Emission Tomography Myocardial Perfusion Imaging Research Articles

PET imaging in heart failure: the role of new tracers.

Positron emission tomography (PET) myocardial perfusion imaging is being increasingly used for the detection of coronary artery disease. In the presence of significant left ventricle dysfunction, the assessment of myocardial ischemia and viability by PET plays a role in the identification of patients who may benefit from revascularization. In addition to these, new PET tracers may play a role in the assessment of underlying pathophysiology and therapeutic options in heart failure. Studies have shown the ability of sympathetic innervation imaging to assess the risk of cardiac death, arrhythmia, and disease progression. New tracers have been tested for the assessment of angiogenesis and other mechanisms involved in myocardial repair after infarction. Furthermore, new tracers may play a role in detection of inflammatory cardiomyopathies, especially cardiac sarcoidosis, which is a diagnostic challenge for current methods. In addition to the assessment of prognosis and etiology, the value of new PET tracers will depend on their ability to guide selection of therapies and incorporation into clinical management algorithms in heart failure. This review describes recent advances in applications of cardiac PET in heart failure with emphasis on potential roles of new tracers.

Prognostic value of normal positron emission tomography myocardial perfusion imaging in patients with known or suspected coronary artery disease: a meta-analysis.

Several studies have confirmed high diagnostic performance of positron emission tomography (PET) myocardial perfusion imaging (MPI) in patients with known or suspected coronary artery disease. However, whether the superior diagnostic accuracy could translate into improved mortality outcomes remains unknown. The aim of this study was to define the prognostic value of normal PET MPI. PubMed and EMBASE were searched to identify related studies up to June 2016. All studies using PET MPI to evaluate subjects with known or suspected coronary artery disease and providing absolute number of patients with a negative test and primary data on clinical outcomes with a follow-up time ≥3 months were included for analysis. The search yielded 11 studies comprising 20,471 patients for final analysis. The negative-predictive value (NPV) for cardiac death, all-cause death and major adverse cardiovascular events (MACE) were 98.80% [95% confidence interval (CI), 97.64%-99.39%], 94.89% (95% CI: 92.99-96.30%) and 90.26% (95% CI: 78.01-96.03%), over 36.9 months of follow-up for cardiac death, over 26.8 months for all-cause death and 35.7 months for MACE. The corresponding annualized event rates were 0.39%, 2.29% and 3.27%, respectively. In subgroup analyses of different imaging analysis methods for PET MPI, studies using perfusion abnormity had a similar NPV as compared with those using coronary flow reserve (98.46% vs 98.86%, p-value = NS), with a corresponding annualized event rate after negative tests (equal to 1 - NPV) as 0.45% and 0.42%, respectively. Normal PET has a high NPV for cardiac death, MACE and all-cause mortality. Different indexes used for PET imaging analysis have a comparable prognostic value. Advances in knowledge: A normal PET MPI conferred a very low risk of cardiac death of 0.39% per year, which is close to that of a normal aged-matched population.

Association Between High-Sensitivity Cardiac Troponin Levels and Myocardial Ischemia During Mental Stress and Conventional Stress

ObjectivesThis study sought to investigate whether patients with mental stress–induced myocardial ischemia will have high resting and post–mental stress high-sensitivity cardiac troponin I (hs-cTnI). BackgroundHs-cTnI is a marker of myocardial necrosis, and its elevated levels are associated with adverse outcomes. Hs-cTnI levels may increase with exercise in patients with coronary artery disease. Mental stress–induced myocardial ischemia is also linked to adverse outcomes. MethodsIn this study, 587 patients with stable coronary artery disease underwent technetium Tc 99m sestamibi–single-photon emission tomography myocardial perfusion imaging during mental stress testing using a public speaking task and during conventional (pharmacological/exercise) stress testing as a control condition. Ischemia was defined as new/worsening impairment in myocardial perfusion using a 17-segment model. ResultsThe median hs-cTnI resting level was 4.3 (interquartile range [IQR]: 2.9 to 7.3) pg/ml. Overall, 16% and 34.8% of patients developed myocardial ischemia during mental and conventional stress, respectively. Compared with those without ischemia, median resting hs-cTnI levels were higher in patients who developed ischemia either during mental stress (5.9 [IQR: 3.9 to 8.3] pg/ml vs. 4.1 [IQR: 2.7 to 7.0] pg/ml; p < 0.001) or during conventional stress (5.4 [IQR: 3.9 to 9.3] pg/ml vs. 3.9 [IQR: 2.5 to 6.5] pg/ml; p < 0.001). Patients with high hs-cTnI (cutoff of 4.6 pg/ml for men and 3.9 pg/ml for women) had greater odds of developing mental (odds ratio [OR]: 2.4; 95% confidence interval [CI]: 1.5 to 3.9; p < 0.001) and conventional (OR: 2.4; 95% CI: 1.7 to 3.4; p < 0.001) stress-induced ischemia. Although there was a significant increase in 45-min post–treadmill exercise hs-cTnI levels in those who developed ischemia, there was no significant increase after mental or pharmacological stress test. ConclusionsIn patients with coronary artery disease, myocardial ischemia during either mental stress or conventional stress is associated with higher resting levels of hs-cTnI. This suggests that hs-cTnI elevation is an indicator of chronic ischemic burden experienced during everyday life. Whether elevated hs-cTnI levels are an indicator of adverse prognosis beyond inducible ischemia or whether it is amenable to intervention requires further investigation.

