TABLE 2.

Summary of the Optical Methods Reviewed in this Manuscript, Including Their Approximate Typical Resolutions, Sensing Depths, and Available Sources of Contrast (Cross References to Categories Listed in Table 1)

Method	Lateral spatial resolution	Sensing depth	Source(s) of contrast
Fiber-based optical  spectroscopy	Point measurements or coarse  scanning (>1 mm) (12)	~0.1–10 mm, depending on probe  geometry and wavelength	1, 2, 3, 4, 5, and 6
Optical coherence  tomography (OCT)	4–20 microns (15)	1 mm	2 and 5 primarily, possible to  do 1 and 4
Photoacoustic  tomography (PAT)/  photoacoustic  microscopy (PAM)	45 μm to 1 mm (scalable with  depth) (16)	Several cm (16)	1 and 4
Diffuse optical  tomography (DOT)	mm to cm (17)	Several cm (17)	1, 2, 4, and 5
Fluorescence molecular  tomography (FMT)	Sub-mm to cm (18, 19)	Several cm (18, 19)	Primarily 6, also 3
Intravital microscopy and  microendoscopy	200 nm (15)	Several hundred microns (19, 20)	1, 2, 3, 4, 5, and 6