British Journal of Radiology 74 (2001),384-392 © 2001 The British Institute of Radiology
Magnetic resonance evaluation of the pericardium
W H T Smith, MRCP,
D J Beacock, MRCP,
A J P Goddard, FRCR,
T N Bloomer, MRCP,
J P Ridgway, PhD and
U M Sivananthan, MD, FRCR
Cardiac Magnetic Resonance Unit, The General Infirmary at Leeds, Leeds LS1 3EX, UK
Correspondence: Dr W Smith, Institute for Cardiovascular Research, Level 10 the Worsley Building, University of Leeds, Leeds LS2 9JT, UK
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Abstract
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Magnetic resonance (MR) is well suited to imaging the pericardium. High resolution images synchronized with the cardiac cycle can be obtained in any plane. The wide field of view allows additional anatomical and functional information to be obtained from adjacent structures such as the aorta, pleura, lungs and mediastinum. MR is particularly useful in cases of pericardial constriction without an associated effusion, in patients with complex or loculated pericardial effusions and in pericardial tumours. In this article we illustrate the characteristic MR features of a variety of pericardial pathologies.
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Introduction
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Pericardial pathology is usually assessed initially by echocardiography, which is widely available and provides functional as well as anatomical information. However, echocardiography is limited by a low signal-to-noise ratio of the pericardium and is more difficult in obese patients or in those with obstructive lung disease. The full extent of the pericardium is not imaged in any selected plane owing to the small field of view. Magnetic resonance (MR) provides excellent images of the entire pericardium without the need for iv contrast medium or ionizing radiation. MR removes many of the problems of imaging patients with chronic obstructive pulmonary disease or obesity, as long as they are not too obese to fit into the scanner. The images in this article have been obtained from different MR systems with field strengths of 0.5 T, 1.0 T and 1.5 T. The imaging protocols given in Table 1
represent those currently used on a Philips (Best, Holland) ACS NT 1.5 T research system.
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MRI appearances of normal pericardium
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T1 weighted spin echo imaging demonstrates the pericardium as a thin band of low signal due to its mainly fibrous structure and lack of water content. The pericardium is usually bordered by epicardial and pericardial fat, which has high signal on T1 images. The normal pericardial thickness is approximately 2 mm, and this is best evaluated anatomically on axial imaging (Figure 1). Breath-hold or real-time cine gradient echo images of the ventricles, and velocity phase map images of the atrioventricular valves are useful for assessing the functional impact of pericardial pathology.
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Figure 1. Normal pericardium. (a) T1 axial spin echo images show the pericardium as a narrow band of low signal intensity over the free wall of the right heart and the posterior wall of the left ventricle (arrows). (b) The space between the main pulmonary artery and the aorta (the aortopulmonary recess) (open arrow) is in continuity with the transverse sinus. Pericardial fluid may collect in this recess and potentially mimic the appearance of dissection.
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Pericardial cysts
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These rare remnants of defective embryological development of the pericardium are benign, although right ventricular outflow tract obstruction has been described [1]. They are clinically indistinguishable from pericardial diverticula and exist as unilocular, thin walled structures, which may be attached intimately or by a pedicle to the pericardium. They occur in the pericardiophrenic angle, much more commonly on the right (Figure 2), and may calcify.
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Figure 2. Pericardial cyst. Axial T1 spin echo images show the extent of the cyst (arrows), with indentation of the right ventricular free wall and right atrium. The signal intensity is high due to recent haemorrhage into the cyst, which caused the acute presentation. Right ventricular filling was impaired on the cine images.
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Pericardial defects
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Pericardial defects are uncommon. The majority of cases are congenital, but defects can result from surgery or trauma. They are usually first recognized as an incidental finding on a chest radiograph but may present with chest pain [2, 3], possibly related to left atrial herniation through the defect (Figure 3) leading to ischaemic necrosis. A spectrum of abnormalities exists, ranging from small defects to total absence of the pericardium. The most common defect is an absence of the entire left side of the pericardium.
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Figure 3. Pericardial defect. (a) Axial spin echo image shows discontinuation of the pericardium (open arrows) over the left atrium. (b) The coronal spin echo image shows an enlarged left atrial appendage, which has herniated through the defect (arrows).
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Acute pericarditis
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The diagnosis of acute pericarditis is usually suspected clinically and is supported by serological markers of inflammation, with or without evidence of infection. MRI can identify the frequently associated effusion and can visualize inflammatory involvement of the pericardium and other mediastinal structures (Figure 4).
