Myocardial Perfusion Imaging Studies Research Articles

Three years' registry on myocardial perfusion imaging patients in Ain shams university nuclear cardiology unit

Abstract Background The development in nuclear myocardial perfusion imaging (MPI) has provided diagnostic and prognostic implications in CAD patients, leading to an explosive increase in the performanceofthesestudies. Thisexpansionofimagingspectrumisassociatedwithwidespread concern regarding imaging utilization and increased healthcare costs. There is no comparative data that guide the use of these modalities with respect to appropriateness and patients’ benefit. Targeted data collection, through registry studies, enable analysis of both quality and outcomes with big advantages of reflecting real world daily practice and identifying the gaps in care which may not otherwise be feasible in high-quality randomized control trials. Objective To explore the extent to which stress myocardial perfusion imaging (MPI) studies met published appropriate use criteria (AUC), and the real world practice in the nuclear cardiology unit of Ain shams University. Patients and Methods It was a retrospective cohort study that included 2598 patients who underwent myocardial perfusion imaging in Ain Shams university nuclear cardiology unit throughout the period from January 2017 to December2019. All patients were subjected to thorough demographic data, history of cardiovascular risk factors (arterial hypertension, diabetes mellitus, smoking, family history of premature cardiovascular diseases), indication of the test, preprocedural ECG, ejection fraction by echocardiography, previous coronary angiography and PCI or CABG, calculation of pretest probability and Framingham risk score, determination of appropriateness use criteria and stress-rest Tc 99m imaging to detect the presence of ischemia and one day Tc 99m imaging to detect viability. Results The study included 2598 patients with mean age of 57.76 years, with male predominance (68.1%), 38.2% were diabetics and 53% had hypertension. The most common indications to undergo MPI was the exclusion of CAD as a cause of chest pain in 38.8% of patients followed by the evaluation of symptomatic post PCI patients in 21.9%. Moreover 63.8% of patients showed appropriate tests, while 18.6% of patients showed uncertain tests. Whereas 17.6% of patients had inappropriate studies. 81% of appropriate tests showed positive results of SPECT. Whereas in the inappropriate and the uncertain category, the negative test for ischemia predominated. Conclusion We have established that appropriateness criteria are effective in identifying appropriateness of SPECT in a university center located in Cairo. Also, we concluded that in our unit the appropriate tests were more prominent than inappropriate and unclassified tests. Most of the appropriate studies were positive for ischemia. While, most of the inappropriate and uncertain tests were normal and the commonest cause of referral for MPI was exclusion of CAD as a cause of chest pain.

Age- and Sex-Specific Myocardial Blood Flow Values in Patients Without Coronary Atherosclerosis on Rb-82 PET Myocardial Perfusion Imaging.

Quantitative myocardial blood flow (MBF) on positron-emission tomography myocardial perfusion imaging is a measure of the overall health of the coronary circulation. The ability to adequately augment blood flow, measured by myocardial blood flow reserve (MBFR), is associated with lower major adverse cardiovascular events and all-cause mortality. The age-specific ranges of MBFR in patients without demonstrable coronary artery disease have not been well established. We aimed to determine the effect of age and sex on MBF in a cohort of patients without demonstrable coronary artery disease. Patients who underwent positron-emission tomography myocardial perfusion imaging studies from 2012 to 2022 on positron-emission tomography/computed tomography cameras were included if the summed stress score was 0, the coronary calcium score was 0, and the left ventricular ejection fraction was ≥50%. Those with known coronary artery disease, prior history of coronary intervention, diabetes, heart/kidney/liver transplant, cirrhosis, or chronic kidney disease stage IV+ were excluded. MBF was calculated using a net retention model (ImagenQ, Cardiovascular Imaging Technologies, Kansas City), and quantile regression models were developed to predict MBF. Among 2789 patients (age 59.9±13.0 years, 76.4% females), median rest MBF was 0.73 (0.60-0.91) mL/min·g, stress MBF was 1.72 (1.41-2.10) mL/min·g, and MBFR was 2.31 (1.96-2.74). Across all ages, males augmented MBF in response to vasodilator stress to a greater degree than females but achieved lower absolute stress MBF. Younger males in particular achieved a higher MBFR than their female counterparts, and this gap narrowed with increasing age. Predicted MBFR for a 20-year-old male was 3.18 and female was 2.50, while predicted MBFR for an 80-year-old male was 2.17 and female was 2.02. In patients without demonstrable coronary artery disease, MBFR is higher in younger males than younger females and decreases with age in both sexes. Age- and sex-specific MBFR may be important in risk prediction and guidance for revascularization and warrant further study.

