Edward T. D. Hoey

MRI and CT appearances of cardiac tumours in adults

Primary cardiac tumours are rare, and metastases to the heart are much more frequent. Myxoma is the commonest benign primary tumour and sarcomas account for the majority of malignant lesions. Clinical manifestations are diverse, non-specific, and governed by the location, size, and aggressiveness. Imaging plays a central role in their evaluation, and familiarity with characteristic features is essential to generate a meaningful differential diagnosis. Cardiac magnetic resonance imaging (MRI) has become the reference technique for evaluation of a suspected cardiac mass. Computed tomography (CT) provides complementary information and, with the advent of electrocardiographic gating, has become a powerful tool in its own right for cardiac morphological assessment. This paper reviews the MRI and CT features of primary and secondary cardiac malignancy. Important differential considerations and potential diagnostic pitfalls are also highlighted.

Dual-energy CT pulmonary angiography: a novel technique for assessing acute and chronic pulmonary thromboembolism

Dual-energy computed tomography (DECT) involves the acquisition of CT datasets using two different photon spectra. Recent advances in CT technology, particularly the introduction of dualsource CT systems, have led to renewed interest in the application of DECT techniques. A dual-source CT system (Somatom Definition, Siemens Medical Solutions, Forchheim, Germany) has two x-ray tubes and two detectors that are mounted on the gantry at a 90 angular offset. The tubes can be operated at identical kilovoltage exposures to provide high temporal resolution (83 ms) for cardiac imaging or alternatively, they can be operated at two different energies. Hounsfield unit values for low atomic number materials (such as soft tissues) do not vary much with the kilovoltage exposure; however, materials with high atomic numbers, such as iodine, exhibit very differing degrees of attenuation at 80 kV compared with 140 kV. This effect can be exploited to obtain spectral information and differentiate iodine from other materials by acquiring datasets at two different energy levels. The ability of a dual-source system to simultaneously acquire two spiral acquisitions during the same phase of contrast enhancement excludes temporal changes in enhancement between acquisitions and spatial misregistration, which are the major limiting factors when attempting to apply this technique using a single-source system.

Cardiac causes of pulmonary arterial hypertension: assessment with multidetector CT

The causes of pulmonary arterial hypertension (PAH) are diverse and include multiple congenital and acquired cardiac diseases as well as diseases primarily affecting the pulmonary vasculature, lung, pleura and chest wall. The traditional role of CT in evaluating PAH includes assessment of pulmonary vasculature and lung parenchyma with limited assessment of the heart. Advances in multidetector CT technology with improved spatial and temporal resolution now permit accurate delineation of cardiac morphology. CT pulmonary angiography (CTPA) is widely utilised in the workup of patients with suspected pulmonary vascular disease and can identify both pulmonary and cardiac causes. As the initial presentation for CTPA is often precipitated by nonspecific, unexplained symptoms and therefore undertaken by a general radiologist, it is important that a systematic approach to the interpretation of these studies, including cardiac evaluation, is routinely adopted. This paper reviews the CT evaluation in pulmonary hypertension with a particular focus on the cardiac causes, their subclassification into congenital systemic to pulmonary shunts and secondary to left heart disease, and their imaging features. It emphasises the use of a systematic approach to interpretation of CTPA examinations both in patients with known PAH and those with previously unsuspected disease.

CT appearances of pleural tumours.

Computed tomography (CT) is the imaging technique of choice for characterizing pleural masses with respect to their location, composition, and extent. CT also provides important information regarding invasion of the chest wall and surrounding structures. A spectrum of tumours can affect the pleura of which metastatic adenocarcinoma is the commonest cause of malignant pleural disease, while malignant mesothelioma is the most common primary pleural tumour. Certain CT features help differentiate benign from malignant processes. This pictorial review highlights the salient CT appearances of a range of tumours that may affect the pleura.

