Raman and FTIR imaging of lung tissue: Bronchopulmonary sequestration

Bronchopulmonary sequestration (BPS) involves abnormal pulmonary tissue lacking trancheobronchial connection and having a separate vascular supply that arises from the thoracic or abdominal aorta. For the first time, BPS is studied by Raman and Fourier-transform infrared (FTIR) imaging. Cryosections were mounted on calcium fluoride substrates from tissue samples of two BPS patients. Raman images were collected at a step size of 66-100 μm to assess the whole tissue section, and at a lower step size of 10 μm to resolve details in selected areas. FTIR images were collected at resolutions of 63 and 4 μm per pixel. Data sets were segmented by cluster analyses, and the spectra of each cluster were compared. The spectra revealed higher red blood cell content and lower collagen and lipid content in BPS than in an additional tissue section from the BPS margin. Comparison with previous Raman and FTIR images of congenital cystic adenomatoid malformations (CCAM) and normal lung tissue suggested that the marginal tissue sample of the BPS patient contains CCAM. We conclude that CCAM and BPS are biochemically distinct, which enable the differential diagnosis of lung malformations by specific vibrational spectroscopic fingerprints.