Radiological characteristics of atrial myxoma in Cardiac Computed Tomography

Radiological characteristics of atrial myxoma in Cardiac Computed Tomography

Journal of Cardiovascular Computed Tomography xxx (2017) 1e3 Contents lists available at ScienceDirect Journal of Cardiovascular Computed Tomography...

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Journal of Cardiovascular Computed Tomography xxx (2017) 1e3

Contents lists available at ScienceDirect

Journal of Cardiovascular Computed Tomography journal homepage: www.JournalofCardiovascularCT.com

Research paper

Radiological characteristics of atrial myxoma in Cardiac Computed Tomography Kawa Haji*, Arthur Nasis Monash Cardiovascular Research Centre, MonashHEART, Monash Health and Monash University Department of Medicine (MMC), Melbourne, Australia

a r t i c l e i n f o

a b s t r a c t

Article history: Received 23 November 2016 Received in revised form 31 January 2017 Accepted 6 February 2017 Available online xxx

Background: Although the primary role of Cardiac Computed Tomography (CCT) is assessment of the coronary arteries, the technique also allows detailed examination of cardiac structures and other cardiac pathologies including cardiac myxoma. However, limited data exists regarding the CCT characteristics of cardiac myxoma. Objective: To describe the radiological characteristics of a series of cardiac myxomas in CCT. Methods: We retrospectively identified all patients at our tertiary urban referral centre with cardiac myxoma on CCT over a seven-year period between July 2008 and July 2015. We describe the CCT characteristics of eight cases. Seven of them had histologically documented myxoma after surgical removal, while one patient had a lesion suggestive of myxoma on echocardiography and CCT. Results: Eight patients were diagnosed with cardiac myxoma, comprising five females and three males. Seven of eight myxomas were located in the left atrium and one in the right atrium. Seven myxomas were polypoid in shape and one myxoma was villous. The average size was 22  26 mm. Calcification was present in half of the myxomas and average attenuation was 74 ± 46 Hounsfield Units. Conclusion: CCT has an important role in assessment of cardiac structures. This series highlights the radiological characteristics of cardiac myxoma. © 2017 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

Keywords: Myxoma Cardiac tumor Cardiac Computed Tomography

1. Introduction

2. Materials and methods

Myxoma is the most common benign primary tumor of the heart, comprising up to 50e70% of all benign cardiac tumors.1 While transthoracic echocardiography (TTE) remains the first line diagnostic tool, in recent years Cardiac Computed Tomography (CCT) is increasingly utilized for evaluation of cardiac masses.2,3 Additionally, myxoma may be incidentally diagnosed on CCT when the test is performed for other reasons like assessment of coronary artery disease.4 There is limited data about the imaging characteristics of myxoma on CCT. The purpose of this report is to describe the radiological characteristics of a series of cardiac myxomas diagnosed with CCT to aid in the diagnosis of this rare, yet potentially serious condition.

We searched the CCT database at our tertiary urban referral center, Monash Medical Centre, Melbourne, Australia and identified 8 patients with myxoma on CCT over a seven-year period between July 2008 and July 2015. Seven patients had histologically documented myxoma after surgery, while one patient had a lesion suggestive of myxoma on echocardiography and CCT, and the patient was managed conservatively as a consequence of being considered unsuitable for surgery. All studies were performed on a 320-detector row system (AquilionOne Dynamic Volume CT, Toshiba Medical Systems, Tokyo, Japan). A bolus of 60e100 ml of iopromide (Ultravist 370, Bayer HealthCare) was injected into an antecubital vein at a flow rate of 5e7 ml/s (depending on the patient's body mass index), followed by 50 ml saline. Scanning was triggered in the arterial phase using automated contrast bolus tracking, with a region of interest placed in the left ventricle manually triggered at a threshold of 180 Hounsfield Units. An axial scanning technique was used with slice collimation 0.5 mm and gantry rotation speed 350 ms. No concurrent table movement was required as the scanner provided

Abbreviations: CCT, Cardiac Computed Tomography; ECG, Electrocardiogram; HU, Hounsfield unit; MSv, millisiever; TTE, transthoracic echocardiogram. * Corresponding author. MonashHEART, Monash Cardiovascular Research Centre, 246 Clayton Road, Clayton, 3168, Australia. E-mail address: [email protected] (K. Haji).

http://dx.doi.org/10.1016/j.jcct.2017.02.002 1934-5925/© 2017 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

Please cite this article in press as: Haji K, Nasis A, Radiological characteristics of atrial myxoma in Cardiac Computed Tomography, Journal of Cardiovascular Computed Tomography (2017), http://dx.doi.org/10.1016/j.jcct.2017.02.002

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K. Haji, A. Nasis / Journal of Cardiovascular Computed Tomography xxx (2017) 1e3

Fig. 1. A,b,c Multiple CCT multiplanar reconstructed views of a typical polypoid atrial myxoma attached to the interatrial septum. It contains calcification around the rim with central Hounsfield unit attenuation of 47 ± 31. D,e,f Multiple CCT multiplanar reconstructed views of a typical polypoid atrial myxoma attached to the right atrial wall. It is non-calcified with Hounsfield unit attenuation of 58 ± 40. The myxoma can be seen crossing the tricuspid valve into the right ventricle.

