Novelties in Imaging of Thoracic Sarcoidosis

Abstract

Sarcoidosis is a systemic granulomatous disease affecting various organs, and the lungs are the most commonly involved. According to guidelines, diagnosis relies on a consistent clinical picture, histological demonstration of non-caseating granulomas, and exclusion of other diseases with similar histological or clinical picture. Nevertheless, chest imaging plays an important role in both diagnostic assessment, allowing to avoid biopsy in some situations, and prognostic evaluation. Despite the demonstrated lower sensitivity of chest X-ray (CXR) in the evaluation of chest findings compared to high-resolution computed tomography (HRCT), CXR still retains a pivotal role in both diagnostic and prognostic assessment in sarcoidosis. Moreover, despite the huge progress made in the field of radiation dose reduction, chest magnetic resonance (MR), and quantitative imaging, very little research has focused on their application in sarcoidosis. In this review, we aim to describe the latest novelties in diagnostic and prognostic assessment of thoracic sarcoidosis and to identify the fields of research that require investigation.

Keywords: CXR; HRCT; chest MR; prognostic assessment; radiomics; sarcoidosis.

Figure 1

Stage IV pulmonary sarcoidosis. Comparison between (a) standard chest HRCT acquisition (effective dose 3.3 mSv) and (b) Ultra-low dose acquisition (effective dose 0.8 mSv) with a 75% radiation dose reduction. Fibrotic changes—specifically irregular interstitial thickening (asterisk) and traction bronchiectasis (arrows)—are clearly evident at Ultra-low dose acquisition. Mediastinal calcified lymph nodes are also evident.

Figure 2

Radiomics workflow and its application in sarcoidosis.

Figure 3

CXR of patients with thoracic sarcoidosis. (a) Scadding stage I showing bilateral hilar enlargement. (b) Scadding stage II showing bilateral hilar enlargement and parenchymal reticulation and micronodules. (c) Scadding stage III showing bilateral micronodules without significant hilar enlargement. (d) Scadding stage IV showing upward retraction of hila with bronchial distortion and reticular opacities.