Myocardial Perfusion Imaging Test Research Articles

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.

Asistolia tras la administración de regadenosón en un estudio de imagen de perfusión miocárdica

Asistolia tras la administración de regadenosón en un estudio de imagen de perfusión miocárdica

Impact of myocardial perfusion and coronary calcium on medical management for coronary artery disease.

Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) remains one of the most widely used imaging modalities for the diagnosis and prognostication of coronary artery disease (CAD). Despite the extensive prognostic information provided by MPI, little is known about how this influences the prescription of medical therapy for CAD. We evaluated the relationship between MPI with computed tomography (CT) attenuation correction and prescription of acetylsalicylic acid (ASA) and statins. We performed a retrospective analysis of consecutive patients who underwent SPECT MPI at a single centre between 2015 and 2021. Myocardial perfusion abnormalities and coronary calcium burden were assessed, with attenuation correction imaging 77.8% of patients. Medication prescriptions before and within 180 days after the test were compared. Associations between abnormal perfusion and calcium burden with ASA and statin prescription were assessed using multivariable logistic regression. In total, 9908 patients were included, with a mean age 66.8 ± 11.7 years and 5337 (53.9%) males. The prescription of statins increased more in patients with abnormal perfusion (increase of 19.2 vs. 12.0%, P < 0.001). Similarly, the presence of extensive CAC led to a greater increase in statin prescription compared with no calcium (increase 12.1 vs. 7.8%, P < 0.001). In multivariable analyses, ischaemia and coronary artery calcium were independently associated with ASA and statin prescription. Abnormal MPI testing was associated with significant changes in medical therapy. Both calcium burden and perfusion abnormalities were associated with increased prescriptions of medical therapy for CAD.

Impact of appropriateness in clinical practice: data from a single-centre nuclear cardiology laboratory.

To verify the level of appropriateness of referral to our nuclear cardiology laboratory for stress myocardial perfusion imaging (MPI) and explore the correlation between test appropriateness patterns and ischaemia. In 1870 consecutive patients (mean age 73 ± 12 years; 33% female) undergoing MPI, the level of imaging test appropriateness was evaluated according to the 2023 Appropriate Use Criteria (AUC) and the current European Society of Cardiology (ESC) guidelines for the management of chronic coronary syndromes. The evidence of moderate-to-severe ischaemia (i.e. summed difference score >7) was recorded. According to the AUC criteria, the MPI of 1638 (88%), 130 (7%), and 102 (5%) patients could be classified as 'appropriate', 'inappropriate', and 'uncertain', respectively. Similarly, in 1685 (90%) patients, the referral to MPI was adherent to ESC guidelines, while in 185 (10%), it was not. The majority of appropriate MPI tests showed the presence of moderate-to-severe ischaemia (55%), while only a limited number (10%; P < 0.05) of MPI tests with uncertain clinical appropriateness or clearly inappropriate indications did not. In patients managed adherently to ESC guidelines, invasive coronary angiography more frequently showed obstructive coronary artery disease (CAD) (93 vs. 47%, P < 0.001) and led to coronary revascularization (65 vs. 23%, P < 0.001) compared with patients managed non-adherently. In a single-centre, single-national, single-modality population, the current rate of appropriate MPI tests is high. Appropriate referrals are associated with a higher probability of moderate-to-severe ischaemia and better downstream resource utilization than inappropriate ones.

Second-Line Myocardial Perfusion Imaging to Detect Obstructive Stenosis: Head-to-Head Comparison of CMR and PET