Effect of methoxy group position on biological properties of 18F–labeled benzyl triphenylphosphonium cations

Introduction18F–labeled phosphonium cations targeting mitochondrial membrane potential would be promising for positron emission tomography (PET) myocardial perfusion imaging (MPI). The purpose of this study was to examine the influence of additional methoxy group and its different positions on myocardium uptake and pharmacokinetics properties of 18F–labeled benzyl triphenylphosphonium cations. MethodIn this study, three novel 18F–labeled phosphonium cations, [18F]4-(fluoromethyl)benzyltris(4-methoxyphenyl) phosphonium cation (1b), [18F]4-(fluoromethyl)benzyltris(2-methoxyphenyl) phosphonium cation (2b) and [18F]4-(fluoromethyl)benzyltris(3-methoxyphenyl) phosphonium cation (3b), were efficiently prepared by a One-Pot method starting from the substitution of non-carried-added fluoride-18. Radiotracers were purified by HPLC. Physicochemical properties, in vitro cell uptake assay, in vivo mice biodistribution and rat micro-PET imaging were investigated. ResultsResults suggested that the position of methoxy group exhibited significant effect on the biological properties of 18F–labeled benzyl triphenylphosphonium cations. The addition of methoxy group on orth- or meta-position of the radiotracers accelerated the radioactivity clearance from liver. The para-radiotracer had the highest uptake in the heart and other non-targeting organs. According to the biodistribution data, 2b (ortho-) displayed the fastest liver clearance and highest heart-to-background ratios. And its rat micro-PET images at 60min post-injection revealed a good visualization of heart and favorable heart-to-background contrast. Nevertheless, 2b exhibited a lower initial liver uptake and quicker liver clearance compared with 99mTc-sestamibi. ConclusionThe ortho- compound (2b) displayed the most favorable biological properties as a potential MPI agent to acquire high contrast images early after injection.

Fused cardiac hybrid imaging with coronary computed tomography angiography and positron emission tomography in patients with complex coronary artery anomalies.

To provide data on the value of fused cardiac hybrid imaging with coronary computed tomography angiography (CCTA) and positron emission tomography myocardial perfusion imaging (PET-MPI) in patients with complex coronary artery anomalies (CCAA). This is a retrospective, single-center study. Seven consecutive patients with CCAA (mean 57±7y, 86% were male) who underwent clinically indicated hybrid CCTA/PET-MPI between 2005 and 2015 in our clinic were included. The findings from both modalities and fused cardiac hybrid imaging were evaluated in these patients. Out of the seven patients with CCAA, two patients had Bland-White-Garland anomaly, two patients showed a coronary artery fistula, two patients showed a "single right," and one patient showed a "single left" coronary artery. Semiquantitative fused hybrid CCTA/PET-MPI depicted inferolateral scar matching the territory of a nonanomalous vessel with significant concomitant coronary artery disease (CAD) in one patient only. In contrast, analysis of quantitative myocardial blood flow (MBF) as assessed by fused hybrid CCTA/PET-MPI revealed abnormally reduced flow capacities in the territories subtended by the anomalous vessels in 4 patients. In this case series of middle-aged patients with CCAA, perfusion defects as assessed by semiquantitative PET-MPI were rare and attributable to concomitant CAD rather than to the anomalous vessel itself. By contrast, impaired MBF as assessed by quantitative hybrid CCTA/PET-MPI was revealed in the majority of patients in the vessel territories subtended by the anomalous coronary artery itself. Fused hybrid CCTA/PET-MPI incorporating information on morphology and on semiquantitative and quantitative myocardial perfusions may provide added value for the management of patients with CCAA.