Splenic switch-off in [15O]H2O-positron emission tomography myocardial perfusion imaging using parametric blood flow images

BackgroundEvaluation of sufficient adenosine response constitutes a significant challenge in myocardial perfusion imaging (MPI). Splenic switch-off in MPI studies denotes a visually (qualitatively) reduced splenic radiotracer signal during adenosine stress and is considered indicative of sufficient cardiac vasodilation. In this study, we examined semi-quantitative and quantitative approaches to splenic switch-off assessment using [15O]H2O-PET with either summed activity images or calculated parametric splenic blood flow images. MethodsCohort 1: 90 clinical patients undergoing [15O]H2O MPI in whom adenosine response was considered clinically adequate were identified to characterize the corresponding splenic switch-off. Spleen stress/rest-ratio (SSR-ratio) was calculated as spleen stress signal intensity/spleen rest signal intensity on both summed activity and parametric blood flow images.Cohort 2: Twenty-five patients with repeat MPI due to suspected insufficient adenosine response were identified to observe if splenic switch-off on the initial MPI could predict the outcome of the repeat MPI.Cohort 3: Fifty-four patients who were considered adenosine responders on MPI and who had a coronary angiogram (CAG) follow-up within 3 months after MPI served as a separate validation group. ResultsSplenic switch-off was present in most patients with a clinically sufficient adenosine response (Cohort 1), illustrated by both visual (74.4%–86.7%), semi-quantitative (summed activity images) (85.6%), and quantitative (parametric blood flow images) (92.2%) evaluation, which corresponds to the distribution in patients with sufficient adenosine response and follow-up CAG (Cohort 3). In patients suspected of insufficient adenosine response on the initial MPI (Cohort 2), the repeat MPI only yielded different myocardial blood flow (MBF) results if the initial SSR-ratio was >0.90 on splenic parametric blood flow images. Conclusionquantitative splenic switch-off assessment on parametric blood flow images was superior to the semi-quantitative splenic switch-off approach. Patients with a suspected insufficient initial adenosine response and SSR-ratio >0.90 can benefit from a repeat MPI. Thus, the integration of quantitative splenic switch-off using parametric blood flow images in the evaluation of adenosine response may support future clinical decision-making.

DEMIST: A Deep-Learning-Based Detection-Task-Specific Denoising Approach for Myocardial Perfusion SPECT.

There is an important need for methods to process myocardial perfusion imaging (MPI) single-photon emission computed tomography (SPECT) images acquired at lower-radiation dose and/or acquisition time such that the processed images improve observer performance on the clinical task of detecting perfusion defects compared to low-dose images. To address this need, we build upon concepts from model-observer theory and our understanding of the human visual system to propose a detection task-specific deep-learning-based approach for denoising MPI SPECT images (DEMIST). The approach, while performing denoising, is designed to preserve features that influence observer performance on detection tasks. We objectively evaluated DEMIST on the task of detecting perfusion defects using a retrospective study with anonymized clinical data in patients who underwent MPI studies across two scanners (N = 338). The evaluation was performed at low-dose levels of 6.25%, 12.5%, and 25% and using an anthropomorphic channelized Hotelling observer. Performance was quantified using area under the receiver operating characteristics curve (AUC). Images denoised with DEMIST yielded significantly higher AUC compared to corresponding low-dose images and images denoised with a commonly used task-agnostic deep learning-based denoising method. Similar results were observed with stratified analysis based on patient sex and defect type. Additionally, DEMIST improved visual fidelity of the low-dose images as quantified using root mean squared error and structural similarity index metric. A mathematical analysis revealed that DEMIST preserved features that assist in detection tasks while improving the noise properties, resulting in improved observer performance. The results provide strong evidence for further clinical evaluation of DEMIST to denoise low-count images in MPI SPECT.

