Worldwide Variation in the Use of Nuclear Cardiology Camera Technology, Reconstruction Software, and Imaging Protocols

Real world experience with [99mTc]Tc-HYNIC-iPSMA SPECT prostate cancer detection: interim results from the global NOBLE registry

PURPOSE

[99mTc]Tc-HYNIC-iPSMA is a novel technetium-99m-labelled small molecule inhibitor of the prostate-specific membrane antigen (PSMA) for detecting prostate cancer (PC). The objective of this registry was to collect and evaluate [99mTc]Tc-HYNIC-iPSMA patient data and images to establish the safety and tolerability, and clinical utility of this agent in imaging at different stages of PC.

METHODS

Patients 18 to 80 years old with primary staging and metastatic PC were eligible. Patients unable to perform prescribed examinations, undergo a [99mTc]Tc-HYNIC-iPSMA planar and SPECT or SPECT/CT (when available), or sign a patient informed consent form were excluded from the registry. All eligible patients underwent a screening and baseline visit before imaging with [99mTc]Tc-HYNIC-iPSMA. The primary safety endpoint was assessed by collecting and grading all treatment-related adverse events using the Common Terminology Criteria for Adverse Events. Patients were followed until disease progression, death, serious or intolerable adverse events, registry termination by the sponsor, patient withdrawal, or lost to follow-up. Analysis was planned for when data was available from 40 enrolled patients.

RESULTS

40 patients enrolled in 6 countries and received [99mTc]Tc-HYNIC-iPSMA tracer administration followed by planar and SPECT imaging. Of the 40 patients included, investigators reported a change in management due to the [99mTc]Tc-HYNIC-iPSMA imaging in 17/40 of patients (42.5%). No adverse events were reported.

CONCLUSIONS

[99mTc]Tc-HYNIC-iPSMA is a promising option to identify PSMA-positive prostate cancer on SPECT and could improve patient access to PSMA imaging worldwide.

Multimodality Cardiac Imaging and the Imaging Workforce in the United States: Diversity, Disparities, and Future Directions

Innovations in cardiac imaging have fundamentally advanced the understanding and treatment of cardiovascular disease. These advances in noninvasive cardiac imaging have also expanded the role of the cardiac imager and dramatically increased the demand for imagers who are cross-trained in multiple modalities. However, we hypothesize that there is significant variation in the availability of cardiac imaging expertise and a disparity in the adoption of advanced imaging technologies across the United States. To evaluate this, we have brought together the leaders of cardiovascular imaging societies, imaging trainees, as well as collaborated with national imaging accreditation commissions and imaging certification boards to assess the state of cardiac imaging and the diversity of the imaging workforce in the United States. Aggregate data confirm the presence of critical gaps, such as limited access to imaging and imaging expertise in rural communities, as well as disparities in the imaging workforce, notably among women and underrepresented minorities. Based on these results, we have proposed solutions to promote and maintain a robust and diverse community of cardiac imagers and improve equity and accessibility for cardiac imaging technologies.

Stress-First Myocardial Perfusion Imaging

Stress-first approaches to myocardial perfusion imaging provide diagnostically and prognostically accurate perfusion data equivalent to a full rest-stress study while saving time in the imaging laboratory and reducing the radiation exposure to patients and laboratory staff. Unfortunately, implementing a stress-first approach in a nuclear cardiology laboratory involves significant challenges such as the need for attenuation correction, triage of patients to an appropriate protocol, real-time review of stress images, and consideration of differential reimbursement. Despite it being best practice for both the patient and the laboratory, these impediments have kept the proportions of studies performed stress-first relatively unchanged in North America and world-wide in the last 10 years.

Radiation Dose Assessment for Myocardial Perfusion Imaging: A Single Institution Survey

OBJECTIVE

This study aims to establish a local diagnostic reference level (LDRL) for single-photon emission tomography/computed tomography (SPECT/CT) and positron emission tomography/CT (PET/CT) with respect to myocardial perfusion imaging (MPI).

MATERIALS AND METHODS

The acquisition protocol and dosimetry data on the MPI procedures of five SPECT/CT scans and one PET/CT scan were collected. Data on technitum-99m sestamibi (^99mTc-sestamibi), ^99mTc-tetrofosmin, thallium-201 (²⁰¹Tl), and rubidium-82 (⁸²RB) were all collected from one centre via questionnaire booklets. Descriptive data analysis was used to analyse all variables, and the 50th percentile was used to analyse each radiation dose quantity.