Synthesis and Evaluation of [(18) F]-Ammonium BODIPY Dyes as Potential Positron Emission Tomography Agents for Myocardial Perfusion Imaging.

Recently, we demonstrated the potential of a [(18) F]-trimethylammonium BODIPY dye for cardiac imaging. This is the first example of the use of the [(18) F]-ammonium BODIPY dye for positron emission tomography (PET) myocardial perfusion imaging (MPI). In this report, we extend our study to other ammonium BODIPY dyes with different nitrogen substituents. These novel ammonium BODIPY dyes were successfully prepared and radiolabeled by the SnCl4 -assisted (18) F-(19) F isotopic exchange method. The microPET results and the biodistribution data reveal that nitrogen substituent changes have a significant effect on the in vivo and pharmacological properties of the tracers. Of the novel [(18) F]-ammonium BODIPY dyes prepared in this work, the [(18) F]-dimethylethylammonium BODIPY is superior in terms of myocardium uptake and PET imaging contrast. These results support our hypothesis that the ammonium BODIPY dyes have a great potential for use as PET/optical dual-modality MPI probes.

Integration of Quantitative Positron Emission Tomography Absolute Myocardial Blood Flow Measurements in the Clinical Management of Coronary Artery Disease.

In the >40 years since planar myocardial imaging with(43)K-potassium was introduced into clinical research and management of patients with coronary artery disease (CAD), diagnosis and treatment have undergone profound scientific and technological changes. One such innovation is the current state-of-the-art hardware and software for positron emission tomography myocardial perfusion imaging, which has advanced it from a strictly research-oriented modality to a clinically valuable tool. This review traces the evolving role of quantitative positron emission tomography measurements of myocardial blood flow in the evaluation and management of patients with CAD. It presents methodology, currently or soon to be available, that offers a paradigm shift in CAD management. Heretofore, radionuclide myocardial perfusion imaging has been primarily qualitative or at best semiquantitative in nature, assessing regional perfusion in relative terms. Thus, unlike so many facets of modern cardiovascular practice and CAD management, which depend, for example, on absolute values of key parameters such as arterial and left ventricular pressures, serum lipoprotein, and other biomarker levels, the absolute levels of rest and maximal myocardial blood flow have yet to be incorporated into routine clinical practice even in most positron emission tomography centers where the potential to do so exists. Accordingly, this review focuses on potential value added for improving clinical CAD practice by measuring the absolute level of rest and maximal myocardial blood flow. Physiological principles and imaging fundamentals necessary to understand how positron emission tomography makes robust, quantitative measurements of myocardial blood flow possible are highlighted.

0005 : Prognostic value of myocardial perfusion SPECT without significant perfusion defect using a dual isotope protocol and a novel CZT camera: interim results of the PROMHETE study

New dedicated cardiac gamma cameras using CZT detectors have shown significant improvement over the Anger camera regarding physical parameters, and their diagnostic performances have been validated in clinical studies. To date, few studies have evaluated the prognostic value of a low to intermediate risk single-photon emission tomography (SPECT) myocardial perfusion imaging (MPI) with these cameras, and only one with a HSDI stress thallium-201/rest Technetium-99m protocol on a CZT camera. The study included patients who had no or minimal perfusion defects (<10% of the LV myocardium) on a HS-DI MPI following a symptom-limited treadmill test or a pharmacological stress testing. These 578 patients were followed for 3.3±0.4 years (95% complete). The main endpoint was the occurrence a hard cardiac event (cardiac death or nonfatal myocardial infarction). 212 patients (37%) underwent exercise stress and 366 (63%) had pharmacological stress (of which 89% had dipyridamole and 11% had dobutamine). Mean summed stress score was 0.95±1.2 [0-5]. During the follow-up period 25 hard cardiac events occurred. Annualized event rate was 1.3%/y. In the subgroup of patients undergoing exercise stress test, annualized event rate was 0.43%/y. Multivariate Cox analysis identified age (HR 1.14 [1.08; 1.20], p<0.0001) and rest LVEF (HR 0.95 [0.92; 0.98], p=0.008) as independent predictors of cardiac death or myocardial infarction. Survival analysis showed that the occurrence of cardiac events was significantly higher in patients who had an altered LVEF compared to patients with a normal LVEF (16% vs. 3.8%, p=0.003). The use of a HS-DI protocol on a CZT camera provides prognostic information, comparable to single-isotope protocols on conventional Anger camera, while reducing imaging time and without increasing the injected activity. The author hereby declares no conflict of interest

