CT appearances of focal organizing pneumonia / 实用放射学杂志

ABSTRACT

Objective To analyze the radiologic characteristics of focal organizing pneumonia (FOP) and discuss its values in diagnosis of FOP.Methods 57 lesions of FOP proved by histological examination were studied retrospectively.All of the lesions could be classified into types of nodule(diameter≤30 mm, n=40) and mass(diameter>30 mm, n=17),which were analyzed to explore the imaging characteristics such as location, margin, internal state, and enhancement features.Results 39 lesions were located in the right lung and 18 lesions in the left lung, and 51 lesions in the peripheral and 6 lesions in the inner or middle of the lung.The differences between the location of lobe and lung field were statistically significant.The radiographic common features included air bronchogram were seen in 28 cases, while loose composition sign in 18 cases and vessel convergence in 21 cases.49 lesions occurred in subpleural region, including 34 lesions broad contract with pleura.In 54 lesions with contrast-enhanced CT scan, the difference between arterial phase and plain scan in CT value was 35 HU and difference of venous phase and plain scan was 45 HU, presenting gradual enhancement.14 lesions were inhomogeneous enhancement in mass type and 25 lesions were homogeneous enhancement in nodule type.There were statistic differences in margin, shape, round-glass opacity, necrosis, cave and the relationship with pleura between the nodule type and mass type.Conclusion FOP has specific radiographic features.Enhanced CT scan combining multi planar reformation images is helpful in differential diagnosis.