Background and Objectives: In theory, infrared vibrational bands could be used for
selective photothermolysis of
lipid-rich tissues such as fat, sebaceous glands, or
atherosclerotic plaques. Study Design/Materials and Methods: Absorption spectra of
human fat were measured, identifying promising bands near 1,210 and 1,720 nm.
Photothermal excitation of porcine fat and dermis were measured with a 3.5–5 mm thermal camera
during exposure to the free electron laser (FEL) at Jefferson National Laboratory.
Thermal damage to full-thickness samples exposed at 1,210 nm through a cold
contact window, was assessed by nitrobluetetrazolium chloride staining in situ
and by light microscopy. Results: Photothermal excitation of fat was twice that of dermis,
at lipid absorption bands (1,210, 1,720 nm). At 1,210 nm, a subcutaneous fat
layer several mm thick was damaged by FEL exposure, without apparent injury to overlying
skin.
Conclusion: Selective photothermal targeting of fatty tissues is feasible
using infrared lipid absorption bands. Potential clinical applications are
suggested by this FEL study.