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C. Blazek and V. Blazek
12.1 Motivation
Spontaneous and provoked blood perfusion behavior in healthy, diseased, and treated
skin can be used as clinical indices for several kinds of diseases. Evaluation of the
skin structure and complexion actually consists mostly of qualitative clinical assessment. Technical possibilities for medical imaging in dermatology today are offered
by high-resolution digital photography (e.g. FotoFinder
® ), infrared thermography
(IRT), laser Doppler perfusion imaging (LDPI), and, more recently, also by the
Photoplethysmography Imaging (PPGI
® ) method.
The objective of this study was to present our first experience with PPGI by the
quantification of distributed dermal blood circulation changes in rest and after defined
pharmacological and mechanical skin irritations. The experimental details and the
3D perfusion signal possibilities and their significance of the PPGI system will be
explained in some clinically relevant examples.
12.2 Experimental Setup
In recent years, optoelectronic sensor concepts have gained an important role in functional blood circulation diagnosis because of their non-invasive and non-obstrusive
nature. They are generally accepted by the patients not only during vascular screening
examinations since they don’t cause pain and are devoid of harmful radiation or
ionizing phenomena. Classical Photoplethysmography, here defined as single point
measurement of venous and/or arterial blood volume changes with skin attached
optoelectronic sensor, is a non-invasive technology with a long-standing tradition
[1–4] and fascinating new perspectives [5–8]. At the core of the PPGI system is
an imaging strategy capable of contactless, incorruptible recording, processing and
displaying of image sequences of selected skin areas, in order to visualize the skin
vessels and to analyze dermal perfusion dynamics. Our PPGI experimental setup is
shown in Fig. 12.1.
The selected body area is illuminated mostly by a monochromatic light source
(multiple LED panels). The size of the observed skin/body region and the spatial
resolution can be freely chosen, only depending on the camera lens utilized and the
distance between camera and measured object. To detect the weak light modulation
backscattered from the skin, which is caused by the arterial perfusion (dermal blood
volume pulse), a high-sensitivity scientific camera has to be used. Our setup utilizes
the Life Science Resources UltraPix FE 250 camera, which offers a high dynamic
range of 14 bits and a high readout speed of 5.5 MB/s. The sensor, a silicon frametransfer black and white CCD chip with a pixel volume of 512 × 512, is sensitive in
the visible and near-infrared range of the spectrum. A typical PPGI video record lasts
about 100 s, consists of nearly 1,000 images (by adjusting 10 frames per second) of
the same scenario, and has a mean data volume of 700 MB.
C. Blazek and V. Blazek
12.1 Motivation
Spontaneous and provoked blood perfusion behavior in healthy, diseased, and treated
skin can be used as clinical indices for several kinds of diseases. Evaluation of the
skin structure and complexion actually consists mostly of qualitative clinical assessment. Technical possibilities for medical imaging in dermatology today are offered
by high-resolution digital photography (e.g. FotoFinder
® ), infrared thermography
(IRT), laser Doppler perfusion imaging (LDPI), and, more recently, also by the
Photoplethysmography Imaging (PPGI
® ) method.
The objective of this study was to present our first experience with PPGI by the
quantification of distributed dermal blood circulation changes in rest and after defined
pharmacological and mechanical skin irritations. The experimental details and the
3D perfusion signal possibilities and their significance of the PPGI system will be
explained in some clinically relevant examples.
12.2 Experimental Setup
In recent years, optoelectronic sensor concepts have gained an important role in functional blood circulation diagnosis because of their non-invasive and non-obstrusive
nature. They are generally accepted by the patients not only during vascular screening
examinations since they don’t cause pain and are devoid of harmful radiation or
ionizing phenomena. Classical Photoplethysmography, here defined as single point
measurement of venous and/or arterial blood volume changes with skin attached
optoelectronic sensor, is a non-invasive technology with a long-standing tradition
[1–4] and fascinating new perspectives [5–8]. At the core of the PPGI system is
an imaging strategy capable of contactless, incorruptible recording, processing and
displaying of image sequences of selected skin areas, in order to visualize the skin
vessels and to analyze dermal perfusion dynamics. Our PPGI experimental setup is
shown in Fig. 12.1.
The selected body area is illuminated mostly by a monochromatic light source
(multiple LED panels). The size of the observed skin/body region and the spatial
resolution can be freely chosen, only depending on the camera lens utilized and the
distance between camera and measured object. To detect the weak light modulation
backscattered from the skin, which is caused by the arterial perfusion (dermal blood
volume pulse), a high-sensitivity scientific camera has to be used. Our setup utilizes
the Life Science Resources UltraPix FE 250 camera, which offers a high dynamic
range of 14 bits and a high readout speed of 5.5 MB/s. The sensor, a silicon frametransfer black and white CCD chip with a pixel volume of 512 × 512, is sensitive in
the visible and near-infrared range of the spectrum. A typical PPGI video record lasts
about 100 s, consists of nearly 1,000 images (by adjusting 10 frames per second) of
the same scenario, and has a mean data volume of 700 MB.