Partnering Research and Clinical Practice to Implement a Photon-Counting Detector CT Myocardial Perfusion Imaging Study

Implementation of research studies in clinical practice may encounter institutional, cultural, or resource barriers. Lack of nursing representation during the development of research protocols and decision-making, as well as financial constraints and competing priorities can impact translating research evidence into practice. At a large Midwestern teaching hospital, these barriers are addressed using professional nursing practice and a team-based approach to patient care and innovation, which in turn improves health outcomes for patients. The institution's commitment to nursing research in the radiology department aids in the implementation of innovative imaging technologies with the potential for improved detection and diagnosis of coronary artery disease. This article will outline radiology nursing involvement in the development of a dual-purpose research and clinical exam utilizing advanced computed tomography scanner technology. This article will also show how the institution works through common barriers to nursing research and how its efforts aid in the translation of evidence-based research into clinical practice.

Cardiovascular risk factors and development of nomograms in an Italian cohort of patients with suspected coronary artery disease undergoing SPECT or PET stress myocardial perfusion imaging.

Single-photon emission computed tomography (SPECT) and positron emission tomography (PET) are non-invasive nuclear medicine techniques that can identify areas of abnormal myocardial perfusion. We assessed the prevalence of cardiovascular risk factors in patients with suspected coronary artery disease (CAD) undergoing SPECT or PET stress myocardial perfusion imaging (MPI). Based on significant risk factors associated with an abnormal MPI, we developed a nomogram for each cohort as a pretest that would be helpful in decision-making for clinicians. A total of 6,854 patients with suspected CAD who underwent stress myocardial perfusion imaging by SPECT or PET/CT was studied. As part of the baseline examination, clinical teams collected information on traditional cardiovascular risk factors: age, gender, body mass index, angina, dyspnea, diabetes, hypertension, hyperlipidemia, family history of CAD, and smoking. The prevalence of cardiovascular risk factors was different in the two cohorts of patients undergoing SPECT (n = 4,397) or PET (n = 2,457) myocardial perfusion imaging. A statistical significance was observed in both cohorts for age, gender, and diabetes. At multivariable analysis, only age and male gender were significant covariates in both cohorts. The risk of abnormal myocardial perfusion imaging related to age was greater in patients undergoing PET (odds ratio 4% vs. 1% per year). In contrast, male gender odds ratio was slightly higher for SPECT compared to PET (2.52 vs. 2.06). In the SPECT cohort, smoking increased the risk of abnormal perfusion of 24%. Among patients undergoing PET, diabetes and hypertension increased the risk of abnormal perfusion by 63% and 37%, respectively. For each cohort, we obtained a nomogram by significant risk factors at multivariable logistic regression. The area under the receiver operating characteristic curve associated with the nomogram was 0.67 for SPECT and 0.73 for the PET model. Patients with suspected CAD belonging to two different cohorts undergoing SPECT or PET stress myocardial perfusion imaging can have different cardiovascular risk factors associated with a higher risk of an abnormal MPI study. As crude variables, age, gender, and diabetes were significant for both cohorts. Net of the effect of other covariates, age and gender were the only risk factors in common between the two cohorts. Furthermore, smoking and type of stress test were significant for the SPECT cohort, where as diabetes and hypertension were significant for the PET cohort. Nomograms obtained by significant risk factors for the two cohorts can be used by clinicians to evaluate the risk of an abnormal study.

Comparative predictors of mortality among patients referred for stress single-photon emission computed tomography versus positron emission tomography myocardial perfusion imaging

BackgroundThere is currently little information regarding the usage and comparative predictors of mortality among patients referred for single-photon emission computed tomography (SPECT) versus positron emission tomography (PET) myocardial perfusion imaging (MPI) within multimodality imaging laboratories. MethodsWe compared the clinical characteristics and mortality outcomes among 15,718 patients referred for SPECT-MPI and 6202 patients referred for PET-MPI between 2008 and 2017. ResultsApproximately two-thirds of MPI studies were performed using SPECT-MPI. The PET-MPI group was substantially older and included more patients with known coronary artery disease (CAD), hypertension, diabetes, and myocardial ischemia. The annualized mortality rate was also higher in the PET-MPI group, and this difference persisted after propensity matching 3615 SPECT-MPI and 3615 PET-MPI patients to have similar clinical profiles. Among the SPECT-MPI patients, the most potent predictor of mortality was exercise ability and performance, including consideration of patients’ mode of stress testing and exercise duration. Among the PET-MPI patients, myocardial flow reserve (MFR) was the most potent predictor of mortality. ConclusionsIn our real-world setting, PET-MPI was more commonly employed among older patients with more cardiac risk factors than SPECT-MPI patients. The most potent predictors of mortality in our SPECT and PET-MPI groups were variables exclusive to each test: exercise ability/capacity for SPECT-MPI patients and MFR for PET-MPI patients.

