Table 2.

Experimental specifics and outcomes of in vivo studies

Experimental Conditions	Mode of Imaging	THz Window Used for Imaging	Outcomes	Year	Refs.
Partial-thickness burn induced by a brass brand heated to 180°C and full thickness by heating it to 220°C. Brass applied onto a flat area on rat's abdomen. Postburn images captured starting from 8 min to 72 h	Reflection	0.525 THz with an angle of incidence of 14° and a spot size of 1.1 mm	(a) For partial burn, the immediate observation (within 10 min of injury) was tremendous influx of fluid making both the injury and its surrounding edematous, which tends to settle down after 8 h along with an encircling low reflective tissue and the surrounding skin returning back to normal. The shift in water content captured after 24 h indicated the healing process.	2012	58,59
			(b) Although for full-thickness burn, similar responses were observed after 10 min, which after 8 h showed some contrasting results. The injured area was dehydrated with pronounced emergence of less reflecting ring. The images taken after 24 h, however, showed some shift in water content, was less pronounced indicating its severity, which hinders rehydration of the tissue confirming its histological analysis of full-thickness burn.
			(c) Evolution of all the three zones, namely zone of coagulation, zone of stasis, and zone of hyperemia, was captured with high contrast as early as within 1 h of the burn defining its sensitivity.
A proposed image processing approach	Reflection	0.2–1 THz	THz reflectivity not only depends on water content, but also has correlation with the scattering from different microstructural features prevailing at different skin layers.	2013	61
Both partial and full thickness burns induced on rat models for a side by side comparison of the images	Reflection	Center frequency at 0.439THz with a bandwidth of 0.03THz	(a) The false color images showed a decrease in reflectivity at the injury with an increased reflectivity at the surrounding for partial burn. Whereas for second- and third-degree burn, it showed increased reflectivity all throughout the adjacent areas.	2014	60
			(b) The image contrast reported to be >200:1 delineating the high spatial resolution of the technique.
			(c) The system is claimed to be sensitive enough to register the changes in fluid flow occurring within 15 min of burn induction.
			(d) The results also corresponded to MRI responses.
			(e) THz imaging system was able to comprehend the degree of burn within 3–4 h of injury

MRI, magnetic resonance imaging.