Safety of an i.v. ß-adrenergic blockade protocol for heart rate optimization before coronary CT angiography.

OBJECTIVE: The purpose of this study was to assess the safety of heart rate optimization by use of ß-adrenergic blockade solely by the i.v. route before coronary CT angiography. MATERIALS AND METHODS: The records of 679 patients undergoing CT coronary angiography after receiving i.v. ß-adrenergic blockade were retrospectively analyzed. Health screening was completed before scanning, and heart rate was optimized by administration of i.v. metoprolol titrated to a maximum of 70 mg to achieve a heart rate less than 65 beats/min. RESULTS: The median i.v. dose was 20 mg (range, 5-70 mg). The 679 patients analyzed had a total of 10 complications (1.47%). Major complications, defined as not resolving with observation and analgesia alone, occurred in only three patients (0.44%). These complications included a second-degree atrioventricular block. A total of 299 patients (44.0%) needed more than 20 mg of i.v. metoprolol to achieve target heart rate. Only three patients needed the maximum i.v. dose of 70 mg metoprolol. Target heart rate was reached successfully in 666 patients (98.1%) with doses of less than 70 mg. This study did not show a statistically significant association between increasing complication frequency and increasing dose. CONCLUSION: This study showed that high doses of i.v. metoprolol can be used effectively and with a low rate of major complications to control heart rate before coronary CT angiography in correctly screened patients.

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.

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.

Dual-energy CT angiography for assessment of regional pulmonary perfusion in patients with chronic thromboembolic pulmonary hypertension: initial experience.

OBJECTIVE: This study assessed the utility of dual-energy pulmonary CT angiography (CTA) for noninvasive assessment of regional pulmonary perfusion in patients with chronic thromboembolic pulmonary hypertension (CTEPH). Regional perfusion abnormalities were correlated with hemodynamic parameters and structural abnormalities on pulmonary CTA. SUBJECTS AND METHODS: Twenty patients with CTEPH (11 men and nine women; mean age, 61.5 years) underwent pulmonary CTA with a dual-energy technique. Right heart catheterization data were available in 15 cases. Scan parameters were as follows: tube A, 140 kV (75 mA); tube B, 80 kV (300 mA); gantry rotation, 500 milliseconds; pitch, 0.5; and collimation, 14 × 1.2 mm. An iodine map was generated via three-material-decomposition and was scored for extent of hypoperfusion. Correlation was made with mosaic attenuation pattern, extent of vascular obstruction, and right heart hemodynamics. Iodine attenuation values were analyzed within completely occluded, partially occluded, and disease-free lobes. RESULTS: A strong correlation existed between dual-energy CT-derived perfusion and mosaic attenuation pattern when both lobar (r > 0.6; n = 20; p < 0.006) and whole-lung scores were assessed (r = 0.77; n = 20; p < 0.001). There was no statistically significant correlation between dual-energy CT perfusion and vascular obstructive index, mean pulmonary artery pressure, or pulmonary vascular resistance (p > 0.08). Of 42 completely occluded lobes, 27 (64%) had demonstrable residual perfusion (mismatching), suggesting that blood supply was maintained via systemic collaterals. CONCLUSION: Dual-energy CT can offer a "one-stop" assessment of anatomy and perfusion in CTEPH. The additional information provided by dual-energy CT could have a future role in helping guide patient selection for thromboendarterectomy surgery.

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.

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.

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.

Computed tomography-guided pericardiocentesis: utility in the management of malignant pericardial effusion.

Transthoracic echocardiography is an established means of diagnosing a pericardial effusion and has become the reference guidance modality for drainage of symptomatic collections. However, echocardiographic drainage is not feasible in all patients for a variety of technical and patient-related factors. Computed tomography (CT)-directed pericardiocentesis using a standard Seldinger technique is an alternative means of draining pericardial effusions and overcomes many of the limitations associated with echocardiography. We present a case in which a CT-guided approach was used to successfully drain a malignant pericardial effusion in the emergent setting. Clinicians should be aware of the potential role of CT in this setting.

Cardiac CT: non-coronary applications.

Cardiac CT involves acquisition of high-quality ECG-gated dynamic images of the heart. ECG gating allows exquisite delineation of the coronary arteries, which are subjected to respiratory and cardiac motion. Cardiac CT has an established role in the assessment of coronary artery disease in selected patient groups and permits detailed assessment of cardiac and great vessel anatomy. The technique can also be used for a number of non-coronary applications including assessment of the pericardium, cardiac tumours and pulmonary veins. In this article, these applications are reviewed and the salient imaging findings across a range of structural cardiac disease illustrated.

Sinus venosus atrial septal defect in adults: utility of cardiovascular MRI in resolving this diagnostic dilemma.

Sinus venosus atrial septal defect (SV-ASD) can be a challenging diagnostic problem. It can present with non-specific signs and symptoms and, on imaging, can mimic other causes of right heart dilatation. Transthoracic echocardiography using standard scan planes may be limited, due to the defect and any associated anomalous pulmonary venous drainage lying outside the confines of the fossa ovalis. At our institution, we use cardiovascular magnetic resonance imaging (CMRI) as a problem-solving tool in these patients. In this article, we discuss the utility of CMRI in establishing the diagnosis by presenting our recent experience and illustrating it with sample cases. We wish to highlight the problems relating to making a diagnosis of SV-ASD in adult patients, and how CMRI has contributed to overcoming these in our practice.

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.

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.

The use of carbon dioxide angiography for renal sympathetic denervation: a technical report.

OBJECTIVE: Hypertension is the leading attributable cause of cardiovascular mortality worldwide. Patients with hypertension have multiple comorbidities including high rates of concomitant renal disease. Current pharmacological approaches are inadequate in the treatment of resistant hypertension. Renal sympathetic denervation (RDN) has been shown to effectively treat resistant hypertension. The traditional use of iodinated contrast in RDN is contraindicated in patients with significant renal insufficiency. In patients with renal impairment, carbon dioxide (CO2) can be used as an alternative contrast material for RDN. This article describes the technical aspects of RDN using CO2 angiography. METHODS: Our centre is experienced in the innovative RDN procedure using CO2 angiography. We describe the protocol for CO2 angiography for RDN using a home-made CO2 delivery system and the Symplicity™ (Minneapolis MN 55432 USA) catheter (Medtronic) device. RESULTS: CO2 angiography is an excellent alternative to iodinated contrast for RDN procedures. CONCLUSION: CO2 angiography for RDN is a safe and effective alternative to iodinated contrast. RDN using CO2 angiography is an easy and feasible procedure that can be used in patients with renal insufficiency or iodinated contrast allergies. Advances in knowledge: There is a paucity of descriptive reports for CO2 angiography for RDN and we provide details of the optimal protocol for the procedure. In particular, we describe the use of a Symplicity Spyral™ catheter (Medtronic), which has not been reported to date for use in this procedure.

Multi-detector CT assessment in pulmonary hypertension: techniques, systematic approach to interpretation and key findings.

Pulmonary arterial hypertension (PAH) may be suspected based on the clinical history, physical examination and electrocardiogram findings but imaging is usually central to confirming the diagnosis, establishing a cause and guiding therapy. The diagnostic pathway of PAH involves a variety of complimentary investigations of which computed tomography pulmonary angiography (CTPA) has established a central role both in helping identify an underlying cause for PAH and assessing resulting functional compromise. In particular CTPA is considered as the gold standard technique for the diagnosis of thromboembolic disease. This article reviews the CTPA evaluation in PAH, describing CTPA techniques, a systematic approach to interpretation and spectrum of key imaging findings.