Impact of dual energy cardiac CT for metal artefact reduction post aortic valve replacement

Angle Dependence of Electrode Lead-Related Artifacts in Single- and Dual-Energy Cardiac ECG-Gated CT Scanning-A Phantom Study

Background: The electrodes of implantable cardiac devices (ICDs) may cause significant problems in cardiac computed tomography (CT) because they are a source of artifacts that obscure surrounding structures and possible pathology. There are a few million patients currently with ICDs, and some of these patients will require cardiac imaging due to coronary artery disease or problems with ICDs. Modern CT scanners can reduce some of the metal artifacts because of MAR software, but in some vendors, it does not work with ECG gating. Introduced in 2008, dual-energy CT scanners can generate virtual monoenergetic images (VMIs), which are much less susceptible to metal artifacts than standard CT images. Objective: This study aimed to evaluate if dual-energy CT can reduce metal artifacts caused by ICD leads by using VMIs. The second objective was to determine how the angle between the electrode and the plane of imaging affects the severity of the artifacts in three planes of imaging. Methods: A 3D-printed model was constructed to obtain a 0-90-degree field at 5-degree intervals between the electrode and each of the planes: axial, coronal, and sagittal. This electrode was scanned in dual-energy and single-energy protocols. VMIs with an energy of 40-140 keV with 10 keV intervals were reconstructed. The length of the two most extended artifacts originating from the tip of the electrode and 2 cm above it-at the point where the thick metallic defibrillating portion of the electrode begins-was measured. Results: For the sagittal plane, these observations were similar for both points of the ICDs that were used as the reference location. VMIs with an energy over 80 keV produce images with fewer artifacts than similar images obtained in the single-energy scanning mode. Conclusions: Virtual monoenergetic imaging techniques may reduce streak artifacts arising from ICD electrodes and improve the quality of the image. Increasing the angle of the electrode as well as the imaging plane can reduce artifacts. The angle between the electrode and the beam of X-rays can be increased by tilting the gantry of the scanner or lifting the upper body of the patient.

Computed Tomography in Infectious Endocarditis

Imaging is one of the cornerstones in diagnosis and management of infective endocarditis, underlined by recent guidelines. Echocardiography is the first-line imaging technique, however, computed tomography (CT) has a class I recommendation in native and prosthetic valve endocarditis to detect valvular lesions in case of possible endocarditis and to detect paravalvular and periprosthetic complications in case of inconclusive echocardiography. Echocardiography has a higher diagnostic accuracy than CT in detecting valvular lesions, but not for diagnosing paravalvular lesions where CT is superior. Additionally, CT is useful and recommended by guidelines to detect extracardiac manifestations of endocarditis and in planning surgical treatment including assessment of the coronary arteries. The advent of photon-counting CT and its improved spatial resolution and spectral imaging is expected to expand the role of CT in the diagnosis of infective endocarditis. In this review, we provide an overview of the current role of CT in infective endocarditis focusing on image acquisition, image reconstruction, interpretation, and diagnostic accuracy.

Advances in metal artifact reduction in CT images: A review of traditional and novel metal artifact reduction techniques

Metal artifacts degrade CT image quality, hampering clinical assessment. Numerous metal artifact reduction methods are available to improve the image quality of CT images with metal implants. In this review, an overview of traditional methods is provided including the modification of acquisition and reconstruction parameters, projection-based metal artifact reduction techniques (MAR), dual energy CT (DECT) and the combination of these techniques. Furthermore, the additional value and challenges of novel metal artifact reduction techniques that have been introduced over the past years are discussed such as photon counting CT (PCCT) and deep learning based metal artifact reduction techniques.

Best Practices for Imaging Cardiac Device-Related Infections and Endocarditis: A JACC: Cardiovascular Imaging Expert Panel Statement

The diagnosis of cardiac device infection and, more importantly, accurate localization of the infection site, such as defibrillator pocket, pacemaker lead, along the peripheral driveline or central portion of the left ventricular assist device, prosthetic valve ring abscesses, and perivalvular extensions, remain clinically challenging. Although transthoracic and transesophageal echocardiography are the first-line imaging tests in suspected endocarditis and for assessing hemodynamic complications, recent studies suggest that cardiac computed tomography (CT) or CT angiography and functional imaging with ¹⁸F-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) with CT (FDG PET/CT) may have an incremental role in technically limited or inconclusive cases on echocardiography. One of the key benefits of FDG PET/CT is in its detection of inflammatory cells early in the infection process, before morphological damages ensue. However, there are many unanswered questions in the literature. In this document, we provide consensus on best practices among the various imaging studies, which includes the detection of cardiac device infection, differentiation of infection from inflammation, image-guided patient management, and detailed recommendations on patient preparation, image acquisition, processing, interpretation, and standardized reporting.

Dual-Energy Heart CT: Beyond Better Angiography-Review

Heart CT has undergone substantial development from the use of calcium scores performed on electron beam CT to modern 256+-row CT scanners. The latest big step in its evolution was the invention of dual-energy scanners with much greater capabilities than just performing better ECG-gated angio-CT. In this review, we present the unique features of dual-energy CT in heart diagnostics.