Abstract 17801: Age-Specific Normal Values for Myocardial Blood Flow on 82rb Positron Emission Tomography

Introduction: Positron emission tomography (PET) myocardial perfusion imaging (MPI) is utilized to evaluate ischemia along with myocardial blood flow (MBF). The ability to adequately augment blood flow, measured by myocardial blood flow reserve (MBFR), is a measure of overall health of the coronary circulation and associated with lower major adverse cardiovascular events (MACE) and all-cause mortality. The age-specific ranges of MBFR in patients without demonstrable coronary artery disease (CAD) has not been well established. Hypothesis/Aim: To determine the effect of age on MBF and MBFR in a cohort of patients without demonstrable CAD. Methods: Patients who underwent PET MPI studies from 2012-2022 on Siemens PET/CT cameras were included if Summed Stress Score=0, coronary calcium score=0, and left ventricular ejection fraction ≥50%. Those with prior history of MI or coronary intervention, heart/kidney/liver transplant, cirrhosis, or CKD stage IV+ were excluded. MBF was calculated using a net retention model (ImagenQ, Cardiovascular Imaging Technologies, Kansas City, MO) and multivariable linear regression models were developed to predict MBF. Results: Among 3,235 patients (age 59.5+/-12.6 years, 24.2% male) with median rest MBF 0.74 [0.61-0.92] and stress MBF 1.71 [1.41-2.10], MBFR was 2.28 [1.93-2.72]. With increasing age, rest MBF remained fairly stable while stress MBF and MBFR decreased, such that for every 10 years of age, stress MBF decreased by 0.07 [95% CI 0.05-0.08] mL/min/g and MBFR decreased by 0.12 [95% CI 0.11-0.14] after multivariable adjustment. Age-specific predicted MBFR values are documented in the Table. Conclusions: In patients without demonstrable CAD, the MBFR decreases with age. Abnormal MBFR values under 2.0 may be seen in a significant number of older patients.

Abstract 16082: Racial Differences Among Patients Undergoing Nuclear Myocardial Perfusion Imaging

Introduction: Noninvasive cardiac stress testing is valuable for early diagnosis and optimizing management of patients with coronary artery disease (CAD). Historically, Black patients have experienced both underdiagnosis and undertreatment of CAD. We evaluated racial disparities in patients undergoing nuclear myocardial perfusion imaging (MPI). Different modalities (MPI (SPECT, PET) vs. stress echocardiography) have variations in accuracy, cost and radiation exposure, which may reflect provider biases. Methods: Patient-reported demographics, clinician-reported cardiac risk factors and MPI study characteristics from a large Connecticut health system (2016 - 2022) were compared for Black and White patients in both general and matched cohorts (1:1 matched for demographics and risk factors). Results: The study included 123,069 cardiac stress tests from 10.5% Black and 76.2% White patients (largely similar to overall Connecticut population: 12.7% Black, 78.8% White). Black patients were younger (56.7±13.3 vs. 62.1±13.4 years, p< 0.001), more likely female (58.7 vs. 44.7%, p<0.001) and had more risk factors (Table 1). Black patients were more likely to undergo MPI (66.6 vs. 50.5%, p<0.001), inpatient or observation status testing (17.0 vs. 8.4%, p< 0.001), with pharmacological rather than exercise stress (53.9 vs. 37.0%, p<0.001) than White patients. On analysis of the 1:1 matched cohort, Black patients younger than 65 years were more likely to undergo MPI than White patients (62.1 vs. 57.4%, p<0.001), while the reverse is seen for patients over 65 years old (37.5 vs. 42.5%, p<0.001). Conclusion: Significant demographic and stress testing pattern differences were found between Black and White patients. These findings may reflect racial disparities in cardiovascular care, including access and clinical referral patterns. Further studies are needed to determine if these differences in stress testing strategies impact downstream clinical outcomes.

