Diffuse infiltrative lung disease: Clinical value of sliding-thin-slab maximum intensity projection CT scans in the detection of mild micronodular patterns

PURPOSE: To evaluate sliding-thin-slab maximum intensity projection (MIP) reconstructions in the assessment of micronodular patterns of low profusion in diffuse infiltrative lung disease. MATERIALS AND METHODS: Eighty-one adult patients (mean age, 48 years) with suspicion of pneumoconiosis (n = 25), sarcoidosis (n = 19), smoker bronchiolitis (n = 17), and bronchiolitis of miscellaneous causes (n = 20) underwent 1- and 8-mm-thick conventional computed tomography (CT) and focal spiral CT with generation of 3-, 5- and 8-mm-thick MIP reconstructions. The presence and characterization of micronodular infiltration were analyzed on the two sets of conventional CT scans and on the three sets of MIPs. RESULTS: When conventional CT findings were normal (n = 18 [22%]), MIPs did not demonstrate additional abnormalities. When conventional CT findings were inconclusive (n = 17 [21%]), MIPs enabled detection of micronodules that involved less than 25% of the lung surface. When conventional CT scans depicted micronodules (n = 46 [57%]), MIPs showed the profusion and distribution of micronodules and associated bronchiolar abnormalities better. The sensitivity of MIP (3-mm-thick MIP, 94%; 5-mm-thick MIP, 100%; 8-mm-thick MIP, 92%) was significantly higher than that of conventional CT (8 mm thick, 57%; 1 mm thick, 73%) in the detection of micronodules (P < .001). CONCLUSION: Sliding-thin-slab MIP helps detect mild forms of micronodular infiltration and should be considered a valuable additional tool in the evaluation of diffuse infiltrative lung diseases.