16 cm craniocaudal coverage. Exposure parameters included an xray tube potential of 100e135 kVp and effective tube current of 300e500 mA, based on vendor specifications and the patient's body mass index. Acquisitions were performed with prospective electrocardiogram-triggering using a 70e80% phase window. Imaging was completed within a single ReR interval utilizing a 180 rotation, providing an effective temporal resolution of 175 ms. ECGgated data sets were reconstructed automatically to generate overlapping 0.5 mm slices in 0.25 mm intervals at 75% of the ReR cycle length. A default ‘medium soft tissue’ reconstruction kernel (FC04) was used. CCT datasets were transferred to a post-processing workstation (Vitrea FX 2.0, Vital Images, Minnetonka, MN, USA) for analysis by a cardiologist with more than six years' experience in CCT working in a high volume CCT center, using maximum-intensity projections, multiplanar reconstructions and axial slices along multiple longitudinal and transverse axes. The attenuation value of myxomas in Hounsfield units was measured by placing three regions of interest (all 0.5 cm2) in each lesion, and outside the calcification area with the average value used for reporting.

the investigation of low-to-intermediate risk chest pain. The other three patients had CCT for preoperative work-up after myxoma was diagnosed with TTE. The indication for undertaking TTE was lightheadedness in 2 of 3 and chest pain for the other. Seven myxomas were located in the left atrium (Fig. 1, a-c) and one was located in the right atrium. The most common origin in the left atrium was the inter atrial septum, which was the origin of 4 of the myxomas. The remaining three left atrial myxomas originated from the posterior left atrial wall, the superior part of the left atrium and the superiorposterior part of the left atrium. The right atrial myxoma originated from the posterior right atrial wall. The right atrial myxoma crossed the tricuspid valve (Fig. 1, d-f), however none of the left atrial myxomas were large enough to cross the mitral valve. The average size of all myxoma was 22  26 mm. The shapes were polypoid in 7 and villous in one. Calcification was present in four myxomas, with three displaying coarse multifocal calcification and one displaying patchy calcification around the rim. The average attenuation value was 74 ± 46 Hounsfield Units. Mean patient radiation exposure was 8.5 ± 2.8 millisievert (mSv). Five patients had no to minimal coronary stenosis, while the other three has at least moderate coronary artery stenosis. The mean radiation dose was 8.5 ± 2.8 mSv (Table. 1).

3. Results The eight patients comprised five females and three males. Mean age was 68 ± 8 years (range: 54e80). In five patients, myxoma was diagnosed incidentally in patients who underwent CCT for

4. Discussion This is the largest reported series of atrial myxoma detected

Please cite this article in press as: Haji K, Nasis A, Radiological characteristics of atrial myxoma in Cardiac Computed Tomography, Journal of Cardiovascular Computed Tomography (2017), http://dx.doi.org/10.1016/j.jcct.2017.02.002

K. Haji, A. Nasis / Journal of Cardiovascular Computed Tomography xxx (2017) 1e3

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Table. 1 Myxoma characteristics. Patient Age Gender Location 1 2 3

74 78 63

4 5 6

80 54 73

7 8

60 64

Attachment

Female Left atrium Interatrial septum Female Left atrium Interatrial septum Female Right Posterior atrial wall atrium Male Left atrium Superior part of atrium Female Left atrium Interatrial septum Female Left atrium Basal septum and posterior atrial wall Male Left atrium Superio-posterior atrial wall Male Left atrium Interatrial septum

Shape

Cross atrioventricular valve

Calcification CT attenuation (HU)

