

Author Block: T. Schnitzler, J. H. Sohn; San Francisco, CA/US
Purpose: Interstitial lung disease (ILD) patients have an increased risk of lung cancer, but detection is challenging due to background fibrosis, leading to diagnostic delays. There is limited research on lung cancer in ILD, particularly regarding diagnostic delays. This study aims to analyze delayed lung cancer diagnoses in ILD patients, including tumor stage at diagnosis, growth rates, treatment regimens, and outcomes.
Methods or Background: This retrospective study included ILD patients with concomitant lung cancer (pathology proven or >50% radiologically suspected) from two referral centers. A thoracic radiologist re-reviewed chest CTs to determine the earliest visible and callable lesion time, when it was first deemed suspicious, and its growth rate. Tumor staging, treatment regimens, and outcomes were analyzed. Survival curves were generated using the Kaplan-Meier method, comparing median survival times between delayed and non-delayed cancer cases with the log-rank test.
Results or Findings: Seventy-seven cases of concurrent ILD and lung cancer were identified (53 pathology proven, 24 radiologically presumed). Delayed diagnoses occurred in 47% (36/77) of cases, with an average delay of 3.42 years. These delayed cases had a mean annual growth rate of 293% and a mean doubling time of 3.3 years. An additional 5% (4/61) were diagnosed post-lung transplant. The median survival time was 1269 days for early detection versus 867 days for delayed detection. However, the difference in survival was not statistically significant (p = 0.80).
Conclusion: This study found that 52% of lung cancer cases in ILD had delayed diagnoses, with an average delay of 3.42 years. Despite the delays, there was no significant difference in mortality between early and delayed detection cases.
Limitations: The main limitation is the retrospective study design.
Funding for this study: Swiss Society for Radiology Research Grant 2023
Bangerter-Rhyner Foundation, Basel, Switzerland
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was approved by the local IRB (17-22317)

Author Block: Y. Chen¹, A. Pieters¹, E-R. Andrinopoulou¹, S. Aliberti², M. Loebinger³, P. Ciet¹, J. Chalmers⁴, H. A. W. M. Tiddens¹, .. On Belalf Of Embarc Study Group⁴; ¹Rotterdam/NL, ²Humanitas Research Hospital, Milan/IT, ³London/UK, ⁴Dundee/UK
Purpose: Key features of bronchi in bronchiectasis disease are irreversible widening, wall thickening and mucus plugging. The bronchiectasis registry EMBARC lacks currently objective quantitative metrics for these features. The aim of our study was to analyse EMBARC chest CTs using an AI-based algorithm measuring bronchus and artery (BA) dimensions and ratios and counting mucus plugs (MP).
Methods or Background: 885 CTs from eight EMBARC centres were retrospectively collected for automatic analysis using LungQ (Thirona, The Netherlands), which segments the bronchial tree and identifies segmental (G0) and distal (G1,2,3…) generations. For each BA-pair, the following dimensions are computed: diameters of bronchial outer edge (Bout), inner edge (Bin), and artery (A), and wall thickness (Bwt) and the following BA-ratios: Bout/A, Bin/A, Bwt/A, and bronchial wall area/outer area (Bwa/Boa). Cut-offs for mild and severe bronchial widening are Bout/A>1.1 and >1.5, respectively and for thickening (Bwt/A>0.14). The MP analysis automatically segments the bronchial tree, detects the total number and volume of MP.
Results or Findings: 640 CTs were successfully analysed, identifying 141,978 BA-pairs from G0 until G29 (222 BA-pairs per CT). Bout/A>1.1 or >1.5 were observed in 73% and 39% of all BA-pairs, respectively. Bwt/A>0.14 was observed in 49% of all BA-pairs. The median(IQR) Bout/A, Bin/A, Bwt/A, and Bwa/Boa for G1-6 were 1.34(1.07, 1.72), 1.04(0.81, 1.35), 0.13(0.1, 0.2). MP were found in 83% of CTs, with a median number of 8 plugs and a median volume of 0.44mL per CT.
Conclusion: Our study demonstrates the capability of AI-based algorithms to measure BA-dimensions and detect mucus plugs on chest CT scans of bronchiectasis patients. Our findings show widespread but heterogeneous bronchial widening and thickening, along with the presence of mucus plugs, indicative of active infection and/or inflammation.
Limitations: Retrospective study
Funding for this study: Supported by the Innovative Medicines Initiative and The European Federation of Pharmaceutical Industries and Associations companies under the European Commission–funded Horizon 2020 Framework Program and by Inhaled Antibiotic for Bronchiectasis and Cystic Fibrosis (grant 115721).
EMBARC3 is funded by the European Respiratory Society through the EMBARC3 clinical research collaboration. EMBARC3 is supported by project partners Armata, AstraZeneca, Boehringer Ingelheim, Chiesi, CSL Behring, Grifols, Insmed, Janssen, Lifearc, and Zambon. J.D.C. is supported by the GlaxoSmithKline/Asthma and Lung UK Chair of Respiratory Research.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The study received central ethical approval from the Multicentre Research Ethics Committee in the UK on Jan 8, 2015 (14/SS/1101) and the study is sponsored by the University of Dundee, Dundee, UK.