RESULTS

The reported 50th percentile dose for a one-day stress/rest protocol using ^99mTc-sestamibi (445/1147 MBq) and ^99mTc-tetrofosmin (445/1147 MBq) and for a two-day stress/rest protocol using ^99mTc-sestamibi (1165/1184 MBq) and ^99mTc-tetrofosmin (1221/1184 MBq) are in good agreement with reported national diagnostic reference levels (NDRLs). However, the dose from the study data on a one-day stress/rest protocol using ^99mTc-sestamibi was more than the 50th percentile dose from the Brazilian data (370/1110 MBq) on a similar protocol, and the dose from the study data on a two-day stress/rest protocol using ^99mTc-tetrofosmin was more than the 50th percentile dose (1084/1110 MBq) from the United States data on MPI scans. Regarding the computed tomography (CT) portion of the SPECT/CT framework, the 50th percentile doses were lower than all the identified doses in the data considered in the literature reviewed. However, regarding the CT component of the PET/CT MPI scans, the ⁸²RB dose was more than the recorded doses in the CT data in the published literature.

CONCLUSION

This study determined the LDRL of five SPECT/CT protocols and one PET/CT MPI protocol. The results suggest that there may be opportunities to optimise the patient radiation burden from administered activities in patients undergoing SPECT examinations and the CT components associated with ⁸²RB PET/CT scans without compromising diagnostic image quality.

The Potential of F-18 Flurpiridaz PET/CT Myocardial Perfusion Imaging for Precision Imaging

PURPOSE OF THE REVIEW

Myocardial perfusion imaging (MPI) with single photon emission computed tomography (SPECT) has been the main method for assessing patients with known or suspected coronary artery disease (CAD) for decades. Based on a strong and growing evidence base, positron emission tomography (PET) MPI is increasingly favored when it is available. However, currently available PET perfusion tracers have limitations that have hampered broad utilization.

RECENT FINDINGS

F-18 flurpiridaz is a novel PET MPI agent that is nearing completion of studies necessary to obtain regulatory approval. It has unique capabilities that will facilitate further expansion of PET MPI utilization. In addition, it has characteristics that may define it as the best MPI agent to date, in terms of the potential to equalize accuracy independent of patient size, gender, complexity, or ability to perform exercise stress. The combination of excellent image quality and accurate absolute blood flow quantification hold the potential of its being an ideal precision tool for non-invasive assessment of myocardial blood flow and entire spectrum of ischemic heart disease.

CoroFinder: A New Tool for Real Time Detection and Tracking of Coronary Arteries in Contrast-Free Cine-Angiography

Coronary Angiography (CA) is the standard of reference to diagnose coronary artery disease. Yet, only a portion of the information it conveys is usually used. Quantitative Coronary Angiography (QCA) reliably contributes to improving the measurable assessment of CA. In this work, we developed a new software, CoroFinder, able to automatically identify epicardial coronary arteries and to dynamically track the vessel profile in dye-free frames. The coronary tree is automatically segmented by Frangi’s filter in the angiogram’s frames where vessels are contrasted (“template frames”). Afterward, the image similarity among each template frame and the dye-free images is scored by cross-correlation. Finally, each dye-free image is associated with the most similar template frame, resulting in an estimation of vessel contour. CoroFinder allows locating the position of coronary arteries in absence of contrast dye. The developed algorithm is robust to diverse vessel curvatures, variation of vessel widths, and the presence of stenoses. This article describes the newly developed CoroFinder algorithm and the associated software and provides an overview of its potential application in research and for translation to the clinic.

KSNM60 in Cardiology: Regrowth After a Long Pause

The Korean Society of Nuclear Medicine (KSNM) is celebrating its 60th anniversary in honor of the nuclear medicine professionals who have dedicated their efforts towards research, academics, and the more comprehensive clinical applications and uses of nuclear imaging modalities. Nuclear cardiology in Korea was at its prime time in the 1990s, but its growth was interrupted by a long pause. Despite the academic and practical challenges, nuclear cardiology in Korea now meets the second leap, attributed to the growth in molecular imaging tailored for many non-coronary diseases and the genuine values of nuclear myocardial perfusion imaging. In this review, we describe the trends, achievements, challenges, and perspectives of nuclear cardiology throughout the 60-year history of the KSNM.