CT dimensions of the normal pericardium

Multimodality Imaging in Differentiating Constrictive Pericarditis From Restrictive Cardiomyopathy: A Comprehensive Overview for Clinicians and Imagers

In the evaluation of heart failure, 2 differential diagnostic considerations include constrictive pericarditis and restrictive cardiomyopathy. The often outwardly similar clinical presentation of these 2 pathologic entities routinely renders their clinical distinction difficult. Consequently, initial assessment requires a keen understanding of their separate pathophysiology, epidemiology, and hemodynamic effects. Following a detailed clinical evaluation, further assessment initially rests on comprehensive echocardiographic investigation, including detailed Doppler evaluation. With the combination of mitral inflow characterization, tissue Doppler assessment, and hepatic vein interrogation, initial differentiation of constrictive pericarditis and restrictive cardiomyopathy is often possible with high sensitivity and specificity. In conjunction with a compatible clinical presentation, successful differentiation enables both an accurate diagnosis and subsequent targeted management. In certain cases, however, the diagnosis remains unclear despite echocardiographic assessment, and additional evaluation is required. With advances in noninvasive tools, such evaluation can often continue in a stepwise, algorithmic fashion noninvasively, including both cross-sectional and nuclear imaging. Should this additional evaluation itself prove insufficient, invasive assessment with appropriate expertise may ultimately be necessary.

Deep-Learning Segmentation of Epicardial Adipose Tissue Using Four-Chamber Cardiac Magnetic Resonance Imaging

In magnetic resonance imaging (MRI), epicardial adipose tissue (EAT) overload remains often overlooked due to tedious manual contouring in images. Automated four-chamber EAT area quantification was proposed, leveraging deep-learning segmentation using multi-frame fully convolutional networks (FCN). The investigation involved 100 subjects-comprising healthy, obese, and diabetic patients-who underwent 3T cardiac cine MRI, optimized U-Net and FCN (noted FCNB) were trained on three consecutive cine frames for segmentation of central frame using dice loss. Networks were trained using 4-fold cross-validation (n = 80) and evaluated on an independent dataset (n = 20). Segmentation performances were compared to inter-intra observer bias with dice (DSC) and relative surface error (RSE). Both systole and diastole four-chamber area were correlated with total EAT volume (r = 0.77 and 0.74 respectively). Networks' performances were equivalent to inter-observers' bias (EAT: DSCInter = 0.76, DSCU-Net = 0.77, DSCFCNB = 0.76). U-net outperformed (p < 0.0001) FCNB on all metrics. Eventually, proposed multi-frame U-Net provided automated EAT area quantification with a 14.2% precision for the clinically relevant upper three quarters of EAT area range, scaling patients' risk of EAT overload with 70% accuracy. Exploiting multi-frame U-Net in standard cine provided automated EAT quantification over a wide range of EAT quantities. The method is made available to the community through a FSLeyes plugin.

Review of pericardial disease on computed tomography

Echocardiography has long been the mainstay in the evaluation of cardiac and pericardial disease. As computed tomography (CT) has advanced, it has become a valuable partner in the imaging of the pericardium. The advantages of CT include a larger field of view, multiplanar reconstruction and increased discrimination between various soft tissues and fluids. CT is less operator dependent and can more easily, and reproducibly, image areas of the pericardium for which echocardiography has poor windows such as the right pericardium. The introduction of EKG gating has decreased cardiac motion artifact and can allow functional evaluation although echocardiography remains the primary source of real-time imaging of cardiac and valve motion. It is essential for the skilled cardiac imager to understand the strengths and weaknesses of CT and its role in the definition and assessment of pericardial disease.

Hemopericardium in the acute clinical setting: Are we ready for a tailored management approach on the basis of MDCT findings?

The clinical spectrum of pericardial effusions varies from innocuous serous fluid to life-threatening hemopericardium. A misdiagnosis may be made by similar clinical presentation of acute chest pain/hypotension. Echocardiography is the first-line test for diagnosis of pericardial effusion and its etiology, but sometimes there are different drawbacks to the correct cardiovascular ultrasound diagnosis. Radiologists are reporting an increasing amount of thoracic Multidetector CT examinations at the emergency department. Multidetector CT has now become an established and complementary method for cardiac imaging, and diseases of the pericardium can now be quickly identified with increasing certainty. The aim of this review is to discuss the hemopericardium key Multidetector CT features in acute clinical setting which indicate the need to proceed with predominantly medical or surgical treatment, however, being able to identify forms of bleeding pericardial effusion for which only "a watch and wait strategy" and/or deferred treatment is indicated. In the emergency care setting, radiologists must be aware of different findings of hemopericardium in order to address a tailored and timely management approach.

