New Advice Released on Advanced Imaging for Evaluation of CV Infections

To help guide clinicians in the evaluation of suspected cardiovascular infections, including infective endocarditis (IE) and others, the American Society of Nuclear Cardiology (ASNC) and 10 other professional societies have released consensus recommendations on how best to incorporate advanced radionuclide imaging.

Infections involving native and prosthetic valves, cardiovascular implantable electronic devices (CIEDs), and prosthetic material like grafts, conduits, and patches is a growing problem driven by greater use of implanted devices and a continuing epidemic of injection drug use, according to a writing group chaired by Jamieson Bourque, MD (University of Virginia Health System, Charlottesville). Such infections come with high rates of morbidity and mortality.

In that context, “there’s an important role for advanced imaging with radionuclide techniques to build on the very solid foundation created by echocardiography, CT, clinical evaluation, blood cultures, etc,” Bourque told TCTMD.

He was referring specifically to ¹⁸F-fluorodeoxyglucose (FDG) PET/CT and SPECT/CT leukocyte scintigraphy, which are covered in the new document, published online this week in the Journal of Nuclear Cardiology, Clinical Infectious Diseases, Heart Rhythm, and JACC: Cardiovascular Imaging.

Radionuclide imaging “has been a tool with growing data supporting its use, but there has not been a comprehensive deep dive into the clinical indications and the key diagnostic features and a comprehensive diagnostic algorithm for the use of this tool,” he said.

This new set of recommendations—created with input by experts in imaging, cardiology, electrophysiology, cardiothoracic surgery, and infectious diseases—is the first in a document series called ASNC Imaging Indications (ASNC I²), which will focus on the role of radionuclide imaging in assessing cardiovascular involvement in a range of complex systemic diseases.

These advanced imaging modalities can help improve on the evaluation of cardiovascular infections beyond what’s gleaned from clinical assessment, blood cultures, and echocardiography, which may not be enough to come to a definitive diagnosis.

“Radionuclide imaging with FDG PET/CT and radiolabeled leukocyte scintigraphy SPECT/CT has been shown to improve diagnostic accuracy and in particular can assess periprosthetic involvement, extracardiac manifestations such as embolism of septic material, portal of entry, and then also areas that echocardiography cannot assess, such as pacer pockets in patients with devices, drivelines and pumps in patients with ventricular assist devices [VADs], and in prosthetic material that otherwise would not be visible,” Bourque said.

These new consensus recommendations address the use of ¹⁸F-FDG PET/CT and radiolabeled leukocyte SPECT/CT in the context of other imaging modalities, including echocardiography and cardiac CT angiography. After conducting a literature review, the writing group created consensus diagnostic criteria for cardiovascular infection and an algorithmic approach to diagnosis, with flowcharts covering suspected native or prosthetic valve endocarditis and infection of CIEDs, VADs, and prosthetic material.

The authors also review clinical indications for the use of radionuclide imaging across these various types of cardiovascular infections and provide case examples, with images, to illustrate how these modalities can be used.

Moreover, the document provides ratings of appropriateness when ¹⁸F-FDG PET/CT and radiolabeled leukocyte SPECT/CT are used in various scenarios, with color-coded tables to aid the reader.

“These ratings highlight that evidence demonstrates usefulness but do not imply need to perform advanced imaging,” Bourque et al write. “Study performance should be carefully considered in each individual case by the experts of the local endocarditis team in order to match test performance with appropriate clinical suspicion.”

Asked about key recommendations, Bourque said “there is an increased role in prosthetic valve suspected or known endocarditis, and there is a key role in patients who have equivocal or nondiagnostic workups.”

In addition, “whereas there’s a role for use even in patients with known endocarditis where you’re assessing extracardiac manifestations, the largest role is in the patients in whom there’s possible infective endocarditis or the initial approach rejected infective endocarditis but there’s a moderate or higher clinical suspicion,” he said.

Importantly, Bourque added, “the advanced imaging with radionuclide techniques can help guide medical therapy as well as surgical decision-making.”

Of note, other guidance documents, including endocarditis guidelines from the European Society of Cardiology (ESC), have started to incorporate the use of radionuclide imaging in the evaluation of cardiovascular infections.

“It’s very important to utilize all of the information available,” Bourque stressed, noting that the ESC guidelines provide an important foundation. But “we really feel that this [new] document provides added benefit above that by taking a deeper look and a more granular assessment of clinical indications as well as highlighting key diagnostic features and a diagnostic algorithm and providing some representative clinical cases that show these diagnostic clinical indications and criteria in action” he added. “And so I would hope that people would incorporate this document when considering specific clinical indications for use of radionuclide imaging. It’s an important adjunct to the other documents and guidance that’s already available.”

Along with ASNC, numerous other professional societies were involved in creating the recommendations: the American Association for Thoracic Surgery, the American College of Cardiology, the American Heart Association, the American Society of Echocardiography, the European Association of Nuclear Medicine, the Heart Rhythm Society, the Infectious Diseases Society of America, the Society of Cardiovascular Computed Tomography, the Society of Nuclear Medicine and Molecular Imaging, and the Society of Thoracic Surgeons.