CMR for malignant cardiac tumors: Diagnosis, approach, and follow-up

Key points

  • Cardiac magnetic resonance (CMR) is the gold standard noninvasive imaging modality to assess tissue characteristics in vivo which gives it a unique advantage in discriminating benign cardiac masses from malignant tumors. CMR also provides visualization of tumor invasion, hemodynamic effects, and location relative to surrounding cardiac and extracardiac structures. These features make CMR an essential tool for diagnosis and management of cardiac tumors.

  • The following sequences form part of a comprehensive CMR exam: cine imaging (e.g. balanced steady state free precession (bSSFP)), T1/T2-weighted black-blood (BB) images, T1/T2 mapping, first-pass perfusion, and delayed enhancement imaging. The characteristics of the tumor are often described as hyper/iso/hypo-intense, meaning higher, equal to, or lower signal intensity compared to normal myocardium. For instance, the extensive vascular networks associated with malignant tumors often present as hyperintense on first-pass perfusion and on late gadolinium enhancement (LGE) images. The high volume of intracellular free water content in malignant tumors and the frequently observed surrounding edema may lead to longer T1 and T2 relaxation times. At the same time, necrosis and hemorrhage within the tumor often result in heterogeneous signal on T1W and T2W BB images. The newer T1 and T2 mapping techniques provide quantitative T1 and T2 values, instead of the relative grayscale obtained through T1W and T2W BB imaging, providing an opportunity to further advance the diagnosis of malignant cardiac tumors.

  • CMR limitations include absolute and relative contraindications for imaging in patients with devices that are not MR compatible (e.g., noncompatible pacemakers, internal defibrillators, mechanical circulatory support devices, etc.). Breath-holds are often used in clinical protocols and patients that cannot hold their breath often have decreased image quality. Similarly, the need for ECG gating makes CMR a challenge in patients with irregular heart rhythm as it can lead to acquisition artifacts and poor image quality.







black blood


balanced steady-state free precession


cardiovascular magnetic resonance imaging


central nervous system


computed tomography


first-pass perfusion


fat saturation


fast spin echo


late gadolinium enhancement


left ventricle


right ventricle




steady-state free precession


T1 weighted


T2 weighted


transesophageal echocardiography


transthoracic echocardiography


Cardiac masses entail a heterogeneous group of disorders that can be broadly divided into benign and malignant tumors. Malignant cardiac tumors are exceedingly rare (compared to benign masses) and often present with significant diagnostic and therapeutic challenges. Cardiac magnetic resonance (CMR) imaging has emerged as a key noninvasive technique in their evaluation, primarily due to the superior tissue characterization without ionizing radiation exposure. Moreover, CMR provides visualization of cardiac tumor extension/invasion, relationship with surrounding cardiac and extracardiac structures, and the evaluation of hemodynamic effects. Malignant tumors can be further divided into primary and secondary cardiac malignancies ( Table 14.1 ). Among malignant primary cardiac tumors, the most common are sarcomas which account for about 75% of the cases, while primary cardiac lymphomas, mesotheliomas, neuroendocrine tumors, and others account for the remainder 25% of cases ( Table 14.1 ) . Secondary tumors can invade the heart by direct extension (e.g. pleural mesothelioma), intracavitary spread (e.g. renal cell carcinoma via inferior vena cava or lung carcinoma via pulmonary veins), and hematogenous or lymphatic, metastatic spread. The reports about the prevalence of cardiac metastases vary widely, from 2% to up to 18%; however, these estimates are largely based on autopsies and may not reflect the cases seen in cardiac imaging centers .

Table 14.1
Malignant cardiac tumors—clinical, morphologic, and histopathologic characteristics and management.
Primary cardiac tumors Morphologic characteristics Histopathologic characteristics Treatment considerations and prognosis
Cardiac sarcomas
Angiosarcoma Invasive, sessile, and lobular Present with myocardial infiltration, often highly vascularized with pleomorphism, mitotic figures, and areas of necrosis When possible, surgical resection is recommended and is often considered to treat hemodynamic consequences and reduce tumor burden. Systemic chemotherapy and less often radiation therapy may be considered
Poor prognosis with aggressive course
Undifferentiated sarcoma Large, irregular, intracavitary mass Typical spindle and polygonal cells, filled with eosinophilic cytoplasm
Osteosarcoma Invasive, sessile, lobular Spindle cell lesions with malignant fibrous histiocytoma, microscopic foci areas of osteosarcoma, and chondrosarcoma in the spindle regions
Leiomyosarcoma Invasive, sessile, lobular Blunt nuclei with bundles of spindled cells, areas of necrosis, mitotic cells with epithelioid regions
Synovial cell sarcoma Protruded mass with irregular, gelatinous appearance Monophasic: Only contains spindle cells, no epithelial cells
Biphasic: contains both epithelial and spindle cells
Intimal sarcoma Invasive, arising from large blood vessels and heart Spindle and pleomorphic cells with myxoid area
Fibrous histiocytoma sarcoma (pleomorphic and undifferentiated high grade) Invasive, knoblike lesion
  • Storiform-pleomorphic type: Pleomorphic cells with spoke wheel-like structure

