Shadows bordering the lung on radiographs of normal and obese persons

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.

The ribs: anatomic and radiologic considerations

The ribs are essential structures of the osseous thorax and provide information that aids in the interpretation of radiologic images. Techniques for making precise identification of the ribs are useful in detection of rib lesions and localization of lung lesions. The big rib sign and the vertical displacement sign can be used to differentiate the right and left ribs on lateral chest radiographs. The clavicle, the xiphoid process, and the sternal angle may be used as anatomic landmarks for rib counting on computed tomographic scans. For rib counting on lateral chest radiographs, the sternal angle or the 12th rib may be used. Anatomic rib variants include developmental deformities, cervical rib, and short rib and may mimic true rib diseases. Detection of thoracic deformities such as funnel chest (pectus excavatum) and barrel-shaped thorax requires an awareness of the strong correlation between the transverse appearance of the thorax and costal shape. Shadows around the rib cage (eg, rib companion shadows, sharp lines along the lower margin of the ribs, rib overlying shadows) may mimic pleural and extrapleural disease on frontal chest radiographs. It is imperative that the radiologist be familiar with normal rib anatomy, normal rib variants, and the radiologic appearance of the ribs to prevent misdiagnosis.