BackgroundGuidelines recommend verification of myocardial ischemia by selective second-line myocardial perfusion imaging (MPI) following a coronary computed tomography angiography (CTA) with suspected obstructive coronary artery disease (CAD). Head-to-head data on the diagnostic performance of different MPI modalities in this setting are sparse. ObjectivesThe authors sought to compare, head-to-head, the diagnostic performance of selective MPI by 3.0-T cardiac magnetic resonance (CMR) and 82rubidium positron emission tomography (RbPET) in patients with suspected obstructive stenosis at coronary CTA using invasive coronary angiography (ICA) with fractional flow reserve (FFR) as reference. MethodsConsecutive patients (n = 1,732, mean age: 59.1 ± 9.5 years, 57.2% men) referred for coronary CTA with symptoms suggestive of obstructive CAD were included. Patients with suspected stenosis were referred for both CMR and RbPET and subsequently ICA. Obstructive CAD was defined as FFR ≤0.80 or >90% diameter stenosis by visual assessment. ResultsIn total, 445 patients had suspected stenosis on coronary CTA. Of these, 372 patients completed both CMR, RbPET and subsequent ICA with FFR. Hemodynamically obstructive CAD was identified in 164 of 372 (44.1%) patients. Sensitivities for CMR and RbPET were 59% (95% CI: 51%-67%) and 64% (95% CI: 56%-71%); P = 0.21, respectively, and specificities 84% (95% CI: 78%-89%) and 89% (95% CI: 84%-93%]); P = 0.08, respectively. Overall accuracy was higher for RbPET compared with CMR (73% vs 78%; P = 0.03). ConclusionsIn patients with suspected obstructive stenosis at coronary CTA, CMR, and RbPET show similar and moderate sensitivities but high specificities compared with ICA with FFR. This patient group represents a diagnostic challenge with frequent mismatch between advanced MPI tests and invasive measurements. (Danish Study of Non-Invasive Diagnostic Testing in Coronary Artery Disease 2 [Dan-NICAD 2]; NCT03481712)

The Utility of Coronary CT Angiography in Evaluating Symptomatic Patients with Positive MPI Referred for Coronary Angiography: A Single-center Experience

Background: Patients with suspected or known coronary artery disease (CAD) can be challenging to evaluate. Our study aims to assess the efficacy and utility of coronary computed tomographic angiography (CCTA) as a diagnostic method in patients with abnormal myocardial perfusion imaging (MPI) who were initially referred for Invasive Coronary Angiography (ICA). Methods: This is a single-center retrospective descriptive study. We evaluated 210 patients who underwent CCTA instead of ICA. Data of these patients were documented and analyzed accordingly. Results: Of the 210 patients who underwent CCTA, the procedure was found to be diagnostic in 172 (81.9%) patients. Of these 172 patients, 152 (88.4%) had normal coronaries or minor CAD, and 20 (11.6%) had significant disease requiring subsequent ICA. In 38 (18.1%) patients out of the total cohort, the CCTA was not diagnostic or could not be performed due to technical difficulties, requiring either ICA or another ischemia evaluation diagnostic modality. Conclusion: CCTA is a viable and reliable diagnostic tool for evaluating patients with suspected CAD referred for ICA following an abnormal MPI test. It is recommended as an initial test to rule out significant coronary stenosis and as it can avoid unnecessary ICA.

Impact of the COVID-19 pandemic on the use of myocardial perfusion imaging for the assessment of coronary artery disease: a Brazilian experience

The COVID-19 pandemic and the lockdown period caused deep effects on healthcare, including cardiac imaging, with a possible negative influence on the evaluation of coronary artery disease (CAD). This study aimed to evaluate the impact of the COVID-19 pandemic on myocardial perfusion imaging (MPI) performance and results in a Brazilian, Nuclear Cardiology laboratory. Patients with or without known CAD who underwent MPI in three 30-day periods (pre-pandemic [mid-February to mid-March 2020], lockdown [April-May 2020], and post-lockdown [August 2020]) were studied. MPI volumes dropped from 204 pre-lockdown to 43 during lockdown (78.9% reduction), rising to 248 after lockdown. The use of pharmacologic stress increased from 36.3% to 53.5% during lockdown. The frequency of abnormal MPI tests did not differ significantly among the time intervals, as well as the frequency of myocardial ischemia. Younger age, ≥1 cardiac risk factor, and known CAD were independent predictors of the performance of MPI during the lockdown period. In conclusion, a large reduction of MPI performance occurred during lockdown, when imaging was sought mainly by younger patients, with cardiac risk factors or known CAD. There was no significant difference in the frequency of abnormal MPI or of myocardial ischemia among the periods, which might indicate missed cases of CAD during lockdown; therefore, the consequences of cardiac testing reductions should be continuously assessed.

