Chest magnetic resonance imaging for pneumonia diagnosis in outpatients with lower respiratory tract infection.

We assessed whether magnetic resonance imaging (MRI) is applicable for diagnosing pneumonia among adult outpatients with lower respiratory tract infection.Patients were recruited prospectively when they had symptoms for ≤7 days and fever ≥37.8 °C. The patients underwent high-resolution computed tomography (HRCT), MRI and chest radiography, which were repeated 1 month later if necessary, to verify pneumonia. The duration of MRI examination was 3-4 min.Among 77 patients, HRCT, MRI and radiography identified 32 (41.6%), 30 (39.0%) and 23 (29.9%) cases of pneumonia, respectively (p=0.001). MRI missed two HRCT-identified pneumonia cases due to motion artefacts. Chest radiography resulted in four false-positive pneumonia findings and MRI resulted in none. When HRCT was used as a reference, MRI had a sensitivity of 0.938 (95% CI 0.799-0.983) and specificity of 0.978 (95% CI 0.884-0.996) for the diagnosis of pneumonia, whereas the sensitivity and specificity for chest radiography were 0.719 (95% CI 0.546-0.844) and 0.911 (95% CI 0.793-0.965), respectively.MRI is an accurate, fast and effective method for diagnosing outpatient pneumonia, with better accuracy compared with chest radiography and almost similar accuracy compared with HRCT.