Comparing Thin-Section and Thick-Section CT of Pericardial Sinuses and Recesses

Extremely Large Fluid Collection in the Superior Aortic Recess Misdiagnosed as Mediastinal Tumors: A Report of Two Cases

The superior aortic recess is one of the superior portions of the transverse sinus which is located around the ascending aorta. The fluid collection of the superior aortic recess is sometimes revealed on chest computed tomography, and it becomes more difficult to differentiate from a cystic tumor or lymphadenopathy when the amount of collected fluid is large or the fluid is extended into another area. We report two cases of fluid collection in the superior aortic recess which was misdiagnosed as a cystic mediastinal tumor that underwent surgical resection. An extremely large amount of fluid collection and cephalad extension led us to this clinical course.

Pericardial Recesses on Computed Tomography: Implications for the Pulmonologist

The pericardium comprises a double-walled fibrous-serosal sac that encloses the heart. Reflections of the serosal layer form sinuses and recesses. With advances in multidetector computed tomography (CT) technology, pericardial recesses are frequently detected with thin-section CT. Knowledge of pericardial anatomy on imaging is crucial to avoid misinterpretation of fluid-filled pericardial sinuses and recesses as adenopathy/pericardial metastasis or aortic dissection, which can impact patient management and treatment decisions. The authors offer a comprehensive review of pericardial anatomy and its variations observed on CT, potential pitfalls in image interpretation, and implications for the pulmonologist with respect to unnecessary diagnostic procedures or interventions.

Pitfalls in Oncologic Imaging of the Pericardium on CT and PET/CT

In the oncologic setting, misinterpretation of fluid in pericardial recesses as mediastinal adenopathy or benign pericardial findings as malignant can lead to inaccurate staging and inappropriate management. Knowledge of normal pericardial anatomy, imaging features to differentiate fluid in pericardial sinuses and recesses from mediastinal adenopathy and potential pitfalls in imaging of the pericardium on CT and PET/CT is important to avoid misinterpretation.

Pericardial Recesses Mimicking Mediastinal Adenopathy on CT

Thin-section computed tomography (CT) has improved the detection of pericardial recesses and sinuses. Physiologic fluid in the pericardial recesses and sinuses can mimic mediastinal adenopathy. The misinterpretation of pericardial recesses and other benign pericardial entities in the oncologic setting can lead to inappropriate staging and management. Knowledge of the anatomy of the pericardium with emphasis on the imaging of different pericardial recesses on CT is important to avoid misdiagnosis, unnecessary further investigations, and/or biopsy.

A highly-detailed anatomical study of normal pericardial structures as revealed by in-vivo computed tomography and magnetic resonance images and ex-vivo novel 3D reconstructions from Visible Human Server

The pericardial cavity, sinuses, and recesses are frequently depicted on Computed Tomography (CT) and Magnetic Resonance (MR).

We here review the normal human pericardial structures as provided by MR imaging of young, healthy subject and CT scans acquired after iatrogenic coronary dissection. We compared such radiological information with cadaveric axial and sagittal sections of the human body provided by the Visible Human Server (VHS), Ecole Polytechnique Federale de Lousanne (EPFL), Switzerland.

Uncontrolled Confounders May Lead to False or Overvalued Radiomics Signature: A Proof of Concept Using Survival Analysis in a Multicenter Cohort of Kidney Cancer

Purpose

We aimed to explore potential confounders of prognostic radiomics signature predicting survival outcomes in clear cell renal cell carcinoma (ccRCC) patients and demonstrate how to control for them.

Materials and Methods

Preoperative contrast enhanced abdominal CT scan of ccRCC patients along with pathological grade/stage, gene mutation status, and survival outcomes were retrieved from The Cancer Imaging Archive (TCIA)/The Cancer Genome Atlas-Kidney Renal Clear Cell Carcinoma (TCGA-KIRC) database, a publicly available dataset. A semi-automatic segmentation method was applied to segment ccRCC tumors, and 1,160 radiomics features were extracted from each segmented tumor on the CT images. Non-parametric principal component decomposition (PCD) and unsupervised hierarchical clustering were applied to build the radiomics signature models. The factors confounding the radiomics signature were investigated and controlled sequentially. Kaplan-Meier curves and Cox regression analyses were performed to test the association between radiomics signatures and survival outcomes.

Results

183 patients of TCGA-KIRC cohort with available imaging, pathological, and clinical outcomes were included in this study. All 1,160 radiomics features were included in the first radiomics signature. Three additional radiomics signatures were then modelled in successive steps removing redundant radiomics features first, removing radiomics features biased by CT slice thickness second, and removing radiomics features dependent on tumor size third. The final radiomics signature model was the most parsimonious, unbiased by CT slice thickness, and independent of tumor size. This final radiomics signature stratified the cohort into radiomics phenotypes that are different by cancer-specific and recurrence-free survival; HR (95% CI) = 3.0 (1.5-5.7), p <0.05 and HR (95% CI) = 6.6 (3.1-14.1), p <0.05, respectively.

Conclusion

Radiomics signature can be confounded by multiple factors, including feature redundancy, image acquisition parameters like slice thickness, and tumor size. Attention to and proper control for these potential confounders are necessary for a reliable and clinically valuable radiomics signature.

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.

Computerized tomography of the transverse pericardial sinus: Normal or pathologic?