Exercise capacity as a predictor of coronary microvascular dysfunction

Abstract Introduction Exercise capacity (EC) is an important prognostic test in patients with coronary artery disease (CAD). Positron-emission tomography (PET) is an important risk-stratifying tool to tailor management of patients with coronary artery disease. Purpose We aimed to assess EC in predicting positron emission tomography (PET) myocardial perfusion imaging (MPI) derived coronary flow reserve (CFR). Methods Consecutive patients who had clinically indicated PET MPI and EC were included. EC was defined based on peak metabolic equivalents (METS) achieved during exercise stress test. Myocardial blood flow (MBF) in ml/gm/min was obtained from dynamic PET MPI images at rest and peak hyperemia. The coronary flow reserve (CFR) was calculated as the ratio of stress to rest MBF of the left ventricle. Results The study population consisted of 511 patients who underwent PET MPI and EC testing (mean age 56 (±11), 71% male). Cardiovascular risk factors were prevalent (75% hypertensive, 82% dyslipidemic, 43% diabetics, 27% known CAD). Peak METS &amp;gt;6 was achieved in 81% of patients, and the CFR &amp;lt;2 was present in 27%. In multivariable logistic regression models adjusted for age, sex, cardiovascular risk factors (hypertension, diabetes, dyslipidemia) and medication use (angiotensin converting enzyme inhibitor/angiotensin receptor blocker, statins, beta-blockers), patients with peak METS &amp;gt;6 had a statistically significant lower odds of microvascular dysfunction (CFR &amp;lt;2: OR 0.43, 95% CI 0.26–0.71, p=0.001). Assessment of discrimination showed the model with CFR &amp;lt;2 had an incremental improvement of Harrell's C statistic over clinical variables (0.65 vs 0.69, p=0.02). Conclusion Our findings showed exercise capacity was a good predictor of CFR and microvascular coronary health over and above clinical variables. Further studies are needed to assess the prognostic interplay between EC and CFR. Funding Acknowledgement Type of funding sources: None.

Evaluating the use of pharmacological stress agents during single-photon emission computed tomography myocardial perfusion imaging tests after inadequate exercise stress test

BackgroundPast clinical trial findings suggest that the availability of regadenoson in a nuclear imaging center may affect real-world center practices related to the transition of patients from an inadequate exercise stress test (EST) to a pharmacological stress agent (PSA). Methods and ResultsThis was a cross-sectional study using one-on-one telephone interviews with nuclear imaging center staff to facilitate survey development, followed by an online survey to evaluate patterns and processes around use of PSAs during single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) in patients with inadequate ESTs. Of the 50 participants, 35 (70%) used only regadenoson, 3 (6%) only adenosine, 3 (6%) regadenoson and adenosine, 7 (14%) regadenoson and dipyridamole, and 2 (4%) all 3 agents for converting patients from an inadequate EST to a PSA. Nearly all centers (94%) used protocols to guide conversions. Of 12 centers using > 1 PSA, 11 reported regadenoson to be the most preferred PSA. Total staff time required from PSA transition to post-test monitoring was shortest for regadenoson. ConclusionsCompared to adenosine and dipyridamole, regadenoson is preferred by nuclear imaging center staff and associated with operational efficiencies after inadequate EST in real-world practice SPECT-MPI.

Automated abstraction of myocardial perfusion imaging reports using natural language processing

BackgroundFindings and interpretations of myocardial perfusion imaging (MPI) studies are documented in free-text MPI reports. MPI results are essential for research, but manual review is prohibitively time consuming. This study aimed to develop and validate an automated method to abstract MPI reports. MethodsWe developed a natural language processing (NLP) algorithm to abstract MPI reports. Randomly selected reports were double-blindly reviewed by two cardiologists to validate the NLP algorithm. Secondary analyses were performed to describe patient outcomes based on abstracted-MPI results on 16,957 MPI tests from adult patients evaluated for suspected ACS. ResultsThe NLP algorithm achieved high sensitivity (96.7%) and specificity (98.9%) on the MPI categorical results and had a similar degree of agreement compared to the physician reviewers. Patients with abnormal MPI results had higher rates of 30-day acute myocardial infarction or death compared to patients with normal results. We identified issues related to the quality of the reports that not only affect communication with referring physicians but also challenges for automated abstraction. ConclusionNLP is an accurate and efficient strategy to abstract results from the free-text MPI reports. Our findings will facilitate future research to understand the benefits of MPI studies but requires validation in other settings.

