VALUE AND LIMITATIONS OF THALLIUM-201 SCINTIGRAPHY IN ACUTE PHASE OF MYOCARDIAL-INFARCTION

The diagnostic usefulness of thallium-201 scintigraphy in 200 patients with acute myocardial infarction was examined. The scintiscans showed a defect, suggesting infarction in 165. In all 44 patients studied within 6 h after onset of symptoms the scintiscans indicated a defect. Frequency of positive scans was significantly higher (90 of 96) in patients studied within 24 h after onset than in those (75 of 104) studied later (P < 0.01). When scintigraphy was performed later than 24 h after onset of symptoms, questionable and negative scintiscans were obtained even in patients with moderately elevated transaminase levels. Patients (28) received repeat scans, and within 24 h after onset of symptoms, the size of the defect tended to decrease, probably owing to regression of ischemia. Repeat scintiscans obtained later than 24 h showed fewer changes in defect size (P < 0.05). Thallium-201 scintigraphy gives optimum diagnostic information when performed within 24 h after onset of symptoms.