Abstract 12224: Long Term Mortality in Patients With Low-Risk Myocardial Perfusion Imaging

Introduction: Stress testing is utilized for diagnosis and risk stratification for coronary artery disease, with low-risk myocardial perfusion imaging (MPI) indicating less than 1% cardiac mortality per year. We aimed to determine the long-term cardiac mortality in these patients. Methods: We performed a retrospective observational study of 1,300 patients with low-risk MPI in 2015, including pharmacological and exercise studies in a tertiary care center in Central Massachusetts, USA. Each patient was followed from the time of the MPI study for a total duration of 7 years. All-cause mortality and cardiac death were identified. We calculated the pharmacologic and exercise MPI percentage in patients with cardiac death. A cardiac mortality graph was plotted to observe trends over seven years. Results: Out of the 1,300 patients, 3.2% [n=42; mean age 74.6+/-20 years, 78% male (n=32)] of patients had a cardiac death in the follow-up period of 7 years. The pharmacological MPI group had 5% (n=41) cardiac deaths as compared to 0.2% (n=1) in the exercise MPI with the low Duke Treadmill Score group (p-value 0.04) [Figure 1a]. The cardiac death trend over the seven years revealed the highest mortality in year 6 (19%, n= 8) and the lowest in year 4 (7.1%, n=3) [Figure 1b]. Conclusions: The incidence of long-term cardiac deaths is less than 0.5% each year in patients with low-risk MPI, in both groups. Cardiac mortality was higher in patients who underwent pharmacological stress tests indicating appropriate assessment of underlying cardiac pathology. Exercise MPI depends on multiple variables to be optimal, while all patients undergoing pharmacological MPI are maximally stressed. Extensive, multi-center, controlled studies are necessary to evaluate the differences in risk stratification of low-risk MPI between exercise and pharmacological stress tests.

Optimizing stress-only myocardial perfusion imaging: a clinical prediction model to improve patient selection.

Stress-only single photon emission computed tomography myocardial perfusion imaging (MPI) offers numerous advantages in terms of improved workflow, cost and radiation reduction but is currently not widely utilized due to challenges in selecting appropriate patients for this technique. Data from 5959 individuals were used to derive (N = 4018) and validate (N = 1941) a binomial logistic regression model to predict normal stress MPI studies (stress total perfusion deficit < 4%, ejection fraction ≥ 50%). Model performance was analyzed using receiver operator characteristic curves. A simplified point-scoring system was developed and its impact on imaging workflow was assessed. Significant predictors of abnormal vs. normal stress MPI included male sex, age > 65 years, cardiomyopathy, congestive heart failure, myocardial infarction, angina, and pharmacological stress. The final model and simplified scoring system were associated with areas under the curve of 0.81 (95% CI 0.79-0.83) and 0.80 (95% CI 0.79-0.82) in the validation group, respectively. Use of the scoring system was estimated to result in a decrease of 56.5% in the number of non-contributory imaging studies acquired with minimal patient rescheduling. A prediction tool derived from simple clinical information can identify candidates for stress-only MPI studies with a beneficial impact on departmental workflow.

DuSFE: Dual-Channel Squeeze-Fusion-Excitation co-attention for cross-modality registration of cardiac SPECT and CT.

Myocardial perfusion imaging (MPI) using single-photon emission computed tomography (SPECT) is widely applied for the diagnosis of cardiovascular diseases. Attenuation maps (μ-maps) derived from computed tomography (CT) are utilized for attenuation correction (AC) to improve the diagnostic accuracy of cardiac SPECT. However, in clinical practice, SPECT and CT scans are acquired sequentially, potentially inducing misregistration between the two images and further producing AC artifacts. Conventional intensity-based registration methods show poor performance in the cross-modality registration of SPECT and CT-derived μ-maps since the two imaging modalities might present totally different intensity patterns. Deep learning has shown great potential in medical imaging registration. However, existing deep learning strategies for medical image registration encoded the input images by simply concatenating the feature maps of different convolutional layers, which might not fully extract or fuse the input information. In addition, deep-learning-based cross-modality registration of cardiac SPECT and CT-derived μ-maps has not been investigated before. In this paper, we propose a novel Dual-Channel Squeeze-Fusion-Excitation (DuSFE) co-attention module for the cross-modality rigid registration of cardiac SPECT and CT-derived μ-maps. DuSFE is designed based on the co-attention mechanism of two cross-connected input data streams. The channel-wise or spatial features of SPECT and μ-maps are jointly encoded, fused, and recalibrated in the DuSFE module. DuSFE can be flexibly embedded at multiple convolutional layers to enable gradual feature fusion in different spatial dimensions. Our studies using clinical patient MPI studies demonstrated that the DuSFE-embedded neural network generated significantly lower registration errors and more accurate AC SPECT images than existing methods. We also showed that the DuSFE-embedded network did not over-correct or degrade the registration performance of motion-free cases. The source code of this work is available at https://github.com/XiongchaoChen/DuSFE_CrossRegistration.

