Interstitial lung abnormalities detected incidentally on CT: a Position Paper from the Fleischner Society

Exploring the Potential Value of [ 68 Ga]Ga-FAPI-46 PET/CT for Molecular Assessment of Fibroblast Activation in Interstitial Lung Disease : A Single-Center Pilot Study

BACKGROUND

The aim of the study was to evaluate the association of high-resolution computed tomography (HRCT) findings with pulmonary fibrotic activity in the corresponding regions using [ 68 Ga]Ga-fibroblast activation fibroblast inhibitor (FAPI) PET/CT in patients with interstitial lung disease (ILD). Additionally, the potential of [ 68 Ga]Ga-FAPI-46 PET/CT for evaluating the active fibrosis process and 99m Tc-MIBI scintigraphy for assessing the inflammatory process in ILD patients was also assessed.

METHODS

In this pilot study, 20 ILD patients underwent [ 68 Ga]Ga-FAPI-46 PET/CT and 99m Tc-MIBI SPECT/CT. Additionally, 10 patients without lung or thoracic involvement who were undergoing [ 68 Ga]Ga-FAPI PET/CT for cancer detection were enrolled in the control group. The images were evaluated both visually and semiquantitatively and also compared with HRCT and pulmonary function tests. Multiple quantitative parameters were derived from the lung segments in the PET scan, including SUV max , SUV mean , maximum target-to-liver ratio, mean target-to-liver ratio (TLR mean ), and total lesion FAPI expression for the entire lung, as well as its lobes and zones. Additionally, the maximum Hounsfield unit (HU) and mean HU in HRCT were calculated for the whole lung as well as its lobes and zones. Furthermore, an HRCT fibrosis score (HFS) was defined according to the HRCT findings.

RESULTS

Twenty ILD patients with a mean age of 58.70 (SD, 11.09) years were enrolled. Additionally, 10 control patients were enrolled with a mean age of 57.70 (SD, 15.19) years. Based on visual assessment, the FAPI scan was positive in 12 (60%) patients. Similarly, the MIBI scan was positive in 12 (60%) patients. In the 20 ILD cases, both scans were positive in 6 cases, and both were negative in 2 cases. Six cases showed FAPI-negative and MIBI-positive results, whereas another 6 cases showed FAPI-positive and MIBI-negative results. Comparing the control and ILD patients, there was a significant difference in SUV max , SUV mean , total lesion FAPI expression, TLR mean , maximum HU, and mean HU ( P < 0.05). When comparing HFS with PET-derived parameters in zones, a significant positive correlation was found between HFS and SUV mean , SUV max , maximum target-to-liver ratio, and TLR mean ( P < 0.05). Additionally, a significant difference was noted between FAPI results and HFS ( P = 0.003). An ancillary finding, 9 of 20 (45%) ILD patients showed intense FAPI uptakes in gallbladder, whereas none of the 10 in the control group showed such uptake.

CONCLUSION

The present study may suggest that combining [ 68 Ga]Ga-FAPI PET/CT and 99m Tc-MIBI SPECT/CT yields an additive effect for evaluating ILD-related fibrosis and inflammatory processes over using either modality alone. Furthermore, it appears that [ 68 Ga]Ga-FAPI PET/CT has the potential to ascertain levels of fibrotic activity from population of resident fibroblasts, active fibroblasts, and scar maturation among ILD patients based on their HRCT patterns.

CT Quantification of Interstitial Lung Abnormality and Interstitial Lung Disease: From Technical Challenges to Future Directions

ABSTRACT

Interstitial lung disease (ILD) encompasses a variety of lung disorders with varying degrees of inflammation or fibrosis, requiring a combination of clinical, imaging, and pathologic data for evaluation. Imaging is essential for the noninvasive diagnosis of the disease, as well as for assessing disease severity, monitoring its progression, and evaluating treatment response. However, traditional visual assessments of ILD with computed tomography (CT) suffer from reader variability. Automated quantitative CT offers a more objective approach by using computer-based analysis to consistently evaluate and measure ILD. Advancements in technology have significantly improved the accuracy and reliability of these measurements. Recently, interstitial lung abnormalities (ILAs), which represent potential preclinical ILD incidentally found on CT scans and are characterized by abnormalities in over 5% of any lung zone, have gained attention and clinical importance. The challenge lies in the accurate and consistent identification of ILA, given that its definition relies on a subjective threshold, making quantitative tools crucial for precise ILA evaluation. This review highlights the state of CT quantification of ILD and ILA, addressing clinical and research disparities while emphasizing how machine learning or deep learning in quantitative imaging can improve diagnosis and management by providing more accurate assessments, and finally, suggests the future directions of quantitative CT in this area.

Prevalence and progression rate of interstitial lung abnormalities detected on thoracic CT: a systematic review and meta-analysis

OBJECTIVES

To estimate the pooled prevalence and progression rate of ILAs and identify the risk factors for radiological progression.

MATERIALS AND METHODS

An EMBASE and PubMed search was undertaken, identifying all studies meeting the inclusion criteria performed before May 10, 2023. Random effect models were used to estimate pooled prevalence, ILA progression rates, and odds ratio for radiological progression based on radiological subtype. Subgroup analyses were performed to compare the general and high-risk populations for lung cancer. The quality of the included studies was evaluated using the risk of bias assessment tool for non-randomized studies.

RESULTS

We analyzed 19 studies (241,541 patients) and 10 studies (1317 patients) for the pooled prevalence and progression rate of ILA, respectively. The pooled ILA prevalence was 9.7% (95% CI, 6.1-13.9%). The pooled prevalence was 6.8% (95% CI, 3.1-11.6%) and 7.1% (95% CI, 2.2-14.4%) in the general (six studies) and high-risk population for lung cancer (six studies), respectively. The pooled progression rate was 47.1% (95% CI, 29.1-65.5%). The pooled progression rate was 64.2% (95% CI, 45.0-81.2%, five studies) and 31.0% (95% CI, 8.2-60.5%, five studies) for longer (≥ 4.5 years) and shorter follow-up periods (< 4.5 years), respectively (p = 0.009). Fibrotic ILAs were significantly associated with a higher progression probability (combined OR, 5.55; 95% CI, 1.95-15.82).

CONCLUSIONS

The prevalence of ILAs was approximately 9.7%. Approximately half of the patients exhibited radiological progression, with the rate increasing over a longer follow-up period. Fibrotic ILA was a significant risk factor for radiological progression.

CLINICAL RELEVANCE STATEMENT

The prevalence of interstitial lung abnormalities (ILAs) is approximately 9.7%, with about half exhibiting progression; a longer follow-up duration and fibrotic ILAs are associated with a higher progression rate.

KEY POINTS

ILAs are increasingly recognized as important, but few population data are available. ILAs exhibited a pooled prevalence of 9.7% with a progression rate of 47.1%. Fibrotic ILAs were associated with increased progression likelihood.

Association of interstitial lung abnormalities with cytotoxic agent-induced pneumonitis in patients with malignancy

BACKGROUND AND OBJECTIVE

The association between interstitial lung abnormalities (ILA) and various conditions and diseases, including drug-related pneumonitis (DRP), has been reported. However, the association of the presence of ILA with developing DRP in patients undergoing cytotoxic agent-based chemotherapy, one of the standard treatments for malignancies, remains unclear. This warrants urgent investigation.

METHODS

We included consecutive patients diagnosed with malignancy and treated with cytotoxic agents with/without immune checkpoint inhibitors (ICIs). We used Gray's method and multivariate Fine-Gray sub-distribution hazards analysis to evaluate the cumulative incidence of DRP (common terminology criteria for adverse events grade of ≥3) and the association between ILA and DRP development, respectively.

RESULTS

Among 786 patients, 58 (7.3 %) demonstrated ILA. Patients with ILA were older, predominantly male, and reported a higher smoking history compared to those without ILA. The 90-day cumulative incidence of cytotoxic agent-induced DRP with/without ICIs was significantly higher in patients with ILA than in those without ILA (6.0 % vs. 1.2 %, p = 0.006). Multivariate analysis, adjusted for age, sex, and smoking history, revealed that ILA was associated with an increased risk of developing DRP due to cytotoxic agents with/without ICIs (hazard ratio [HR] 3.11, 95 % confidence interval [CI]: 1.06-9.14, p = 0.039) and cytotoxic agents alone (HR: 5.53, 95 % CI: 1.55-19.7, p = 0.008).

CONCLUSIONS

The presence of ILA is associated with an increased risk of developing DRP in patients undergoing cytotoxic agent-based chemotherapy. Therefore, evaluating the presence of ILA before determining chemotherapy regimens that include cytotoxic agents is recommended.

Optimizing prone CT use for suspected interstitial lung abnormalities

OBJECTIVES

We investigated whether supine chest CT alone suffices for diagnosing ILAs, thereby reducing the need for prone chest CT.

MATERIALS AND METHODS

Patients who underwent prone chest CT for suspected ILAs from January 2021 to July 2023, with matching supine CT within 1 year, were retrospectively evaluated. Five multinational thoracic radiologists independently rated ILA suspicion and fibrosis scores (1 to 5-point) and ILA extent (1-100%) using supine CT first, then combined supine-prone CT after a 1-month washout. We categorized ILA suspicion and fibrosis scores into four diagnostic groups; normal, non-fibrotic, indeterminate-type, and fibrotic ILAs. The areas under the receiver operating characteristic curve (AUCs) of ILA suspicion scores, inter-reader agreement on diagnostic categories, and intra-reader/inter-reader reliability for ILA extent were evaluated.

