Figure 3

Pathological tissue alterations of intracranial vessel walls. (A, B) Label-free multiphoton images of the (A) fragmented IEL and (B) fragmented EEL in comparison to EvG and HE of normal vessel walls and aneurysm walls. Arrows indicate the elastic lamina. (C) Collagen accumulation (arrows) in an aneurysm wall. (D) Raman spectra acquired in the area of the fibromatous wall remodeling shown in C. Arrows indicate collagen bands (817, 855 and 933 cm⁻¹). (E) Intra- and extracellular lipid accumulation (arrows) in an aneurysm wall. (F) Cholesterol deposits in an aneurysm wall (white and black arrows). The overlay of the SHG (blue) and CARS (red) signals visualize cholesterol crystals (magenta). (G) Raman spectra of cholesterol 1 and 2 (cholesterol 1, cholesterol 2) acquired in the region indicated in F. The gray arrow marks the cholesterol band (702 cm⁻¹) and the black arrows the carotene bands (1158, 1521 cm⁻¹). (H) Multiphoton and HE images of foam cells (black arrows) and lipids. Intra (white arrow) and extracellular (gray arrow) lipids are indicated. (I) Coagulated blood (arrows- indicate fibrin structure) and intra-wall haemorrhage shown by MPM and HE. (J) Red blood cells (RBCs-erythrocytes) of the intra-wall haemorrhage/thrombus from I. (K) Raman spectra of coagulated blood shown in I. Gray arrows indicate the bands related to RBC and heme groups of hemoglobin (752, 1563, 1575, 1620 cm^-1).