Biomedical Engineering Reference
In-Depth Information
Fig. 1.46.
Time-sequentially subtracted thermograms before and after analgesic
drug injection. The patient suffered from left-foot pain caused by lumbar disk her-
niation. The lower right thermogram shows baseline data. She complained of right
foot pain where the thermogram shows a hypothermic region. Three minutes af-
ter injection of an analgesic (Neurotropin), her pain was diminished and the skin
temperature of her foot was elevated (
lower left
). When we subtract the baseline
image from the image after injection, we obtain the left upper image. The subtrac-
ted image is called the difference thermogram. The image clearly indicates to us
regions where the temperature was elevated. From (1.15), we understand that the
temperature difference of the image was proportional to the cutaneous blood flow.
The patient's vascular bed responded to the analgesic and dilated the arterial bed.
We can easily see that the blood-flow rate of the region decreases by functional con-
striction of arteries and not by organic obstruction. The upper right image shows
the mean temperature elevation rate distribution in this three minute perior. If the
interval between the images is shorter and the sensitivity of the machine higher,
the image might show us sympathetic vascular control signals
in (1.6)-(1.11), quantities of heat production and dissipation (i.e. of
ΔQr
,
ΔQe
,and
ΔQf
) are calculated to be 1/100 of
ΔQb
[73]. Therefore, the rate
of skin-temperature change in a short time period is calculated by the follo-
wing equation:
Cs × ΔT s
=
ΔQb
+
ΔQc
=
Aρc
[
ΔV s
(
Tb− Ts
)+
VsTs
]+
KcΔTs.
(1.14)
