TABLE 3.

CMR-Based Diagnostic Criteria of Cardiac Masses in Children

	Fibroma	Rhabdomyoma	Malignant	Myxoma	Teratoma	Fatty Deposits in TSCa	Thrombus
Classification	Fibroblastic	Muscular	Various	Endocardial	Ectopic tissue	Lipomatous	Other
Size, cm	2–10	<1–8	1–10	<1–9b	3–7	<1–5	1–2
Location and appearance	Intramyocardial Well circumscribed Solitary ± lobules Septum, free wall, or both LV >RV (can be atrium)	Intracavitary Attached to LV or RV muscle Can be atrium or epicardial Usually multiplec	Commonly SVC/IVC/RA Epicardial, intrapericardial, anterior/posterior mediastinal Infiltratived May cross tissue plane	Typically left atrium but can be any chamber Endocardial, pedunculated, mobile, heterogeneous Mimics other masses: variable location and appearance	Usually intrapericardial, compresses SVC/RA Multilocular, bosselated, solid, and cystic areas May be intramyocardial or intracavitary	Intramyocardial Commonly ventricular septum Epicardial Often multiple	Intracavitary SVC/IVC Endocardial Often in regions of stasis (lines, infarcts)
Cine SSFP	−	−	±	++	+	± (Rim of chemical shift artifact)	±
T1	−	−	±	±	−	+	−
T2	± (Heterogeneous)	±	+	+	+	− (T2/fat suppression)	−
Fat suppression	No	No	No	No	No	Yes	No
FPP	−	−	±	−	−	−	−
LGE	+++ (Fibroma LGE pattern)	−	±	±	±	−	±
Pericardial effusion	Common	Uncommon	Common	Uncommon	Common	No	Uncommon
Other	Usually diagnosed prenatally or in infancy Ventricular arrhythmia Microscopic calcifications and regions of necrosis Gorlin syndrome (15% CMR cases)	Usually diagnosed prenatally or in infancy Tuberous sclerosis (>80% cases) Atrial and ventricular arrhythmias	Pleural effusion Usually older children History of malignancy Chest pain Multiple High mortality Metabolic activity on 18F-FDG PET	Usually older children Greater prevalence in female patients Triad of symptoms: (obstructive, constitutional, and systemic emboli) Carney complex (30% CMR cases)	Usually diagnosed prenatally or in infancy Pericardial/pleural effusion Respiratory symptoms	Older children with tuberous sclerosis	Dark on T1 scout imaging Dark on LGE sequence, long inversion time
Differential diagnosis	Myofibroma	Thrombus	Various	Fibroelastoma Malignant	Hemangioma Pericardial cyst	Lipoma	Rhabdomyoma
	Infectious/Inflammatory	IMT	Rosai-Dorfman	Papillary Fibroelastoma	Benign Myofibroblastic Mass	Neurofibroma	Lipoma	Cyst
Classification	Infectious/inflammatory	Endocardial	Histiocytic	Endocardial	Fibroblastic	Peripheral nerve sheath	Lipomatous	Malformation/ectopic tissue
Size, cm	1–3	<1–6	3–5	<1–2	1–2	5–8	1–5	1–5
Location and appearance	Variable locations Endocardial or intramyocardial	Usually endocardial and intracavitary Can be intramyocardial or intrapericardial RA/RV more common Often polypoid, broad-based	Variable	Endocardial Valve (usually mitral or aortic) Pedunculated Mobile	Outflow tract Well circumscribed	Posterior mediastinal Multiple	Any location Commonly intramyocardial or endocardial May be valvular, pedunculated, mobile	Pericardium Posterior mediastinum (bronchogenic or foregut duplication cyst)
Cine SSFP	+	+	±	+	+	±	−	+
T1	−	±	±	−	−	+	+	±
T2	+	±	±	±	+	+	− (T2/fat suppression)	++
Fat suppression	No	No	No	No	No	No	Yes	No
FPP	−	−	−	±	−	−	−	−
LGE	++	± (Sometimes ++)	++	+	±	−	−	−
Pericardial effusion	Common	Uncommon in infants	Common	Uncommon	Uncommon	Uncommon	Uncommon	Common
Other	Fever Anemia Thrombocytopenia Chest pain Inflammatory pseudotumor Metabolic activity on 18F-FDG-PET	ALK gene expression May be locally aggressive with recurrence and metastasis Heart murmur, fatigue Metabolic activity on 18F-FDG PET/CT	Neuro symptoms Chest pain Metabolic activity on 18F-FDG PET	Murmur Embolic events	Hemodynamic impact	Older children Neurofibromatosis At risk for malignant degeneration	Range of clinical presentations—usually benign, but may cause syncope or sudden death depending on location and risk of embolization	Pericardial cysts may increase in size on repeat imaging
