Thermography in the Diagnosis of Cerebrovascular Disease

Abstract

The significance of strokes as a national health problem is well appreciated by layman and physician alike. Broad governmental programs, designed to deal with this third most common disabling condition plaguing Americans, emphasize the importance of acquiring more knowledge of vascular lesions which affect the brain. The earlier diagnosis of incipient stroke is a worthy practical aspect of the clinical problem, especially when the lesions can be treated by reconstructive vascular surgical operations. One method of assessing blood flow in any portion of the body is by determining the temperature of that part and recognizing a variation from the physiologic state. In the case of the limited external display of the internal carotid artery, sensitive instruments are required to demonstrate a variation of skin temperature from the normal; modern clinical thermography has been shown to be a method of detecting such changes. The “Thermograph” is a medically adapted heat-seeking device developed in connection with space exploration and national defense. Simple bolometers have been used for many years by astronomers to measure heat from the stars. The more complicated thermograph is a motor- driven, scanning, thermal-resistor bolometer that also detects heat spontaneously emitted by various objects. The purpose of this paper is to describe the application of thermography to the diagnosis of vascular disorders in a group of patients with neurologic disturbances, the majority with occlusive or stenotic lesions of the carotid arterial system. A logical anatomic explanation for characteristic thermographic patterns associated with occlusive disease of the common and internal carotid arteries will be proposed. Other aims are to assess the limitations of thermography in the diagnosis of carotid insufficiency, to show how the technic may be used as a method of selecting patients for angiography, and to point out its usefulness in evaluating the effectiveness of treatment. The cases analyzed had the following features: (a) all patients had symptoms or signs suggesting a neurologic disorder consistent with a vascular etiology; (b) all patients had a complete neurologic evaluation by a qualified neurologist at or near the time of thermographic examination; (c) the lesions affecting the cerebral circulation were demonstrated by angiography or established anatomically by operation or necropsy. Technic In thermography, heat energy is changed to electrical energy and greatly amplified by the electronic circuitry of the Thermograph. Following amplification, the electrical energy is converted to light and photographed. A “thermogram” is the resultant two-dimensional photographic image obtained by two to four minutes of scanning and comprises approximately 60,000 individual heat recordings.