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Figure 4. A 22-year-old female presented with pyrexia and pleuritic chest pain. (a) T1 and (b) T2 weighted axial spin echo images show thickened pericardium (arrows). The T2 signal of the pericardium is high, suggesting active inflammation. The patient also had a pericardial effusion (E). Intermediate signal of this fluid on T1 suggests that it is proteinaceous.
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Pericardial effusions
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Accumulation of more than 50 ml of fluid in the pericardial space is abnormal. Simple effusions can be readily identified by echocardiography, but MR gives additional information. MR can identify small or loculated effusions that might be missed on echocardiography. Breath-hold cine images may show the distribution of pericardial fluid change between systole and diastole (Figure 5), which helps to distinguish small effusions from isolated pericardial thickening. MR also allows tissue characterization of the fluid, transudates having absent or low signal on T1 weighted and higher signal on T2 weighted and gradient echo images (Figure 5). Exudates differ by having intermediate signal on both T1 and T2 weighted images (Figure 4
). However, this is more complicated if the fluid is mobile, as the signal may be reduced in spin echo sequences in the same way as the signal from flowing blood is reduced. Haemorrhagic effusions have a high signal acutely on T1 (Figure 6), although the appearance of blood in the pericardial space changes with time (Figure 7) [4, 5].
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Figure 5. A 36-year-old female with hypothyroidism presented with recurrent pericardial effusion. (a–c) Axial spin echo images show a moderate sized pericardial effusion (*). Note the resulting dilatation of the hepatic vein (a). The true extent of the pericardial reflections are well shown, extending further cephalad on the left than the right. Short axis gradient echo images in diastole (d) and in systole (e) showed no impairment of ventricular filling.
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Figure 6. Pericardial haematoma secondary to myocardial rupture in a 60-year-old male with acute myocardial infarction. (a) The T1 axial spin echo image shows complex masses, with flow within and behind the left atrium (LA) and anterior to the right atrium (RA) (asterisks). (b) The posterior wall of the left ventricle shows the site of rupture (arrow).
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Figure 7. Organized pericardial haematoma. A 58-year-old man with a history of previous road traffic accident. (a) T1 weighted and (b) T2 weighted axial spin echo images and (c) the short axis spin echo image show a saddle shaped lesion (H) of low signal intensity lifting the whole of the heart away from the diaphragm. LV, left ventricle; RV, right ventricle; LA, left atrium; RA, right atrium.
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In common with echocardiography, MR can provide useful functional data, with cine images being able to demonstrate right-sided chamber collapse in diastole, a useful early signal in the diagnosis of cardiac tamponade. This is best seen in short axis cine images at the mid ventricular level.
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Pericardial constriction
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Pericardial constriction due to a thickened, calcified and fibrosed pericardium results in impaired ventricular filling. The process may extend to the underlying myocardium, which may be affected by atrophy and fibrosis. The differential diagnosis between pericardial constriction and restrictive cardiomyopathy is difficult, as the clinical and haemodynamic features of the two conditions are very similar. It is an important diagnosis to make, as constriction (in contrast to restrictive cardiomyopathy) can be cured by surgical pericardectomy. MR is a valuable tool in cases where there is diagnostic doubt, with pericardial thickening of more than 4 mm being the key diagnostic feature (Figures 8–10). MR can also clearly depict the characteristic functional sequelae of right atrial dilatation and an early peak to ventricular filling. The pericardium is sometimes not completely removed at pericardectomy, which can lead to a recurrence of symptoms, especially if there is residual pericardium in the atrioventricular groove (Figures 9 and 10).
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Figure 8. A 47-year-old male with increasing dyspnoea and pleural effusions. (a) T1 weighted and (b) T2 weighted axial images show diffusely thickened pericardium (arrow) encasing the heart, with very little pericardial fluid. The extent of the pleural effusions is well seen.
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Figure 9. This 63-year-old man remained symptomatic after pericardectomy for pericardial constriction of unknown aetiology. T1 weighted axial image shows residual thickened pericardium covering the posterior left ventricle (arrows).
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Figure 10. This 53-year-old man had a pericardectomy for pericardial constriction due to tuberculosis 30 years previously but was becoming increasingly breathless, with clinical signs of constriction. T1 axial spin echo images confirm that the anterior aspect of the pericardium has been stripped, but that thickened pericardium remains in the atrioventricular (AV) groove (arrows), with consequent narrowing of the AV ring and dilatation of the right atrium (RA). Note also the residual empyema (*) and consolidation in the left lung.