Fresh Blood Imaging of the Peripheral Vasculature: An Emerging Unenhanced MR Technique

OBJECTIVE There is an increasing demand for MR angiography (MRA) techniques that do not require the administration of exogenous contrast material. Fresh blood imaging utilizes an ECG-gated fast spin-echo sequence to acquire images in both the systolic and diastolic phases of the cardiac cycle. Fast systolic arterial flow is differentiated from slower diastolic flow and a subtraction technique is used to produce angiographic images. We describe the technical aspects of performing lower extremity MRA and illustrate some sample cases. CONCLUSION Fresh blood imaging is an emerging unenhanced MRA technique that has recently become commercially available. Early clinical trials appear promising and it is anticipated that fresh blood imaging will become invaluable, particularly in patients with impaired renal function. Technical refinements are still required to perfect this novel MR application, particularly for the assessment of distal calf and pedal vessels and for the evaluation of patients with arrhythmias and those with impaired cardiac function.

Sinus of Valsalva Aneurysms: Assessment With Cardiovascular MRI

OBJECTIVE The aim of this article is to present the role of cardiovascular MRI in the assessment of sinus of Valsalva aneurysms. An imaging protocol is described, along with a systematic approach to interpret MR findings and a synopsis of key findings. CONCLUSION Radiologists should have a systematic approach to the assessment and evaluation of sinus of Valsalva aneurysms to facilitate optimal patient management.

Cardiovascular MRI for Assessment of Infectious and Inflammatory Conditions of the Heart

OBJECTIVE This article reviews the role of cardiovascular MRI in the diagnosis and characterization of the spectrum of infectious and inflammatory disorders of the heart. An imaging protocol is described, and typical MRI findings are discussed and illustrated. CONCLUSION Radiologists should be aware of the spectrum of infectious and inflammatory conditions that can affect the heart and the role of MRI in conjunction with other imaging techniques in their assessment.

Aortic intramural haematoma: pathogenesis, clinical features and imaging evaluation

Intramural haematoma (IMH) is a localised haemorrhage within the aortic wall. Imaging plays a central role in diagnosing IMH, differentiating it from aortic dissection (AD) and assessing for complications. Imaging is also important for prognostication and to help guide clinical decision making as a number of imaging characteristics have been correlated with increased mortality rates including location, mural thickness and aortic diameter. Multidetector CT is the leading technique for diagnosis and classification of IMH owing to speed of image acquisition, multiplanar capabilities and excellent spatial resolution. MRI is rarely used to investigate the initial presentation of IMH but is frequently used for serial follow-up studies. The clinical outcome of IMH may be favourable, with spontaneous regression over time, or it may be complicated by pericardial tamponade, aortic regurgitation and development of AD. Early surgical management is the treatment of choice for patients with Stanford type A IMH whereas most patients with Stanford type B IMH have a good short-term outcome with aggressive control of hypertension. This article reviews the pathogenesis, clinical features and complications of IMH as well as the role of advanced imaging techniques in its evaluation.

The role of multi-modality imaging for sinus of Valsalva aneurysms

Sinus of Valsalva aneurysms (SVAs) are uncommon but important entities. They are most often congenital in origin, resulting from incomplete fusion of the aortic media to the aortic valve annulus. Less frequently, they may be acquired, usually secondary to infective endocarditis. Unruptured aneurysms may be clinically silent and diagnosed incidentally, but can also produce symptoms as a consequence of mass effect on related structures. Rupture may present with sudden hemodynamic collapse but can have a more insidious onset depending upon the site and size of the perforation. Early diagnosis is imperative and can usually be made reliably by transthoracic echocardiography. However, transesophageal echocardiography may sometimes be required for confirmation. Cardiovascular magnetic resonance imaging (CMRI) and multi-detector computed tomography are being increasingly utilized for evaluation of SVAs and can offer valuable complimentary information. CMRI in particular enables a comprehensive assessment of anatomy, function and flow in a single sitting. Surgical repair forms the mainstay of treatment for both ruptured and unruptured aneurysms and has low complication rates. This article provides an overview of the pathological and clinical aspects of SVAs and discusses in detail the role of advanced imaging modalities in their evaluation.

Evaluation of the Aortic Root With MRI and MDCT Angiography: Spectrum of Disease Findings

OBJECTIVE This article reviews the spectrum of disease processes that may involve the aortic root with particular emphasis on the role of cardiovascular MRI and MDCT angiography in their assessment. Key MRI and MDCT imaging findings are discussed and illustrated. CONCLUSION Radiologists should be aware of the spectrum of disease processes that may involve the aortic root and their appearances at MRI and MDCT angiography.