Author Block: M. M. Sieren¹, H. Graßhoff¹, L. Berkel¹, G. Riemekasten¹, F. Nensa², R. Hosch², J. Barkhausen¹, R. Klöckner¹, F. Wegner¹; ¹Lübeck/DE, ²Essen/DE
Purpose: Systemic Sclerosis (SSc) is a complex connective tissue disorder with variable disease progression and outcome. While chest CT imaging is recommended in all patients to evaluate interstitial lung disease, AI-driven body composition analysis (BCA) can further enhance radiological assessment by providing quantitative imaging biomarkers.

This study aims to assess BCA's ability to predict survival, complications, and disease severity on chest CT.
Methods or Background: CT scans were obtained from a prospectively maintained cohort of 452 SSc patients, including 128 with at least one CT scan and 35 patients with up to three follow-up exams. The follow-up period averaged 36.5±4.5 months. An AI-based 3D BCA algorithm measured muscle volume, adipose tissue compartments, and bone mineral density.

BCA Parameters were evaluated in relation to clinical, laboratory, and functional data on baseline and follow-up scans. Survival prediction was performed using regression analysis, comparing models based on BCA, BMI, and clinical parameters.
Results or Findings: The BCA model outperformed BMI and clinical models in predicting survival (BCA AUC=0.74, BMI AUC=0.49, clinical parameters AUC=0.53). Including longitudinal BCA data further improved the model's AUC to 0.82. Altered BCA parameters were linked to increased odds ratios [with 95% confidence interval] for complications like acral ulcers (1.7 [1.1-1.9]), interstitial lung disease (2.1 [1.4-4.4]), cardiac (2.0 [1.3-3.0]) and gastrointenstinal manifestations (1.6 [1.4-1.9], all p<0.05).
Conclusion: This study highlights that quantitative body composition biomarkers outperform established parameters in predicting survival and specific disease manifestations. These findings provide a blueprint how radiological assessment can transform from primarily qualitative assessment to including previously unavailable quantitative data leading to more personalized patient care, potentially improving outcomes for SSc patients.
Limitations: The study's single-center design and small sample size may limit generalizability, and variations in CT quality could affect AI-based BCA accuracy.
Funding for this study: None.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: Study/protocol number: AZ 22-289

Author Block: Y. Zhang, Y. Wang, X. Yu, J. Wei, H. Wu; Shanghai/CN
Purpose: To develop an imaging protocol for assessing lesion reversibility and a radiomics-based nomogram for predicting lesion reversibility in connective tissue disease-associated interstitial lung disease (CTD-ILD).
Methods or Background: A retrospective study categorized CTD-ILD patients into training, internal and external validation cohorts. An imaging protocol of serial chest CT scans for assessing lesion reversibility was developed, classifying patients as completely reversible (CR) and non-CR groups based on CT lesion changes. Lesions were evaluated using morphological CT features and radiomics signatures at the lung-zone level. Visual, radiomics, and combined nomogram models were developed and compared through receiver operating characteristic (ROC) curve analysis.
Results or Findings: Among 153 patients with 575 affected lung zones, a five-feature radiomics signature significantly correlated with ILD lesion reversibility. The radiomics model showed robust discrimination, comparable to the visual model in the validation cohorts (internal: 0.77, 95% CI: [0.68, 0.86] versus 0.87, 95% CI: [0.81, 0.94], p=0.056; external: 0.73, 95% CI: [0.66, 0.79] versus 0.78, 95% CI: [0.72, 0.84], p=0.20), and inferior to the visual model in the training cohort (0.72, 95% CI: [0.66, 0.79] versus 0.82, 95% CI: [0.77, 0.87], p=0.02). The combined nomogram model outperformed the visual model alone in the training and external validation cohorts (0.86, 95% CI: [0.81, 0.91], p=0.03; 0.82, 95% CI: [0.77, 0.87]; p=0.048).
Conclusion: An imaging protocol was established for assessing lesion reversibility in CTD-ILD. The radiomics signature provided a quantitative approach to predict lesion reversibility. The combined nomogram improved the predictive accuracy beyond morphological features alone.
Limitations: First, clinical information were incomplete and not included in the predictive model. Future research incorporating more clinical information is needed. Second, the manual segmentation of lung zones might introduce bias across various scans.
Funding for this study: None
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: Ethics approval (No. LY2023-019-B) was granted by the institutional review board (IRB) of Shanghai Jiaotong University, School of Medicine, Renji Hospital. The IRB waived informed consent requirement for this retrospective study.