Assessment of inpatient multimodal cardiac imaging appropriateness at large academic medical centers.

BackgroundResponding to concerns regarding the growth of cardiac testing, the American College of Cardiology Foundation (ACCF) published Appropriate Use Criteria (AUC) for various cardiac imaging modalities. Single modality cardiac imaging appropriateness has been reported but there have been no studies assessing the appropriateness of multiple imaging modalities in an inpatient environment.MethodsA retrospective study of the appropriateness of cardiac tests ordered by the inpatient General Internal Medicine (GIM) and Cardiology services at three Canadian academic hospitals was conducted over two one-month periods. Cardiac tests characterized were transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), single-photon emission tomography myocardial perfusion imaging (SPECT), and diagnostic cardiac catheterization.ResultsOverall, 553 tests were assessed, of which 99.8 % were classifiable by AUC. 91 % of all studies were categorized as appropriate, 4 % may be appropriate and 5 % were rarely appropriate. There were high rates of appropriate use of all modalities by GIM and Cardiology throughout. Significantly more appropriate diagnostic catheterizations were ordered by Cardiology than GIM (93 % vs. 82 %, p = <0.01). Cardiology ordered more appropriate studies overall (94 % vs. 88 %, p = 0.03) but there was no difference in the rate of rarely appropriate studies (3 % vs. 6 %, p = 0.23).ConclusionThe ACCF AUC captured the vast majority of clinical scenarios for multiple cardiac imaging modalities in this multi-centered study on Cardiology and GIM inpatients in the acute care setting. The rate of appropriate ordering was high across all imaging modalities. We recommend further work towards improving appropriate utilization of cardiac imaging resources focus on the out-patient setting.

Clinical utility of inappropriate positron emission tomography myocardial perfusion imaging: Test results and cardiovascular events

BackgroundAppropriate use criteria for myocardial perfusion imaging (MPI) were developed to categorize scenarios where MPI might be beneficial (appropriate) or not (inappropriate). Few investigations have evaluated the clinical utility of this categorization strategy, particularly with positron emission tomography (PET) MPI. Methods and ResultsWe conducted this retrospective cohort investigation in a Veterans Affairs (VA) medical center, on predominantly male subjects who underwent PET-MPI. We correlated appropriateness to test result and cardiovascular events. Of 521 subjects, 414 (79.5%) were appropriate, 54 (10.4%) were uncertain, and 53 (10.2%) were inappropriate. PET-MPI was abnormal more often when appropriate or uncertain (28% and 34.6%, respectively, vs 7.7% for inappropriate, P = .003). Among abnormal inappropriate tests, none detected occult ischemia. By Cox regression, summed difference score ≥5 (HR 5.06, 95% CI 2.72-9.44) and an abnormal test result (HR 4.48, 95% CI 2.19-9.14) were associated with higher likelihood of catheterization. Log-rank analysis demonstrated similar likelihood of catheterization when comparing abnormal vs normal test result (P < .0001) and between appropriate, uncertain, and inappropriate tests (P = .024). ConclusionsInappropriate PET-MPI was rarely abnormal, associated with low catheterization rates, and failed to detect occult ischemia for any subjects. The clinical utility of inappropriate PET-MPI is negligible.