Normal and Near Normal Myocardial Perfusion Imaging Data Analysis: Two-Year Major Adverse Cardiac Event

Myocardial perfusion imaging (MPI) is the method most commonly used to assess patients with suspected coronary artery disease for the presence of myocardial ischemia and risk of subsequent adverse cardiac events. Studies are limited on the incidence of major adverse cardiac event (MACE) in patients with normal MPI results. The aim of this study was to investigate the incidence and risk factors of MACE in patients with normal or near-normal MPI results. In this single-center retrospective chart review study, patients who had received MPI tests at a nuclear medicine department of a medical center in 2017 were consecutively enrolled. All of the participants in this study were patients with normal or near-normal MPI results, and were followed for two years to assess the incidence of MACE (death, hospitalized for percutaneous coronary intervention; CABG, heart failure and stroke). Participants with or without MACE were compared to determine whether demographic, comorbidity, and MPI data were significant risk factors. Of the 1,629 participants (age = 70.4 ± 11.3 years, 49.4% male) enrolled, 387 (23.8%) were classified into the normal MPI group and 1,242 (76.2%) were classified into the near-normal MPI group. Notably, 61 participants (15.8%) in the normal MPI group and 206 (16.6%) in the near-normal MPI group experienced MACE events during the two-year follow-up. The risk factors of MACE identified in this study included being older in age, being male, and having poor myocardial perfusion parameters (i.e., ejection fraction) during MPI. Over the two-year study period, 15.8% of the participants with normal MPI results and 16.6% of those with near-normal MPI results experienced major adverse cardiac events. Thus, it is critical to inform patients regarding the potential risk of MACE risk and to educate them on how to mitigate this risk by actively managing their hyperlipidemia level and left ventricular ejection fraction.

Variation in additional testing and patient outcomes after stress echocardiography or myocardial perfusion imaging, according to accreditation status of testing site

BackgroundThe purpose of the present study was to determine whether patients receiving a stress echocardiogram or myocardial perfusion imaging (MPI) test have differences in subsequent testing and outcomes according to accreditation status of the original testing facility. Methods and resultsAn all-payer claims dataset from Maine Health Data Organization from 2012 to 2014 was utilized to define two cohorts defined by an initial stress echocardiogram or MPI test. The accreditation status (Intersocietal Accreditation Commission (IAC), American College of Radiology (ACR) or none) of the facility performing the index test was known. Descriptive statistics and multivariate regression were used to examine differences in subsequent diagnostic testing and cardiac outcomes.We observed 4603 index stress echocardiograms and 8449 MPI tests. Multivariate models showed higher odds of subsequent MPI testing and hospitalization for angina if the index test was performed at a non-accredited facility in both the stress echocardiogram cohort and the MPI cohort. We also observed higher odds of percutaneous coronary interventions (PCI) performed (OR 1.68, 95% CI 1.13-2.50), if the initial MPI test was done in a non-accredited facility. ConclusionCardiac testing completed in non-accredited facilities were associated with higher odds of subsequent MPI testing, hospitalization for angina, and PCI.

Stress myocardial perfusion imaging in patients presenting with syncope: Comparison of PET vs. SPECT

BackgroundThe role of myocardial perfusion imaging (MPI) in patients with suspected coronary artery disease (CAD) presenting with syncope is controversial. We aimed to determine diagnostic yield of MPI for evaluation of syncope in patients without known CAD, as a function of pre-test patient risk and test modality (PET vs SPECT). MethodsBetween 1/2010 and 12/2016, 1324 consecutive patients presenting with syncope without known CAD underwent MPI with PET (n = 640) or SPECT (n = 684). Rates of abnormal MPI (summed difference score (SDS) > 2 or left ventricular ejection fraction (LVEF) reserve ≤ 0 for PET and SDS > 2 or post-stress LVEF ≤ 45% for SPECT) were determined among patients stratified by pre-test risk. In patients who were referred for coronary angiography, diagnostic yield of obstructive CAD was calculated in the overall cohort as well as in a propensity-matched cohort compared to patients without syncope. ResultsAbnormal MPI was noted in 36.5% (201/551) of patients who had PET compared with 13.0% (87/671) who had SPECT (P < 0.001), which is largely related to higher comorbidity burden and greater pre-test CAD risk in the PET population. Among patients who had an abnormal MPI, 8.5% (47/551) with PET and 0.7% (5/671) with SPECT were found to have obstructive CAD if referred for coronary angiography. Patients at intermediate-high pre-test risk had a higher proportion of abnormal MPIs and obstructive CAD as compared to those at low risk in both the PET and SPECT cohorts. The rate of abnormal testing and diagnostic yield of PET MPI was similar and proportionate to pre-test likelihood among matched patients with and without syncope. ConclusionsAmong patients referred for PET MPI with syncope at an intermediate-high pre-test CAD risk, 1 in 3 had an abnormal MPI and 1 in 10 had obstructive CAD. The value of MPI was related to pre-test risk as opposed to the presence of syncope, and MPI testing with PET or SPECT in the low-risk population was low value.