Imaging of Pericardial Disease

Although the pericardium is simply a 2-layered membrane enveloping the heart and great vessels, there are numerous anatomic variations, congenital anomalies, and pathologic conditions that can occur. Although echocardiography is most often the first imaging modality used to assess the pericardium, computed tomography and MR imaging are frequently being used to aid in diagnosis and assess response to therapy. Therefore, detailed knowledge of the pericardium in both its normal and diseased states is important to best direct patient care and potentially improve patient outcomes.

New Cardiac Imaging Algorithms to Diagnose Constrictive Pericarditis Versus Restrictive Cardiomyopathy

PURPOSE OF REVIEW

Echocardiography is the mainstay in the diagnostic evaluation of constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM), but no single echocardiographic parameter is sufficiently robust to accurately distinguish between the two conditions. The present review summarizes the recent advances in echocardiography that promise to improve its diagnostic performance for this purpose. The role of other imaging modalities such as cardiac computed tomography, magnetic resonance imaging, and invasive hemodynamic assessment in the overall diagnostic approach is also discussed briefly.

RECENT FINDINGS

A recent study has demonstrated improved diagnostic accuracy of echocardiography with integration of multiple conventional echocardiographic parameters in to a step-wise algorithm. Concurrently, the studies using speckle-tracking echocardiography have revealed distinct and disparate patterns of myocardial mechanical abnormalities in CP and RCM with their ability to distinguish between the two conditions. The incorporation of machine-learning algorithms into echocardiography workflow permits easy integration of the wealth of the diagnostic data available and promises to further enhance the diagnostic accuracy of echocardiography. New imaging algorithms are continuously being evolved to permit accurate distinction between CP and RCM. Further research is needed to validate the accuracy of these newer algorithms and to define their place in the overall diagnostic approach for this purpose.

Echocardiographic Evaluation of Pericardial Effusion and Cardiac Tamponade

Pericardial effusion (PEff) is defined by an increase in the physiological amount of fluid within the pericardial space. It can appear following different medical conditions, mainly related to inflammation and cardiac surgery. Cardiac tamponade is a critical condition that occurs after sudden and/or excessive accumulation of fluid in the pericardial space that restricts appropriate filling of the cardiac chambers disturbing normal hemodynamics and ultimately causing hypotension and cardiac arrest. It is, therefore, a life-threatening condition that must be diagnosed as soon as possible for correct treatment and management. Echocardiographic evaluation of PEff is paramount for timely and appropriate diagnosis and management. A structured echocardiographic approach including two-dimensional, M-mode, and Doppler echocardiographic evaluation assessing (i) quantity and quality of pericardial fluid, (ii) collapse of cardiac chambers, (iii) respiratory variation of the ventricular diameters, (iv) inferior vena cava collapsibility, and (v) flow patterns in atrioventricular valves should give the bedside clinician the necessary information to appropriately manage PEff. Here, we review these key echocardiographic signs that will ensure an appropriate assessment of a patient with PEff and/or cardiac tamponade.

Computed tomography and magnetic resonance imaging evaluation of pericardial disease

Pericardial diseases are commonly encountered in clinical practice and may present as an isolated process or in association with various systemic conditions. Traditionally transthoracic echocardiography (TTE) has been the method of choice for the evaluation of suspected pericardial disease but increasingly computed tomography (CT) and magnetic resonance imaging (MRI) are also being used as part of a rational multi-modality imaging approach tailored to the specific clinical scenario. This paper reviews the role of CT and MRI across the spectrum of pericardial diseases.

