High-resolution computed tomography (HRCT) is a proved imaging modality for use in assessment of infiltrative lung disease. Findings suggestive of infiltrative lung disease on HRCT scans include ground-glass attenuation, consolidation, nodules, and interlobular septal thickening. Similar patterns, however, may be caused by various vascular abnormalities including regional or diffuse increase in blood flow, pulmonary edema, pulmonary hypertension, and thromboembolism. A correct diagnosis can usually be made by careful analysis of the pulmonary vasculature. Parenchymal abnormalities of vascular origin are associated with increased or decreased vessel diameter, vascular compression, or intraluminal filling defect.