Differential diagnosis	Endocarditis IMT Papillary fibroelastoma	Low-grade sarcoma Myxoma Papillary fibroelastoma Inflammatory pseudotumor	Infectious/inflammatory	Infectious/inflammatory Myxoma	Papillary fibroelastoma	Malignant	Lipomatous hypertrophy of the atrial septum Fatty deposits in TSC	Hydatid cyst Teratoma Lymphatic malformation
	Paraganglioma	Hemangioma		Angiosarcoma	Hemangioendothelioma		Vascular Malformation	Glomus tumor
Classification	Neuroendocrine	Vascular anomaly		Vascular anomaly	Vascular anomaly		Vascular anomaly	Vascular anomaly
Size, cm	3–4	1–5		6–9	3–6		5–10	<1–10
Location and appearance	Intrapericardial, sympathetic chain Blood supply from coronary circulation Multiple vascular channels Encapsulated, well circumscribed	Any location, commonly RA during infancy Commonly inflow tracts Commonly endocardial Vascular channels		Right atrium Infiltrative Extends to epicardium and anterior mediastinum Rapid growth	Right atrium Left atrium Occasionally ventricle May be infiltrative with pericardial or mediastinal extension		Solitary Well circumscribed Intramyocardial or epicardial Heterogenous Lymphatic malformation is commonly in RA, encasing a coronary artery	Single or multiple intramyocardial masses
Cine SSFP	+	+		+	±		+	+
T1	−	±		+	±		+	+
T2	+	+		+	+		+	+
Fat suppression	No	No		No	No		No	−
FPP	+++	++		++	±		±	++
LGE	++ (Peripheral enhancement)	++		+	±		±	++
Pericardial effusion	Uncommon	Infants		Common	Infants		Common	Common
Other	Catecholamine excess: arrhythmia, hypertension Teenagers/young adults Succinate dehydrogenase subunit B mutation associated with malignant disease	Often incidental diagnosis Fatigue Fetal or neonatal presentation: pericardial effusion and tamponade		Malignant Metastatic Older children Chest pain Fatigue Dyspnea Pleural effusion High mortality Metabolic activity on 18F-FDG-PET	Range of behavior with malignant potential including metastasis (epithelioid hemangioendothelioma) Fetal or neonatal presentation: pericardial effusion Kasabach-Merritt phenomenon (consumptive coagulopathy) in kaposiform hemangioendothelioma Metabolic activity on 18F-FDG-PET (described in noncardiac locations)		May have arterial, capillary, venous, and/or lymphatic components Resection may not be possible or may risk injury to cardiac structures Often respiratory symptoms, sometimes asymptomatic	Resection may not be possible or may risk injury to cardiac structures Usually found in the subungual regions of fingers and distal extremities (rare cardiac involvement) Usually benign, may be metastatic or have malignant potential
Differential diagnosis	Vascular anomalies	Teratoma (infants) Angiosarcoma Hemangioendothelioma Paraganglioma		Hemangioendothelioma Other malignancy	Myxoma Hemangioma Angiosarcoma		Pericardial cyst Teratoma	Hemangioma Hemangioendothelioma

The following symbols are used: – indicates isointense or hypointense; ± indicates variable intensity; + indicates hyperintense; ++ indicates strongly hyperintense; and +++ very strongly hyperintense.

^aAlso known as myocardial fatty foci.

^bMyxomas referred for CMR are typically smaller than average and less likely to be located in the left atrium (referral bias).

^cRhabdomyomas referred for CMR are commonly solitary (referral bias).

^dInfiltrative: 1) poorly defined edges; 2) infiltrating myocardium or crossing a tissue plane within the heart; 3) involving both cardiac and extracardiac structures; or 4) appearance of linear growth through a large vessel such as the superior or inferior vena cava.

¹⁸F-FDG = ¹⁸F-fluorodeoxyglucose; ALK = anaplastic lymphoma kinase; CT = computed tomography; IMT = inflammatory myofibroblastic tumor; IVC = inferior vena cava; LV = left ventricle; PET = positron emission tomography; RA = right atrium; RV = right ventricle; SVC = superior vena cava; TSC = tuberous sclerosis complex; other abbreviations as in Tables 1 and 2.