Prognostic value of myocardial perfusion imaging after first-line coronary computed tomography angiography: A multi-center cohort study

PurposeFurther diagnostic testing may be required after a coronary computed tomography angiography (CTA) showing suspected coronary stenosis. Whether myocardial perfusion imaging (MPI) provides further prognostic information post-CTA remains debated. We evaluated the prognosis for patients completing CTA stratified for post-CTA diagnostic work-up using real-world data. MethodsWe identified all patients in our uptake area with angina symptoms undergoing first-time CTA over a 10-year period. Follow-up time was a median of 3.7 years [1.9–5.8]. The primary endpoint was a composite of myocardial infarction or death. The secondary endpoint was late revascularization. ResultsDuring the study period 53,351 patients underwent CTA. Of these, 24% were referred for further down-stream testing, 3,547 (7%) to MPI and 9,135 (17%) to invasive coronary angiography (ICA). The primary and secondary endpoints occurred in 2,026 (3.8%) and 954 (1.8%) patients. Patient-characteristic-adjusted hazard ratios for the primary and secondary endpoint using patients with a normal CTA as reference were 1.37 (1.21–1.55) and 2.50 (1.93–3.23) for patient treated medically, 1.68 (1.39–2.03) and 6.13 (4.58–8.21) for patients referred to MPI and 1.94 (1.69–2.23) and 9.18 (7.16–11.78) for patients referred for ICA, respectively. Adjusted analysis with stratification for disease severity at CTA showed similar hazard ratios for patients treated medically after CTA and patients referred for MPI and treated medically after the MPI. ConclusionIn patients completing coronary CTA, second-line MPI testing seems to identify patients at low risk of future events. MPI seems to have the potential to act as gatekeeper for ICA after coronary CTA.

Development and Piloting of a Patient-Centered Report Design for Stress Myocardial Perfusion Imaging Results

The management of coronary disease epitomizes the call to better engage patients in shared medical decision-making. Myocardial perfusion imaging (MPI) is the foundation of diagnosis, risk stratification, and subsequent therapy; however, MPI reports are currently interpretable by specialists but not patients. To design and test a patient-centered report for stress MPI test results. This qualitative study of outpatients who underwent an MPI stress test and clinicians used a mixed methods approach. Phase 1 (December 2018 to July 2019) used qualitative methods to design a patient-centered reporting tool, with 5 focus groups with 36 patients and 2 focus groups with 27 clinicians. Phase 2 (June to September 2019) consisted of pilot testing the reporting tool with feedback from a structured survey given to patients who received MPI reports before and after implementing the tool. Key themes around patient experiences with the current MPI reporting and their desire for a more useful report were identified, which led to a sample reporting tool after serial iterations with feedback. Differences in patient knowledge and engagement were assessed between patients before and after implementation of the new reporting tool using χ2 tests. From patient focus groups (26 patients; mean [SD] age, 66.3 [9.6] years, 9 [35%] women), 3 themes on the inadequacies of current MPI reporting were identified: (1) inconsistent delivery of results, (2) use of medical jargon, and (3) unclear posttest course. We identified 5 themes for a more patient-centered MPI report: desire for written information, discussion of the report with medical personnel, presentation of results in simple language with use of visual graphics, comparisons with normal results, and personalized risk estimates. In a pilot survey with 123 patients split into a pre-implementation group (69 patients; mean [SD] age, 68.2 [8.5] years; 27 [51%] women) and a postimplementation group (54 patients; mean [SD] age, 66.4 [8.7] years; 30 [56%] women), the patient-centered report led to more patients reading the entire report (45 [83%] vs 46 [67%]; P = .04) and improved knowledge of future risk of cardiac events (41 [76%] vs 20 [29%]; P < .001). There was also a numerically higher percentage of patients who found the report easy to read (45 [83%] vs 44 [68%]; P = .05) and understand (42 [78%] vs 43 [66%]; P = .16), although these results were not statistically significant. This study identified key elements of a patient-centered report design for stress MPI test results, which improved patient engagement and knowledge. These preliminary data support further implementation and study of a more patient-centered MPI report.

