From the Guidelines
Chest CT, specifically high-resolution computed tomography (HRCT) of the chest, is the best screening tool for interstitial lung disease (ILD). According to the 2023 American College of Rheumatology (ACR)/American College of Chest Physicians (CHEST) guideline for the screening and monitoring of ILD in people with systemic autoimmune rheumatic diseases 1, HRCT chest has a sensitivity of 95.7% and specificity of 63.8% for the detection of ILD. This guideline conditionally recommends screening with HRCT chest over history and physical examination or pulmonary function tests (PFTs) alone for people with systemic autoimmune rheumatic diseases (SARDs) at increased risk of developing ILD.
Key Points
- HRCT chest provides detailed images of lung tissue, allowing visualization of characteristic patterns of ILD, such as reticular opacities, honeycombing, ground-glass opacities, and traction bronchiectasis.
- The combination of HRCT chest and PFTs is preferred over PFTs alone, as they provide complementary information about the presence and pattern of ILD (HRCT) and physiologic impact (PFTs) 1.
- Chest radiography is not recommended as a screening test for ILD due to its low sensitivity (58%–64%) 1.
- Radiation exposure from HRCT chest is a consideration, but the diagnostic benefit generally outweighs this risk, and the amount of exposure is low, with an extremely low risk of radiation-induced malignancy on a per-scan basis 1.
Recommendations
- For people with SARDs at increased risk of developing ILD, screening with HRCT chest and PFTs is conditionally recommended over PFTs alone 1.
- HRCT chest should be performed with thin-slice images obtained during full inspiration, sometimes with additional expiratory images to assess for air trapping, and no contrast is typically needed.
- Prompt referral for chest HRCT is recommended for patients with suspected ILD, followed by evaluation by a pulmonologist experienced in ILD management for proper interpretation and subsequent diagnostic workup.
From the Research
Imaging Modalities for Interstitial Lung Disease
- Chest radiograph is the first imaging modality for approaching diffuse infiltrative lung disease (DILD) 2
- High-resolution CT (HRCT) is considered the best imaging tool for evaluating the pulmonary interstitium and diagnosing DILD 2, 3
High-Resolution CT in Interstitial Lung Disease
- HRCT is the radiological imaging technique that most closely reflects changes in lung structure 3
- HRCT findings can suggest the most probable diagnosis when combined with their anatomic distribution 3
- The presence of classic HRCT features often obviates the need for biopsy 3
Diagnostic Accuracy of HRCT
- HRCT has a pivotal role in the differential diagnosis of smoking-related interstitial lung diseases 4
- HRCT evaluation is the central diagnostic tool in discerning idiopathic pulmonary fibrosis (IPF) from other interstitial lung diseases (ILDs) 5
- Implementation of new guidelines for HRCT categorization in ILD patients may be associated with greater inter-interpreter variability 5
Clinical Applications of HRCT
- HRCT can be used to determine the most appropriate biopsy site in patients with atypical findings 3
- HRCT can help identify incidental interstitial lung abnormalities that may suggest early ILD in patients without clinical suspicion for ILD 6
- HRCT findings can be used to monitor disease progression in patients with ILD 6