Further Information on the Science of Thermography

Medical DITI is a noninvasive adjunctive diagnostic technique that allows the examiner to visualize 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 visualized in color on a monitor. This visual image graphically maps the body temperature and is referred to as a thermogram. The spectrum of colors 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.

Medical DITI's major clinical 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 diagnosis made by the clinician.

Medical DITI has been used extensively in human medicine in the U.S.A., Europe and Asia for the past 20 years. Until now, cumbersome equipment has hampered its diagnostic and economic viability. Current state of the art PC based IR technology designed specifically for clinical application has changed all this.

Clinical uses for DITI include; 

  • To define the extent of a lesion of which a diagnosis has previously been made;
  • To localize an abnormal area not previously identified, so further diagnostic tests can be performed;
  • To detect early lesions before they are clinically evident;
  • 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 localized 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. 

Medical DITI is filling the gap in clinical diagnosis ...

  • X ray, C.T. Ultrasound and M.R.I. etc., are tests of anatomy.
  • E.M.G. is a test of motor physiology.
  • DITI is unique in its capability to show physiological change and metabolic processes. It has also proven to be a very useful complementary procedure to other diagnostic modalities.

Unlike most diagnostic modalities DITI is non invasive. It is a very sensitive and reliable means of graphically mapping and displaying skin surface temperature. With DITI you can diagnosis, evaluate, monitor and document a large number of injuries and conditions, including soft tissue injuries and sensory/autonomic nerve fibre dysfunction.

Medical DITI can offer considerable financial savings by avoiding the need for more expensive investigations.

Medical DITI can graphically display the very subjective feeling of pain by objectively displaying the changes in skin surface temperature that accompany pain states.

Medical DITI can show a combined effect of the autonomic nervous system and the vascular system, down to capillary dysfunctions. The effects of these changes show as asymmetry's in temperature distribution on the surface of the body.

Medical DITI is a monitor of thermal abnormalities present in a number of diseases and physical injuries. It is used as an aid for diagnosis and prognosis, as well as therapy follow up and rehabilitation monitoring, within clinical fields that include Rheumatology, neurology, physiotherapy, sports medicine, oncology, pediatrics, orthopedics and many others.

Results obtained with medical DITI systems are totally objective and show excellent correlation with other diagnostic tests.

The controlling mechanism for thermal emission and dermal microcirculation is the sympathetic nervous system. There is a persistent vasomotor tone in the peripheral arterioles and precapillary sphincters. This tone allows the dermal vessels to stay in a partially constricted state so as to inhibit excess heat loss from a higher core temperature. The autonomic regulation involves synapse of preganglionic sympathetic fibers to postganglionic. The postganglionic fibers travel to vascular structures and modulate alpha receptor function in the dermal microcirculation. When there is increased sympathetic function vasospasm will occur due to further vessel constriction and there will be decreased thermal emission at the cutaneous level. This may occur due to either increased postganglionic fibers function/irritation or hypersensitization of the alpha receptors in the dermal microcirculation allowing increased binding of catecholamines. Increased thermal emission will conversely be seen due to situations of decreased postganglionic function (such as seen in denervation) or alpha receptor blockade (receptor fatigue due to release of vasoactive substances such as substance P).

Muscle, joint, osseous, ligament and nerve injuries all cause the patient to perceive pain. Pain sensation is carried by afferent stimulation of C-nociceptors. These unmyelinated fibers do have a percentage of sympathetics. Pain is then processed centrally and up to the brain via the spinothalamic tracts. The patient may feel pain at the area of injury and at sites distant to the area of injury. This is called referred pain.

Much research has been done documenting referred pain in myofascial syndromes and somatic visceral conditions. These referred pain zones are believed to be a somatocutaneous sympathetic response. They work via a common autonomic neural network. The somatosympathetic response can be imaged by Thermography. Pain is believed to be a neurogenic and autonomic response to injury and DITI findings have been found to correlate well to the patient’s report of painful areas and is well suited for diagnostic purposes in athletic injuries. Thermography is not a picture of pain; however, it is a picture of autonomic dysfunction which seems to correlate well with regions of pain.