RESULTS

This study included 69 patients (mean age 67.2 ± 7.2 years; 36 women), with 23 age- and sex-matched patients in each group: normal, non-fibrotic ILAs, and fibrotic ILAs. The pooled AUC for ILA suspicion and inter-reader agreement on diagnostic categories improved for non-fibrotic ILAs with prone CT (AUC 0.76 to 0.92, p < 0.001; Fleiss kappa 0.25 to 0.51, p = 0.004), but not for fibrotic ILAs (AUC 0.94 to 0.99, p = 0.06; Fleiss kappa 0.63 to 0.72, p = 0.08). ILA extent was 1-2% smaller with prone CT for both ILA types (p < 0.001).

CONCLUSION

For fibrotic ILAs, supine CT alone exhibited substantial diagnostic accuracy and inter-reader agreement, while the diagnosis of non-fibrotic ILAs benefited from adding prone CT. Supine CT alone slightly overestimated extent regardless of ILA type.

KEY POINTS

Question Prone CT is recommended when interstitial lung abnormalities (ILAs) are suspected on supine CT, but its benefits remain underexplored. Findings Supine CT alone sufficed for diagnosing fibrotic ILAs, while prone CT improved non-fibrotic ILA diagnosis and reduced extent overestimation for both types. Clinical relevance Omitting prone CT reduces extra time, space, and radiation exposure without compromising the diagnosis of fibrotic ILAs, which have higher rates of progression and mortality risks, enhancing patient comfort and simplifying patient management.

Association of Ground-Glass Opacities with Systemic Inflammation and Progression of Emphysema

Rationale: Ground-glass opacities (GGOs) in the absence of interstitial lung disease are understudied. Objectives: To assess the association of GGOs with white blood cells (WBCs) and progression of quantified chest computed tomography emphysema. Methods: We analyzed data of participants in the SPIROMICS study (Subpopulations and Intermediate Outcome Measures in COPD Study). Chest radiologists and pulmonologists labeled regions of the lung as GGOs, and the adaptive multiple feature method (AMFM) trained the computer to assign those labels to image voxels and quantify the volume of the lung with GGOs (%GGOAMFM). We used multivariable linear regression, zero-inflated negative binomial, and proportional hazards regression models to assess the association of %GGOAMFM with WBCs, changes in percentage emphysema, and clinical outcomes. Measurements and Main Results: Among 2,714 participants, 1,680 had chronic obstructive pulmonary disease (COPD) and 1,034 had normal spirometry. Among participants with COPD, on the basis of multivariable analysis, current smoking and chronic productive cough were associated with higher %GGOAMFM. Higher %GGOAMFM was cross-sectionally associated with higher WBC and neutrophil concentrations. Higher %GGOAMFM per interquartile range at visit 1 (baseline) was associated with an increase in emphysema at 1-year follow-up visit by 11.7% (relative increase; 95% confidence interval, 7.5-16.1%; P < 0.001). We found no association between %GGOAMFM and 1-year FEV1 decline, but %GGOAMFM was associated with exacerbations and all-cause mortality during a median follow-up of 1,544 days (interquartile interval, 1,118-2,059). Among normal spirometry participants, we found similar results, except that %GGOAMFM was associated with progression to COPD at 1-year follow-up. Conclusions: Our findings suggest that GGOAMFM is associated with increased systemic inflammation and emphysema progression.

Progressive Early Interstitial Lung Abnormalities in Persons at Risk for Familial Pulmonary Fibrosis: A Prospective Cohort Study

Rationale: Relatives of patients with familial pulmonary fibrosis (FPF) are at increased risk to develop FPF. Interstitial lung abnormalities (ILAs) are a radiologic biomarker of subclinical disease, but the implications of very mild abnormalities remain unclear. Objectives: To quantify the progression risk among FPF relatives with abnormalities below the threshold for ILAs as described by the Fleischner Society and to describe the characteristics of participants with new or progressive ILAs during observation. Methods: Asymptomatic FPF relatives undergo serial screening high-resolution chest computed tomography. For this analysis, early ILAs (no minimum threshold of lung involvement) were subclassified as mild (all interstitial abnormalities involve <5% of a lung zone) or moderate (any abnormality involves >5%). Identification of new or progressive ILAs on high-resolution chest computed tomography and the development of pulmonologist-diagnosed clinical FPF were defined as progression. Covariate-adjusted logistic regression identified progression-associated characteristics. Measurements and Main Results: From 2008 to 2023, 273 participants in follow-up procedures were 53.2 ± 9.4 years of age at enrollment, 95 (35%) were men, and 73 of 268 (27%) were ever-smokers. During a mean follow-up period of 6.2 ± 3.0 years, progression occurred among 31 of 211 (15%) of those with absence of ILAs at enrollment, 32 of 49 (65%) of those with mild ILAs, and 10 of 13 (77%) of those with moderate ILAs. Subjects with mild ILAs had 9.15 (95% confidence interval, 4.40-19.00; P < 0.0001) times and those with moderate ILAs had 17.14 (95% confidence interval, 4.42-66.49; P < 0.0001) times the odds of progression as subjects without ILAs. Conclusions: In persons at risk for FPF, minor interstitial abnormalities, including reticulation that is unilateral or involves <5% of a lung zone, frequently represent subclinical disease.

Development, Progression, and Mortality of Suspected Interstitial Lung Disease in COPDGene

Rationale: Some with interstitial lung abnormalities (ILA) are suspected to have interstitial lung disease (ILD), a subgroup with adverse outcomes. Rates of development and progression of suspected ILD and their effect on mortality are unknown. Objectives: To determine rates of development, progression, and mortality in those with suspected ILD and assess effects of individual ILD and progression criteria. Methods: Participants from COPDGene (Genetic Epidemiology of Chronic Obstructive Pulmonary Disease) with ILA characterization and FVC at enrollment and 5-year follow-up were included. ILD was defined as ILA and fibrosis and/or FVC < 80% predicted. Prevalent ILD was assessed at enrollment and incident ILD and progression were assessed at 5-year follow-up. Computed tomography (CT) progression was assessed visually and FVC decline as relative change. Multivariable Cox regression tested associations between mortality and prevalent ILD, incident ILD, and progression groups. Measurements and Main Results: Of 9,588 participants at enrollment, 268 (2.8%; 51% of ILA) had prevalent ILD. Those with prevalent ILD had 51% mortality after median 10.6 years, which was higher than those with ILA without prevalent ILD (henceforth ILA) (33%; hazard ratio [HR], 2.0; P < 0.001). The subgroup of prevalent ILD with only fibrosis criteria (FVC ≥ 80%) had worse mortality (58%) than ILA (HR, 2.2; P < 0.001). A total of 98 participants with prevalent ILD completed 5-year follow-up: 33% had stable CT and relative FVC decline <10%, 6% had FVC decline ≥10% only, 39% had CT progression only, and 22% had both CT progression and FVC decline ≥10%. Mortality rates were 31%, 50%, 45%, and 45%, respectively; those with only CT progression had worse mortality than those with ILA (HR, 2.6; P = 0.005). At 5-year follow-up, incident ILD occurred in 148/4,842 participants without prevalent ILD (5.5/1,000 person-years) and had worse mortality than ILA (HR, 2.4; P < 0.001). Conclusion: Rates of mortality and progression are high among those with suspected ILD in COPDGene; fibrosis and radiologic progression are important predictors of mortality.

Longitudinal microcomputed tomography detects onset and progression of pulmonary fibrosis in conditional Nedd4-2 deficient mice

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease, which is usually diagnosed late in advanced stages. Little is known about the subclinical development of IPF. We previously generated a mouse model with conditional Nedd4-2 deficiency (Nedd4-2-/-) that develops IPF-like lung disease. The aim of this study was to characterize the onset and progression of IPF-like lung disease in conditional Nedd4-2-/- mice by longitudinal micro-computed tomography (CT). In vivo micro-CT was performed longitudinally in control and conditional Nedd4-2-/- mice at 1, 2, 3, 4, and 5 mo after doxycycline induction. Furthermore, terminal in vivo micro-CT followed by pulmonary function testing and post mortem micro-CT was performed in age-matched mice. Micro-CT images were evaluated for pulmonary fibrosis using an adapted fibrosis scoring system. Histological assessment of lung collagen content was conducted as well. Micro-CT is sensitive to detect the onset and progression of pulmonary fibrosis in vivo and to quantify distinct radiological IPF-like features along disease development in conditional Nedd4-2-/- mice. Nonspecific interstitial alterations were detected from 3 mo, whereas key features such as honeycombing-like lesions were detected from 4 mo onward. Pulmonary function correlated well with in vivo (r = -0.738) and post mortem (r = -0.633) micro-CT fibrosis scores and collagen content. Longitudinal micro-CT enables in vivo monitoring of the onset and progression and detects radiological key features of IPF-like lung disease in conditional Nedd4-2-/- mice. Our data support micro-CT as a sensitive quantitative endpoint for the preclinical evaluation of novel antifibrotic strategies.NEW & NOTEWORTHY IPF diagnosis, particularly in early stages, remains challenging. In this study, micro-CT is used in conditional Nedd4-2-/- mice to closely monitor the onset and progression of progressive pulmonary fibrosis in vivo. Together with high-resolution post mortem micro-CT, this allowed us to track how nonspecific lung lesions develop into key IPF-like features. This approach offers a noninvasive method to monitor pulmonary fibrosis, providing a quantitative endpoint for the preclinical evaluation of novel antifibrotic strategies.

