Thermography and Osteosarcoma

Abstract

Preliminary studies indicate that thermography is useful in evaluating patients with osteosarcoma. It may be employed to determine local extent and vascularity of the primary tumor, recurrence, and metastases. The thermogram may present findings not immediately detectable by conventional diagnostic methods. Procedure We utilize a high-speed infrared scanning device, the Pyroscan, which gives 40,000 separate temperature measurements in thirty seconds and records on newspaper facsimile paper. These scans measure a temperature range of 6° C with sensitivity of 0.3° C. The polarity is modified so that the warmer areas are recorded darker than the colder areas. The scans are performed in a room in which the temperature is 68° F, and the skin areas to be measured are exposed to this environment for eight minutes prior to thermography. Nineteen patients with osteosarcoma have been evaluated in two and a half years. The involved site was scanned in four positions; anteroposterior, postero-anterior, and both laterals. Also, total-body scans were obtained preceding biopsy to determine the presence of metastases to the lung, liver, lymph nodes, and bones. Repeated scans are taken at regular intervals after diagnosis and treatment. Primary Tumor The primary tumor was accurately outlined in the 14 patients who presented with a primary lesion. and the scans were correlated with roentgen findings (Fig. 1). In one patient with an osteosarcoma of the distal femur an unexpected tumor extension was found in the proximal portion of the femur (Fig. 2). “Skip areas” may not be demonstrated by roentgenography. “Skip areas” in osteosarcoma are uncommon, but when found contraindicate any surgical procedure short of disarticulation. In several patients the scans showed a large vessel or vessels emerging from the warm area of the tumor (Fig. 1). In each of these patients, pulmonary metastases were discovered within a short time. These large vessels may be an ominous prognostic sign. Metastases Metastatic lesions and recurrent tumor were detected often, and frequently the thermogram was the first evidence of disease. Pulmonary metastases were often indicated by increased skin temperature over the lesion. The mechanism for this increased skin temperature is unknown. In several patients the pulmonary metastases could not be detected by conventional roentgenography. In one patient, after the warm area of the thorax was discovered subsequent tomography confirmed the presence of metastatic nodular lesions (Fig. 3). In another patient pulmonary metastases did not become manifest on conventional roentgenography or tomography until some time after they were detected thermographically. In one instance an unsuspected metastatic bone deposit was discovered by the total-body thermographic survey and was indicated by a warm area directly over the involved bone. This was confirmed roentgenographically (Fig. 4).