Polypoid 19  17 Polypoid 24  22 Polypoid 39  69

No No Tricuspid valve

No Yes No

47 ± 31 64 ± 59 58 ± 40

990 468 704

Villous 20  17 Polypoid 33  43 Polypoid 8  9

No No No

Yes No No

68 ± 30 51 ± 34 54 ± 31

662 357 806

Polypoid 23  18 Polypoid 13  15

No No

Yes Yes

109 ± 63 139 ± 82

445 416

with CCT, the majority of which were diagnosed incidentally in patients undergoing CCT for investigation of suspected coronary artery disease in low or intermediate risk chest pain. The findings show that cardiac myxomas typically are well-defined, lobulated, mobile round masses usually with a narrow pedicle. They are often heterogeneous with foci of calcification. Our series has shown CCT to be an excellent modality to assess size, shape, location, and calcification of myxomas. Similar to previous smaller reports, the majority of identified myxomas were located in the left atrium and attached to the interatrial septum.5e7 The other CCT features of myxoma include mobile, polypoid, round or oval masses with low attenuation and they may have calcification.7,8 The above findings are different from other common cardiac lesions. For example, thrombi are generally smaller, have lower attenuation, do not take up contrast and their location is dependent on the underlying cardiac abnormality.7 Fibroelastomas are small, smooth, hypodense and irregular valvular tumors, which can be difficult to identify on CCT because of their small sizes that average 1 cm.8 Malignant metastases in the heart, which are the most common malignant heart tumors, are larger in size, mainly intramural, irregular and ill-defined. Metastases can be associated with other abnormalities like pericardial effusion or lesions elsewhere in the heart,8 unlike myxomas which are generally isolated. The above emphasizes that CCT is capable of identifying incidental but clinically relevant non-atherosclerotic cardiovascular abnormalities, to help the reading physician to formulate a differential diagnosis and be aware of the possibility of myxoma in such patients, particularly in an era where CCT is being performed with increasing frequency to investigate chest pain syndromes. Diagnosing myxoma has always been a challenge due to their rarity, variety and non-specific symptoms. Before echocardiography, almost all cases of myxoma were diagnosed post mortem. Twodimensional echocardiography currently constitutes the first line tool for diagnosing cardiac myxoma and its accuracy has been well established, with the transesophageal approach superior to the transthoracic approach.1,6 However, as image quality and ease of acquisition for CCT and cardiac magnetic resonance imaging continue to improve and both methods are being more widely employed, CCT and cardiac magnetic resonance playing an increasingly important role in the contemporary diagnosis of myxoma, partly due to their superior resolution.9 Compared to other imaging modalities, the advantages of CCT include rapid acquisition, high and isotropic spatial resolution and the ability to assess coronary anatomy which may be required prior to surgery. Another important benefit of CCT in myxoma patients is comprehensive information about cardiac anatomy, which can be paramount for cardiothoracic surgical planning. Potential disadvantages of CCT include the use of radiation and intravenous

Size (mm)

Radiation (DLP)

contrast, as well as lower temporal resolution compared to echocardiography and magnetic resonance imaging.9 This series has all the potential limitations of any retrospective cohort study including selection bias.10 Nonetheless the description of imaging characteristics of myxoma will help reading and attending in the diagnosis of cardiac myxoma on CCT when sufficient imaging cannot be obtained from other modalities. At this stage TTE remains the gold standard in diagnosing myxoma and the role of CCT is complimentary. Despite the small number of patients in this series, which may potentially limit the generalizability of reported findings, this report is one of the largest published series of cardiac myxoma diagnosed by CCT. 5. Conclusion CCT has an important role in assessment of cardiac structures. In an era where CCT is being performed with increasing frequency, this series highlights the radiological characteristics of this rare condition on CCT to help physicians with diagnosis. Conflict of interest statement I declare that all the above authors do not have any matters which might give rise to a real or perceived conflict of interest. References [1.]. Reynen K. Cardiac myxomas. N Engl J Med. 1995;333:1610e1617. [2.]. ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 Appropriate Use Criteria for Cardiac Computed Tomography. [3.]. Noninvasive Coronary Artery Imaging: Current Clinical Applications Cardiac Society of Australia and New Zealand. 2010. [4.]. Knickelbine T, Lesser J, Haas T, et al. Identification of unexpected non atherosclerotic cardiovascular disease with coronary CT angiography. JACC. Cardiovasc Imaging. 2009;2:1085e1092. [5.]. Pinede L, Duhaut P, Loir R. Clinical presentation of left atrial cardiac myxoma. Med Baltim. 2011;80:159e172. [6.]. Muigge A, Daniel W, Haverich A, Lichtlen P. Diagnosis of noninfective cardiac mass lesions by two-dimensional echocardiography comparison of the transthoracic and transesophageal approaches. Circulation. 1991;83:70e78. [7.]. Scheffel H, Baumueller S, Stolzmann P, et al. Atrial myxomas and thrombi: comparison of imaging features on CT. AJR Am J Roentgenol. 2009;192: 639e645. [8.]. Rajiah P, Kanne J, Kalahasti V, Schoenhagen P. Computed tomography of cardiac and pericardiac masses. J Cardiovasc Tomogr. 2011;5:16e29. [9.]. Araoz P, Mulvagh S, Tazelaar H, et al. CT and MR imaging of benign primary cardiac neoplasm wit echocardiographic correlation. Radiographics. 2000;20: 1303e1319. [10.]. von Elm E, Altman D, Egger M, et al. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies for the STROBE initiative. Lancet. 2007;370: 1453e1457.

Please cite this article in press as: Haji K, Nasis A, Radiological characteristics of atrial myxoma in Cardiac Computed Tomography, Journal of Cardiovascular Computed Tomography (2017), http://dx.doi.org/10.1016/j.jcct.2017.02.002