Routine clinical use of 15O-water cardiac PET: Initial experience with a novel automated solution

Abstract Funding Acknowledgements Type of funding sources: None. Introduction While considered the gold standard for cardiac perfusion imaging and myocardial blood flow quantitation, the use of 15O-water has been largely restricted to research purposes. The practical hurdles associated with the ultra-short half-life of the tracer and the lack of dedicated software have hampered the routine clinical use of 15O-water and novel solutions have been sought to obviate the issues limiting its use. An innovative bedside 15O-water generator designed for simple push button operation and high patient through-put has been developed and recently installed at our institution and utilized clinically under a magistral exception. The system also includes an infusion device and a dedicated display and analysis software. We report the initial experience utilizing such solution for routine clinical use of 15O-water. Methods The first routine human myocardial perfusion imaging tests with PET 15O-water were conducted at our institution in December 2020. The 15O-water was produced and infused using the bed-side water generator. The activity per scan was 400 MBq in 20-35 mL of saline infused at a speed of 1-2 mL/s. Each exam consisted of a low-dose CT followed by a 4 min rest dynamic PET scan and, finally, a 4 min stress dynamic PET scan. Pharmacological stress was induced using a 6 min infusion of adenosine (0.14 mg/kg/min) starting 2 min prior to the stress PET scan. The exam time (time from initiation of the low dose CT to the end of the stress PET scan) was monitored. Images were analyzed using the dedicated software. Results Since its implementation on December 7, 2020 and as of February 23, 2021, all patients referred to the hospital for cardiac perfusion imaging have been studied with this approach. Over this period of time, a total of 295 patients have been imaged with an average of 6 patients per day (a total of 50 scan days, 3-8 patients per day). The median total exam time was 22 min (85% of the exams were within 25 min and 95% below 30 min). Conclusion Routine clinical use of 15O-water PET has been practically implemented utilizing a novel bedside generator and infusion solution. The system has proven to be reliable and efficient. This initial experience suggests that a very high patient throughput is achievable with improved resource utilization. The expected high diagnostic accuracy of the test is being evaluated with the dedicated imaging software.

Anomalous origin of coronary artery from the opposite aortic sinus of Valsalva-a single center experience with a therapeutic conundrum

Background: Coronary artery anomalies are rare congenital abnormalities, most often found incidentally on conventional coronary angiography and CT angiography (CTA). CTA better delineates the origin and course of anomalous coronaries. Anomalous origin of coronary artery from the opposite aortic sinus of Valsalva (ACAOS) has a prevalence of 1% with a very few having an interarterial (malignant) course. There is limited literature, especially in the Indian population, dealing with this topic.Methods: In this retrospective observational study, angiographic data of 8500 consecutive patients from June 2011 to December 2019 at a large tertiary care hospital in western India was analyzed. Patients diagnosed with ACAOS underwent CTA for delineation of the exact anatomy. Those with a non-malignant course with evidence of ischemia clinically or on stress myocardial perfusion imaging (MPI), underwent PCI. Others with a non-malignant course were medically managed. Patients with malignant (interarterial) course were revascularized by coronary artery bypass graft (CABG) surgery in case of LCA involvement or positive MPI test. Asymptomatic patients with negative MPI were managed medically. Clinical follow-up over 12 months of patients undergoing PCI and those with a malignant course showed no major adverse cardiovascular events (MACE).Results: Of the 8500 patients studied, 74 (0.87%) had ACAOS. Of these, 51 (68.9%) patients had anomalous origin of right coronary artery (RCA) from the left aortic sinus, 21 (28.4%) had anomalous origin of the circumflex artery (Cx) from the right aortic sinus and two patients (2.7%) had an anomalous origin of the left main coronary artery (LCA) from the right aortic sinus. Interarterial course was found in five (6.7%) patients. Of these, four patients underwent CABG-one asymptomatic patient with LCA from right aortic sinus and three with positive MPI in anomalous RCA. All five patients with malignant course and ten patients who underwent PCI were free of MACE over 12 months’ clinical follow up.Conclusions: ACAOS is a rare anomaly and if interarterial course is excluded, then PCI is feasible in selected cases with significant stenosis. Patients with malignant course with inducible ischemia or LCA involvement should undergo surgical revascularisation.

Coronary microvascular dysfunction: An important interpretation on the clinical significance of transient ischemic dilation of the left ventricle on myocardial perfusion imaging.

