13 Concluding Remarks and New Horizons in Skin Perfusion Studies
227
Fig. 13.4 Growing of the scientific papers, related to the terms “photoplethysmography imaging”
and “remote photoplethysmography”. Presented results are based on number of findings in different
databases (SUMMON searching engine of the CTU Prague and others). This statistic should not
be taken as a precise analysis, but clearly demonstrates the development of the research field
serve as a surrogate parameter for respiratory rate and depth of breathing [15]. This
method was extended to neonatal monitoring by our group [16–19].
IRTI differs from PPGI in that it is passive (no injection of energy required)
and hence operational at night. Yet, as skin perfusion is the dominant mean of the
body to carry heat energy from the core to the periphery, it can be assumed that
local temperature is somewhat correlated to local perfusion. Hence, local perfusion
amplitude and local skin temperature may carry similar information.
With this assumption in mind, our group was the first to propose fusion of these
two camera-based modalities [20]. As an illustrative example of the potential of
this concept, Fig. 13.5 shows some results from a pig trial [21]. Pathophysiological
phenomena like centralization due to sepsis can be easily detected, as both peripheral temperature and peripheral perfusion amplitude are affected. Similarly, events
like arterial embolism which in fact cause local malperfusion of a leg was nicely
demonstrated.
Image fusion is a classical image processing topic, and a variety of methods is
available. In general, the closer the angle of attack of both camera systems, the easier
is an algorithmic fusion. For illustration, Fig. 13.6 gives an example of imaging
quality that can already be achieved in such a case.
Furthermore, camera systems where PPGI and IRTI camera systems are physically integrated are currently coming to market. However, spatial resolution remains
a critical issue and must be matched when image fusion is attempted.
227
Fig. 13.4 Growing of the scientific papers, related to the terms “photoplethysmography imaging”
and “remote photoplethysmography”. Presented results are based on number of findings in different
databases (SUMMON searching engine of the CTU Prague and others). This statistic should not
be taken as a precise analysis, but clearly demonstrates the development of the research field
serve as a surrogate parameter for respiratory rate and depth of breathing [15]. This
method was extended to neonatal monitoring by our group [16–19].
IRTI differs from PPGI in that it is passive (no injection of energy required)
and hence operational at night. Yet, as skin perfusion is the dominant mean of the
body to carry heat energy from the core to the periphery, it can be assumed that
local temperature is somewhat correlated to local perfusion. Hence, local perfusion
amplitude and local skin temperature may carry similar information.
With this assumption in mind, our group was the first to propose fusion of these
two camera-based modalities [20]. As an illustrative example of the potential of
this concept, Fig. 13.5 shows some results from a pig trial [21]. Pathophysiological
phenomena like centralization due to sepsis can be easily detected, as both peripheral temperature and peripheral perfusion amplitude are affected. Similarly, events
like arterial embolism which in fact cause local malperfusion of a leg was nicely
demonstrated.
Image fusion is a classical image processing topic, and a variety of methods is
available. In general, the closer the angle of attack of both camera systems, the easier
is an algorithmic fusion. For illustration, Fig. 13.6 gives an example of imaging
quality that can already be achieved in such a case.
Furthermore, camera systems where PPGI and IRTI camera systems are physically integrated are currently coming to market. However, spatial resolution remains
a critical issue and must be matched when image fusion is attempted.