Hypersensitivity pneumonitis radiologic features in interstitial lung diseases

Area of Science:

• Pulmonary Medicine
• Radiology
• Diagnostic Imaging

Background:

• Radiologic criteria for hypersensitivity pneumonitis (HP) rely on four key features in high-resolution computed tomography (HRCT): ground glass opacities, mosaic attenuation, air-trapping, and centrilobular nodules.
• Evidence supporting these specific criteria is currently limited, necessitating further investigation.

Purpose of the Study:

• To assess the prevalence of HP-compatible features (HPCF) in various interstitial lung diseases (ILDs).
• To determine the association between HPCF and HP diagnosis.
• To evaluate the predictive value of the amount of HPCF and the performance of existing radiologic guidelines for HP diagnosis.

Main Methods:

• A retrospective analysis of consecutive ILD patients who underwent HRCT between 2016 and 2021 across three medical centers.
• Assessment of HPCF prevalence in different ILDs and their correlation with HP diagnosis.
• Evaluation of the diagnostic performance of ATS/JRS/ALAT and CHEST HP guidelines using HPCF amount and patient data, including those with diagnostic biopsies.

Main Results:

• Out of 436 ILD patients, 56 (13%) had HP. All four HPCF were significantly more common in HP patients (p < 0.001).
• Air-trapping emerged as the strongest independent predictor of HP (AOR 4.1). Centrilobular nodules were nearly exclusive to HP and smoking-related ILDs.
• The quantity of HPCF on HRCT demonstrated excellent predictive ability for HP diagnosis (AUC 0.85). Current guidelines showed high specificity for typical HP and high sensitivity for compatible HP, but low positive predictive values.

Conclusions:

• The presence and quantity of HPCF on HRCT are valuable predictors of HP diagnosis in real-world clinical practice.
• Existing radiologic criteria for HP show good diagnostic performance but offer opportunities for refinement and improvement.