A predictive model for post-COVID-19 pulmonary parenchymal abnormalities based on dual-center data

Documented radiological and physiological anomalies among coronavirus disease 2019 survivors necessitate prompt recognition of residual pulmonary parenchymal abnormalities for effective management of chronic pulmonary consequences. This study aimed to devise a predictive model to identify patients at risk of such abnormalities post-COVID-19. Our prognostic model was derived from a dual-center retrospective cohort comprising 501 hospitalized COVID-19 cases from July 2022 to March 2023. Of these, 240 patients underwent Chest CT scans three months post-infection. A predictive model was developed using stepwise regression based on the Akaike Information Criterion, incorporating clinical and laboratory parameters. The model was trained and validated on a split dataset, revealing a 33.3% incidence of pulmonary abnormalities. It achieved strong discriminatory power in the training set (area under the curve: 0.885, 95% confidence interval 0.832-0.938), with excellent calibration and decision curve analysis suggesting substantial net benefits across various threshold settings. We have successfully developed a reliable prognostic tool, complemented by a user-friendly nomogram, to estimate the probability of residual pulmonary parenchymal abnormalities three months post-COVID-19 infection. This model, demonstrating high performance, holds promise for guiding clinical interventions and improving the management of COVID-19-related pulmonary sequela.

Development of Imaging Complexity Biomarkers for Prediction of Symptomatic Radiation Pneumonitis in Patients with Non-Small Cell Lung Cancer, Focusing on Underlying Lung Disease

Objectives: We aimed to develop imaging biomarkers to predict radiation pneumonitis (RP) in non-small cell lung cancer (NSCLC) patients undergoing thoracic radiotherapy. We hypothesized that measuring morphometric complexity in the lung using simulation computed tomography may provide objective imaging biomarkers for lung parenchyma integrity, potentially forecasting the risk of RP. Materials and Methods: A retrospective study was performed on medical records of 175 patients diagnosed with NSCLC who had received thoracic radiotherapy. Three indices were utilized to measure the morphometric complexity of the lung parenchyma: box-counting fractal dimension, lacunarity, and minimum spanning tree (MST) fractal dimension. Patients were dichotomized into two groups at median values. Cox proportional hazard models were constructed to estimate the hazard ratios for grade ≥ 2 or grade ≥ 3 RP. Results and Conclusions: We found significant associations between lung parenchymal morphometric complexity and RP incidence. In univariate Cox-proportional hazard analysis, patients with a lower MST fractal dimension had a significantly higher hazard ratio of 2.296 (95% CI: 1.348-3.910) for grade ≥ 2 RP. When adjusted for age, sex, smoking status, category of the underlying lung disease, category of radiotherapy technique, clinical stage, histology, and DLCO, patients with a lower MST fractal dimension showed a significantly higher hazard ratio of 3.292 (95% CI: 1.722-6.294) for grade ≥ 2 RP and 7.952 (95% CI: 1.722 36.733) for grade ≥ 3 RP than those with a higher MST fractal dimension. Patients with lower lacunarity exhibited a significantly lower hazard ratio of 0.091 (95% CI: 0.015-0.573) for grade ≥ 3 RP in the adjusted model. We speculated that the lung tissue integrity is captured by morphometric complexity measures, particularly by the MST fractal dimension. We suggest the MST fractal dimension as an imaging biomarker for predicting the occurrence of symptomatic RP after thoracic radiotherapy.

Pulmonary fibrosis may begin in infancy: from childhood to adult interstitial lung disease

BACKGROUND

Childhood interstitial lung disease (chILD) encompasses a group of rare heterogeneous respiratory conditions associated with significant morbidity and mortality. Reports suggest that many patients diagnosed with chILD continue to have potentially progressive or fibrosing disease into adulthood. Over the last decade, the spectrum of conditions within chILD has widened substantially, with the discovery of novel entities through advanced genetic testing. However, most evidence is often limited to small case series, with reports disseminated across an array of subspecialty, clinical and molecular journals. In particular, the frequency, management and outcome of paediatric pulmonary fibrosis is not well characterised, unlike in adults, where clear diagnosis and treatment guidelines are available.

METHODS AND RESULTS

This review assesses the current understanding of pulmonary fibrosis in chILD. Based on registry data, we have provisionally estimated the occurrence of fibrosis in various manifestations of chILD, with 47 different potentially fibrotic chILD entities identified. Published evidence for fibrosis in the spectrum of chILD entities is assessed, and current and future issues in management of pulmonary fibrosis in childhood, continuing into adulthood, are considered.

CONCLUSIONS

There is a need for improved knowledge of chILD among pulmonologists to optimise the transition of care from paediatric to adult facilities. Updated evidence-based guidelines are needed that incorporate recommendations for the diagnosis and management of immune-mediated disorders, as well as chILD in older children approaching adulthood.

Computed tomography morphological assessments of central airways in interstitial lung abnormalities and idiopathic pulmonary fibrosis

BACKGROUND

Little is known about whether central airway morphological changes beyond traction bronchiectasis develop and affect clinical outcomes in patients with idiopathic pulmonary fibrosis (IPF). This study aimed to compare central airway structure comprehensively between patients with IPF, subjects with interstitial lung abnormality (ILA), and those without ILA (control) using computed tomography (CT). We further examined the prognostic impact of IPF-specific CT airway parameters in patients with IPF.

METHODS

This retrospective study included male patients with IPF, and male health checkup subjects divided into those with ILA and control based on lung cancer screening CT. Using an artificial intelligence-based segmentation technique, the extent of fibrotic regions in the lung was quantified. After airway tree segmentation, CT parameters for central airway morphology, including the lumen area of the extrapulmonary airways (LAextra), wall and lumen area of the segmental/subsegmental intrapulmonary airways (WAintra and LAintra), tracheal distortion (tortuosity and curvature) and bifurcation angle of the main carina, were calculated.

RESULTS

There were 106 patients with IPF, 53 subjects with ILA, and 1295 controls. Multivariable models adjusted for age, height and smoking history revealed that LAintra and WAintra were larger in both ILA and IPF, and that tracheal tortuosity and curvature were higher in IPF, but not in ILA, than in the control, whereas the bifurcation angle did not differ between the 3 groups. According to multivariable Cox proportional hazards models including only patients with IPF, increased WAintra was significantly associated with greater mortality (standardized hazard ratio [95% confidence interval] = 1.58 [1.17, 2.14]), independent of the volume of fibrotic regions, normal-appearing regions, or the whole airway tree in the lung.

CONCLUSION

Increased lumen area and wall thickening of the central airways may be involved in the pathogenesis of ILA and IPF, and wall thickening may affect the prognosis of patients with IPF.

Long-Term Clinical, Radiological, and Mortality Outcomes Following Pneumonitis in Nonsmall Cell Lung Cancer Patients Receiving Immune Checkpoint Inhibitors: A Retrospective Analysis

AIMS

Despite known short-term mortality risk of immune checkpoint inhibitor (ICI) pneumonitis, its impact on 1-year mortality, long-term pulmonary function, symptom persistence, and radiological resolution remains unclear.

METHODS

We retrospectively analyzed 71 nonsmall cell lung cancer (NSCLC) patients treated with anti-PD(L)1 monoclonal antibodies between 2018-2021, who developed pneumonitis. Clinical and demographic covariates were collected from electronic medical record. Cox regression assessed associations with mortality, while logistic regression evaluated associations with persistent symptoms, hypoxemia, and radiological resolution.

RESULTS

Steroid-refractory pneumonitis (hazard ratio [HR] = 15.1, 95% confidence interval [95% CI]:3.9-57.8, P < .0001) was associated with higher 1-year mortality compared to steroid-responsive cases. However, steroid-resistant (odds ratio [OR] = 1.4, 95% CI: 0.4-5.1, P = .58) and steroid-dependent (OR = 0.4, 95% CI: 0.1-1.2, P = .08) pneumonitis were not. Nonadenocarcinoma histology (OR = 6.7, 95% CI: 1.6-46.6, P = .01), grade 3+ pneumonitis (OR = 4.6, 95% CI: 1.3-22.7, P = .03), and partial radiological resolution (OR = 6.3, 95% CI: 1.8-23.8, P = .004) were linked to increased pulmonary symptoms after pneumonitis resolution. Grade 3+ pneumonitis (OR = 8.1, 95% CI: 2.3-31.5, P = .001) and partial radiological resolution (OR = 5.45, 95% CI: 1.29-37.7, P = .03) associated with residual hypoxemia. Nonadenocarcinoma histology (OR = 3.6, 95% CI: 1.01-17.6, P = .06) and pretreatment ILAs (OR = 4.8, 95% CI: 1.14-33.09, P = .05) were associated with partial radiological resolution.

