Diagnostic Performance of Cardiac Magnetic Resonance Imaging and Echocardiography in Evaluation of Cardiac and Paracardiac Masses




Echocardiography is the preferred initial imaging method for assessment of cardiac masses. Cardiac magnetic resonance (CMR) imaging, with its excellent tissue characterization and wide field of view, may provide additional unique information. We evaluated the predictive value of echocardiography and CMR imaging parameters to identify tumors and malignancy and to provide histopathologic diagnosis of cardiac masses. Fifty patients who underwent CMR evaluation of a cardiac mass with subsequent histopathologic diagnosis were identified. Echocardiography was available in 44 of 50 cases (88%). Echocardiographic and CMR characteristics were evaluated for predictive value in distinguishing tumor versus nontumor and malignant versus nonmalignant lesions using histopathology as the gold standard. The Wilcoxon rank-sum test was used to compare the 2 imaging methods’ ability to provide the correct histopathologic diagnosis. Parameters associated with tumor included location outside the right atrium, T2 hyperintensity, and contrast enhancement. Parameters associated with malignancy included location outside the cardiac chambers, nonmobility, pericardial effusion, myocardial invasion, and contrast enhancement. CMR identified 6 masses missed on transthoracic echocardiography (4 of which were outside the heart) and provided significantly more correct histopathologic diagnoses compared to echocardiography (77% vs 43%, p <0.0001). In conclusion, CMR offers the advantage of identifying paracardiac masses and providing crucial information on histopathology of cardiac masses.


The primary objective of this study was to evaluate the predictive value of echocardiography and cardiac magnetic resonance (CMR) imaging parameters to identify cardiac tumors and malignant masses ( Table 1 ), as well as to diagnose the histopathology for cardiac masses using histologic confirmation as the gold standard. We hypothesized that CMR provides incremental diagnostic value to echocardiography.



Table 1

World Health Organization 2015 classification of tumors of the heart





















































































Benign tumors and tumor-like lesions
Rhabdomyoma
Histiocytoid cardiomyopathy
Hamartoma of mature cardiac myocytes
Adult cellular rhadomyoma
Cardiac myxoma
Papillary fibroelastoma
Haemangioma, NOS
Capillary Haemangioma
Cavernous Haemangioma
Cardiac fibroma
Lipoma
Cystic tumor of the atrioventricular node
Granular cell tumor
Schwannoma
Tumors of uncertain behavior
Inflammatory myofibroblastic tumor
Paraganglioma
Germ cell tumors
Teratoma, mature
Teratoma, immature
Yolk sac tumor
Malignant Tumors
Angiosarcoma
Undifferentiated pleomorphic sarcoma
Osteosarcoma
Myxofibrosarcoma
Leiomyosarcoma
Rhabdomyosarcoma
Synovial sarcoma
Miscellaneous sarcomas
Cardiac lymphomas
Metastatic tumors
Tumors of the pericardium
Solitary fibrous tumor, malignant and nonmalignant
Angiosarcoma
Synovial sarcoma
Malignant mesothelioma
Germ cell tumors
Teratoma, mature and immature
Mixed germ cell tumor


Methods


Our study was approved by the institution review board at our medical center in compliance with the Health Insurance Portability and Accountability Act.


We retrospectively identified 171 patients (58% men, age 55 ± 19 years) referred for CMR evaluation of cardiac/paracardiac mass from October 2004 to February 2011. Of these 171 patients, 121 patients were managed conservatively ( Figure 1 ). Six malignant masses were managed conservatively because of poor surgical candidacy, unresectability, and patient preference. Tissue for histopathology was obtained in 50 patients through either percutaneous (n = 7) or surgical (n = 43) approaches after CMR study; 44 had echocardiograms.




Figure 1


Summary of patients included in cohort.


