Several specific high-resolution computed tomography patterns correlate with survival in patients with idiopathic pulmonary fibrosis

CT Honeycombing and Traction Bronchiectasis Extent Independently Predict Survival across Fibrotic Interstitial Lung Disease Subtypes

Background Prognostic value of radiologic features in interstitial lung disease (ILD) has been predominantly studied in idiopathic pulmonary fibrosis, but findings vary. The relative importance of features versus guideline-defined patterns in predicting outcomes is unknown. Purpose To identify radiologic features that are independently associated with transplant-free survival beyond clinical predictive factors across all ILD subtypes, and to identify whether individual features versus patterns are more important for prognostication. Materials and Methods This is a secondary analysis of the prospective Canadian Registry for Pulmonary Fibrosis. Consecutive patients with ILD were evaluated in standardized multidisciplinary discussions between January 2021 and March 2022. Radiologic features on thin-section CT images were quantified, and guideline-defined usual interstitial pneumonia (UIP) and fibrotic hypersensitivity pneumonitis (fHP) patterns were assigned. Multivariable Cox analysis was used to assess the associations of radiologic features with transplant-free survival, and nested models were used to test the relative importance of features compared with patterns. Results A total of 1593 patients (mean age, 66 years ± 12 [SD]; 800 male) were included. The following four features were associated with transplant-free survival: extent of honeycombing (hazard ratio, 1.20; 95% CI; 1.06, 1.36 per 10% increase in lung involvement; P = .005), extent of traction bronchiectasis (hazard ratio, 1.18; 95% CI: 1.10, 1.26 per 10% increase; P < .001), pulmonary artery diameter (hazard ratio, 1.03; 95% CI: 1.01; 1.04 per 1-mm increase; P = .002), and presence of subpleural sparing (hazard ratio, 0.76; 95% CI: 0.56, 0.96; P = .03). Guideline-defined patterns were not independently associated with survival in a model that included these four radiologic features, each of which retained its prognostic value. Conclusion The extent of fibrosis was predictive of worse outcomes across all ILD subtypes in a dose-dependent fashion and independent of well-recognized clinical prognostic factors. Guideline-defined UIP and fHP patterns each helped risk-stratify patients in isolation but lost prognostic value when accounting for the extent of fibrosis, suggesting that their previous association with mortality is based on these patterns acting as surrogates for a greater extent of fibrosis. © RSNA, 2025 Supplemental material is available for this article. See also the editorial by Wells in this issue.

Mortality-related risk factors of idiopathic pulmonary fibrosis: a systematic review and meta-analysis

Background

Idiopathic pulmonary fibrosis (IPF) has high mortality and poor prognosis, which brings enormous burdens to families and society. We conducted this meta-analysis to analyze and summarize the risk factors associated with mortality in IPF, hoping to provide reference for clinical prevention and treatment of IPF.

Methods

We conducted a comprehensive search of PubMed, Cochrane Library, Embase, and Web of Science from inception to August 10, 2023, to include cohort studies on mortality in patients with IPF. Two researchers independently screened the studies and extracted data. The Newcastle-Ottawa Scale (NOS) was used to assess the methodological quality of studies. Hazard ratios (HRs) and 95% confidence intervals (CIs) were reported to identify risk factors for mortality in IPF. In addition, we also carried out sensitivity analysis, Begg's and Egger's tests to evaluate the heterogeneity and publication bias.

Results

Eighteen studies comprising 8,408 patients were included. The meta-analysis suggested that age (HR =1.03; 95% CI: 1.01, 1.04; P<0.001), forced vital capacity (FVC) (HR =0.97; 95% CI: 0.96, 0.99; P=0.005), FVC to predicted value ratio (FVC% pred) (HR =0.98; 95% CI: 0.97, 0.99; P<0.001), diffusing capacity of the lungs for carbon monoxide to predicted value ratio (DLCO% pred) (HR =0.98; 95% CI: 0.97, 0.99; P<0.001), gender-age-physiology (GAP) index (HR =1.70; 95% CI: 1.20, 2.40; P=0.003), and lung cancer (HR =2.75, 95% CI: 1.23, 6.15; P=0.01) were mortality-related risk factors in patients with IPF. Whereas, gender, smoking, body mass index (BMI), diffusing capacity of the lungs for carbon monoxide (DLCO), C-reactive protein (CRP), 6-minute walking distance (6MWD), pulmonary hypertension, gastroesophageal reflux, and cardiovascular disease were not statistically associated with death.

