Objective: The purpose of this study was to determine the frequency with which a mosaic pattern of lung attenuation is seen on chest CT scans in patients with various causes of pulmonary artery hypertension (PAH).
Materials and methods: Chest CT scans of 64 patients with known PAH were reviewed to assess the patterns of lung attenuation. Patterns of lung attenuation were divided into three categories: class I, homogeneous lung parenchymal attenuation; class II, slightly heterogeneous lung attenuation that does not conform to the anatomic boundaries of the secondary pulmonary lobule; and class III (mosaic pattern), heterogeneous lung attenuation in geographic regions with well-defined borders corresponding to the anatomic units of single or multiple secondary pulmonary lobules. The patients medical histories were reviewed to determine the primary cause of PAH for each patient.
Results: Peak pulmonary artery pressure of the patients in our study averaged 74 mm Hg (range, 36-194 mm Hg). Twenty-one patients had PAH due to lung disease: 17 patients, due to cardiac disease; and 23 patients, due to vascular disease. Three other patients had PAH due to miscellaneous causes. Of the 23 patients with PAH due to vascular disease, 17 patients (74%) had a mosaic pattern of lung attenuation. Of the 21 patients with PAH due to lung disease, one patient (5%) had a mosaic pattern of lung attenuation. Among the 17 patients with PAH due to cardiac disease, two patients (12%) had a mosaic pattern of lung attenuation. A mosaic pattern of lung attenuation was seen significantly more often in patients with PAH due to vascular disease than in patients with PAH due to cardiac or lung disease.
Conclusion: A mosaic pattern of lung attenuation can be seen on CT scans in patients with PAH due to vascular disease, cardiac disease, or lung disease. However, the mosaic pattern is seen significantly more often in patients with PAH due to vascular disease than in patients with PAH due to cardiac or lung disease.