Recent Developments in Vascular Imaging Techniques in Tissue Engineering and Regenerative Medicine

Table 1

Summary of nonoptical, optical, and hybrid imaging modalities for vascular imaging in tissue engineering [18, 21, 25, 28, 54].

	Modality	Imaging contrast	Spatial resolution (µm)	Imaging depth (mm)	Anatomical/physiological parameters
Nonoptical method	X-ray/CT^1	X-ray absorption	100	Full body	Bone structure, blood vessels imaging (with contrast agent)
	MRI	Tissue relaxation (T1, T2), proton density	25^2–100	Full body	Soft tissue structure, blood vessels imaging (with contrast agent)
	US	Ultrasound scattering	30	300	Soft tissue structure, blood flow (Doppler ultrasound)
	PET	Radioisotope concentration	1000	Full body	Blood flow
Optical method	OCT	Optical scattering	1–10	1-2	Blood flow, hemoglobin oxygen saturation (SO2)^3
	1PFM	Fluorescence, scattering	1-2	0.2–0.5	Microvascular morphology, blood flow
	2PFM	Fluorescence	1-2	0.5–1.0	Microvascular morphology, blood oxygenation
	OPS	Optical absorption	1–5	0.5–1.0	Total hemoglobin concentration (HbT)
	LSI	Blood flow	10	0.1–0.3	Blood flow
Hybrid method	PAI	Optical absorption	0.1–800	0.1–70	HbT, SO2, blood flow, blood vessel structure

¹micro-CT can provide 1 µm resolution with limited imaging depth.
²with very high strength magnetic fields.
³It can be measured by integrating OCT with hyperspectral imaging.