Safety and clinical utility of combined intravenous dipyridamole/symptom-limited exercise stress test with thallium-201 imaging in patients with known or suspected coronary artery disease.

Dipyridamole-induced coronary hyperemia with 201Tl myocardial perfusion scintigraphy can detect ischemic regions in individuals unable to perform adequate exercise, but it has several limitations. Symptom-limited exercise supplementation to intravenous dipyridamole can potentially overcome them, but the safety and diagnostic accuracy for this combination has not been established. Between 1987 and 1991, 441 consecutive patients were assessed for combined symptom-limited exercise test preceded by i.v. dipyridamole. Clinical records could not be obtained for 37 patients, and 40 patients were not exercised because they were unable; therefore 384 patients (mean age 58 +/- 9.8 yr, 278 men) underwent symptom-limited exercise preceded by 0.56 mg/kg of dipyridamole and followed by planar 201Tl perfusion scintigraphy. Following dipyridamole infusion, systolic blood pressure fell by 10 +/- 14 mmHg and heart rate increased by 8 +/- 11 bpm. Adverse effects were experienced by 77 people (dizziness in 44; headache in 11; nausea in 9; syncope in 2 and chest pain in 11). Exercise heart rate was 69% +/- 16% of predicted maximum and ST shift was -0.9 +/- 0.9 mm. Following exercise, seven patients required aminophylline (four after dizziness, two after headache, one after chest pain), which was uniformly successful. There were no episodes of prolonged chest pain, MI, death or serious arrhythmia. Safety was maintained for people with severe triple coronary artery disease, the elderly (> 70 yr) and those with significant pulmonary disease. Sensitivity was 95% for at least one with > 70% luminal stenosis and 94% for at least one with > 40% luminal stenosis. Specificity was 28% and 53% respectively. The addition of a symptom-limited exercise test to i.v. dipyridamole is safe for all groups of patients referred for 201Tl study.

The scintigraphic findings in Paget's disease of bone.

Bone scans and radiographic skeletal surveys have been done in 41 patients who had Paget's disease. The scintigraphic findings are consistent with what is known of the pathophysiology of Paget's disease. Diseased bone demonstrates increased vascularity, an increased degree of uptake of bone-seeking radiotracers and, in appropriate bones, evidence of marrow replacement. The bone scintiscan is a more sensitive indicator of the extent of polyostotic Paget's disease than conventional radiograph, demonstrating 34% more lesions. Because it reflects shorter term changes in osteoblastic activity the bone scan is of some value in providing immediate objective evidence of the therapeutic effectiveness of Mithramycin which has been used in this study in the treatment of the minority of patients with pain in Pagetoid bone. A technique for documenting alterations in uptake by diseased bone numerically is presented. Upon treatment with Mithramycin the ratio of abnormal uptake in relation to normal bone fell from 8.7 to 3.9.