What is Thermal Imaging
Overview of Digital Infrared Thermal Imaging:
DITI is a non-invasive screening technique that allows the examiner to visualise and quantify changes in skin surface temperature. An infrared scanning device is used to convert infrared radiation emitted from the skin surface into electrical impulses that are visualised in colour on a monitor. This visual image graphically maps the body temperature and is referred to as a thermogram. The spectrum of colours indicate an increase or decrease in the amount of infrared radiation being emitted from the body surface. Since there is a high degree of thermal symmetry in the normal body, subtle abnormal temperature asymmetry’s can be easily identified.
DITI’s major value is in its high sensitivity to pathology in the vascular, muscular, neural and skeletal systems and as such can contribute to the pathogenesis and screening made by the clinician.
DITI maybe useful:
To define the extent of a lesion of which a screening has previously been made;
To localise an abnormal area not previously identified, so further screening tests can be performed;
To monitor the healing process before the patient is returned to work or training.
Skin blood flow is under the control of the sympathetic nervous system. In normal people there is a symmetrical dermal pattern which is consistent and reproducible for any individual. This is recorded in precise detail with a temperature sensitivity of 0.01°C by DITI.
The neuro-thermography application of DITI measures the somatic component of the sympathetic nervous system by assessing dermal blood flow. The sympathetic nervous system is stimulated at the same anatomical location as its sensory counterpart and produces a ‘somato sympathetic response’. The somato sympathetic response appears on DITI as a localised area of altered temperature with specific features for each anatomical lesion.
The mean temperature differential in peripheral nerve injury is 1.5°C. In sympathetic dysfunction’s (RSD / SMP / CRPS) temperature differentials ranging from 1° C to 10° C depending on severity are not uncommon. Rheumatological processes generally appear as ‘hot areas’ with increased temperature patterns. The pathology is generally an inflammatory process, i.e. synovitis of joints and tendon sheaths, epicondylitis, capsular and muscle injuries, etc.
Both hot and cold responses may co-exist if the pain associated with an inflammatory focus excites an increase in sympathetic activity. Also, vascular conditions are readily demonstrated by DITI including Raynauds, Vasculitis, Limb Ischemia, DVT, etc.