European Association of Cardiovascular Imaging (EACVI) position paper: Multimodality imaging in pericardial disease

Although pericardial diseases are common in the daily clinical practice and can result in a significant morbidity and mortality, imaging of patients with suspected or known pericardial disorders remain challenging. Multimodality imaging is part of the management of pericardial diseases. Echocardiography, cardiac computed tomography, and cardiovascular magnetic resonance are often used as complementary imaging modalities. The choice of one or multiple imaging modalities is driven by the clinical context or conditions of the patient. The scope of the present document is to highlight the respective role of each technique according to the clinical context in the diagnosis and management of pericardial diseases.

Evaluation of the Pericardium with CT and MR

The pericardium plays an important role in optimizing cardiac motion and chamber pressures and serves as a barrier to pathology. In addition to pericardial anatomy and function, this review article covers a variety of pericardial conditions, with mention of potential pitfalls encountered during interpretation of diagnostic imaging. Normal and abnormal appearance of pericardium on CT and MR imaging is emphasized, including dynamic imaging correlates of pericardial pathophysiology.

Incidental Cardiac Findings on Thoracic Imaging

The cardiac structures are well seen on nongated thoracic computed tomography studies in the investigation and follow-up of cardiopulmonary disease. A wide variety of findings can be incidentally picked up on careful evaluation of the pericardium, cardiac chambers, valves, and great vessels. Some of these findings may represent benign variants, whereas others may have more profound clinical importance. Furthermore, the expansion of interventional and surgical practice has led to the development and placement of new cardiac stents, implantable pacemaker devices, and prosthetic valves with which the practicing radiologist should be familiar. We present a collection of common incidental cardiac findings that can be readily identified on thoracic computed tomography studies and briefly discuss their clinical relevance.

MR, CT, and PET imaging in pericardial disease

Although echocardiography remains the standard diagnostic tool for identifying pericardial diseases, procedures with better delineation of morphology and heart function are often required. The pericardium consists of an inner visceral (epicardium) and outer parietal layer (pericardium), which constitute for the pericardial cavity. Pericardial effusion can occur as transudate, exudate, pyopneumopericardium, or hemopericardium. Potential causes are inflammatory processes, that is, pericarditis due to autoimmune or infective reasons, neoplasms, irradiation, or systemic disorders, chronic renal failure, endocrine, or metabolic diseases. Pericardial fat can mimic pericardial effusion. Using various image-acquisition sequences, MRI allows identifying and separating fluid and solid structures. Fast spin-echo T1-weighted sequences with black-blood preparation are favourably used for morphological evaluation. Fast spin-echo T2-weighted sequences, particularly with fat saturation, and short-tau inversion-recovery sequences are useful to visualize oedema and inflammation. For further tissue characterization, delayed inversion-recovery imaging is used. Therefore, image acquisition is performed at 5-20 min subsequent to contrast agent administration, the so-called technique of late gadolinium enhancement. Ventricular volumes and myocardial mass can be assessed accurately by steady-state free-precession sequences, which is required to measure cardiac function and ventricular wall stress. Constrictive pericarditis usually results from chronic inflammatory processes leading to increased stiffness, which impedes the slippage of both pericardial layers and thereby the normal cardiac filling. CT imaging can favourably assess pericardial calcification. Thus, MR and CT imaging allow a comprehensive delineation of the pericardium. Superior to echocardiography, both methods provide a larger field of view and depiction of the complete chest including abnormalities of the surrounding mediastinum and lungs. PET provides unique information on the in vivo metabolism of 18-fluorodeoxyglucose that can be superimposed on CT findings and is useful for identifying inflammatory processes or masses, for example neoplasms. These imaging techniques provide advanced information of anatomy and cardiac function to optimize the pericardial access, for example by the AttachLifter system, for diagnosis and treatment.

Symptomatic pericardial effusion after chemoradiation therapy in esophageal cancer patients

PURPOSE

We investigated clinical and treatment-related factors as predictors of symptomatic pericardial effusion in esophageal cancer patients after concurrent chemoradiation therapy.