The transverse pericardial sinus is a uniquely located structure subdivided into many parts. However, discrepancies still exist on the nomenclature and divisions. As noninvasive diagnostic technology such as CT and MR imaging improve, the transverse pericardial sinus and constituent recesses are visualized with more clarity, increasing the risk for misinterpretation. In this review, we will explore the anatomy of the transverse pericardial sinus and associated recesses with the goal of heightening awareness regarding the differential diagnosis between normal and pathological states as seen on CT. In addition, the inconsistencies of the right lateral superior aortic recess are also addressed. Last, we describe the clinical and surgical significance of the transverse pericardial sinus. Clin. Anat. 30:61-70, 2017. © 2016 Wiley Periodicals, Inc.

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.

Fluid collection in the right lateral portion of the superior aortic recess mimicking a right mediastinal mass: assessment with chest posterior anterior and MDCT

Objective

We observed patients in whom the fluid collection in the right lateral portion of the superior aortic recess on computed tomography (CT) scans mimicked a right anterior mediastinal mass on chest PA radiographs. The purpose of this study was to assess chest PA and CT features of these patients.

Materials and Methods

All chest PA radiographs and CT scans in 9 patients were reviewed by two radiologists on a consensus basis; for the presence of pleural effusion, pulmonary edema and heart size on chest PA radiographs. For the portion of the fluid collection in the superior aortic recess (SAR), a connection between the right lateral portion of the SAR (rSAR) and posterior portion of the SAR (pSAR) on CT scans, and the distance between the right lateral margin of the rSAR and the right lateral margin of the superior vena cava.

Results

Fluid collection in the rSAR on CT scans caused a right anterior mediastinal mass or a bulging contour on chest PA radiographs in all women patients. All patients showed cardiomegaly, five patients had pleural effusion, and two patients had mild pulmonary edema. Further, eight patients showed a connection between the rSAR and the pSAR.

Conclusion

The characteristic features of these patients are the right anterior mediastinal mass-like opacity due to fluid collection in the rSAR, are bulging contour with a smooth margin and cardiomegaly regardless of pulmonary edema on the chest PA radiographs, and fluid connection between the rSAR and the pSAR on CT scans.

Cardiac tamponade following transbronchial needle aspiration

Bronchoscopic transbronchial fine needle aspiration of the mediastinum is generally known as a safe procedure. Complications such as pneumothorax, pneumomediastinum, major bronchial haemorrhage and significant bleeding after a major vessel puncture are rare events. We report the first case, to our knowledge, of life-threatening cardiac tamponade following transbronchial fine needle aspiration in precarinal location.

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.

High-riding superior pericardial recess: temporal change can help distinguish from mediastinal pathology

A high-riding superior pericardial recess is an infrequently encountered normal variant which may mimic mediastinal pathology. We present a patient in whom a high-riding superior pericardial recess could confidently be diagnosed on a neck CT due to its change in size and shape demonstrated on a chest CT which was done 4 minutes later.

Prevalence of “high-riding” superior pericardial recesses on thin-section 16-MDCT scans

OBJECTIVE

The aim of this study was to evaluate the prevalence of "high-riding" superior pericardial recess (HRSPR) on thin-section (1 mm) 16-multidetector computed tomography (MDCT) scans.

MATERIALS AND METHODS

Three hundred and fourteen consecutive chest CT scans obtained with a thin-section 16 MDCT were retrospectively evaluated. The prevalence and characteristic of HRSPR were analyzed.

RESULTS

HRSPR was depicted in 21 patients (11 men and 10 women) (6.6%) who ranged in age from 28 to 72 years (mean age, 57 years). The extended recesses were rounded/oval shaped in five patients and triangular, spindle, half moon or irregular shaped in the other 16 patients.

CONCLUSION

Our data suggest as HRSPRs are more frequently and better depicted on thinsection MDCT scans, and this improves the capability to distinguish this superior extension of the superior aortic recess from abnormal findings such as lymphadenopathy, cystic lesions, and aortic dissection.

The high-riding superior aortic recess of the pericardium: MRI visualization in a child

We report a 4-year-old child with a high-riding superior aortic recess of the pericardium, initially misdiagnosed as a possible vascular malformation. The anatomy of the pericardial recesses is reviewed.

Pericardial ???Sleeve??? Recess of Right Inferior Pulmonary Vein Mimicking Adenopathy

OBJECTIVE

The purpose of this study was to assess the computed tomography (CT) features of the pericardial "sleeve" recess of the right inferior pulmonary vein misinterpreted as adenopathy.

METHOD

Six patients with fluid in the pericardial sleeve recess mistaken for adenopathy were retrospectively identified. The following CT features were assessed: location of fluid in relation to the vein, size, shape, attenuation, and mass effect on the inferior pulmonary vein.

RESULTS

The most common presentation was fluid inferior and posterior to the vein. The anterior and posterior components are typically spindle shaped, whereas the superior and inferior components are ovoid. The attenuation values of the fluid ranged from 2-32 H (mean = 13 H). None of the fluid collections exerted mass effect on the right inferior pulmonary vein.

CONCLUSION

Although fluid in the right pulmonary venous sleeve pericardial recess can mimic adenopathy, this accumulation has a characteristic appearance, and knowledge of this normal variant is useful in preventing misinterpretation.