Detection of Myocardial Sarcoidosis by Thallium 201 Imaging

Thallium 201 myocardial perfusion scanning revealed focal left ventricular defects at rest in four of 30 patients (13 percent) with systemic sarcoidosis. All the defects decreased in size during thallium stress imaging, a finding opposite of that usually seen in myocardial ischemia. Nine patients had abnormal right ventricular visualization at rest. Thus, 11 of 30 (37 percent) had abnormal resting myocardial scand. Two of the four patients with left ventricular defects were studied serially for up to 1.5 years to evaluate response to corticosteroid therapy. The myocardial defect diminished in one patient, whereas the second patient, maintained for 2 years on low doses of steroids, had no resolution. In patients suspected of focal myocardial involvement by sarcoidosis on thallium scanning dynamic changes in scan defects can occur during exercise which are the reverse of those usually seen in coronary artery disease. These defects probably represent myocardial sarcoid. Right ventricular uptake generally appears to correlate with the severity of pulmonary involvement by sarcoidosis, yet does not appear to be a specific finding.