METHODS AND MATERIALS

We reviewed 214 consecutive primary esophageal cancer patients treated with concurrent chemoradiation therapy between 2001 and 2010 in our institute. Pericardial effusion was detected on follow-up computed tomography. Symptomatic effusion was defined as effusion ≥grade 3 according to Common Terminology Criteria for Adverse Events v4.0 criteria. Percent volume irradiated with 5 to 65 Gy (V5-V65) and mean dose to the pericardium were evaluated employing dose-volume histograms. To evaluate dosimetry for patients treated with two-dimensional planning in the earlier period (2001-2005), computed tomography data at diagnosis were transferred to a treatment planning system to reconstruct three-dimensional plans without modification. Optimal dosimetric thresholds for symptomatic pericardial effusion were calculated by receiver operating characteristic curves. Associating clinical and treatment-related risk factors for symptomatic pericardial effusion were detected by univariate and multivariate analyses.

RESULTS

The median follow-up was 29 (range, 6-121) months for eligible 167 patients. Symptomatic pericardial effusion was observed in 14 (8.4%) patients. Dosimetric analyses revealed average values of V30 to V45 for the pericardium and mean pericardial doses were significantly higher in patients with symptomatic pericardial effusion than in those with asymptomatic pericardial effusion (P<.05). Pericardial V5 to V55 and mean pericardial doses were significantly higher in patients with symptomatic pericardial effusion than in those without pericardial effusion (P<.001). Mean pericardial doses of 36.5 Gy and V45 of 58% were selected as optimal cutoff values for predicting symptomatic pericardial effusion. Multivariate analysis identified mean pericardial dose as the strongest risk factor for symptomatic pericardial effusion.

CONCLUSIONS

Dose-volume thresholds for the pericardium facilitate predicting symptomatic pericardial effusion. Mean pericardial dose was selected based not only on the optimal dose-volume threshold but also on the most significant risk factor for symptomatic pericardial effusion.

Pericardial disease: value of CT and MR imaging

The pericardium represents an important focus of morbidity and mortality in patients with cardiovascular disease. Fortunately, in recent years knowledge regarding this enigmatic part of the heart and the diagnosis of related diseases has substantially advanced. To a large extent, this can be attributed to the availability of several noninvasive cardiac imaging modalities. Transthoracic echocardiography, which combines structural and physiologic assessment, is the first-line technique for examination of patients suspected of having or known to have pericardial disease; however, cardiac computed tomography (CT) and magnetic resonance (MR) imaging are becoming increasingly popular for the study of this part of the heart. Modern multidetector CT scanners merge acquisition speed and high spatial and contrast resolution, with volumetric scanning to provide excellent anatomic detail of the pericardium. Multidetector CT is by far the modality of choice for depiction of pericardial calcifications. MR imaging is probably the best imaging modality for the acquisition of a comprehensive view of the pericardial abnormalities. MR imaging combines cardiac and pericardial anatomic assessment with tissue characterization and appraisal of the effects of pericardial abnormalities on cardiac performance. This review aims to elucidate the role of the pericardium and its interaction with the remainder of the heart in normal and pathologic conditions. It focuses on the rapidly evolving insights regarding pericardial disease provided by modern imaging modalities, not infrequently necessitating reconsideration of evidence that has thus far been taken for granted.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13121059/-/DC1.

Pericardial disease--anatomy and function

Imaging of patients with suspected or known pericardial disease remains challenging. Echocardiography is the first-line investigation for pericardial disease but it has specific limitations in terms of its abilities to visualise the pericardium fully and to identify extracardiac pathology. Cardiac cross-sectional imaging by both MRI and CT has developed significantly and now has an important role in the investigation of pericardial disease. This article examines the appearances of both healthy and diseased pericardium using CT and MRI. The typical imaging findings across a wide range of conditions are illustrated and the roles of CT and MRI are reviewed. The relative merits and weaknesses of each modality are explored and the specific functional techniques that are available are introduced.

Constrictive pericarditis and restrictive cardiomyopathy in the modern era

The differentiation between constrictive pericarditis and restrictive cardiomyopathy can be clinically challenging. Pericardial constriction results from scarring and consequent loss of pericardial elasticity leading to impaired ventricular filling. Restrictive cardiomyopathy is characterized by a nondilated rigid ventricle, severe diastolic dysfunction and restrictive filling producing hemodynamic changes, similar to those in constrictive pericarditis. While constrictive pericarditis is usually curable by surgical treatment, restrictive cardiomyopathy requires medical therapy and in appropriate patients, the definitive treatment is cardiac transplantation. Sufficient differences exist between the two conditions to allow noninvasive differentiation, but no single diagnostic tool can be relied upon to make this distinction. Newer echocardiographic techniques such as speckle-track imaging, velocity vector imaging, as well as cardiac computed tomography and cardiac MRI can help differentiate constriction from restriction with high sensitivity and specificity. Outcomes are better with early diagnosis of constriction in particular and early surgical resection.

