Table 1.

Comparison of different types of PA imaging systems

	OR-PAM	OR-PACT	AR-PAM	AR-PACT
Lateral Resolution	several hundred nms to several μmsa	several μmsa	tens of μms to hundreds of μmsb	hundreds of μmsc
Axial Resolutiond	tens of μms	tens of μms	tens of μms to hundreds of μms	hundreds of μms
Imaging Depth	<1 mme	<1 mme	1-20 mmf	10-70 mmf
Imaging Speed	tens of minutes	< 1 minute	tens of minutes	< 1 minute
Biomedical Applications	Brain [31, 32]	Brain [33]	Tumor [26, 34]	Tumor [1, 30]
	Tumor angiogenesis [35]	Blood vessel [25, 36]	SLNg [37]	SLNg [38, 39]
	Oxygen saturation [32, 40]		Brain [41, 42]	Brain [43, 44]
	Oxygen metabolism [45]		Whole body [46]	Whole body [28, 47]
	Hemodynamics [48]
	Subcellular imaging [17, 49]

^aOptical dependent, determined by NA (numerical aperture) of optical lens and optical wavelength

^bAcoustic dependent, determined by NA of acoustic lens and acoustic central frequency

^cAcoustic dependent, determined by acoustic central frequency

^dAcoustic dependent, determined by acoustic frequency bandwidth

^eOptical ballistic regime

^fOptical diffusive regime

^gSLN: Sentinel Lymph Node