To further investigate the clinical significance of transient ischemic dilation (TID) on myocardial perfusion imaging (MPI) by analyzing the effect of anisodamine hydrobromide (a drug that can effectively ameliorate microcirculation) on the patients with isolated TID and the findings of previous literatures. Total 107 patients with isolated TID (TID value≥1.11) were randomly divided into group A (n = 36; intravenous administration of anisodamine hydrobromide), group N (n = 36; intravenous administration of isosorbide dinitrate), and group C (n = 35; intravenous administration of normal saline). MPI and treadmill exercise test (TET) were performed again after 14-day course of intervention. Pre- and post-intervention frequencies of symptom were recorded. In group A, after intervention of anisodamine hydrobromide, the summed stress score (SSS) and TID value on MPI significantly decreased than those before intervention (P < 0.001), the durations of exercise (DEs) and metabolic equivalents (METs) in TET notably ascended (P < 0.001), as well as the symptom remarkably improved. In group N and group C, there were no significant differences in SSS, TID value, DEs, METs, and frequencies of symptom between pre- and post-intervention (P > 0.05). No significant improvement of symptoms in group N before and after treatment. TID with perfusion defect may usually predict a possibility of severe and extensive coronary artery disease (CAD). An isolated TID should be considered as a likelihood of coronary microvascular dysfunction (CMD). TET and coronary CT angiography (cCTA) are extremely helpful for the antidiastole on CAD and CMD. The administration of anisodamine hydrobromide might be an optional treatment for the patients with isolated TID.

Abstract 340: Evaluating the Use of Pharmacological Stress Agents During Single-photon Emission Computed Tomography Myocardial Perfusion Imaging Tests After Inadequate Exercise Stress Test

Objective: To evaluate how pharmacological stress agents (PSAs) are used during single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) for patients (pts) with an inadequate exercise stress test (EST). Methods: This was a cross-sectional study. One-on-one telephone interviews with nuclear imaging center staff were used to develop an online survey, which was administered to evaluate patterns/processes around PSA use during SPECT-MPI in pts with inadequate EST. Eligible survey participants included nuclear technicians, nurses, physicians, and imaging center managers/directors with sufficient familiarity with SPECT-MPI/use of PSAs. Primary endpoint measures included gaining insights on how imaging centers convert to PSAs after inadequate EST and associated resource use. Results: Of 50 participating centers, 35 (70%) used only regadenoson (REG), 3 (6%) only adenosine (ADN), 3 (6%) REG and ADN, 7 (14%) REG and dipyridamole (DP), and 2 (4%) all 3 agents for converting pts after inadequate EST. Most centers (94%) used protocols to guide conversions. Post-test monitoring, including monitoring of pt performance and managing adverse reactions after completion of SPECT-MPI following PSA, was not conducted by 66%, 38%, and 56% of centers using REG, ADN, and DP, respectively. Same-day conversion occurred for 92%, 89%, and 98% of pts for REG, ADN, DP, respectively; the mean (standard deviation) number of pts converted in the past 30 days were 29.6 (44.1), 9.3 (9.9), and 1.9 (1.8), respectively. After an inadequate EST, average pt wait times to receiving REG, ADN, or DP were 4.9, 12.4 or 17.4 min, respectively; among centers using REG, 60% administered the PSA within a mean of 3 min, compared to 11% (1 center) using DP and no centers using ADN. Nearly 100%, 38%, and 11% of REG, ADN, and DP centers, respectively, reported that PSA administration was “not at all complex.” Of the centers using &gt;1 PSA, 92% found REG to be the most preferred PSA (overall) among staff. Total staff time (aggregating time for multiple staff members who may have worked concurrently at each step) required from PSA transition to post-test monitoring was shortest for REG ( Table ). Conclusions: Imaging center staff prefer REG and its use is associated with operational efficiencies during SPECT-MPI after inadequate EST.

SEGMENTATION OF 2D MYOCARDIAL PERFUSION SPECT IMAGES

Myocardial perfusion imaging (MPI) is a widely used and non-invasive diagnostic method for the detection of patients with suspected or known ischemic heart disease. MPI test is commonly realized by single photon emission computed tomography (SPECT). This test provides several images illustrating the function of the heart muscle. Appropriate segmentation of those images play a crucial role for the diagnosis of heart disease. Consequently, this paper proposes a segmentation method for 2D myocardial perfusion SPECT images acquired in both stress and rest cases. In this way, an expert can make visual assessment of the changes in the stress and rest images easily. Hence, possible heart diseases would be identified based on those changes without a need of using polar maps or reference databases.