  • Giant tumor cell type : giant cells with a strong eosinophilic cytoplasm and irregular nuclei

  • Inflammatory type : Large number of foamy yellow tumor cells mixed with a large number of inflammatory cells

  • Myxoid type: Round or star-shaped, in a loose mucus matrix

Rhabdomyosarcoma Invasive, lobular Embryonal type with rhabdomyoblasts containing abundant glycogen and expressing desmin, myoglobin, and myogenin
Primary cardiac lymphoma Lobular, multiple lesions Commonly diffuse large B-cell lymphoma. Other variations include Burkitt lymphoma, T-cell lymphoma, and low-grade B-cell lymphoma Chemotherapy and immunotherapy, no role for surgery
Pericardial mesothelioma Pericardial effusion and a tumor encasing the heart Combination of epithelial or sarcomatous lesions, and/or biphasic Highly aggressive with poor prognosis
Palliative management
Secondary cardiac tumors Smooth surface, often multiple lesions Varies depending on the primary disease Cardiac involvement confers a similar prognosis to stage IV cancer
Management directed toward primary disease
Metastatic melanoma Smooth surface, often multiple lesions Malignant epithelioid cells with prominent nucleoli and frequent mitoses Systemic therapy with targeted therapy per clinical guidelines

In this chapter we describe current clinical indications for CMR and detailed CMR imaging protocol recommended for the comprehensive assessment and management of cardiac tumors. We then provide examples of applied CMR imaging and specific CMR findings with primary and secondary cardiac tumors.

Role of CMR imaging in establishing the diagnosis

The initial identification and evaluation of a cardiac mass most often starts with the readily available transthoracic echocardiogram (TTE). Echocardiographic findings, in turn, frequently represent an indication for CMR to (a) confirm abnormal cardiac mass (vs normal anatomical structure as described in Table 14.2 ) and (b) further differentiate between benign, malignant, and nontumorous masses (e.g. thrombus). CMR imaging protocols can be employed to evaluate hemodynamics, morphology, pericardial invasion, size, location, homogeneity, and signal characteristics of cardiac masses, and thus aid in differentiation between benign and malignant tumors . Features concerning for malignancy include large tumor size, involvement of the pericardium and the right heart, tissue heterogeneity, and high extracellular volume (ECV) determined by T1 mapping before and after gadolinium contrast infusion. A position paper published in 2020 by the Society of Cardiovascular Magnetic Resonance (SCMR) outlines clinical indications for the use of CMR in the evaluation and management of cardiac masses . Beyond diagnosis and differentiation of malignant masses, CMR is recommended for guidance of surgical therapy, assessment of treatment effect, as well as posttreatment surveillance ( Table 14.3 ) .

Table 14.2
Normal heart structures that may be misinterpreted as cardiac tumors .
Anatomical structure Comments
Crista terminalis Seen as a protuberance in the right atrium, may be perceived as angiosarcoma or primary cardiac lymphoma
Eustachian valve Frequently observed in the right atrium
“Coumadin ridge” Lies in the left atrium, in between the left atrial appendage and the left superior pulmonary vein
Chiari network Occasionally seen in the right atrium near the entry site of inferior vena cava and coronary sinus
Moderator band Seen in the right ventricle
False tendons of LV Seen in the left ventricle

Table 14.3
Society of cardiovascular magnetic resonance (SCMR) recommendations for CMR use in evaluation and management of cardiac tumors .
CMR indications Level of evidence
I. Suspected cardiac mass I
II. Differentiation between benign, malignant, and nontumorous masses I
III. Guide surgery and/or biopsy if this is deemed appropriate I
IV. Follow-up of benign cardiac tumors that do not require urgent intervention for changes over time I
V. Evaluation of tumor resection/debulking, monitoring recurrence after surgery, and regression or progression after chemotherapy or radiotherapy I
VI. Extracardiac extension of cardiac tumors or cardiac extension of tumors originating from surrounding structures I
VII. Impact of cardiac masses on hemodynamics I

Most clinically indicated CMR images are obtained on 1.5T field strength magnets, though in recent years 3T imaging has been making a significant advance in quality and availability. The signal intensity of a neoplastic lesion is dependent on the tissue morphology and CMR parameters employed to obtain the images. Fig. 14.4 illustrates a CMR protocol recommended for the evaluation of cardiac masses . Axial plane images with T1-weighted (T1W) and T2-weighted (T2W) sequences are used for native tissue characterization and are the first step in CMR evaluation. In recent years, the evolution of CMR parametric mapping has provided us with the ability to quantify myocardial tissue alterations based on T1, T2, and T2*(star) relaxation times and extracellular volume (ECV) measurements . In turn, these values can be used in conjunction with qualitative T1W and T2W images in differentiating between cardiac tumors. For instance, a hypointense mass on T1W (or low T1 on T1 mapping) may represent a calcified tumor, meanwhile, hyperintensity on T1W images (high T1 on T1 mapping) can be seen in masses with high-fat content (e.g. lipomas and liposarcomas), hemorrhagic or highly vascularized tumors (e.g. angiosarcoma and hemangioma), as well as in melanomas ( Table 14.5 ). On T2W images, highly vascularized tumors such as angiosarcoma present with hyperintense signal (high T2 on T2 mapping), in contrast to fibrous tumors which are hypointense (low T2 on T2 mapping). Importantly, the most common benign primary tumor, cardiac myxoma, also presents as bright/hyperintense on T2W and with high values on T2 mapping and in instances may present a diagnostic challenge ( Fig. 18.8 ).