Noninvasive imaging techniques of constrictive pericarditis

Constrictive pericarditis (CP) is the result of scarring and loss of elasticity of the pericardial sac, resulting in external impedance of cardiac filling. It can occur after virtually any pericardial disease process. Patients typically present with signs and symptoms of right heart failure and/or low cardiac output. An important pathophysiological hallmark of CP is exaggerated ventricular interdependence and impaired diastolic filling. Echocardiography is the initial imaging modality for diagnosis of CP. Unfortunately, no echocardiographic sign or combination of signs is pathognomonic for CP. CT scan and cardiac MRI are other imaging techniques that can provide incremental diagnostic information. CT scan can easily detect pericardial thickening and calcification, while cardiac MRI provides a comprehensive evaluation of the pericardium, myocardium and cardiac physiology. Occasionally, a multimodality approach needs to be considered for the conclusive diagnosis of CP.

Multimodality imaging of pericardial diseases

Pericardial disease is an important cause of morbidity and mortality in patients with cardiovascular disease. Inflammatory diseases of the pericardium constitute a spectrum ranging from acute pericarditis to chronic constrictive pericarditis. Other important entities that involve the pericardium include benign and malignant pericardial masses, pericardial cysts, and diverticula, as well as congenital absence of the pericardium. Recent advances in multimodality noninvasive cardiac imaging have solidified its role in the management of patients with suspected pericardial disease. The physiologic and structural information obtained from transthoracic echocardiography and the anatomic detail provided by cardiac computed tomography and magnetic resonance have led to growing interest in the complementary use of these techniques. Optimal management of the patient with suspected pericardial disease requires familiarity with the key imaging modalities and the ability to choose the appropriate imaging tests for each patient. This report reviews the imaging modalities most useful in the assessment of patients with pericardial disease, with an emphasis on the complementary value of multimodality cardiac imaging.

[Chronic pericarditis: CT and MR imaging features]

A diagnosis of constrictive pericarditis is suggested by the presence of pericardial thickening (>=4 mm in thickness) and abnormal motion of the interventricular septum. Additional findings have been reported: tubular appearance of the right or left ventricles, dilatation of the vena cava, atrial dilatation or abnormal diastolic expansion of one or both ventricles. In patients with suspected chronic pericarditis, CT can more easily demonstrate the presence of pericardial calcifications compared to US and MRI, as well as detect the presence of mediastinal adenopathy and lung lesions, suggesting tuberculosis. Septal motion analysis should be performed during protodiastole and systole using a cine technique with both CT and MR.

Imaging the pericardium: appearances on ECG-gated 64-detector row cardiac computed tomography

Multidetector row computed tomography (MDCT) with its high spatial and temporal resolution has now become an established and complementary method for cardiac imaging. It can now be used reliably to exclude significant coronary artery disease and delineate complex coronary artery anomalies, and has become a valuable problem-solving tool. Our experience with MDCT imaging suggests that it is clinically useful for imaging the pericardium. It is important to be aware of the normal anatomy of the pericardium and not mistake normal variations for pathology. The pericardial recesses are visible in up to 44% of non-electrocardiogram (ECG)-gated MDCT images. Abnormalities of the pericardium can now be identified with increasing certainty on 64-detector row CT; they may be the key to diagnosis and therefore must not be overlooked. This educational review of the pericardium will cover different imaging techniques, with a significant emphasis on MDCT. We have a large research and clinical experience of ECG-gated cardiac CT and will demonstrate examples of pericardial recesses, their variations and a wide variety of pericardial abnormalities and systemic conditions affecting the pericardium. We give a brief relevant background of the conditions and reinforce the key imaging features. We aim to provide a pictorial demonstration of the wide variety of abnormalities of the pericardium and the pitfalls in the diagnosis of pericardial disease.