Author Block: A. M. Bucher¹, E. Frodl¹, F. G. Meinel², M. M. Sieren³, M. A. Fink⁴, M. S. May⁵, M. S. Kim⁶, T. Vogl¹, A. Surov⁷; ¹Frankfurt/DE, ²Rostock/DE, ³Lübeck/DE, ⁴Heidelberg/DE, ⁵Erlangen/DE, ⁶Essen/DE, ⁷Minden/DE
Purpose: This study evaluates the prognostic significance of pleural effusion (PE) in COVID-19 patients across 13 German centers, part of the RACOON (Radiological Cooperative Network) project. We aimed to assess the relationship between PE and key clinical outcomes, in a large multicentre study.
Methods or Background: In this retrospective study, 1183 COVID-19 patients (29.3% women, 70.7% men) underwent chest CT to assess the presence, volume, and density of PE. We analyzed associations between PE and clinical outcomes including 30-day mortality, ICU admission, and mechanical ventilation. We used univariable and multivariable regression analyses, adjusting for confounders such as the COVID-19 CT severity score.
Results or Findings: PE was identified in 31.5% of patients. A significant correlation was found between PE and 30-day mortality (47.5% in non-survivors vs. 27.3% in survivors, p<0.001). PE presence independently predicted mortality with a hazard ratio (HR) of 2.22 (95% CI 1.65-2.99, p<0.001). However, PE volume and density were not significantly associated with mortality. ICU admission was necessary in 46.8% of patients, and 26.7% required mechanical ventilation. PE presence was also linked to ICU admission and ventilation but not its volume or density.
Conclusion: Pleural effusion is a significant independent predictor of 30-day mortality in COVID-19 patients, irrespective of its volume or density. These findings underscore the importance of including PE detection in routine CT assessments to enhance clinical decision-making and patient care.
Limitations: This retrospective study was limited to German tertiary care centers, which may not represent other settings.
Funding for this study: Funded by „NUM 2.0“ (FKZ: 01KX2121)
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: IRB approval for this retrospective multi centre study was obtained (20-719).

Author Block: A. Nehvi, M. Mobini, S. Buckingham, L. Mills; Stevenage/UK
Purpose: This audit evaluates whether follow-up chest radiographs are being performed for adults diagnosed with Community-Acquired Pneumonia (CAP) according to British Thoracic Society (BTS) guidelines. A gap was identified when many patients did not receive a follow-up chest X-ray within six weeks, prompting an audit to identify barriers and gaps in care.
Methods or Background: CAP affects 0.5% to 1% of UK adults annually and carries a mortality risk of 5-14%. Follow-up X-rays are crucial to ensure the resolution of pneumonia and to exclude underlying conditions such as lung cancer.

The first cycle retrospectively reviewed 50 adult patients diagnosed with CAP between November 2023 and March 2024. The second cycle repeated the review from March to July 2024, after implementing several interventions. Data were collected to assess compliance with follow-up X-ray recommendations, virtual Pneumonia clinic (VPC) referrals, and Casualty (CAS) alerts.
Results or Findings: In the first cycle, only 32.6% of patients received follow-up X-rays within six weeks, with 67.4% failing to comply. Among those discharged from the emergency department, 67.8% did not have a follow-up X-ray. Referrals to the Virtual Pneumonia Clinic (VPC) were low (23.2%), and only 5% of reports included a CAS alert.

Following interventions aimed at raising awareness among doctors, improving documentation, enhancing patient education, and increasing CAS alerts, the second cycle showed significant improvement. Compliance with follow-up X-rays increased to 70%, with VPC referrals rising to 77% and CAS alerts reaching 73%. The compliance rate for follow-up X-rays among patients discharged from emergency care increased from 32.2% to 65%.
Conclusion: A marked improvement in adherence to BTS guidelines after targeted interventions, lead to more follow-up X-rays, VPC referrals, and CAS alerts.
Limitations: 1) Retrospective Design

2)Small sample size

3) Single-Centered Audit
Funding for this study: East and North Hertfordshire NHS Trust.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The study was approved by the trust ethics committee and audit department