Conclusions

Age, FVC, FVC% pred, DLCO% pred, GAP index, and lung cancer have been identified as potential risk factors for mortality in patients with IPF. Due to the limited number and quality of included studies, the conclusions need to be verified by further studies.

Volume changes of diseased and normal areas in progressive fibrosing interstitial lung disease on inspiratory and expiratory computed tomography

PURPOSE

The diagnosis of progressive fibrosing interstitial lung disease (PF-ILD) using computed tomography (CT) is an important medical practice in respiratory care, and most imaging findings for this disease have been obtained with inspiratory CT. It is possible that some characteristic changes in respiration may be seen in normal and diseased lung in PF-ILD, which may lead to a new understanding of the pathogenesis of interstitial pneumonia, but it has never been examined. In this study, we collected and selected inspiratory and expiratory CT scans performed in pure PF-ILD cases, and evaluated the volumes of diseased and normal lung separately by manual detection and 3-dimensional volumetry to characterize the dynamic features of PF-ILD.

MATERIALS AND METHODS

Cases were collected retrospectively from a total of 753 inspiratory and expiratory CT scans performed at our hospital over a 3-year period. Sixteen cases of pure PF-ILD, excluding almost all other diseases, were included. We measured their diseased, normal, and the whole lung volumes manually and evaluated the correlation of their values and their relationship with respiratory function tests (FVC, FVC%-predicted, and DLCO%-predicted).

RESULTS

The relative expansion rate of the diseased lung is no less than that of the normal lung. The "Expansion volume of total lung" divided by the "Expansion volume of normal lung" was found to be significantly associated with DLCO%-predicted abnormalities (p = 0.0073).

CONCLUSION

The diseased lung in PF-ILD retained expansion capacity comparable to the normal lung, suggesting a negative impact on respiratory function.

Radiological usual interstitial pneumonia pattern is associated with two-year mortality in patients with idiopathic pulmonary fibrosis

Introduction

The new diagnostic guidelines for idiopathic pulmonary fibrosis (IPF) did not rule out the possibility of combining the radiological patterns of usual interstitial pneumonia (UIP) and probable UIP, given the similar management and diagnostic capacity. However, the prognostic implications of these patterns have not been fully elucidated, with different studies showing heterogeneous results. We applied the new criteria to a retrospective series of patients with IPF, assessing survival based on radiological patterns, findings, and their extension.

Methods

Two thoracic radiologists reviewed high-resolution computed tomography images taken at diagnosis in 146 patients with IPF, describing the radiological findings and patterns. The association of each radiological finding and radiological patterns with two-year mortality was analysed.

Results

The two-year mortality rate was 40.2% in IPF patients with an UIP radiological pattern versus 7.1% in those with probable UIP. Compared to the UIP pattern, probable UIP was protective against mortality, even after adjusting for age, sex, pulmonary function, and extent of fibrosis (hazard ratio (HR) 0.23, 95% confidence interval (CI) 0.06-0.99). Receiving antifibrotic treatment was also a protective factor (HR 0.51, 95%CI 0.27-0.98). Honeycombing (HR 3.62, 95%CI 1.27-10.32), an acute exacerbation pattern (HR 4.07, 95%CI 1.84-8.96), and the overall extent of fibrosis (HR 1.04, 95%CI 1.02-1.06) were predictors of mortality.

Conclusions

In our series, two-year mortality was higher in patients with IPF who presented a radiological pattern of UIP versus probable UIP on the initial scan. Honeycombing, an acute exacerbation pattern, and a greater overall extent of fibrosis were also predictors of increased mortality. The prognostic differences between the radiological pattern of UIP and probable UIP in our series would support maintaining them as two differentiated patterns.

Factors influencing long-term outcomes in fibrotic interstitial lung disease (F-ILD) diagnosed through multidisciplinary discussion (MDD): a prospective cohort study

BACKGROUND

The diagnostic process for fibrotic interstitial lung disease (F-ILD) is notably intricate, necessitating a multidisciplinary discussion to achieve consensus based on both clinical and radiological features. This study investigated the shared and distinctive long-term mortality predictors among the two primary phenotypes of F-ILD, namely idiopathic pulmonary fibrosis (IPF) and connective tissue disease-associated interstitial lung disease (CTD-ILD).