Computed Tomographic Screening of Pulmonary Arterial Hypertension in Candidates for Lung Transplantation

INTRODUCTION

Computed tomography (CT) is essential to evaluate candidates for lung transplantation (LT) We sought to correlate identification of pulmonary arterial hypertension (PAH) via CT to echocardiographic (Eco) and/or hemodynamic observations (Hd) as well as the pathological findings (Path) at posttransplant pneumonectomy.

MATERIALS AND METHODS

The study included 24 consecutive months follow-up of 71 patients who were referred for LT evaluation with 54 undergoing LT. Study parameters included CT [diameter of the principal pulmonary artery (PPA) >or= 29 mm), PPA/diameter of the ascending aorta (AA) ratio > 1; diameter of the lobar artery (LA)/diameter of the lobar bronchiole (LB) ratio > 1 in three or more lobes; thickening of the anterosuperior pericardial recess (>15 mm); mosaic lung density pattern]; PAPs via Eco and/or Hd, and findings Path of PAH. Statistical analysis included chi-square and Pearson correlation coefficient.

RESULTS

Thirty-five patients had PAH. Significant relationships (P < .05) were observed between PAH (Eco and/or Hd) and PPA, PPA/AA, and LA/LB. The sensitivity of the finding PPA >or= 29 mm was 65.9%, and 85.7% when combined with LA/LB > 1. In the Path study, 14/54 patients revealed alterations compatible with PAH. Significant relationships (P < .05) were observed between PAH via Path and PPA (CT) and between PAH via Path and PAH (Eco and/or Hd).

CONCLUSIONS

CT is useful for the detection of PAH. Findings of PAH via CT were indicative of the need for further confirmatory studies. In contrast, the absence of findings with CT does not exclude the possible presence of PAH.

Rare case of Nocardia asteroides pericarditis in a human immunodeficiency virus-infected patient

Nocardia asteroides was isolated after prolonged culture from the pericardial fluid of a human immunodeficiency virus-infected patient. The lengthy duration required for culture growth and identification of this N. asteroides isolate affected both initial therapeutic decisions and patient management. A proposed algorithm for the microbiological workup of pericardial fluid for possible Nocardia spp. is described in an effort to improve the timeliness of results.

Computed tomography and magnetic resonance imaging of the pericardium: anatomy and pathology

The purpose of this article is to review the characteristics of computed tomography (CT) and magnetic resonance imaging (MRI) of the pericardium and pericardial diseases. Because patients with pericardial diseases usually present with nonspecific symptoms, these diseases may not be detected until they have reached an advanced stage. It is therefore important to distinguish between normal pericardial structure and disease. Multiplanar reconstruction images of CT and MRI are useful for evaluating faint changes of the pericardium. The specific pericardial diseases described in this article include pericardial cyst, constrictive pericarditis, pericarditis with radiation pericarditis, postoperative pericardial hematoma, and cardiac tamponade due to a paracardiac mass (lymphoma).

Constrictive pericarditis versus restrictive cardiomyopathy: challenges in diagnosis and management

This is the case of a patient who presented with severe right-sided heart failure due to diastolic dysfunction that caused a dilemma of differential diagnosis between restrictive cardiomyopathy and constrictive pericarditis. Restrictive cardiomyopathy was diagnosed based on noninvasive and invasive hemodynamic testing. However, the patient did not respond to therapy and succumbed to worsening heart failure and multiple comorbidities. Clinical features of right heart failure with edema, ascites, jugular venous distention, and tender hepatomegaly are commonly seen in clinical practice. When systolic function is determined to be normal, diastolic causes of heart failure must be ruled out. These include myocardial disorders with a broad range of pathologies leading to restrictive physiology, of which amyloidosis is a prototype. Pericardial disorders leading to diastolic heart failure are usually in the form of constrictive physiology, when pericardial tamponade is ruled out. Differentiation between restrictive and constrictive pathologies is often difficult and requires careful attention to hemodynamic and Doppler echocardiographic features. We report a case of severe right heart failure illustrating some of the complexities in decision-making and the importance of meticulous hemodynamic and ancillary testing in the diagnosis and treatment of this often fatal condition.

