Fig 1.
Schematic of imaging setups, (A) imaging setup for tissue phantom experiments (top view), (B) imaging setup for Intralipid® phantom and in-vivo experiments (side view).
Fig 2.
Fluorescence emission profiles of ICG (in PBS, plasma, and ethanol) and IR-E1050 (in PBS and plasma) at (A) 10, (B) 20, and (C) 50 µM.
Fig 3.
Intralipid® phantom study of ICG in NIR-I and NIR-II window.
(A) Fluorescence images in NIR-II (top panel) and NIR-I window of glass capillary filled with ICG in plasma (50µM) at depths of 1, 2, and 4 mm in 1% Intralipid®. 785 nm laser used for excitation. Scale bars are 50 mm. (B) Normalized intensity loss of ICG in plasma, in NIR-I and NIR-II as a function of depth. (C) Full-width-half-maximum (FWHM) of capillary glass tube filled with ICG in plasma as a function of depth in Intralipid®, showing loss of feature consistency in NIR-I compared to the NIR II. For NIR-I camera standard deviation of the signal intensity in the air was 0, which causes an indefinite value of CNR, for the NIR-I and NIR-II comparisons we plotted both Normalized Intensities and FWHM as in [24]. While for tissue phantoms and in-vivo experiments we report CNR values.
Fig 4.
NIR-I and NIR-II images of tissue phantoms with inserted tubes containing ICG or IR-E1050 in plasma.
Chicken muscle tissue (top panel) ICG in NIR-I (A) and NIR-II window (B). IR-E1050 in NIR-II (C). Calf liver tissue (bottom panel), ICG in NIR-I (D) and NIR-II window (E). IR-E1050 in NIR-II (F). Top capillary tube is 3 mm and bottom tube is 6 mm from the surface. Scale bar is 5mm.
Fig 5.
CNR in capillary tubes embedded at 3 and 6 mm depth from surface in (A) chicken muscle tissue, and (B) calf liver tissue. Tubes were filled with ICG or IR-E1050 in PBS and plasma and imaged in NIR-I (ICG) and NIR-II (ICG and IR-E1050) window.
Fig 6.
In vivo sub-surface vascular imaging with ICG and IR-E1050.
Representative images of the hind limb in a mouse in; (A) visible light, (B) NIR-II window obtained after i.v. administration of IR-E1050, (C) NIR-II window obtained after i.v. administration of ICG, and (D) NIR-I window after i.v. administration of ICG. (C) and (D) is the same animal. NIR images at 5 minutes post injection.
Fig 7.
CNR in femoral vessel of animals injected with ICG or IR-E1050 in NIR-I (ICG) and NIR-II (ICG and IR-E1050) window (n = 5).