Prognostic value of positron emission tomography myocardial perfusion imaging beyond traditional cardiovascular risk factors: Systematic review and meta-analysis

BackgroundDespite substantive growth in utilization of positron emission tomography (PET) myocardial perfusion imaging (MPI), evidence on its prognostic value is limited. We aimed to comprehensively evaluate the prognostic literature of PET perfusion measures according to the most recent American Heart Association recommendations for assessment of novel cardiovascular biomarkers. MethodsWe searched the literature for studies reporting associations of PET MPI measures and outcomes in patients with known or suspected coronary artery disease. We documented hazard ratios (HR) and 95% confidence intervals (CI) of association effects and quantitatively synthesized them with random-effects meta-analyses. Discrimination, calibration and risk reclassification after addition of PET MPI measures to standard prognostic models were documented. ResultsWe identified 20 eligible studies with median n=551 patients. In meta-analyses, the extents of ischemic and scarred myocardium were significantly associated with cardiac death. Meta-analyses of multivariate estimates for abnormal summed stress score ≥4 and myocardial perfusion reserve <2 revealed significant associations with major adverse cardiovascular events [HR (95% CI) 2.30 (1.53–3.44) and 2.11 (1.33–3.36), respectively]. Changes in model discrimination, calibration or risk reclassification were reported in 5 studies (8 prognostic evaluations). There were marginal improvements in discrimination based on C index and no improvements in model calibration. Net reclassification index ranged from 9.8% to 14.2% and risk classification was significantly improved in 4/5 prognostic evaluations. ConclusionsPET MPI measures were strongly associated with adverse patient outcomes. Risk classification was more consistently improved than discrimination and calibration after addition of PET MPI measures, but reporting of such metrics was overall limited.

Current and Future Status of PET Myocardial Perfusion Tracers

Over the last 2 decades, positron emission tomography (PET) myocardial perfusion imaging has been proven to be highly valuable for the detection and grading of coronary artery disease. Furthermore, its diagnostic accuracy seems to outperform on single photon emission computed tomographic myocardial perfusion imaging not least because of the potential of absolute quantification of myocardial blood flow. In a clinical setting, however, the use of PET is still limited. One major hampering factor is the lack of an ideal PET perfusion tracer for daily clinical routine. This article aims to review the currently available PET myocardial perfusion tracers as well as the question if those tracers that are being developed and about to be translated into clinics have the potential to overcome this issue.

Bilateral coronary artery to pulmonary trunk fistulae detected by coronary angiography and evaluated by ECG-gated SPECT myocardial perfusion imaging: report of two cases.

Coronary artery fistulae (CAF) are anomalies related to coronary artery abnormal termination. This is a very rare congenital malformation accounting for about 0.2-0.4% of congenital cardiac anomalies, but in some patients it can be haemodynamically important. Single-photon emission computed tomography or positron emission tomography myocardial perfusion imaging (MPI) using radioactive agents is widely used in clinical practice for cardiac ischaemia detection as a very sensitive and non-invasive tool. We are going to present 2 patients with bilateral CAFs to the pulmonary trunk without signs of the rest or stress ischaemia in MPI.

Comparison of the Diagnostic Accuracy of PET and SPECT for Coronary Artery Disease

Noninvasive assessment with a technique such as single-photon emission computed tomography (SPECT) or positron emission tomography (PET) myocardial perfusion imaging (MPI) is common and appropriate before coronary angiography to define coronary anatomy. The diagnostic accuracy of these techniques has been extensively studied with over well over 100 publications reporting the sensitivity, specificity, area under the receiver operating characteristic curve, and diagnostic odds ratio for identifying coronary artery disease with both of them throughout their evolution. Meta-analytic techniques have emerged to combine diagnostic accuracy studies while retaining the 2-dimensional value of sensitivity and specificity data. Recent diagnostic accuracy meta-analyses estimated sensitivity and specificity for SPECT for coronary artery disease at 85 %–88 % and 76 %–85 %, respectively, and the corresponding values for PET at 90 %–92 % and 81 %–88 %. These meta-analytic estimates will be reviewed along with areas of ongoing work with myocardial blood flow measurement and hybrid SPECT/CT and PET/CT imaging systems that will continue improve the diagnostic performance of nuclear techniques.