CONCLUSIONS

Steroid refractory pneumonitis increases 1-year mortality in NSCLC patients. Pretreatment ILAs may signal predisposition to fibrosis-related outcomes, seen as partial resolution, which in turn is associated with postresolution symptoms and residual hypoxemia. These findings offer insights for identifying patients at risk of adverse outcomes post-pneumonitis resolution.

Interstitial Lung Abnormalities on Unselected Abdominal and Thoracoabdominal CT Scans in 21 118 Patients

Background Interstitial lung abnormalities (ILAs) are incidental CT findings suggesting early interstitial lung disease. However ILA prevalence data are scarce in an unselected routine clinical setting. Purpose To evaluate the prevalence, underreporting rate, and potential clinical impact of ILAs recognizable on either abdominal CT scans or thoracoabdominal CT scans in a routine clinical setting of unselected patients. Materials and Methods Consecutive abdominal or thoracoabdominal CT scans from unselected inpatients and outpatients (age, ≥50 years; without any available prior chest CT and no clinical history of disease against the diagnosis of ILA) from a single-center tertiary hospital between January 2008 and December 2015 were retrospectively reviewed for the presence of ILAs and compared with the original clinical reports from the CT scans. Radiologic progression of ILA was evaluated by comparing consecutive CT points. Multivariable models adjusted for age, sex, race/ethnicity, oncologic disease, and cardiovascular disease were used to assess factors associated with odds of ILAs progression and all-cause and cause-specific mortality. Results Among 21 118 patients (median age, 72 years [IQR, 64-80 years]; 11 028 [52.2%] female patients), ILAs were observed in 362 (1.7%) patients, notably in 222 (1.0%) patients who had fibrotic features at CT. ILAs were recognized in 122 of 9415 (1.3%) and 240 of 11 703 (2.1%) of abdominal and thoracoabdominal CT scans, respectively. Of available original reports for 360 patients, 158 (43.9%) of all ILAs were not originally reported. Traction bronchiectasis index was the CT factor associated with higher odds of ILA progression (odds ratio, 3.47; 95% CI: 1.83, 6.58; P < .001). Fibrotic ILAs had a fourfold higher risk of respiratory-cause mortality (hazard ratio, 4.01; 95% CI: 2.02, 7.92; P < .001) compared with patients without ILAs. Conclusion The prevalence of ILAs was 1.7% in a large, unselected sample of patients who underwent either abdominal or thoracoabdominal CT for various clinical indications. Despite their prognostic significance, 43.9% of ILAs were unreported. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Hata in this issue.

Impact of preexisting interstitial lung disease on outcomes of lung cancer surgery: A monocentric retrospective study

INTRODUCTION

Interstitial lung disease (ILD) is a known risk factor for lung cancer (LC). However, the surgical risk of LC in patients with ILD remains unclear. Therefore, we conducted a single-center retrospective study to assess clinical features and outcomes of LC population who underwent surgery with or without ILD.

METHODS

Patients who underwent surgery for LC between January 2006 and June 2023 in our center were assessed using data extracted from the nationwide EPITHOR thoracic surgery database. Suspicion of ILD was based on patients' records. Confirmation of ILD was then made on the patient's medical and radiological history. Patients were classified according to the pattern of ILD. The study aimed to describe the outcomes after lung cancer resection in patients with confirmed LC-ILD group compared to those without ILD (LC-non-ILD): post-operative complications, disease-free survival (DFS) and overall survival (OS). A subgroup analysis was also performed on patients with idiopathic pulmonary fibrosis and lung cancer (LC-IPF).

RESULTS

4073 patients underwent surgery for LC at Assistance Publique des Hôpitaux de Marseille between January 2006 and June 2023. Of these, 4030 were in the LC-non-ILD group and 30 were LC-ILD patients. In the LC-ILD group, the predominant CT scan pattern was probable UIP (50 %). OS was not significantly lower in the LC-ILD group (45 months versus 84 months, p = 0.068). Dyspnea and tumor size were identified as potential univariate predictors of OS. No significant differences were observed on post-operative complications or their severity. The most common post-operative complications in the LC-ILD group were prolonged air leak, respiratory failure, or pneumonia. 13 patients had cancer recurrence in the LC-ILD group.

CONCLUSION

Our study provides a comprehensive analysis of a LC-ILD population features and outcome when undergoing surgery for LC. Patients with LC-ILD appeared to have a reduced OS compared with LC-non-ILD. Further investigations with larger prospective studies could be useful to confirm and develop these preliminary findings.

Long-Term Follow-Up of Interstitial Lung Abnormalities in Low-Dose Chest CT in Health Screening: Exploring the Predictors of Clinically Significant Interstitial Lung Diseases Using Artificial Intelligence-Based Quantitative CT Analysis

Purpose

This study examined longitudinal changes in interstitial lung abnormalities (ILAs) and predictors of clinically significant interstitial lung diseases (ILDs) in a screening population with ILAs.

Materials and Methods

We retrieved 36891 low-dose chest CT records from screenings between January 2003 and May 2021. After identifying 101 patients with ILAs, the clinical findings, spirometry results, and initial and follow-up CT findings, including visual and artificial intelligence-based quantitative analyses, were compared between patients diagnosed with ILD (n = 23, 23%) and those who were not (n = 78, 77%). Logistic regression analysis was used to identify significant parameters for the clinical diagnosis of ILD.

Results

Twenty-three patients (n = 23, 23%) were subsequently diagnosed with clinically significant ILDs at follow-up (mean, 8.7 years). Subpleural fibrotic ILAs on initial CT and signs of progression on follow-up CT were common in the ILD group (both p < 0.05). Logistic regression analysis revealed that emerging respiratory symptoms (odds ratio [OR], 5.56; 95% confidence interval [CI], 1.28-24.21; p = 0.022) and progression of ILAs at follow-up chest CT (OR, 4.07; 95% CI, 1.00-16.54; p = 0.050) were significant parameters for clinical diagnosis of ILD.

Conclusion

Clinically significant ILD was subsequently diagnosed in approximately one-quarter of the screened population with ILAs. Emerging respiratory symptoms and progression of ILAs at follow-up chest CT can be predictors of clinically significant ILDs.

First-line chemoimmunotherapy for patients with small-cell lung cancer and interstitial lung abnormality: CIP risk and prognostic analysis

BACKGROUND

Patients with non-small-cell lung cancer (NSCLC) receiving immunotherapy face a potential risk of developing checkpoint inhibitor-related pneumonitis (CIP). However, there is no clear understanding of the specific link between interstitial lung abnormality (ILA) and CIP in patients with small-cell lung cancer (SCLC). In addition, the prognosis of SCLC patients with ILA who receive chemoimmunotherapy is uncertain. Our study aimed to investigate the effect of ILA on the occurrence of CIP in SCLC patients receiving first-line chemoimmunotherapy and to assess its relationship with prognosis.

METHODS

We conducted a retrospective analysis of SCLC patients who received chemoimmunotherapy as a first-line treatment between January 2018 and April 2024. The diagnosis of ILA was assessed by two experienced pulmonologists based on pretreatment chest computed tomography images. We investigated independent risk factors for CIP using logistic regression analysis and factors affecting PFS and OS using Cox regression analysis.

RESULTS

A total of 128 patients with SCLC were included in the study. ILA was present in 41 patients (32.03%), and CIP occurred in 16 patients (12.50%). In multivariate logistic regression analysis, previous ILA (OR, 5.419; 95% CI, 1.574-18.652; p = 0.007) and thoracic radiation therapy (TRT) (OR, 5.259; 95% CI, 1.506-18.365; p = 0.009) were independent risk factors for CIP. ILA (HR, 2.083; 95% CI, 1.179-3.681; p = 0.012) and LDH (HR, 1.002; 95% CI, 1.001-1.002; p < 0.001) were statistically significant for increased mortality risk in multivariate Cox regression analysis.

CONCLUSIONS

In SCLC patients receiving first-line chemoimmunotherapy, baseline ILA is a risk factor for CIP and is associated with poorer prognosis.

Prognostic Impact of Pulmonary Diseases in 952 Patients with Thoracic and/or Abdominal Aortic Aneurysm

Background/Objectives: Pulmonary diseases are common in patients with thoracic aortic aneurysm (TAA) and abdominal aortic aneurysm (AAA). Although high prevalences of chronic obstructive pulmonary disease and lung cancer (LC) are known, the prevalence of these and other pulmonary diseases regarding their relation to the outcome of TAA and/or AAA are not determined. Methods: Pulmonary diseases present at aortic aneurysm (AA) diagnosis and follow-up periods and cause of death of 952 patients with TAA, AAA, or TAA + AAA (including thoracoabdominal AA) treated at our institution in Japan were retrospectively analyzed. Cox regression analysis was used to investigate potential risk factors of mortality. Results: The mean patient age was 72.4 years, and the median follow-up was 4.92 years. At diagnosis, 528 (55.5%) patients had pulmonary diseases, including emphysema without interstitial lung disease (ILD) or LC, LC, idiopathic pulmonary fibrosis (IPF) without LC, non-IPF ILD without LC, and interstitial lung abnormalities (ILAs) without LC in 250, 85, 65, 15, and 58 patients, respectively. During follow-up, LC and acute exacerbation (AE) of IPF developed in 50 and 12 patients, respectively. In 213 patients who died, there were 45 (21.1%) aortic disease-related deaths. Other causes of death included LC (27.7%), cardiovascular events (9.4%), pneumonia (5.6%), and interstitial lung disease (4.7%). In a multivariate Cox regression hazard model, age; larger maximum aneurysm diameter; and coexisting LC, IPF, or concomitant cancer were associated with poor prognosis. Conclusions: In patients with AA, not only age and aneurysm diameter but also coexisting LC and IPF were prognostic factors for mortality.

