Non-linear imaging and characterization of atherosclerotic arterial tissue using combined SHG and FLIM microscopy

Atherosclerosis is one of the leading causes of death in the Western World and its characterization is extremely interesting from the diagnostic point of view. Here, we employed combined SHG-FLIM microscopy to characterize arterial tissue with atherosclerosis. The shorter mean fluorescence lifetime measured within plaque depositions (1260 ± 80 ps) with respect to normal arterial wall (1480 ± 100 ps) allowed discriminating collagen from lipids. SHG measurements and image analysis demonstrated that the normal arterial wall has a more anisotropic Aspect Ratio (0.37 ± 0.02) with respect to plaque depositions (0.61 ± 0.02) and that the correlation length can be used for discriminating collagen fibre bundles (2.0 ± 0.6 μm) from cholesterol depositions (4.1 ± 0.6 μm). The presented method has the potential to find place in a clinical setting as well as to be applied in vivo in the near future. Graphic composition of SHG and FLIM images representing normal arterial wall and plaque depositions. Atherosclerosis is among the most widespread cardiovascular diseases and its early diagnosis is crucial for avoiding life threatening consequences. Non-linear microscopy can diagnose tissues and atherosclerosis in a label-free modality, opening the way for a clinical use of these optical techniques. Combined SHG-FLIM microscopy is demonstrated to be extremely powerful for diagnosing and characterizing atherosclerosis.