Transthoracic echocardiography (TTE) was performed using commercially available equipment (iE33, Sono 7500; Philips Healthcare, Andover, Massachusetts). Images were obtained in standard views. Transesophageal echocardiography (TEE) was also performed using commercially available equipment and standard imaging planes. Contrast agents were not used. Echocardiography studies were clinically interpreted by level 3-trained cardiologists at our institution. TTE was performed in 38 of 44 cases, TEE alone in 6 of 44 cases, and both TTE and TEE in 11 of 44. The reports were reviewed for imaging parameters (see statistical analysis). If a mass was missed on TTE and seen on TEE (as in 1 case), TEE served as the reference point.


CMR studies were performed on a 1.5-T (Avanto or Sonata) or 3.0-T (TimTrio or Verio) MR system (Siemens Healthcare, Erlangen, Germany) using a torso and spine coil in conjunction with electrocardiographic gating. Imaging was performed with standard cardiac mass evaluation protocol consisting of the following sequences in all patients: (1) scout images to identify cardiac axes, (2) black-blood double inversion recovery imaging of the thorax in axial and sagittal planes, (3) cine 2-dimensional steady-state free precession (SSFP) imaging in stacked horizontal long axis (4-chamber) and short-axis planes to cover the entire heart, (4) T1-weighted and T2-weighted fast turbo spin echo and short tau inversion recovery sequences, (5) dynamic first-pass perfusion after an intravenous injection of 0.15 mmol/kg gadolinium-DTPA, (6) precontrast and postcontrast 3-dimensional volumetric interpolated breath-hold sequence performed in the axial planes, and (7) postcontrast T1-weighted fast turbo spin echo and inversion recovery late gadolinium enhancement imaging (5 to 10 minutes after contrast). CMR studies were clinically interpreted by 1 of 3 level 3 CMR-trained physicians at our institution. The finalized CMR reports were reviewed for information on characteristics of the mass.


Continuous data are reported as mean ± SD, and categorical data are expressed as frequency or percentage. Individual morphologic features (location, size, number, mobility, myocardial infiltration, and presence of pericardial or pleural effusion) and imaging characteristics (homogenous/heterogeneous, signal intensity on T1/T2-weighted sequences, and contrast enhancement on first-pass enhancement and late gadolinium enhancement) were evaluated as potentially useful imaging measures for mass diagnosis using binary logistic regression analysis. The Wilcoxon rank-sum test was used to compare the number of times a correct histologic diagnosis was provided by each imaging study using pathology as the reference standard. All statistical tests were conducted at the 2-sided 5% significance level using SAS 9.3 (SAS Institute, Cary, North Carolina).




Results


Fifty patients (50% men, mean age 46 ± 17 years) had histologic diagnosis of their cardiac mass ( Table 2 ). Pathologically confirmed malignant tumors occurred at almost the same frequency in men and women (11 of 25, 44% men vs 10 of 25, 40% women). A total of 10 of 50 patients had a preexisting cancer diagnosis. Of those, 6 of 10 had recurrence of disease on pathology, 2 of 10 had a new primary cancer diagnosis, and 2 of 10 were diagnosed with a thrombus. Location of tumors is listed in Table 3 .



Table 2

Patient characteristics including final pathologic diagnosis (n = 50)









































































































































































All Patients ( n=50 ) Men ( n=25 ) Women ( n=25 )
Age (mean ± SD) 46±17 46±17 46±17
Previous Cancer History 10 4 6
History of Atrial Fibrillation 2 2 0
History of CVA 3 1 2
Non-tumor 15 8 7
Thrombus 9 4 5
Mitral valve with myxoid degeneration 2 2 0
Pericardial cyst 1 1 0
Non-neoplastic liver 1 0 1
Thymic cyst 1 0 1
Intramyocardial cyst 1 1 0
Benign Tumor 14 6 8
Myxoma 9 5 4
Papillary fibroelastoma 3 0 3
Lipoma 1 1 0
Lipoleiomyoma 1 0 1
Malignant Tumor 21 11 10
Teratoma 2 0 2
Paraganglioma 2 1 1
Thymoma 2 1 1
Hodgkin’s lymphoma 1 1 0
Diffuse large B-cell lymphoma 3 1 2
Non-small cell adenocarcinoma 1 0 1
Metastatic breast cancer 1 0 1
Metastatic clear cell renal cancer 1 0 1
Poorly differentiated sarcoma 1 1 0
Osteosarcoma 1 1 0
Fibrosarcoma 1 1 0
Liposarcoma 2 1 1
Desmoplastic sarcoma 1 1 0
Rhabdomyosarcoma 1 1 0
Angiosarcoma 1 1 0