Genomic and Serological Rheumatoid Arthritis Biomarkers, MUC5B Promoter Variant, and Interstitial Lung Abnormalities

RATIONALE

Rheumatoid arthritis (RA) has been implicated in interstitial lung disease (ILD) as majority of studies have been comprised of patients with known RA. However, it remains unclear whether an underlying risk for RA in combination with genetic risk for pulmonary fibrosis is associated with radiological markers of early lung injury and fibrosis in broader population samples.

OBJECTIVE

Determine whether genetic and serological biomarkers of RA risk in combination with the MUC5B (rs35705950) risk allele (T) are associated with interstitial lung abnormalities (ILA) on computed tomography (CT) scans.

METHODS

Associations of RA-risk HLA-DRB1 alleles (*04:01, *04:08, *04:05, *04:04, *10:01) and serum RA autoantibodies with ILA in the Multi-Ethnic Study of Atherosclerosis (MESA, n=4,018) and COPDGene (n=5,963) cohorts were modeled using logistic regression and adjusted for age, sex, self-reported race and ethnicity, smoking history, body mass index, and principal components of genetic ancestry.

RESULTS

The prevalence of an RA risk HLA-DRB1 allele was 16.5% and 21.9% in MESA and COPDGene, respectively. ILA was present in 3.9% and 11% in MESA and COPDGene, respectively. An RA risk HLA-DRB1 allele was not significantly associated with ILA in MESA and COPDGene. In MESA, higher serum levels of IgA rheumatoid factor (RF) and anti-cyclic citrullinated peptide were associated with an odds ratio (OR) for ILA of 1.20 (95% CI 1.07-1.35) and 1.19 (95% CI 1.04-1.37), respectively. Among smokers without baseline ILA, per doubling of IgM RF was associated with an OR for ILA 10 years later of 1.25 (95% CI 1.08-1.43). Associations were not significantly different by MUC5B risk allele status.

CONCLUSIONS

RA-related HLA-DRB1 alleles were not associated with ILA, whereas higher serum levels of IgM RF among smokers without baseline ILA were associated with subsequent ILA.

Interstitial Lung Abnormality: Narrative Review of the Approach to Diagnosis and Management

TOPIC IMPORTANCE

As interstitial lung abnormalities (ILAs) are increasingly recognized on imaging and in clinical practice, identification and appropriate management are critical. We propose an algorithmic approach to the identification and management of patients with ILAs.

REVIEW FINDINGS

The radiologist initially identifies chest CT scan findings suggestive of an ILA pattern and excludes findings that are not consistent with ILAs. The next step is to confirm that these findings occupy > 5% of a nondependent lung zone. At this point, the radiologic pattern of ILA is identified. These findings are classified as non-subpleural, subpleural nonfibrotic, and subpleural fibrotic. It is then incumbent on the clinician to ascertain if the patient has symptoms and/or abnormal pulmonary physiology that may be attributable to these radiologic changes. Based on the patient's symptoms, physiological assessment, and risk factors for interstitial lung disease (ILD), we recommend classifying patients as having ILA, at high risk for developing ILD, probable ILD, or ILD. In patients identified as having ILA, a multidisciplinary discussion should evaluate features that indicate an increased risk of progression. If these features are present, serial monitoring is recommended to be proactive. If the patient does not have imaging or clinical features that indicate an increased risk of progression, then monitoring is recommended to be reactive. If ILD is subsequently diagnosed, the management is disease specific.

SUMMARY

We anticipate this algorithmic approach will aid clinicians in interpreting the radiologic pattern described as ILA within the clinical context of their patients.

Interstitial lung abnormality in COPD is inversely associated with the comorbidity of lung cancer

BACKGROUND

Interstitial lung abnormality (ILA) has been recognized as a pertinent factor in the development and prognosis of various pulmonary conditions. However, its correlation with co-morbidities remains understudied. The current study endeavors to elucidate the association between ILA and both clinical features and co-morbidities in patients with chronic obstructive pulmonary disease (COPD).

METHODS

A retrospective cohort comprising 1131 hospitalized patients diagnosed with COPD was examined in this observational study. Patients were dichotomously classified based on the presence or absence of ILA, and subsequent analyses scrutinized disparities in demographic, clinical, and laboratory profiles, alongside co-morbid conditions, between the two subgroups.

RESULTS

Of the 1131 COPD patients, 165 (14.6%) exhibited ILA. No statistically significant differences were discerned between COPD patients with and without ILA concerning demographic, clinical, or laboratory parameters, except for levels of circulating fibrinogen and procalcitonin. Nevertheless, a notable discrepancy emerged in the prevalence of multiple co-morbidities. Relative to COPD patients devoid of ILA, those presenting with ILA manifested a diminished prevalence of lung cancer (OR = 0.50, 95% CI: 0.30-0.83, p = 0.006), particularly of the lung adenocarcinoma (OR = 0.32, 95% CI: 0.15-0.71, p = 0.005). Additionally, the presence of ILA in COPD was positively associated with heart failure (OR = 1.75, 95% CI: 1.04-3.00, p = 0.040) and cancers other than lung cancer (OR = 2.27, 95% CI: 1.16-4.39, p = 0.012).

CONCLUSION

These findings demonstrate that the presence of ILA is associated with co-morbidities of COPD, particularly lung cancer.

Clinical utility of lung ultrasound for the detection of interstitial lung disease in patients with rheumatoid arthritis

OBJECTIVE

To establish the diagnostic value of lung ultrasound (LUS) in patients with rheumatoid arthritis (RA) for the detection of interstitial lung disease (ILD).

METHODS

A cross-sectional study was performed. Consecutive patients with RA (American College of Rheumatology/European League Against Rheumatism 2010 criteria) who had a chest high-resolution computed tomography (HRCT) performed within 12 months before inclusion, regardless of symptomatology, were included. Demographic, clinical, laboratory, and pharmacological data were recorded. Each patient underwent a LUS with assessment of B-lines (BL) and pleural irregularities (PI). HRCT was considered the gold standard for the confirmatory diagnosis of ILD. Receiver operating characteristic (ROC) curves were calculated to test the ability of LUS findings (BL and PI) in discriminating patients with ILD.

RESULTS

A total of 104 RA patients were included, of which 21.8% had ILD. Patients with ILD had more BL (median 26 versus 1, p<0.001) and PI (median 16 versus 5, p<0.001) than patients without ILD. The diagnostic accuracy in ROC curves was as follows: area under the curve (AUC) 0.88 and 95% confidence interval (CI) 0.78-0.93 for BL and AUC 0.82 and 95% CI 0.74-0.89 for PI. The best cut-off points for (ILD detection) discriminating the presence of significant interstitial lung abnormalities were 8 BL and 7 PI.

CONCLUSIONS

The presence of 8 BL and/or 7 PI in the LUS showed an adequate cut-off value for discriminating the presence of significant interstitial lung abnormalities, evocative of ILD.

Neoadjuvant and Adjuvant Treatments for Early Stage Resectable NSCLC: Consensus Recommendations From the International Association for the Study of Lung Cancer

Advances in the multidisciplinary care of early stage resectable NSCLC (rNSCLC) are emerging at an unprecedented pace. Numerous phase 3 trials produced results that have transformed patient outcomes for the better, yet these findings also require important modifications to the patient treatment journey trajectory and reorganization of care pathways. Perhaps, most notably, the need for multispecialty collaboration for this patient population has never been greater. These rapid advances have inevitably left us with important gaps in knowledge for which definitive answers will only become available in several years. To this end, the International Association for the Study of Lung Cancer commissioned a diverse multidisciplinary international expert panel to evaluate the current landscape and provide diagnostic, staging, and therapeutic recommendations for patients with rNSCLC, with particular emphasis on patients with American Joint Committee on Cancer-Union for International Cancer Control TNM eighth edition stages II and III disease. Using a team-based approach, we generated 19 recommendations, of which all but one achieved greater than 85% consensus among panel members. A public voting process was initiated, which successfully validated and provided qualitative nuance to our recommendations. Highlights include the following: (1) the critical importance of a multidisciplinary approach to the evaluation of patients with rNSCLC driven by shared clinical decision-making of a multispecialty team of expert providers; (2) biomarker testing for rNSCLC; (3) a preference for neoadjuvant chemoimmunotherapy for stage III rNSCLC; (4) equipoise regarding the optimal management of patients with stage II between upfront surgery followed by adjuvant therapy and neoadjuvant or perioperative strategies; and (5) the robust preference for adjuvant targeted therapy for patients with rNSCLC and sensitizing EGFR and ALK tumor alterations. Our primary goals were to provide practical recommendations sensitive to the global differences in biology and resources for patients with rNSCLC and to provide expert consensus guidance tailored to the individualized patient needs, goals, and preferences in their cancer care journey as these are areas where physicians must make daily clinical decisions in the absence of definitive data. These recommendations will continue to evolve as the treatment landscape for rNSCLC expands and more knowledge is acquired on the best therapeutic approach in specific patient and disease subgroups.

