Detection of cardiac myxomas with non-contrast chest CT

Background: Cardiac myxomas are sources of systemic embolism. Currently a large volume of chest CT and calciumscoring CT scans are performed without contrast injection. Purpose: To evaluate the diagnostic capability of non-contrast CT covering heart in detecting cardiac myxomas. Material and Methods: This retrospective study included 36 non-contrast CT scans of 36 consecutive patients (16 men, 20 women) who underwent CT scan before surgery for left atrial myxomas and 20 patients without myxoma as a control group. Two independent readers who were blinded to medical information reviewed non-contrast CT scans of 36 patients with cardiac myxomas and 20 scans in the control group patients. They determined the presence of lesions suspicious of myxomas using a five-point scale. The other reader measured attenuation number in the noncalcific areas of the tumors and sizes of the masses on the non-contrast CT images. Results: The average attenuation of cardiac myxoma (22.5 Hounsfield units [HU]; range, 8.9-32.9 HU) and adjacent unopacified blood (44.6 HU; range, 31.5-57 HU) were significantly different (P>0.001). Twelve cardiac myxomas (31.6%) had internal calcification and all of them were detected by both of readers. Cardiac myxomas were measured smaller on non-contrast CT (mean, 3.5 cm; range, 1.1-9.7 cm) than on pathologic specimens (mean, 4.1 cm, 1.4-10.0 cm) (P<0.001). Considering grade 3-5 on a five-grade scale as the detectability, the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of non-contrast CT in detecting cardiac myxomas were 88.8%/ 86.1%, 95.0%/100%, 96.9%/100%, 82.6%/80.0%, and 91.1%/91.1%, by reader 1 and reader 2, respectively and there was good inter-observer reliability (kappa value=0.92, P=0.157). Conclusion: Non-contrast CT scan is useful for detecting cardiac myxomas. Therefore, radiologists should be familiar with imaging findings of cardiac myxomas on non-contrast CT.