Cardiac fibroblast activation after acute myocardial infarction: pilot study using technetium 99m-iFAP SPECT

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Instituto Nacional de Investigaciones Nucleares (ININ). Background/Introduction Excessive fibrosis and persistent active fibroblasts can lead to increased left ventricular stiffness and, thus, heart failure. Cardiac remodeling is an important factor in the prognosis of patients after an acute myocardial infarction (AMI), and fibroblast activation is mandatory for repair and regeneration of the damage. There's an increasing use of molecular imaging in cardiovascular processes, such as molecules targeting fibroblast activation protein (FAP). FAP inhibitors (iFAP) radiolabeled with 68Ga in PET/CT have demonstrated adequate biodistribution and high uptake by activated fibroblasts in patients with cardiovascular risk factors and after acute myocardial infarction. Unfortunately, PET is not always widely available or cost-effective. Purpose This pilot study evaluates the feasibility of imaging activated fibroblast using 99mTc-iFAP SPECT in patients after AMI and its correlation with myocardial perfusion imaging (MPI), cardiac magnetic resonance (CMR) and invasive coronary angiography (ICA). Methods A prospective study with recent first AMI and non-previous known coronary artery disease patients were included. They underwent 99mTc-MIBI MPI SPECT and 99mTc-iFAP SPECT (including whole-body scan and thorax anterior static image acquired at 20, 60, and 120 min for the iFAP) and CMR/ICA within 14 days (+-2) after AMI. Qualitative and quantitative analysis was performed using a 17 segments model using QPS (Cedars Sinai) to determine the infarct extension from MPI and the correlation with the 99mTc-iFAP uptake pattern. A visual grading scale was established to assess localized tracer uptake and segments belonging to the hypoperfused area of the culprit's vessel. CMR yielded an area of injury with late gadolinium enhancement (LGE) and correlated with MPI studies. Results Five patients with STEMI were included (mean age of 63). Localized uptake of 99mTc-iFAP was observed in all patients with according to the affected coronary territory detected by ICA in 100% of patients (four anterior STEMI, one inferior STEMI). No radiotracer uptake was observed in the non-infarcted territories. Agreement between myocardial iFAP uptake, MIBI myocardial perfusion defect, CMR LGE, and ICA findings are presented in figure 1. An agreement of mismatch in polar maps between iFAP and MPI was performed, obtaining an excellent mismatch pattern in all patients, especially in transmural infarct segments. The best quality image was obtained at 60 minutes. Conclusions We successfully carried out the first pilot study with the patented 99mTc-iFAP molecule with SPECT technique. 99mTc-iFAP is a promising novel biomarker in assessing myocardial injury in sites where PET/CT is unavailable. There is an excellent correlation between iFAP uptake with the perfusion defect, LGE, and invasive anatomical obstruction findings. It is feasible and necessary to extend the inclusion of patients to a larger sample.

Splenic switch-off to assess adequacy of adenosine stress for myocardial perfusion imaging studies

Splenic switch-off to assess adequacy of adenosine stress for myocardial perfusion imaging studies

Advances in the Assessment of Coronary Artery Disease Activity with PET/CT and CTA.

Non-invasive testing plays a pivotal role in the diagnosis, assessment of progression, response to therapy, and risk stratification of coronary artery disease. Although anatomical plaque imaging by computed tomography angiography (CTA) and ischemia detection with myocardial perfusion imaging studies are current standards of care, there is a growing body of evidence that imaging of the processes which drive atherosclerotic plaque progression and rupture has the potential to further enhance risk stratification. In particular, non-invasive imaging of coronary plaque inflammation and active calcification has shown promise in this regard. Positron emission tomography (PET) with newly-adopted radiotracers provides unique insights into atheroma activity acting as a powerful independent predictor of myocardial infarctions. Similarly, by providing a quantitative measure of coronary inflammation, the pericoronary adipose tissue density (PCAT) derived from standard coronary CTA enhances cardiac risk prediction and allows re-stratification over and above current state-of-the-art assessments. In this review, we shall discuss the recent advances in the non-invasive methods of assessment of disease activity by PET and CTA, highlighting how these methods could improve risk stratification and ultimately benefit patients with coronary artery disease.

