Imaging pneumonia in immunocompetent and immunocompromised individuals.

PURPOSE OF REVIEW The article aims to indicate the current role of radiological imaging in immune competent and immunocompromised patients with pneumonia. The radiological findings in the most common conditions will be reviewed. RECENT FINDINGS Three basic patterns of radiographic abnormality are recognized: lobar (nonsegmental) pneumonia; bronchopneumonia (lobular pneumonia); and interstitial pneumonia. The chest radiograph remains the initial radiological investigation. Computed tomography (CT) is more sensitive than the chest radiograph. The appearances on CT with certain infections such as mycoplasma, invasive aspergillosis, and pneumocystis, in the appropriate clinical setting, may allow a treatment decision to be made when obtaining fluid or tissue for culture is problematical. MRI technology is advancing and this technique may provide an option for follow-up of chronic disease in younger patients in whom radiation exposure is a concern, but MRI does not yet match CT as a diagnostic test in this field. SUMMARY Radiology retains a key role in diagnosing pneumonia, excluding pneumonia, following up patients to check for resolution and to evaluate potential complications. The chest radiograph remains the initial examination. CT is more sensitive and with certain infections more specific. MRI provides an option for monitoring progress, although cannot yet match CT as an initial diagnostic test