Scintigraphic imaging of the heart in dogs damaged by irradiation

: The paper verified literature data assuming that the heart damage caused by irradiation of thorax may be scintigraphically detected by means of 99mTc-pyrophosphate. Three dogs underwent a single irradiation of thorax with a gamma cobalt source by the Dose 40 Gy. The myocardium scan was performed 24 hours, 20 days, 50 days, 80 days and 93 days after the irradiation. The scintigraphic examination proved to be negative at all the intervals observed. A comparison of the scan with morphological findings and with radioactivity of tissue samples after the dogs were sacrificed 93 days after the irradiation proved that the negativity of the pyrophosphate scintigraphy was caused by a minimum damage of the myocardium and not by an inability of 99mTc-pyrophosphate to be incorporated into radiation lesions. The data in literature on myocardium damage by irradiation appear to be considerably exaggerated.