Fig. 14.4, CMR imaging techniques—a comprehensive protocol for evaluation of cardiac masses. Abbreviations: LV , left ventricle; BB , black blood; SSFP , steady-state free precession; FSE , fast pin echo; fat sup , fat suppression; bSSFP , balanced steady-state free precession; LGE , late gadolinium enhancement.

Table 14.5
CMR characteristics of malignant cardiac tumors.
Tumor Preferential location T1W T2W LGE Cine images
Primary cardiac sarcomas
Angiosarcoma Right atrium Heterogeneous hypo- and hyperintensity due to hemorrhage and necrosis Heterogeneous hyperintense, “cauliflower” appearance Heterogeneous enhancement pattern with marked surface enhancement (“sunray appearance”) and central necrosis Fixed on the wall with a broad base, does not move with the heart
Impaired right atrium and ventricular motion
Undifferentiated sarcoma Left atrium Isointense Slightly hyperintense Heterogeneous enhancement Hypo- or isointense
Rhabdomyosarcoma Frequently involves the valves
Commonly not confined to one chamber
Isointense Hyperintense Homogeneous enhancement with areas of low central intensity due to necrosis Isointense
Osteosarcoma Left atrium Heterogeneously hypointense Hyperintense Nonspecific due to calcification Hypo- or isointense
Leiomyosarcoma Posterior left atrium, pulmonary vein and mitral valve Isointense or
to myocardium
Hyperintense Markedly enhanced Hypo-or isointense
Primary cardiac lymphoma Right atrium
(often involves more than one chamber)
Isointense Heterogeneously hyperintense Heterogeneous enhancement, with area of low enhancement in the center of the lesion Isointense, large soft tissue mass
Pericardial mesothelioma Pericardial space Homogeneously isointense Heterogeneously hyperintense with areas of necrosis Markedly heterogeneous enhancement Hypointense nodule
Metastatic melanoma Right heart Hyperintense Hyperintense Heterogeneous enhancement Nodular hyperintense appearance in the myocardium
Other metastatic involvement Pericardium Hypointense Hyperintense Heterogeneous enhancement Varies depending on the primary

In contrast to qualitative assessment on T1W and T2W images, mapping permits quantification and may allow visualization of the disease process related to intra- and extracellular disturbances. Though current clinical evidence is scarce, mapping techniques can be used to characterize masses, pericardial effusion, and fatty lesions within the heart. For example, vascularized tumors with high water content have long T1 and T2 relaxation times, while they have low T1 values postcontrast update due to significant gadolinium contrast uptake . Although significant advances have been made in parametric mapping techniques, future research and validation are needed before routine clinical application for diagnoses of cardiac tumors. When describing T1W and T2W imaging with hyperintense or hypointense findings for various tumors, this information can also be obtained using T1 and T2 mapping.

Steady-state free precession (SSFP) technique is a valuable sequence to assess the relationship between the tumor with the myocardium, pericardium, blood pool, valves, and adjacent tissues. Assessment of tumor movement with respect to normal cardiac structure during cardiac cycle provides information on tumor attachment and whether tumor growth is invasive. Additionally, the hemodynamic effects on cardiac pumping and valvular function can be evaluated by cine SSFP images. Also, phase contrast flow imaging can be used to quantify hemodynamic effects with, e.g. increases in flow velocity if the tumor is affecting ejection or filling of blood.

Beyond native tissue characteristics, gadolinium contrast infusion can be employed to discern cardiac masses from normal cardiac structure through first-pass perfusion and late gadolinium enhancement (LGE). First-pass perfusion is conducted with dynamic imaging during infusion of contrast and is an important method to identify tumor vascularity and presence of necrosis. Masses such as hemangioma and to a lesser degree angiosarcoma tend to show early enhancement after contrast infusion and are easily distinguishable from other lesions . As malignant tumors frequently cause tissue necrosis by obliteration of capillary beds, first-pass perfusion images may exhibit dark central areas (necrosis) with hyperenhancement of the surrounding tissue, an important diagnostic measure to differentiate benign from malignant tumors. Late gadolinium enhancement (LGE) sequences are obtained 10 min postcontrast administration. Benign cardiac masses more often present as markedly homogeneous enhancing lesions (with the exception of myxoma), while malignant tumors present heterogeneous contrast enhancement due to extensive vascularity and necrosis. To discriminate normal myocardium from neoplastic masses, the inversion time is set to null normal cardiomyocytes as the exact inversion time varies depending upon patient physiology, timing postcontrast administration, and type of sequence.

Primary malignant tumors

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