Ultra-high resolution spectral photon-counting CT outperforms dual layer CT for lung imaging: Results of a phantom study

PURPOSE

The purpose of this study was to compare lung image quality obtained with ultra-high resolution (UHR) spectral photon-counting CT (SPCCT) with that of dual-layer CT (DLCT), at standard and low dose levels using an image quality phantom and an anthropomorphic lung phantom.

METHODS

An image quality phantom was scanned using a clinical SPCCT prototype and an 8 cm collimation DLCT from the same manufacturer at 10 mGy. Additional acquisitions at 6 mGy were performed with SPCCT only. Images were reconstructed with dedicated high-frequency reconstruction kernels, slice thickness between 0.58 and 0.67 mm, and matrix between 5122 and 10242 mm, using a hybrid iterative algorithm at level 6. Noise power spectrum (NPS), task-based transfer function (TTF) for iodine and air inserts, and detectability index (d') were assessed for ground-glass and solid nodules of 2 mm to simulate highly detailed lung lesions. Subjective analysis of an anthropomorphic lung phantom was performed by two radiologists using a five-point quality score.

RESULTS

At 10 mGy, noise magnitude was reduced by 29.1 % with SPCCT images compared to DLCT images for all parameters (27.1 ± 11.0 [standard deviation (SD)] HU vs. 38.2 ± 1.0 [SD] HU, respectively). At 6 mGy with SPCCT images, noise magnitude was reduced by 8.9 % compared to DLCT images at 10 mGy (34.8 ± 14.1 [SD] HU vs. 38.2 ± 1.0 [SD] HU, respectively). At 10 mGy and 6 mGy, average NPS spatial frequency (fav) was greater for SPCCT images (0.75 ± 0.17 [SD] mm-1) compared to DLCT images at 10 mGy (0.55 ± 0.04 [SD] mm-1) while remaining constant from 10 to 6 mGy. At 10 mGy, TTF at 50 % (f50) was greater for SPCCT images (0.92 ± 0.08 [SD] mm-1) compared to DLCT images (0.67 ± 0.06 [SD] mm-1) for both inserts. At 6 mGy, f50 decreased by 1.1 % for SPCCT images, while remaining greater compared to DLCT images at 10 mGy (0.91 ± 0.06 [SD] mm-1 vs. 0.67 ± 0.06 [SD] mm-1, respectively). At both dose levels, d' were greater for SPCCT images compared to DLCT for all clinical tasks. Subjective analysis performed by two radiologists revealed a greater median image quality for SPCCT (5; Q1, 4; Q3, 5) compared to DLCT images (3; Q1, 3; Q3, 3).

CONCLUSION

UHR SPCCT outperforms DLCT in terms of image quality for lung imaging. In addition, UHR SPCCT contributes to a 40 % reduction in radiation dose compared to DLCT.

Clinical and radiological pattern of olaparib-induced interstitial lung disease

BACKGROUND

PARP inhibitors (PARPi) are used in the treatment of ovarian, breast, pancreatic, and prostate cancers. Pneumonitis has been identified as a potential side effect, with a higher meta-analysis-assessed risk for olaparib versus other PARPi. Olaparib-induced interstitial lung disease (O-ILD) was first described within the Japanese population, with few information available for Caucasian patients.

METHODS

We performed a retrospective study by pooling data from the French and Belgian pharmacovigilance databases from 2018 to 2022. Patients with O-ILD were included following a central review by: 1) pharmacologists using the French drug causality assessment method; 2) senior pneumologists or radiologists, using the Fleischner Society's recommendations.

RESULTS

Five patients were identified and analysed. All were females, with ovarian or breast cancer. Median age at O-ILD diagnosis was 71 (38-72) years old, with no smoking history. Median delay between treatment initiation and symptom occurrence was 12 (6-33) weeks. Pneumonitis severity assessed using the Common Terminology Criteria for Adverse Events V5 was Grade 3 (n = 4) or 2 (n = 1). CT-scan review (n = 3) described hypersensitivity pneumonitis reaction as a common pattern. Bronchioalveolar lavage (n = 4) revealed lymphocytic alveolitis. Treatments relied on olaparib discontinuation (n = 5) and glucocorticoid intake (n = 4), with no fatal issue. Safe re-challenge with PARPi occurred in two patients. Forty additional O-ILD cases were identified in the WHO VigiBase database, including one fatal case.

CONCLUSIONS

PARPi-ILD is a rare but potentially life-threatening disease, presenting as a hypersensitivity pneumonitis pattern within 3 months of PARPi initiation. Treatment primarily relies on medication discontinuation. Re-challenging with another PARPi could be considered.

CLINICAL TRIAL NUMBER

CEPRO #2023-010.

ESR Essentials: imaging in fibrotic lung diseases-practice recommendations by the European Society of Thoracic Imaging

Fibrotic lung diseases (FLDs) represent a subgroup of interstitial lung diseases (ILDs), which can progress over time and carry a poor prognosis. Imaging has increased diagnostic discrimination in the evaluation of FLDs. International guidelines have stated the role of radiologists in the diagnosis and management of FLDs, in the context of the interdisciplinary discussion. Chest computed tomography (CT) with high-resolution technique is recommended to correctly recognise signs, patterns, and distribution of individual FLDs. Radiologists may be the first to recognise the presence of previously unknown interstitial lung abnormalities (ILAs) in various settings. A systematic approach to CT images may lead to a non-invasive diagnosis of FLDs. Careful comparison of serial CT exams is crucial in determining either disease progression or supervening complications. This 'Essentials' aims to provide radiologists a concise and practical approach to FLDs, focusing on CT technical requirements, pattern recognition, and assessment of disease progression and complications. Hot topics such as ILAs and progressive pulmonary fibrosis (PPF) are also discussed. KEY POINTS: Chest CT with high-resolution technique is the recommended imaging modality to diagnose pulmonary fibrosis. CT pattern recognition is central for an accurate diagnosis of fibrotic lung diseases (FLDs) by interdisciplinary discussion. Radiologists are to evaluate disease behaviour by accurately comparing serial CT scans.

Outcome of immune checkpoint inhibitor treatment in non-small cell lung cancer patients with interstitial lung abnormalities: clinical utility of subcategorizing interstitial lung abnormalities

Interstitial lung abnormalities (ILAs) are immune checkpoint inhibitor (ICI)-related pneumonitis (ICI-P) risk factors. However, the relationship between imaging patterns and immunotherapy outcomes, and treatment strategies remain unclear in patients with non-small cell lung cancer (NSCLC) and ILAs. We retrospectively evaluated patients with ILAs-complicated NSCLC who received ICI therapy. ILAs were subcategorized as non-subpleural, subpleural non-fibrotic, and subpleural fibrotic (SF) based on the 2020 position paper by the Fleischner Society. We investigated ICI-P incidence, ICI-P risk factors, lung cancer prognosis, and ILAs radiological progression. Of the 481 ICI-treated patients, 79 (16.4%) had ILAs (45 non-SF and 34 SF). The ICI-P cumulative incidence (hazard ratio, 4.57; 95% confidence interval [CI], 1.90-10.98; p = 0.001) and any grade and grade ≥ 3 ICI-P incidences were higher in patients with SF-ILAs than in those with non-SF-ILAs (all grades: 7/45 [15.6%)] vs. 18/34 [52.9%]; p < 0.001; grade ≥ 3: 1/45 [2.2%] vs. 10/34 [29.4%]; p = 0.001). According to multivariate analysis, SF-ILAs independently predicted ICI-P (odds ratio, 5.35; 95% CI 1.62-17.61; p = 0.006). Patients with SF-ILAs had shorter progression-free and overall survival and higher ICI-P-related respiratory failure death rates than those with non-SF-ILAs. Approximately 2.5 times more patients with SF-ILAs showed progression by the 2-year follow-up than those with non-SF-ILAs. SF-ILAs is an independent strong predictor of ICI-P development in patients with NSCLC, may increase ICI-P severity, worsen prognosis, and accelerate ILAs progression. ILAs subcategorization is an important treatment strategy for patients with lung cancer treated with ICIs.

