Myocardial imaging with dipyridamole: Comparison of the sensitivity and specificity of 201Tl versus MUGA

Myocardial imaging was performed at rest and after dipyridamole infusion using ²⁰¹Tl and ⁹⁹Tc^m-gated blood pool studies (MUGA). Of 38 patients studied, 21 had coronary artery disease (CAD) and 17 were normal. With ²⁰¹Tl imaging, 19 of 21 patients with CAD (sensitivity 88%) showed perfusion defects during dipyridamole. Of 17 normals 6 (specificity 65%) showed clear perfusion defects during dipyridamole. With MUGA, 2 of 15 patients with CAD (sensitivity 13%) developed abnormal wall motion during dipyridamole; both patients developed ST depression >1 mm. Of 10 normals none developed abnormal wall motion. Twenty six of 38 patients developed angina during dipyridamole, which was reversed by aminophylline in 24 of 26. We suggest that dipyridamole infusion is effective for ²⁰¹Tl-perfusion imaging, and easily performed, but is not suitable for MUGA studies where ischaemia is the required end-point.