Differentiation of Primary Cardiac Tumors from Metastatic Tumors by Non-invasive Cardiac Imaging

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Background: Various imaging modalities are used to identify and characterize cardiac masses. While echocardiography remains the preferred imaging modality to evaluate cardiac masses, computed tomography (CT), magnetic resonance imaging (MRI), and ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET)/CT are being increasingly employed to assess cardiac mass lesions. However, the clinical value of non-invasive cardiac imaging for differentiating between primary cardiac mass and metastatic lesions has not yet been examined in detail. The purpose of the present study was to evaluate the diagnostic utility of non-invasive cardiac imaging for differentiating primary cardiac tumors from metastatic lesions, and non-tumorous lesions.
Methods: A retrospective review was conducted on 22 cardiac mass lesions in 20 patients assessed by cardiac imaging (at least one of CT, MRI, or ¹⁸F-FDG PET/CT) between December 2005 and March 2017. CT findings included the tumor size, location, existence of calcification, and morphology of the base portion of the lesion. MRI parameters included signals with T1-weighted imaging (T1WI), T2WI, mobility with cine imaging, and contrast enhancement. Tracer uptake by each cardiac lesion using ¹⁸F-FDG PET/CT was also evaluated.
Results: Among 17 cardiac mass lesions assessed by contrast-enhanced CT, all cardiac myxomas and papillary fibroelastomas had a pedunculated base portion. All metastases located in the cavity had a sessile base portion (P=0.0035). Malignant tumors (metastases and malignant lymphoma) had no mobility, while cardiac myxomas had a slightly higher frequency of mobility with cine MRI (0% vs. 100%, P=0.0667). Among the four lesions for which ¹⁸F-FDG PET/CT was performed, the three malignant lesions had strong ¹⁸F-FDG uptake, while the benign lesion showed insignificant accumulation.
Conclusions: The characteristics of the base portion of cardiac mass were useful for differentiating primary cardiac tumors from metastatic cardiac tumors. Cine MRI also exhibited diagnostic utility for differentiating between primary cardiac tumors and metastases. Therefore, non-invasive cardiac imaging may be employed to differentiate cardiac mass lesions. The accurate diagnosis of cardiac mass lesions may require the assessment of multiple characteristics on images.