Air Pollution Exposure and Interstitial Lung Features in SPIROMICS Participants with Chronic Obstructive Pulmonary Disease

Rationale: It is unknown whether air pollution is associated with radiographic features of interstitial lung disease in individuals with chronic obstructive pulmonary disease (COPD). Objectives: To determine whether air pollution increases the prevalence of interstitial lung abnormalities (ILA) or percent high-attenuation areas (HAA) on computed tomography (CT) in individuals with a heavy smoking history and COPD. Methods: We performed a cross-sectional study of SPIROMICS (Subpopulations and Intermediate Outcome Measures in COPD Study), focused on current or former smokers with COPD. Ten-year exposure to particulate matter ⩽2.5 μm in aerodynamic diameter (PM2.5), nitrogen oxides (NOx), nitrogen dioxide (NO2), and ozone before enrollment CT (completed between 2010 and 2015) were estimated with validated spatiotemporal models at residential addresses. We applied adjusted multivariable modified Poisson regression and linear regression to investigate associations between pollution exposure and relative risk (RR) of ILA or increased percent HAA (between -600 and -250 Hounsfield units), respectively. We assessed for effect modification by MUC5B-promoter polymorphism (variant allele carriers GT or TT vs. GG at rs3705950), smoking status, sex, and percent emphysema. Results: Among 1,272 participants with COPD assessed for HAA, 424 were current smokers, and 249 were carriers of the variant MUC5B allele. A total of 519 participants were assessed for ILA. We found no association between pollution exposure and ILA or HAA. Associations between pollutant exposures and risk of ILA were modified by the presence of MUC5B polymorphism (P value interaction term for NOx = 0.04 and PM2.5 = 0.05) and smoking status (P value interaction term for NOx = 0.05; NO2 = 0.01; and ozone = 0.05). With higher exposure to NOx and PM2.5, MUC5B variant carriers had an increased risk of ILA (RR per 26 ppb NOx, 2.41; 95% confidence interval [CI], 0.97-6.0; and RR per 4 μg ⋅ m-3 PM2.5, 1.43; 95% CI, 0.93-2.2, respectively). With higher exposure to NO2, former smokers had an increased risk of ILA (RR per 10 ppb, 1.64; 95% CI, 1.0-2.7). Conclusions: Exposure to ambient air pollution was not associated with interstitial features on CT in this population of heavy smokers with COPD. MUC5B modified the association between pollution and ILA, suggesting that gene-environment interactions may influence prevalence of interstitial lung features in COPD.

Idiopathic dendriform pulmonary ossification as the phenotype of interstitial lung abnormalities: CT-pathologic correlation and prevalence

BACKGROUND AND PURPOSE

Idiopathic dendriform pulmonary ossification (DPO) is mostly asymptomatic, and detected incidentally in lung CT. There have been no reports on the precise CT-pathologic correlation and the prevalence of idiopathic DPO. This study aimed to clarify the histological background and prevalence of idiopathic DPO.

MATERIALS AND METHODS

Sixteen patients with histologically confirmed idiopathic DPO (12 men and 4 women; mean age, 38.8 years; range 22-56 years) were identified in a nationwide epidemiological survey. Local HRCT findings of pre-biopsy examinations, such as branching, round, linear structures with or without high attenuation were compared side by side with histological findings. The attenuation of branching, round, and linear structures was classified into three-point levels on bone window images (width, 2500 HU; level, 500 HU). Furthermore, we collected continuous pulmonary CT images of 8111 cases for checking up metastasis from extrathoracic malignancy at a single institution, and evaluated the prevalence of interstitial lung abnormalities (ILAs) and DPO.

RESULTS

In all 16 cases, branching (n = 15, 93%), round (n = 5, 31%), or linear (n = 5, 31%) structures were identified, histologically corresponding to dendriform ossification and cicatricial organizing pneumonia (OP)/fibrosis. Histologically, ossification was confirmed in all the 16 patients. However, in two cases, a highly attenuated structure could not be detected on the pre-biopsy CT of the same area. Regarding the prevalence of idiopathic DPO, 283 (3.5%) of 8111 patients had ILAs, of which a total of 26 (0.3% of all cases, 9.2% of ILAs cases) had DPO.

CONCLUSION

Idiopathic DPO showed linear or branching structures with or without high attenuation on CT, corresponded to ossification, cicatricial OP/fibrosis. DPO was seen in 9.2% of ILAs cases. Idiopathic DPO is one of pathologic phenotypes of ILAs.

Automated Interstitial Lung Abnormality Probability Prediction at CT: A Stepwise Machine Learning Approach in the Boston Lung Cancer Study

Background It is increasingly recognized that interstitial lung abnormalities (ILAs) detected at CT have potential clinical implications, but automated identification of ILAs has not yet been fully established. Purpose To develop and test automated ILA probability prediction models using machine learning techniques on CT images. Materials and Methods This secondary analysis of a retrospective study included CT scans from patients in the Boston Lung Cancer Study collected between February 2004 and June 2017. Visual assessment of ILAs by two radiologists and a pulmonologist served as the ground truth. Automated ILA probability prediction models were developed that used a stepwise approach involving section inference and case inference models. The section inference model produced an ILA probability for each CT section, and the case inference model integrated these probabilities to generate the case-level ILA probability. For indeterminate sections and cases, both two- and three-label methods were evaluated. For the case inference model, we tested three machine learning classifiers (support vector machine [SVM], random forest [RF], and convolutional neural network [CNN]). Receiver operating characteristic analysis was performed to calculate the area under the receiver operating characteristic curve (AUC). Results A total of 1382 CT scans (mean patient age, 67 years ± 11 [SD]; 759 women) were included. Of the 1382 CT scans, 104 (8%) were assessed as having ILA, 492 (36%) as indeterminate for ILA, and 786 (57%) as without ILA according to ground-truth labeling. The cohort was divided into a training set (n = 96; ILA, n = 48), a validation set (n = 24; ILA, n = 12), and a test set (n = 1262; ILA, n = 44). Among the models evaluated (two- and three-label section inference models; two- and three-label SVM, RF, and CNN case inference models), the model using the three-label method in the section inference model and the two-label method and RF in the case inference model achieved the highest AUC, at 0.87. Conclusion The model demonstrated substantial performance in estimating ILA probability, indicating its potential utility in clinical settings. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Zagurovskaya in this issue.

Quantitative analysis of interstitial lung abnormalities on computed tomography to predict symptomatic radiation pneumonitis after lung stereotactic body radiotherapy

BACKGROUND AND PURPOSE

Symptomatic radiation pneumonitis (SRP) is a complication of thoracic stereotactic body radiotherapy (SBRT). As visual assessments pose limitations, artificial intelligence-based quantitative computed tomography image analysis software (AIQCT) may help predict SRP risk. We aimed to evaluate high-resolution computed tomography (HRCT) images with AIQCT to develop a predictive model for SRP.

MATERIALS AND METHODS

AIQCT automatically labelled HRCT images of patients treated with SBRT for stage I lung cancer according to lung parenchymal pattern. Quantitative data including the volume and mean dose (Dmean) were obtained for reticulation + honeycombing (Ret + HC), consolidation + ground-glass opacities, bronchi (Br), and normal lungs (NL). After associations between AIQCT's quantified metrics and SRP were investigated, we developed a predictive model using recursive partitioning analysis (RPA) for the training cohort and assessed its reproducibility with the testing cohort.

RESULTS

Overall, 26 of 207 patients developed SRP. There were significant between-group differences in the Ret + HC, Br-volume, and NL-Dmean in patients with and without SRP. RPA identified the following risk groups: NL-Dmean ≥ 6.6 Gy (high-risk, n = 8), NL-Dmean < 6.6 Gy and Br-volume ≥ 2.5 % (intermediate-risk, n = 13), and NL-Dmean < 6.6 Gy and Br-volume < 2.5 % (low-risk, n = 133). The incidences of SRP in these groups within the training cohort were 62.5, 38.4, and 7.5 %; and in the testing cohort 50.0, 27.3, and 5.0 %, respectively.

CONCLUSION

AIQCT identified CT features associated with SRP. A predictive model for SRP was proposed based on AI-detected Br-volume and the NL-Dmean.

High resolution computed tomography in systemic sclerosis: From diagnosis to follow-up

Early diagnosis of interstitial lung disease (ILD) and pulmonary hypertension (PH) is crucial in systemic sclerosis (SSc) for both management and treatment. However, diagnosing SSc-ILD can be challenging because symptoms of lung involvement are often non-specific at the early stages of disease. High-resolution computed tomography (HRCT) of the chest is recognized as the most accurate imaging modality for baseline and follow-up evaluation of SSc-ILD. Key features of SSc-ILD on HRCT include a non-specific interstitial pneumonia (NSIP) pattern, with peripheral ground-glass opacities and extensive traction bronchiectasis. Less common HRCT manifestations include usual interstitial pneumonia (UIP) pattern, followed by diffuse alveolar damage (DAD), diffuse alveolar hemorrhage (DAH) and organizing pneumonia (OP). The extent of disease on HRCT is known to relate with prognosis and serial assessments can be helpful in monitoring disease progression or treatment response. We discuss the main chest computed tomography (CT) manifestations of SSc, highlighting the role of imaging at both baseline and follow-up evaluations.

Nonfibrotic (cellular) hypersensitivity pneumonitis with and without slight lung distortion

BACKGROUND

According to international diagnostic guidelines for hypersensitivity pneumonitis (HP), cases with both nonfibrotic and fibrotic lesions are classified by the predominant feature. Therefore, some cases with nonfibrotic HP, have inflammatory lesions alone, while others have a mixture of fibrosis and inflammation. We investigated the impact of slight fibrotic lesions in nonfibrotic HP.

METHODS

This retrospective study included nonfibrotic HP cases with <10% of lung distortion on high-resolution CT. We divided the cases into two groups: those with pure ground glass opacities (GGOs) without lung distortion and those with slight lung distortion of <10%.

