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.
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