Features of cardiac disease demonstrated on CT pulmonary angiography

The heart and mediastinal structures can be overlooked at CT pulmonary angiogram (CTPA). This pictorial review will demonstrate the features of cardiac disease that may be evident on a CTPA. CTPA allows assessment of not only the pulmonary arteries for embolism, but also of the bronchi, lung parenchyma, mediastinum and heart. Co-existent underlying or incidental cardiac disease is often present. Potentially life-threatening alternative diagnoses in a patient with chest symptoms can be reliably identified. Pathologies of the myocardium including hypertrophic cardio myopathy, pericardial disease, valvular disease, coronary artery disease, and intracardiac abnormalities are demonstrated pictorially. CTPA is increasingly used for the detection of pulmonary embolism. Most patients investigated have pathology other than PE as a cause of their symptoms. Frequently information about the heart is produced that provides important clues to determine the cause for the presenting symptoms and signs or reveals co-existing pathology. It is important to have a clear understanding of the features of cardiac disease which may be seen on a CTPA.

CT and MR Imaging of Pericardial Disease

In the evaluation of pericardial disease, computed tomography (CT) and magnetic resonance (MR) imaging traditionally have been used as adjuncts to echocardiography. However, CT and MR imaging are particularly useful as sensitive and noninvasive methods for evaluating loculated or hemorrhagic pericardial effusion, constrictive pericarditis, and pericardial masses. Both CT and MR imaging provide excellent delineation of the pericardial anatomy and can aid in the precise localization and characterization of various pericardial lesions, including effusion, constrictive pericarditis and pericardial thickening, pericardial masses, and congenital anomalies such as partial or complete absence of the pericardium. Both modalities provide a larger field of view than does echocardiography, allowing the examination of the entire chest and detection of associated abnormalities in the mediastinum and lungs. Soft-tissue contrast on CT scans and MR images also is superior to that on echocardiograms. Given the many potential applications of these modalities in the evaluation of pericardial diseases, familiarity with the CT and MR imaging features of these diseases is important.

Imaging of pericardial disease

Pericardial pathology is most often identified by its effect on cardiac function. Echocardiography is usually performed first in evaluation of pericardial disease, but is occasionally limited or indeterminate. MR imaging is often helpful in these cases, offering superior soft tissue contrast and the ability to image the entire pericardium and its relationship to cardiac structure and function. Many of the techniques recently developed for myocardial imaging are equally applicable to the pericardium and frequently assist in the diagnosis of pericardial disease. In this article, the authors review MR imaging techniques for pericardial imaging, discuss the appearance of the normal pericardium, and illustrate pathologic and congenital conditions of the pericardium.

Imaging of the pericardium

Computed tomography (CT) and magnetic resonance imaging (MRI) are modalities well suited for imaging of the pericardium and pericardial disease. Both offer excellent resolution with a wide field of view. Both have advantages and disadvantages when compared with each other and with echocardiography. Establishing the diagnosis of constrictive pericarditis is a common indication for CT or MRI of the pericardium. Pericarditis, neoplasms, effusions, and congenital anomalies are additional conditions involving the pericardium that can be diagnosed with CT and MRI.

Unusual radiologic findings in the thorax after radiation therapy

Radiation therapy is used to treat many intrathoracic and chest wall malignancies. A variety of changes may occur after radiation therapy to the thorax. Radiation therapy produces dramatic effects in the lung. Pulmonary necrosis is an uncommon, severe, late complication of adjuvant postoperative radiation therapy. Bronchiolitis obliterans with organizing pneumonia is a distinct clinicopathologic entity characterized by patchy, migratory, peripheral air-space infiltrates. Radiation therapy can also cause spontaneous pneumothorax, mesothelioma, and lung cancer. In the mediastinum, radiation therapy may cause thymic cysts, calcified lymph nodes, and esophageal injuries. Cardiovascular complications of radiation therapy are often delayed and insidious. Premature coronary artery stenosis occurs after radiation therapy to the mediastinum. Radiation therapy may also give rise to calcifications of the ascending aorta, pericardial disease, valvular injuries, and conduction abnormalities. Women who undergo thoracic irradiation before the age of 30 years have a high risk of developing a second breast cancer. Radiation-induced sarcomas are an infrequent but well-recognized complication of radiation therapy. Other chest wall injuries due to radiation therapy are osteochondroma and rib or clavicle fractures. Knowledge of the imaging features of injuries caused by radiation therapy can prevent misinterpretation as recurrent tumor and may facilitate further treatment.