RESULTS

In this study, 37 cases were included. The mean baseline forced vital capacity (FVC) was 109% in the pure GGO group and 96% in the slight lung distortion group (p = 0.038). After 1 year, the reticular shadows appeared or increased more in the slight lung distortion group than in the pure GGO group (16% vs. 8%, p = 0.030). The time to medication initiation was significantly shorter in the slight lung distortion group than in the pure GGO group (p = 0.044). %FVC decreased by ≥ 5% from diagnosis in no cases with the pure GGO and in two cases with the slight lung distortion (-11.0% for 9.5 years and -10.7% for 1.3 years, respectively).

CONCLUSIONS

The slight distortion group exhibited a higher rate of worsening and new appearance of reticular shadows after 1 year and a shorter time to first medication compared to the pure GGO group.

Genetics and Genomics of Pulmonary Fibrosis: Charting the Molecular Landscape and Shaping Precision Medicine

Recent genetic and genomic advancements have elucidated the complex etiology of idiopathic pulmonary fibrosis (IPF) and other progressive fibrotic interstitial lung diseases (ILDs), emphasizing the contribution of heritable factors. This state-of-the-art review synthesizes evidence on significant genetic contributors to pulmonary fibrosis (PF), including rare genetic variants and common SNPs. The MUC5B promoter variant is unusual, a common SNP that markedly elevates the risk of early and established PF. We address the utility of genetic variation in enhancing understanding of disease pathogenesis and clinical phenotypes, improving disease definitions, and informing prognosis and treatment response. Critical research gaps are highlighted, particularly the underrepresentation of non-European ancestries in PF genetic studies and the exploration of PF phenotypes beyond usual interstitial pneumonia/IPF. We discuss the role of telomere length, often critically short in PF, and its link to progression and mortality, underscoring the genetic complexity involving telomere biology genes (TERT, TERC) and others like SFTPC and MUC5B. In addition, we address the potential of gene-by-environment interactions to modulate disease manifestation, advocating for precision medicine in PF. Insights from gene expression profiling studies and multiomic analyses highlight the promise for understanding disease pathogenesis and offer new approaches to clinical care, therapeutic drug development, and biomarker discovery. Finally, we discuss the ethical, legal, and social implications of genomic research and therapies in PF, stressing the need for sound practices and informed clinical genetic discussions. Looking forward, we advocate for comprehensive genetic testing panels and polygenic risk scores to improve the management of PF and related ILDs across diverse populations.

Microscopic Small Airway Abnormalities Identified in Early Idiopathic Pulmonary Fibrosis In Vivo Using Endobronchial Optical Coherence Tomography

Rationale: Idiopathic pulmonary fibrosis (IPF) affects the subpleural lung but is considered to spare small airways. Micro-computed tomography (micro-CT) studies demonstrated small airway reduction in end-stage IPF explanted lungs, raising questions about small airway involvement in early-stage disease. Endobronchial optical coherence tomography (EB-OCT) is a volumetric imaging modality that detects microscopic features from subpleural to proximal airways. Objectives: In this study, EB-OCT was used to evaluate small airways in early IPF and control subjects in vivo. Methods: EB-OCT was performed in 12 subjects with IPF and 5 control subjects (matched by age, sex, smoking history, height, and body mass index). Subjects with IPF had early disease with mild restriction (FVC: 83.5% predicted), which was diagnosed per current guidelines and confirmed by surgical biopsy. EB-OCT volumetric imaging was acquired bronchoscopically in multiple, distinct, bilateral lung locations (total: 97 sites). IPF imaging sites were classified by severity into affected (all criteria for usual interstitial pneumonia present) and less affected (some but not all criteria for usual interstitial pneumonia present). Bronchiole count and small airway stereology metrics were measured for each EB-OCT imaging site. Measurements and Main Results: Compared with the number of bronchioles in control subjects (mean = 11.2/cm3; SD = 6.2), there was significant bronchiole reduction in subjects with IPF (42% loss; mean = 6.5/cm3; SD = 3.4; P = 0.0039), including in IPF affected (48% loss; mean: 5.8/cm3; SD: 2.8; P < 0.00001) and IPF less affected (33% loss; mean: 7.5/cm3; SD: 4.1; P = 0.024) sites. Stereology metrics showed that IPF-affected small airways were significantly larger, more distorted, and more irregular than in IPF-less affected sites and control subjects. IPF less affected and control airways were statistically indistinguishable for all stereology parameters (P = 0.36-1.0). Conclusions: EB-OCT demonstrated marked bronchiolar loss in early IPF (between 30% and 50%), even in areas minimally affected by disease, compared with matched control subjects. These findings support small airway disease as a feature of early IPF, providing novel insight into pathogenesis and potential therapeutic targets.

Chronic Chest Computed Tomography Findings Following COVID-19 Pneumonia

Respiratory symptoms are a frequent manifestation of patients with post-acute sequela of SARS-CoV-2 (PASC), also known as long-COVID. Many cohorts of predominantly hospitalized patients have shown that a significant subset may have persistent chest computed tomography findings for more than 12 months after the acute infection. Proper understanding of the evolving long-term imaging findings and terminology is crucial for accurate imaging interpretation and patient care. The goal of this article is to review the chronic chest computed tomography findings of patients with PASC and common pitfalls.

Association between interstitial lung abnormality and mortality in patients with esophageal cancer

PURPOSE

To investigate the relationship between interstitial lung abnormalities (ILAs) and mortality in patients with esophageal cancer and the cause of mortality.

MATERIALS AND METHODS

This retrospective study investigated patients with esophageal cancer from January 2011 to December 2015. ILAs were visually scored on baseline CT using a 3-point scale (0 = non-ILA, 1 = indeterminate for ILA, and 2 = ILA). ILAs were classified into subcategories of non-subpleural, subpleural non-fibrotic, and subpleural fibrotic. Five-year overall survival (OS) was compared between patients with and without ILAs using the multivariable Cox proportional hazards model. Subgroup analyses were performed based on cancer stage and ILA subcategories. The prevalences of treatment complications and death due to esophageal cancer and pneumonia/respiratory failure were analyzed using Fisher's exact test.

RESULTS

A total of 478 patients with esophageal cancer (age, 66.8 years ± 8.6 [standard deviation]; 64 women) were evaluated in this study. Among them, 267 patients showed no ILAs, 125 patients were indeterminate for ILAs, and 86 patients showed ILAs. ILAs were a significant factor for shorter OS (hazard ratio [HR] = 1.68, 95% confidence interval [CI] 1.10-2.55, P = 0.016) in the multivariable Cox proportional hazards model adjusting for age, sex, smoking history, clinical stage, and histology. On subgroup analysis using patients with clinical stage IVB, the presence of ILAs was a significant factor (HR = 3.78, 95% CI 1.67-8.54, P = 0.001). Subpleural fibrotic ILAs were significantly associated with shorter OS (HR = 2.22, 95% CI 1.25-3.93, P = 0.006). There was no significant difference in treatment complications. Patients with ILAs showed a higher prevalence of death due to pneumonia/respiratory failure than those without ILAs (non-ILA, 2/95 [2%]; ILA, 5/39 [13%]; P = 0.022). The prevalence of death due to esophageal cancer was similar in patients with and without ILA (non-ILA, 82/95 [86%]; ILA 32/39 [82%]; P = 0.596).

CONCLUSION

ILAs were significantly associated with shorter survival in patients with esophageal cancer.

[Interstitial lung diseases : From imaging to treatment]

BACKGROUND

The role of radiology in the diagnosis of interstitial lung diseases (ILDs) has evolved over time, in part replacing histology. Radiology now represents a pillar of diagnostics and monitoring in ILDs.

OBJECTIVE

To what extent does radiology influence diagnostics and treatment in ILDs?

MATERIALS AND METHODS

A literature review was conducted, and current findings were discussed in the context of clinical data.

RESULTS

Radiology plays a crucial role in the diagnosis of ILDs. Within the framework of the multidisciplinary conference, it provides specific CT patterns such as usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP), and organizing pneumonia (OP), or helps in identifying cystic lung diseases. Multicompartment diseases can be detected, and pulmonary hypertension or extrapulmonary involvement of the respective diseases can be suspected. Progressive pulmonary fibrosis requires radiologic assessment as one of the required criteria. Interstitial lung abnormalities are usually detected by radiological studies performed for an unrelated indication.

CONCLUSION

Radiology plays an important role within the multidisciplinary conference to determine both diagnosis and treatment with antifibrotic or anti-inflammatory drugs, or a combination of both.

[Interstitial lung abnormalities : What the radiologist needs to know]

Interstitial lung abnormalities (ILA) are incidental findings on computed tomography (CT), particularly in elderly patients and smokers. They describe mild interstitial abnormalities that can be progressive and turn into overt interstitial lung disease (ILD). In recent years, ILA have increasingly come into focus because several large cohort studies have shown poorer clinical outcomes and increased mortality for patients with ILA compared to those without ILA. The radiological classification into nonsubpleural, subpleural nonfibrotic and subpleural fibrotic as well as the assessment over time can-together with clinical risk factors-help estimate clinical outcome. Clinical management of patients with ILA includes exclusion of ILD and risk-adapted control intervals, especially in the presence of risk factors.