Key points
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Cardiac CT has several advantages including wide availability, rapid acquisition time, excellent isotropic spatial resolution, and multiplanar reconstruction capabilities.
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CT is a robust technique for assessment of the relationship of the mass to the myocardium, cardiac valves, pericardium, coronary arteries, great vessels including pulmonary and systemic, and adjacent tissues, such as lung and lymph nodes, in a way that no other imaging modality can often reach.
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Metastasis to the heart is more common than a primary malignant tumor.
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Metastasis may involve the heart and pericardium by one of four pathways: retrograde lymphatic extension, hematogenous spread, direct contiguous extension, or transvenous extension. The predominant route is a retrograde lymphatic extension.
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The most common primary malignant cardiac mass is sarcoma and angiosarcoma is the most common.
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The right atrium is the most common cardiac chamber involved by a primary malignant tumor.
CT has emerged as an important imaging modality in the evaluation of cardiac and paracardiac masses. CT has several advantages including wide availability and rapid acquisition time, excellent isotropic spatial resolution, and multiplanar reconstruction capabilities. CT demonstrates excellent, three-dimensional rendering of the masses, which is essential for surgical planning. The wide field of view of CT enables visualization of paracardiac and other extracardiac structures, which is essential for staging malignancies.
Malignant masses are often more challenging to specifically diagnose, but the differential diagnosis can often be narrowed, and more importantly, the examination may document the extent of the lesion and presence or absence of additional (extracardiac) metastatic lesions, perform preoperative coronary evaluation, and be used to help plan biopsy or resection.
Cardiac computed tomography (CT) is particularly helpful in establishing the presence of thrombus versus enhancing tissue, and the pattern of enhancement in perfused masses may lead to insights that a mass is hypervascular, has a dominant fibrous component, or demonstrates features typical of a vascular malformation.
Newer techniques, such as CT perfusion and dual energy CT, may be useful in characterizing tissue and enhancement characteristics .
Tissue characterization
Metastases to the heart and pericardium are much more common than primary cardiac tumors and are generally associated with a poor prognosis. A primary malignant tumor is less common than a primary benign tumor, with most of them being sarcomas. Imaging features of tumors in CT that help distinguish benign from malignant neoplasms include location, size, margins, the presence of a feeding artery, calcification, or pericardial effusion ( Table 12.1 ) .
| Feature | Benign | Malignant |
|---|---|---|
| Location | More on left side | More in right atrium |
| Size | Small | Large, may fill chamber |
| Margin | Smooth, well defined | Lobulated, ill defined, invasive, infiltrative |
| Invasion | None | Myocardium, pericardium, extracardiac |
| Attachment | Pedicle may be seen | Broad based |
| Feeding Vessels | Absent | May be present |
| Calcification | Rare, except for small foci in fibroma, myxoma | Large foci in osteosarcoma |
| Pericardial Effusion | Not seen | Suspicious for malignancy |
| Metastasis | None | May be present |
Technical issues
See Chapter 11 .
Primary malignant cardiac tumors
Sarcoma
Sarcoma is the most common primary cardiac malignancy, accounting for one-third of cases .
Angiosarcoma is the most common type of sarcoma .
Angiosarcoma
These tumors usually arise from the right atrium or pericardium but may also arise from the pulmonary artery. Up to 25% of these tumors are partly intracavitary and can cause valvular obstruction, right-sided heart failure, and pericardial tamponade with hemorrhagic fluid. Two main morphologic types have been described in angiosarcoma. The first is a well-defined mass protruding into a cardiac chamber; the second is a diffusely infiltrative mass extending along the pericardium .
On CT imaging ( Fig. 12.2 ), a low-attenuation intracavitary mass, which may be irregular or nodular and usually arising from the right atrial free wall with areas of necrosis, may be seen . Tumor infiltration of the myocardium, compression of the cardiac chambers, direct extension into the pericardium with features of pericardial thickening or effusions, and involvement of the great vessels are other features discernible on CT imaging.
On post-contrast enhancement acquisition, the tumors show a heterogeneous enhancement pattern . Multiple lesions occur in 60% of patients, and pulmonary metastases are present in 66%–89% .
Undifferentiated sarcoma
On CT, these tumors appear as large, irregular, low-attenuation intracavitary lesions . Tumor infiltration of the myocardium may appear as thickening and irregularity. The tumor may also manifest as a hemorrhagic mass replacing the pericardium, similar to angiosarcoma. Several reports have demonstrated a tendency to involve the valves .
Rhabdomyosarcoma
This tumor is the most common cardiac malignancy in infants and children. There is a slight male predilection, but because there is no predilection for any cardiac chamber.
Rhabdomyosarcomas may arise anywhere in the myocardium and are more likely than other sarcomas to involve or arise from cardiac valves .
They are often multiple and may invade the pericardium .
In contrast to angiosarcomas, rhabdomyosarcomas tend to always involve the myocardium, and when they involve the pericardium, the appearance is that of nodular masses rather than sheetlike thickening of the pericardium . CT imaging may demonstrate a smooth or irregular low-attenuation mass in a cardiac chamber. CT is also useful in identifying extracardiac extension of the tumor ( Fig. 12.3 ) .
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