In this lecture titled "HRCT: Tackling Perilymphatic Disease," Dr. Jeffrey Galvin discusses the significance of septal lines and lymphatics in understanding various diseases. He highlights the role of lymphatics, discovered in the 1950s, and their connection to interlobular septae. The talk emphasizes the impact of inhaled substances, such as particles or bacteria, on lymphatic patterns and the development of diseases like sarcoidosis. Dr. Galvin explores three common abnormalities causing septal lines: edema, fibrosis, and tumor. He provides insights into recognizing these abnormalities through imaging, illustrating cases like congestive heart failure, eosinophilic pneumonia, pulmonary alveolar proteinosis, and lymphangitic carcinomatosis. The lecture concludes with a comprehensive overview of central line predominance and its association with edema, prolonged inflammation, fibrosis, and tumor-related conditions.