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

Abstract

To evaluate sliding-thin-slab maximum intensity projection (MIP) reconstructions in the assessment of micronodular patterns of low profusion in diffuse infiltrative lung disease. Eighty-one adult patients (mean age, 48 years) with suspicion of pneumo-coniosis (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. 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). 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.