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Pericardial tumours
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Tumours involving the pericardium are uncommon and are mostly due to direct invasion or secondary spread, occurring late in the disease process. Secondary spread is most commonly from the lung (Figure 11), breast, lymphoma and oesophagus. The commoner types of primary pericardial tumours include: mesothelioma [6], lipoma and sarcoma, although rarer tumours are sometimes seen [7, 8] (Figures 12 and 13). The pericardium may even suffer paraneoplastic involvement, leading to thickening and consequent constriction without evidence of metastatic spread (Figure 14). High resolution images enable tissue planes to be clearly demarcated and the wide field of view allows the extent of tumour spread to be determined.
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Figure 11. Direct invasion of the pericardium by primary lung carcinoma in a 70-year-old man. This T1 axial spin echo image shows the primary lung tumour (T) obliterating the pericardium and directly invading the right atrium.
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Figure 12. Lipomatous infiltration of the interatrial septum in an asymptomatic 68-year-old female. (a) T1 weighted and (b) T2 weighted axial spin echo images show the lesion (asterisk) with signal intensity similar to that of fat. (c) A fat suppressed inversion recovery sequence demonstrated signal reduction, indicating that there is likely to be a significant adipose content.
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Figure 13. Malignant haemangiopericytoma in a 53-year-old female who presented with rapid onset of dyspnoea. The T1 weighted spin echo image shows a mass lesion contiguous with the pericardium (arrows), compressing and distorting the right atrium (RA) and right ventricle (RV).
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Figure 14. Paraneoplastic pericardial involvement in a 65-year-old man with primary lung tumour. T1 spin echo axial image shows the primary lesion in the lower lobe of the left lung (T). Marked thickening of the pericardium is seen (arrows). Surgical biopsies of the pericardium were clear of malignant cells.
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Conclusion
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MR provides a comprehensive non-invasive assessment of pericardial pathology. Image resolution and field of view are unrivalled by other imaging modalities, and the heart and great vessels can be imaged at the same time. MR is particularly helpful in the differential diagnosis of pericardial constriction shown by a thickened pericardium and restrictive cardiomyopathy, removing the need for diagnostic thoracotomy in some patients. As MR becomes more widely available, it is likely to become an important part of the investigation of patients with pericardial pathology.
Received for publication March 1, 2000.
Accepted for publication June 9, 2000.
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References
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Ng AF, Olak J. Pericardial cyst causing right ventricular outflow tract obstruction. Ann Thorac Surg 1997;63:1147–8.[Abstract/Free Full Text]
-
Rusk RA, Kenny A. Congenital pericardial defect presenting as chest pain. Heart 1999;81:327–8.[Free Full Text]
-
Gassner I, Judmaier W, Fink C, Lener M, Waldenberger F, Scharfetter H, Hammerer I. Diagnosis of congenital pericardial defects, including a pathognomic sign for dangerous apical ventricular herniation, on magnetic resonance imaging. Br Heart J 1995;74:60–6.[Abstract/Free Full Text]
-
Vilacosta I, Gomez J, Dominguez J, Dominguez L, Banuelos C, Ferreiros J, et al. Massive pericardiac hematoma with severe constrictive pathophysiologic complications after insertion of an epicardial pacemaker. Am Heart J 1995;130:1298–300.[Medline]
-
Zellner C, Chou TM, Higgins C, Kaiser R, Schiller NB. Images in cardiovascular medicine. Pericardial hematoma after primary angioplasty complicated by coronary rupture. Circulation 1998;98:183.[Free Full Text]
-
Gossinger HD, Siostrzonek P, Zangeneh M, Neuhold A, Herold C, Schmoliner R, Laczkovics A,et al. Magnetic resonance imaging findings in a patient with pericardial mesothelioma. Am Heart J 1988;115:1321–2.[Medline]
-
Beghetti M, Prieditis M, Rebeyka IM, Mawson J. Images in cardiovascular medicine. Intrapericardial teratoma. Circulation 1998;97:1523–4.[Free Full Text]
-
Bruna J, Lockwood M. Primary heart angiosarcoma detected by computed tomography and magnetic resonance imaging. Eur Radiol 1998;8:66–8.[Medline]
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Abstract
Introduction