METHODS

We included patients with F-ILD diagnosed from December 2018 to December 2019 and conducted follow-up assessments until February 2023. Age, gender, usual interstitial pneumonia (UIP) pattern, gender-age-physiology (GAP) score, modified Medical Research Council (mMRC) dyspnea score, antifibrotic agent use, pulmonary function test parameters, and six-minute walking test (6MWT) parameters were recorded at baseline and used as mortality predictors in a multivariate Cox regression model.

RESULTS

We enrolled 104 ILD patients. The survival rate of non-IPF patients was more than twice that of IPF patients (78.9% vs. 34%, p < 0.001), and the survival rate of patients with a GAP score of 0-2 was more than twice that of patients with a score of > 2 (93.2% vs. 36.6%, p < 0.001). Older age, male gender, definite UIP pattern, higher GAP score, higher mMRC dyspnea score, lower forced expiratory volume in one second/forced vital capacity (FEV1/FVC), shorter 6MWT distance, and lower initial and final SpO2 were also associated with higher long-term mortality (p < 0.05). In multivariable analysis, only a GAP score of > 2 (hazard ratio [HR]:16.7; 95% confidence interval [CI] 3.28-85.14; p = 0.001) and definite UIP pattern (HR: 4.08; 95% CI 1.07-15.5; p = 0.039) were significantly associated with overall mortality.

CONCLUSION

The long-term mortality rate of IPF patients was higher than that of CTD-ILD patients. The GAP score and UIP patterns were significant mortality predictors for both IPF and CTD-ILD patients.

Radiological findings based comparison of functional status in patients who have post-covid lung injury or idiopathic pulmonary fibrosis

BACKGROUND

Following COVID-19 infection, some patients acquired lung injury and fibrosis. Idiopathic pulmonary fibrosis is characterized by lung fibrosis. Both post-COVID lung injury and idiopathic pulmonary fibrosis cause loss of respiratory function and involvement of the lung parenchyma. We aimed to compare respiratory related functional characteristics and radiological involvement between post-COVID lung injury and idiopathic pulmonary fibrosis.

METHODS

A single center, cross-sectional study was applied. Patients with post-COVID lung injury and idiopathic pulmonary fibrosis included in the study. All patients underwent the 6-minute walk test, as well as the Borg and MRC scales. Radiological images were evaluated and scored for lung parenchymal involvement. The impact of post-COVID lung injury and idiopathic pulmonary fibrosis on respiratory functions of were compared. The relationship of functional status and radiological involvement, as well as the effect of potential confounding factors were investigated.

RESULTS

A total of 71 patients were included in the study. Forty-eight (67.6%) of the patients were male and the mean age was 65.4 ± 10.3 years. Patients with post-COVID lung injury had greater 6-minute walk test distance and duration, as well as higher oxygen saturations. The MRC and Borg dyspnea scores were comparable. At radiologic evaluation, ground glass opacity scores were higher in patients with post-COVID lung injury, whereas pulmonary fibrosis scores were higher in patients with idiopathic pulmonary fibrosis. However, the total severity scores were similar. While pulmonary fibrosis score was found to have a negative correlation with 6-minute walk test distance, test duration, and pre- and post-test oxygen saturation levels, there was a positive correlation with oxygen saturation recovery time and MRC score. There was no relationship between ground glass opacity and the functional parameters.

CONCLUSIONS

Despite having equal degrees of radiological involvement and dyspnea symptom severity, PCLI patients exhibited higher levels of functional status. This might be due to different pathophysiological mechanisms and radiological involvement patterns of both diseases.

High-Resolution Computed Tomography of Fibrotic Interstitial Lung Disease

While radiography is the first-line imaging technique for evaluation of pulmonary disease, high-resolution computed tomography (HRCT) provides detailed assessment of the lung parenchyma and interstitium, allowing normal anatomy to be differentiated from superimposed abnormal findings. The fibrotic interstitial lung diseases have HRCT features that include reticulation, traction bronchiectasis and bronchiolectasis, honeycombing, architectural distortion, and volume loss. The characterization and distribution of these features result in distinctive CT patterns. The CT pattern and its progression over time can be combined with clinical, serologic, and pathologic data during multidisciplinary discussion to establish a clinical diagnosis. Serial examinations identify progression, treatment response, complications, and can assist in determining prognosis. This article will describe the technique used to perform HRCT, the normal and abnormal appearance of the lung on HRCT, and the CT patterns identified in common fibrotic lung diseases.