COMPARISON OF DIAGNOSTIC PERFORMANCE OF CT MYOCARDIAL PERFUSION WITH Rb-82 PET MYOCARDIAL PERFUSION IMAGING

Coronary Multidetector Computed Tomography Angiography (CCTA) is a robust method for the detection of coronary artery disease (CAD), with high diagnostic accuracy for morphologic assessment of coronary artery stenosis. Vasodilator contrast-enhanced CT Myocardial Perfusion Imaging (CT MPI) has been used for the identification of perfusion abnormalities as a surrogate of myocardial ischemia, with good correlation with Technetium radionuclide based Methods of myocardial perfusion Imaging. Rubidium-82 Positron Emission Tomography (Rb PET) Myocardial Perfusion Imaging is considered the gold standard for the assessment of myocardial ischemia in CAD.

Effects of sex on coronary microvascular dysfunction and cardiac outcomes.

Coronary microvascular dysfunction (CMD) is a prevalent and prognostically important finding in patients with symptoms suggestive of coronary artery disease. The relative extent to which CMD affects both sexes is largely unknown. We investigated 405 men and 813 women who were referred for evaluation of suspected coronary artery disease with no previous history of coronary artery disease and no visual evidence of coronary artery disease on rest/stress positron emission tomography myocardial perfusion imaging. Coronary flow reserve was quantified, and coronary flow reserve <2.0 was used to define the presence of CMD. Major adverse cardiac events, including cardiac death, nonfatal myocardial infarction, late revascularization, and hospitalization for heart failure, were assessed in a blinded fashion over a median follow-up of 1.3 years (interquartile range, 0.5-2.3 years). CMD was highly prevalent both in men and women (51% and 54%, respectively; Fisher exact test =0.39; equivalence P=0.0002). Regardless of sex, coronary flow reserve was a powerful incremental predictor of major adverse cardiac events (hazard ratio, 0.80 [95% confidence interval, 0.75-086] per 10% increase in coronary flow reserve; P<0.0001) and resulted in favorable net reclassification improvement (0.280 [95% confidence interval, 0.049-0.512]), after adjustment for clinical risk and ventricular function. In a subgroup (n=404; 307 women/97 men) without evidence of coronary artery calcification on gated computed tomography imaging, CMD was common in both sexes, despite normal stress perfusion imaging and no coronary artery calcification (44% of men versus 48% of women; Fisher exact test P=0.56; equivalence P=0.041). CMD is highly prevalent among at-risk individuals and is associated with adverse outcomes regardless of sex. The high prevalence of CMD in both sexes suggests that it may be a useful target for future therapeutic interventions.

CFR and FFR Assessment with PET and CTA: Strengths and Limitations

Positron emission tomography (PET) myocardial perfusion imaging (MPI) has high diagnostic accuracy and prognostic value. PET-MPI can also be used to quantitatively evaluate regional myocardial blood flow (MBF). This technique also allows the calculation of the coronary flow reserve (CFR)/myocardial flow reserve (MFR), which is the ratio of MBF at peak hyperemia to resting MBF. Coronary computed tomography angiography (CTA) is a non-invasive method for accurate detection and exclusion of high-grade coronary stenoses, when compared to an invasive coronary angiography reference standard. However, CTA assessment of coronary stenoses tends toward overestimation, and CTA cannot determine physiologic significance of lesions. Recent advances in computational fluid dynamics and image-based modeling permit calculation of non-invasive fractional flow reserve derived from CT (FFRCT), without the need for additional imaging, modification of acquisition protocols, or administration of medications. In this review, we cover the CFR/MFR assessment by PET and FFR assessment by CT.

Prognostic value of Rb-82 positron emission tomography myocardial perfusion imaging in coronary artery bypass patients

We sought to determine the prognostic value of positron emission tomography (PET) myocardial perfusion imaging (MPI) in patients with prior coronary artery bypass graft (CABG) surgery. PET MPI has recently been shown to provide incremental risk stratification for patients with suspected coronary artery disease (CAD), but the prognostic utility of PET MPI in CABG patients has not been well studied. A multi-centre PET registry of 7061 patients who underwent Rb-82 PET MPI from four participating centres was screened. Nine hundred and fifty-three CABG patients were identified and their images were analysed. Outcomes of all-cause mortality and cardiac death were collected. With a mean follow-up of 2.4 ± 1.4 years, 128 (13.4%) all-cause deaths and 44 (4.6%) cardiac deaths were observed. Multivariable analyses, adjusted for clinical variables, demonstrated that the summed stress score (SSS) was a significant independent predictor of both all-cause mortality [HR: 1.60 (per 1 category increase in SSS); 95% CI: 1.34-1.92; P < 0.001] and cardiac death (HR: 1.80; 95% CI: 1.33, 2.44; P < 0.001). The receiver-operator characteristic (ROC) curves showed that the addition of SSS increased the area under the curve (AUC) from 0.645 to 0.693 (P = 0.014) for all-cause mortality, and from 0.612 to 0.704 (P = 0.027) for cardiac death. SSS also improved the net reclassification improvement (NRI) for all-cause mortality (category-free NRI = 0.422; 95% CI: 0.240-0.603; P < 0.001) and cardiac death (category-free NRI = 0.552; 95% CI: 0.268-0.836; P < 0.001). PET MPI provides independent and incremental prognostic value to clinical variables in predicting all-cause mortality and cardiac death in CABG patients.