Bold indicates timing of new category.

CVA = cerebrovascular accident.



Table 3

Location of masses












































Location Non-Tumor Benign Tumor Malignant Tumor
Right Atrium 8 3 5
Right Ventricle 0 2 2
Left Atrium 2 8 0
Left Ventricle 2 0 1
Pericardium 0 0 5
Epicardial 0 0 1
Extracardiac 3 1 8


In 44 cases (88% of cohort) with echocardiography, CMR was performed after echocardiography at mean interval of 13 ± 34 days. CMR identified a mass lesion in all cases that underwent intervention for histologic diagnosis. CMR was performed 20 ± 34 days before intervention.


In 5 of 44 cases (11%), TTE (TEE not performed) did not identify a mass that was later seen on CMR and pathology. All 5 masses were >3 cm on CMR. Of the missed masses, 2 were in the anterior mediastinum, 2 in the pericardium ( Figure 2 ), and 1 in the left atrium. There was an additional paracardiac mass located in the middle mediastinum that was initially visualized on left heart catheterization, missed on TTE but visualized on TEE.




Figure 2


Sixty-eight-year-old man with previously resected cardiac sarcoma with new onset atrial fibrillation. TTE in basal short-axis view retrospectively demonstrates a mass (arrow) in the inferior RV, missed on initial evaluation. Cine CMR in short-axis view demonstrates an intrapericardial mass near the inferior RV wall, which is hyperintense to myocardium on T2-weighted images with peripheral contrast enhancement on first-pass and late gadolinium enhancement images. Histopathology demonstrated angiosarcoma. An infiltrative mass with extensive areas of hemorrhage is seen at low power magnification (H&E: 4×) with infiltration into cardiac muscle (H&E: 10×). High power magnification (H&E: 40×) shows slit-like vessels lined by atypical cells with plump irregular nuclei and prominent nucleoli, with multiple mitoses. Tumor cells are reactive for CD31 (a protein expressed in vascular tumors) on immunohistochemistry. LV = left ventricle; H&E = hematoxylin and eosin stain; RV = right ventricle; SSFP = steady-state free precession.


Table 4 demonstrates individual age-adjusted and gender-adjusted echocardiography and CMR parameters associated with tumor and malignancy.



Table 4

Echocardiography and cardiac magnetic resonance imaging parameters predictive of tumor or malignancy





























































Echocardiography Parameters Unadjusted Adjusted for
Age and Gender
Tumor
(P -value)
Malignancy
(P -value)
Tumor
(P -value)
Malignancy
(P- value)
Location outside the right atrium 0.0063 0.4037 0.0049 0.4661
Location outside the atria and ventricles 0.0405 0.0054 0.0444 0.0044
Size > 1 cm 0.1351 0.9470 0.1224 0.9137
Non-Mobility 0.5994 0.0031 0.5084 0.0039
Number of Masses 0.5165 0.3371 0.5181 0.4324
Myocardial Invasion 0.2300 0.1470 0.3543 0.2233
Pericardial Effusion 0.6863 0.0049 0.4578 0.0088
Pleural Effusion 1.0000 0.3864 0.9999 0.3798

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Nov 27, 2016 | Posted by in CARDIOLOGY | Comments Off on Diagnostic Performance of Cardiac Magnetic Resonance Imaging and Echocardiography in Evaluation of Cardiac and Paracardiac Masses
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