When is CT scanning indicated for the evaluation of interstitial lung disease?
CT is more sensitive and more specific than chest radiography for interstitial abnormalities. In advanced cases with obvious chest radiographic findings, chest radiographs may be diagnostic. However, in most cases, CT will provide increased information about the distribution and severity of disease. Patients with apparently normal or minimally abnormal chest radiographs in whom there is a clinical suspicion of interstitial lung disease should receive a thin-section chest CT scan to evaluate better for the presence of interstitial lung disease. Patients with chest radiographs that are nonspecific may benefit from a CT study, which in many cases allows the clinician to narrow the differential diagnosis. Lastly, CT provides improved characterization of the extent of disease. In cases in which therapeutic decisions are based on imaging evidence of progression, stability, or regression of disease, CT scanning is indicated.