A multicenter evaluation of the appropriate use of single-photon emission tomography myocardial perfusion imaging in Greece

BackgroundThis study evaluates the appropriate use of myocardial perfusion imaging (MPI) and determines patterns and variables associated with inappropriate testing. MethodsOver a 10-month period data were collected prospectively from consecutive patients referred for MPI in four academic departments and an appropriate use grade was assigned (appropriate, uncertain, inappropriate, and unclassifiable scans) according to established criteria. ResultsAmong 3,032 referrals appropriate MPI had 72.8% of patients and 19.2% of studies were inappropriate, the remaining being uncertain (7.2%) or unclassifiable (0.8%). In multivariate analysis the asymptomatic status (odds ratio 10.7, P < .001), good functional capacity (odds ratio 1.9, P < .001), an interpretable resting electrocardiogram (odds ratio 1.8, P = .004), an age <65 years (odds ratio 1.5, P = .001) and the absence of diabetes (odds ratio 1.7, P < .001) or dyslipidemia (odds ratio 1.3, P = .014) were independent predictors of inappropriate scintigraphy. The most common indication for inappropriate testing was the assessment of asymptomatic patients <2 years after percutaneous coronary intervention (PCI) (38.9%). ConclusionsThe appropriate use of MPI is relatively high, but a considerable proportion of inappropriate scans is noted which is associated with markers of lower risk. The most common source of inappropriate testing is the assessment of asymptomatic patients <2 years after PCI.

Phase II Safety and Clinical Comparison With Single-Photon Emission Computed Tomography Myocardial Perfusion Imaging for Detection of Coronary Artery Disease

This was a phase II trial to assess flurpiridaz F 18 for safety and compare its diagnostic performance for positron emission tomography (PET) myocardial perfusion imaging (MPI) with Tc-99m single-photon emission computed tomography (SPECT) MPI with regard to image quality, interpretative certainty, defect magnitude, and detection of coronary artery disease (CAD) (≥50% stenosis) on invasive coronary angiography (ICA).In pre-clinical and phase I studies, flurpiridaz F 18 has shown characteristics of an essentially ideal MPI tracer.One hundred forty-three patients from 21 centers underwent rest-stress PET and Tc-99m SPECT MPI. Eighty-six patients underwent ICA, and 39 had low-likelihood of CAD. Images were scored by 3 independent, blinded readers.A higher percentage of images were rated as excellent/good on PET versus SPECT on stress (99.2% vs. 88.5%, p < 0.01) and rest (96.9% vs. 66.4, p < 0.01) images. Diagnostic certainty of interpretation (percentage of cases with definitely abnormal/normal interpretation) was higher for PET versus SPECT (90.8% vs. 70.9%, p < 0.01). In 86 patients who underwent ICA, sensitivity of PET was higher than SPECT (78.8% vs. 61.5%, respectively, p = 0.02). Specificity was not significantly different (PET: 76.5% vs. SPECT: 73.5%). Receiver-operating characteristic curve area was 0.82 ± 0.05 for PET and 0.70 ± 0.06 for SPECT (p = 0.04). Normalcy rate was 89.7% with PET and 97.4% with SPECT (p = NS). In patients with CAD on ICA, the magnitude of reversible defects was greater with PET than SPECT (p = 0.008). Extensive safety assessment revealed that flurpiridaz F 18 was safe in this cohort.In this phase 2 trial, PET MPI with flurpiridaz F 18 was safe and superior to SPECT MPI for image quality, interpretative certainty, and overall CAD diagnosis.