Computed Tomography Myocardial Perfusion Imaging Study Group: Pioneering Collaborative Efforts to Transform Cardiovascular Imaging in Asia

Computed Tomography Myocardial Perfusion Imaging Study Group: Pioneering Collaborative Efforts to Transform Cardiovascular Imaging in Asia

Abstract 10426: An Interesting Presentation of Angina Due to Left Posterolateral to Right Posterolateral Coronary Artery Fistula

Background: Arterial-to-arterial fistula between right posterolateral and left posterolateral coronary arteries is rare and available literature on it is scarce. Case Presentation: A 60-year-old male with type 2 diabetes mellitus and dyslipidemia presented with shortness of breath and chest tightness. Given his symptoms and poor functional status, myocardial perfusion imaging with regadenoson was performed. The myocardial perfusion imaging study was abnormal with evidence of ischemia in the inferoseptal myocardium. The patient proceeded to the cardiac catheterization lab for selective right and left coronary angiography. Contrast injection revealed non-obstructive coronaries; however, an arterial-to-arterial fistula between the right posterolateral (RPL) branch and left posterolateral (LPL) branch was present (Figure 1A and 1B). Further characterization of the fistula showed the presence of left-to-right and right-to-left filling, indicating a LPL to RPL coronary artery fistula (CAF). The patient was managed conservatively with aspirin, statin, and anti-anginal therapy. Conclusion: There remains a need for diagnostic and therapeutic guidelines to address CAF. Conservative treatment is an option for small CAFs and serves as a potential alternative to catheter-based and surgical closure.

Current status of nuclear cardiology practice in Latin America and the Caribbean, in the era of multimodality cardiac imaging approach: 2022 update.

Cardiovascular diseases (CVDs) are the leading cause of mortality in Latin America and the Caribbean (LAC), with the risk in men being slightly higher than in women. The coronavirus disease 2019 (COVID-19) pandemic caused a significant reduction in the number of cardiac diagnostic procedures globally and in particular in LAC. Nuclear cardiology is available in the region, but there is variability in terms of existing technology, radiopharmaceuticals, and human resources. In the region, there are 2385 single photon emission computed tomography (SPECT) and 315 PET scanners, Argentina and Brazil have the largest number. There is an increasing number of new technologies such as cadmium-zinc-telluride (CZT) cardiac-dedicated gamma cameras, SPECT/computed tomography (CT), and PET/CT. All countries performed myocardial perfusion imaging studies, mainly gated-SPECT; the rest are multi-gated acquisition, mainly for cardiac toxicity; detection of viability; rest gated SPECT in patients with dilated cardiomyopathy, and bone-avid tracer cardiac scintigraphy for transthyretin cardiac amyloidosis diagnosis. Regarding other non-nuclear cardiac imaging modalities, Argentina, Colombia, and Chile have the highest ratio of CT scanners, while Brazil, Argentina, and Chile show the highest ratio of MRI scanners. The development of nuclear cardiology and other advanced imaging modalities is challenged by the high cost of equipment, lack of equipment maintenance and service, insufficient-specific training both for imaging specialists and referring clinicians, and lack of awareness of cardiologists or other referring physicians on the clinical applications of nuclear cardiology. Another important aspect to consider is the necessity of implementing cardiac imaging multimodality training. A joint work of nuclear medicine specialists, radiologists, cardiologists, and clinicians, in general, is mandatory to achieve this goal. National, regional, and international cooperation including support from scientific professional societies such as the American Society of Nuclear Cardiology and Latin American Association of Biology and Nuclear Medicine Societies, cardiological societies, and organizations such as the International Atomic Energy Agency, and Pan American Health Organization, as well as government commitment are key factors in the overall efforts to tackle the burden of cardiovascular diseases in the region.

Automated Analysis vs. Expert Reading in Nuclear Cardiology: Correlations with the Angiographic Score.

