Imaging in the diagnosis and management of fibrosing interstitial lung diseases

Abstract

High-resolution computed tomography (HRCT) plays a pivotal role in the diagnosis and management of interstitial lung diseases (ILDs), particularly given the approval of antifibrotic agents for conditions like idiopathic pulmonary fibrosis and progressive pulmonary fibrosis. Diagnosing fibrotic pulmonary disorders through HRCT involves a detailed and methodical examination. The identification of specific lung tissue changes, including ground-glass opacities and reticulation, along with signs of fibrosis like honeycombing, traction bronchiectasis and lung volume loss, establishes clear HRCT patterns indicative of various ILDs. The reliability of these patterns in predicting pathological conditions depends largely on the clinical context. For instance, when a usual interstitial pneumonia pattern is present, the predictive value of this diagnosis is so high that a lung biopsy is considered to be redundant. This review intends to delineate the HRCT signs of fibrosis, elucidate the specific radiological patterns of fibrotic lung diseases, and identify the clinical circumstances under which these patterns emerge. Additionally, we introduce and discuss novel imaging techniques that hold promise for the diagnosis, screening and early detection of ILDs.

FIGURE 1

a) Axial computed tomography (CT) of a patient with usual interstitial fibrosis displaying a cluster of thin-walled cysts at the lung periphery, known as honeycombing. b) Axial CT of a patient with emphysema demonstrating grouped areas of centrilobular emphysema, which may resemble honeycombing. Unlike honeycombing, centrilobular emphysema appears as very thin-walled structures without associated volume loss or traction bronchiectasis. c) Axial CT of a patient with extensive traction bronchiectasis, where the grouped traction bronchiectasis and bronchiolectasis might mimic honeycombing. d) Minimum intensity projection of the same section confirming the presence of traction bronchiectasis.

FIGURE 2

a) Axial computed tomography (CT) of a patient with nonspecific interstitial pneumonia, illustrating extensive ground-glass opacities alongside traction bronchiectasis. Notably, the bronchi exhibit varicose dilation without peripheral tapering, indicated by arrows. b) Axial CT of a patient with nonspecific interstitial pneumonia demonstrates a marked volume loss. There is a noticeable shift of the oblique fissures towards the posterior (arrows), deviating from their typical placement in healthy lungs.

FIGURE 3

a) Axial and b) sagittal computed tomography (CT) reformations of a patient with typical usual interstitial pneumonia (UIP), exhibiting reticular abnormalities, traction bronchiectasis, and honeycombing with a basal and subpleural predominance. Importantly, there are no features suggestive of an alternative diagnosis such as extensive ground-glass opacities, consolidations, or centrilobular nodules. c) Axial and d) sagittal CT reformations of a patient displaying a probable UIP pattern characterised by reticular abnormalities and traction bronchiectasis, absent honeycombing, and a basal and subpleural predominance, without any indicative changes of other diagnoses. e) Axial and f) sagittal CT reformations of a patient with nonspecific interstitial pneumonia presenting as extensive ground-glass opacities predominantly in basal and peripheral areas. g) Axial and h) sagittal CT reformations of a patient with fibrotic hypersensitivity pneumonia demonstrate extensive air trapping (*), a sign of small airway disease, along with fibrosis indicators such as extensive reticular abnormalities and ground-glass opacities, with distorted lung architecture typically located randomly or with a mid-lung predominance.