Reticulation pattern without honeycombing on high-resolution CT is associated with the risk of disease progression in interstitial lung diseases

Background

The disease course of idiopathic pulmonary fibrosis (IPF) is progressive and occasionally, other types of interstitial lung disease (ILD) may progress similarly to IPF. This study aimed to evaluate risk factors for disease progression within 24 months in patients with various ILDs.

Methods

This prospective study obtained 97 patients with a suspected ILD who underwent a transbronchial lung cryobiopsy. The extent of several high-resolution computed tomography (HRCT) patterns was assessed. Due to the inclusion criteria the study population presented a low extent of honeycombing and definite usual interstitial pneumonia (UIP) pattern on HRCT suggesting an early stage of ILD. Disease progression within 24 months despite treatment was defined as a relative decline of ≥ 10% in forced vital capacity (FVC), or a relative decline in FVC of ≥ 5% and one of the three additional criteria: (1) a decline in diffusion capacity to carbon monoxide (DLCO) ≥ 15%; (2) increased fibrosis on HRCT; (3) progressive symptoms, or progressive symptoms and increased fibrosis on HRCT. The same definition was utilized in patients with IPF and other ILDs. Risk factors for disease progression were evaluated in a multivariable logistic regression model.

Results

Disease progression was revealed in 52% of the patients with ILD, 51% of the patients with IPF, and 53% of the patients with other types of ILD. A high extent of reticulation on HRCT (Odds ratio [OR] 3.11, 95% Confidence interval [CI] 1.21–7.98, P = 0.019) and never smoking (OR 3.11, CI 1.12–8.63, P = 0.029) were associated with disease progression whereas platelet count (OR 2.06 per 100 units increase, CI 0.96–4.45, P = 0.065) did not quite reach statistical significance.

Conclusion

Higher extent of reticulation on HRCT and never smoking appeared to associate with the risk of disease progression within 24 months in ILD patients without honeycombing. Approximately half of the patients with ILD revealed disease progression, and similar proportions were observed in patients with IPF and in other types of ILD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02105-9.

Radiological and Physiological Predictors of IPF Mortality

Background and Objectives: Idiopathic pulmonary fibrosis (IPF) has a variable clinical course, which ranges from being asymptomatic to progressive respiratory failure. The purpose of this study was to evaluate the novel clinical parameters of IPF patients who receive an anti-fibrotic agent. Materials and Methods: From January 2011 to January 2021, we identified 39 IPF patients at Okinawa Chubu Hospital. Clinical information was obtained, such as laboratory data, pulmonary function test (PFT) results, and chest images, including of soft tissue thickness and the high-resolution computed tomography (HRCT) pattern at diagnosis. Results: The mean age was 72.9 ± 7.0 (53–85); 27 patients were men and 12 were women. The mean body mass index was 25.1 ± 3.9 (17.3–35). Twenty-four were active smokers and the median number of packs per year was 20. Regarding laboratory findings, mean white blood cell (WBC), lactate dehydrogenase (LDH), and Krebs Von den Lungen-6 (KL-6) values were 7816 ± 1859, 248 ± 47, and 1615 ± 1503, respectively. In PFT, the mean percent predicted FVC, percent predicted total lung capacity, percent predicted functional residual capacity (FRC), and percent predicted diffusion capacity of the lung for carbon monoxide (DLco) were 66.8 ± 14.9%, 71.8 ± 13.7%, 65 ± 39.6%, and 64.6 ± 27.9%, respectively. In chest radiological findings, soft tissue thickness at the right 9th rib was 26.4 ± 8.8 mm. Regarding chest HRCT patterns, 15 showed the definite usual interstitial pneumonia (UIP) pattern, 16 showed the probable UIP pattern, and eight showed the indeterminate for UIP pattern. In the treatment, 24 patients received pirfenidone and 15 patients took nintedanib. The mean observation period was 38.6 ± 30.6 months and 24 patients died. The median survival time was 32.4 months (0.9–142.5). Multivariate analysis adjusted for age showed that both soft tissue thickness [Hazard ratio (HR): 0.912, 95% confidence interval (CI): 0.859–0.979, p-value: 0.009] and percent FRC [HR: 0.980, 95% CI: 0.967–0.992, p-value: 0.002] were robust predictors of IPF mortality. Conclusions: In IPF patients treated with anti-fibrotic agents, both soft tissue thickness at the right 9th rib shown on the chest radiograph and %FRC can be novel predictors of IPF mortality.