Raman mapping and FTIR imaging of lung tissue: congenital cystic adenomatoid malformation.

Vibrational spectroscopic methods are able to
analyze the biochemical composition of tissues and their pathological changes at the molecular
level. Cryosections were prepared on calcium fluoride substrates from CCAMs and from normal
lung tissue of two infant patients who underwent surgery. Raman maps were collected at a step size
of 100 lm in order to assess the whole tissue section and at a smaller step size of 10 lm in order to
resolve details in selected areas. FTIR images were collected in the macroscopic and microscopic
modes. Data sets were segmented by cluster analysis and the mean spectra of each cluster were
compared. At low lateral resolution a lower red blood cell content and higher lipid content were
found in CCAMs than in normal lung tissue. At higher lateral resolution, accumulations of lipids
and glycogen were identified in CCAMs. The lipid aggregates contain a high concentration of
phosphatidylcholine. It is discussed how the combined application of Raman mapping and FTIR
imaging might improve the differential diagnosis of lung malformations and how both modalities
might be applied to other bioanalytical and biomedical problems in the future.