Types of Medical Imaging Techniques

The first imaging techniques developed for medicine, x-rays, were discovered in 1985 by William Roentgen, and they were first used in medicine in 1896 (Lentle and Aldrich, 1997). Early radiology was chiefly concerned with skeletal morphology. Traditional x-rays are recorded on film, but recent developments in digital imaging have led to x-rays images being stored digitally in a computer rather than on film. Modern developments have led to computer tomography scans (CT)in which a fan beam of x-radiation sweeps through 360 degrees while detectors provide a digital readout of the amount of radiation and so the degree to which it has been attenuated, which allows a reconstruction of a sectional display of body structure in terms of electron density. Next came the positron emission tomography (PET) scans which use the emission of positrons during radionuclide decay and their resultant gamma ray production on interaction with electrons to provide an "autoradiograph" of the body. Single gamma rays emitted by radionuclides such as 99mTc, 123I, and 111In are used in single photon emission computer tomography (SPECT) scans which detects tracer distribution in multiple organ sections. Ultrasound is another commonly used imaging device in modern medicine, using sound waves to produce real time images in which signal strength is proportional to reflection from tissue interfaces. Doppler shift analysis - in which the perceived pitch of sound waves varies with the velocity of its so

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Thermograms can be used to diagnose headaches. Ford and Ford (1997) reviewed thermograms of 993 patients with migraine with and without aura, chronic daily headache, cluster headache, post traumatic headache, and other headache types. Of these 855 (86.1 percent) patients had abnormal thermograms, usually characterized by decreased supraorbital thermal emission. In patients with migraine without aura, 85.4 percent had abnormal thermograms, as did 89.1 percent of those with migraine with auras. Abnormal thermograms were also found in 85.7 percent of patients with cluster headache, 84.8 percent of patients with posttraumatic headache, and 82.8 percent of patients with various types of headaches. This study suggests digital infrared thermograms are useful in diagnostic tests of headaches. Laparoscopic infrared imaging can be used as an adjunct to direct imaging to assist in the identification of various anatomic structures and to assess tissue viability during laparoscopic procedures (Cadeddu, Jackman and Schulam, 2001). In clinical evaluations, infrared imaging proved useful in differentiating between blood vessels and other anatomic structures. Vessel identification, assessment of organ perfusion, and transperitoneal loca

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