Background and Objectives: Myocardial perfusion imaging (MPI) has an important role in the non-invasive investigation of coronary artery disease. The interpretation of MPI studies is mainly based on the visual evaluation of the reconstructed images, while automated quantitation methods may add useful data for each patient. However, little evidence is currently available regarding the actual incremental clinical diagnostic performance of automated MPI analysis. In the present study, we aimed to assess the correlation between automated measurements of Summed Stress Score (SSS), Summed Rest Score (SRS) and Summed Difference Score (SDS), with the corresponding expert reading values, using coronary angiography as the gold standard. Materials and Methods: The study was conducted at the Nuclear Medicine Laboratory of the University Hospital of Larissa, Larissa, Greece, οver an one-year period (January 2019–January 2020). 306 patients, with known or suspected coronary artery disease, were enrolled in the study. Each participant underwent a coronary angiography, prior to or after the scintigraphic study (within a three-month period). Either symptom-limited treadmill test, or pharmacologic testing using adenosine or regadenoson, was performed in all participants, and the scintigraphic studies were carried out using technetium 99m (99mTc) tetrofosmin (one-day stress/rest protocol). Coronary angiographies were scored according to a 4-point scoring system (angiographic score; O: normal study, 1: one-vessel disease, 2: two-vessel disease, 3: three-vessel disease). Moreover, automated measurements of SSS, SRS and SDS were derived by three widely available software packages (Emory Cardiac Toolbox, Myovation, Quantitative Perfusion SPECT). Results: Interclass Correlation Coefficients of SSS, SRS and SDS between expert reading and software packages were moderate to excellent. Visually defined SSS, SRS and SDS were significantly correlated with the corresponding results of all software packages. However, visually defined SSS, SRS and SDS were more strongly correlated with the angiographic score, indicating a better performance of expert reading when compared to automated analysis. Conclusions: Based on our results, visual evaluation continues to have a crucial role for the interpretation of MPI images. Software packages can provide automated measurements of several parameters, particularly contributing to the investigation of cases with ambiguous scintigraphic findings.

Diagnostic accuracy of stress CMR to evaluate chronic coronary syndromes: an updated meta-analysis

Abstract Background Stress cardiovascular magnetic resonance (CMR) imaging is utilised for the evaluation of patients with stable chest pain and intermediate or high pre-test likelihood of coronary artery disease (CAD). Purpose To provide an updated synthesis of diagnostic accuracy of stress CMR imaging for the diagnosis of anatomically and functionally significant CAD in patients with stable chest pain and suspected or known CAD. Methods After prospective registration and approval of the study protocol, we performed a systematic review and meta-analysis of studies published between 2000 through 2021, enrolling ≥100 patients, and reporting on the diagnostic accuracy of stress CMR imaging to diagnose anatomically and functionally significant CAD with invasive coronary angiography (ICA) or ICA and fractional flow reserve (FFR &amp;lt;0.80) as the reference standard. The novel split component synthesis method was used through the SCSmeta function in R. The meta-analysis yielded pooled diagnostic indicators including diagnostic odds ratio (DOR), sensitivity, specificity, positive likelihood ratio (pLR), negative likelihood ratio (nLR) and area under the curve (AUC). Results We identified a total of 32 studies pooling an overall population of 7,678 individuals (mean age 62 years, 70% males, CAD prevalence 52%). Compared with ICA (29 studies, 7,360 patients), stress CMR yielded a pooled DOR of 19.2 (95% CI: 12.5–29.4), a sensitivity of 84% (95% CI: 79–88%), a specificity of 79% (95% CI: 73–84%), a pLR of 3.9 (95% CI: 3.0–5.3), a nLR of 0.2 (95% CI: 0.2–0.3), and an AUC of 0.81 (95% CI: 0.78–0.84) for the detection of anatomically obstructive CAD. Compared with ICA and FFR (8 studies, 1,196 patients), stress CMR yielded a pooled DOR of 26.4 (95% CI: 10.6–65.9), a sensitivity of 81% (95% CI: 68–89), a specificity of 86% (95% CI: 75–93%), a pLR of 5.8 (95% CI: 3.0–11.4), a nLR of 0.2 (95% CI: 0.1–0.4), and an AUC of 0.84 (0.77–0.89) for the detection of functionally obstructive CAD. Higher diagnostic accuracy was observed for 3 Tesla myocardial perfusion imaging studies to detect both anatomically and functionally obstructive CAD, with pooled DORs of 24.3 and 33.2, respectively. Conclusions In patients with stable chest pain and known or suspected CAD, stress CMR imaging yields high diagnostic accuracy to detect both anatomically and functionally obstructive CAD. Stress CMR perfusion imaging at 3 Tesla is to be associated with overall greater diagnostic accuracy. Funding Acknowledgement Type of funding sources: None.