Assessment Of Myocardial Perfusion Research Articles

Erratum: Limitations of Quantitative Blush Evaluator (QuBE) as myocardial perfusion assessment method on digital coronary angiograms

Quantitative Blush Evaluator (QuBE) is a software application that allows quantifying myocardial perfusion in coronary angiograms after a percutaneous coronary intervention. QuBE has some limitations such as the application of a crude filter to remove large scale structures and the absence of correction for cardiac motion. This study investigates the extent of these limitations and we hypothesize that enhanced image analysis methods can provide improvements.We calculated QuBE scores of 117 patients from the HEBE Trial and determined its association with the Myocardial Blush Grade (MBG) score. Accuracy of large-structure removal is qualitatively assessed for various sizes of a median filter. The influence of cardiac motion was evaluated by comparing the blush curve and QuBE score of the native QuBE with manually motion-corrected QuBE for 40 patients. The effect of different kernel sizes and motion correction to a potential improvement of the association between QuBE score and MBG was studied.In our population, there was no significant association between QuBE score and MBG (p = 0.14). Median filters of various kernel sizes were unable to remove large structure related noise. Variations in filters and cardiac movement correction did not result in an improvement in the association with MBG scores (observer 1: p = 0.66; observer 2: p = 0.72).There was no significant association of QuBE with MBG scores in our population, which suggests that QuBE is not suitable for a quantitative assessment of myocardial perfusion. Alternative kernel sizes for the large structure removal filter and cardiac motion correction did not improve QuBE performance.Further improvements of QuBE to overcome its inherent limitations are necessary in order to establish QuBE as a reliable myocardial perfusion assessment method.

Limitations of Quantitative Blush Evaluator (QuBE) as myocardial perfusion assessment method on digital coronary angiograms

Quantitative Blush Evaluator (QuBE) is a software application that allows quantifying myocardial perfusion in coronary angiograms after a percutaneous coronary intervention. QuBE has some limitations such as the application of a crude filter to remove large scale structures and the absence of correction for cardiac motion. This study investigates the extent of these limitations and we hypothesize that enhanced image analysis methods can provide improvements. We calculated QuBE scores of 117 patients from the HEBE Trial and determined its association with the Myocardial Blush Grade (MBG) score. Accuracy of large-structure removal is qualitatively assessed for various sizes of a median filter. The influence of cardiac motion was evaluated by comparing the blush curve and QuBE score of the native QuBE with manually motion-corrected QuBE for 40 patients. The effect of different kernel sizes and motion correction to a potential improvement of the association between QuBE score and MBG was studied. In our population, there was no significant association between QuBE score and MBG (p = 0.14). Median filters of various kernel sizes were unable to remove large structure related noise. Variations in filters and cardiac movement correction did not result in an improvement in the association with MBG scores (observer 1: p = 0.66; observer 2: p = 0.72). There was no significant association of QuBE with MBG scores in our population, which suggests that QuBE is not suitable for a quantitative assessment of myocardial perfusion. Alternative kernel sizes for the large structure removal filter and cardiac motion correction did not improve QuBE performance. Further improvements of QuBE to overcome its inherent limitations are necessary in order to establish QuBE as a reliable myocardial perfusion assessment method.

Value of Myocardial Perfusion Assessment With Coronary Computed Tomography Angiography in Patients With Recent Acute-Onset Chest Pain

ObjectivesThe authors sought to perform a randomized controlled trial to evaluate the clinical efficacy of combined examination with coronary computed tomography angiography (CTA) and computed tomography perfusion imaging (CTP) compared to coronary CTA alone. BackgroundStress myocardial CTP may increase diagnostic specificity when added to coronary CTA in patients suspected of having ischemic heart disease. MethodsPatients recently hospitalized for acute-onset chest pain, who had acute coronary syndrome had been ruled out by normal electrocardiograms, normal troponin levels, and relief of symptoms, and who had a clinical indication for outpatient noninvasive testing, were screened for inclusion in the CATCH-2 (CArdiac cT in the treatment of acute CHest pain 2) trial (NCT02014311). Patients were randomized 1:1 to examination with coronary CTA or coronary CTA+CTP. The primary endpoint was the frequency of coronary revascularization among patients referred for invasive coronary angiography (ICA) based on index computed tomography evaluation. Secondary endpoints were invasive procedural complications at index-related ICA, post-index cardiac death, hospital admittance because of recurrence of chest pain, unstable angina pectoris, or acute myocardial infarction, ICA, and revascularization. ResultsAmong 300 patients allocated to the coronary CTA+CTP group, 41 (14%) were referred for ICA compared with 89 (30%) allocated to coronary CTA (p < 0.0001). The primary endpoint occurred in 50% of coronary CTA+CTP patients versus 48% of invasively examined patients (p = 0.85). The total number of revascularizations was significantly lower in the coronary CTA+CTP group compared to the coronary CTA group (n = 20 [7%] vs. n = 42 [14%]; p = 0.0045). At median follow-up of 1.5 years, the occurrence of secondary endpoints was similar in the 2 groups. ConclusionsA post-discharge diagnostic strategy of coronary CTA+CTP safely reduces the need for invasive examination and treatment in patients suspected of having ischemic heart disease. (CArdiac cT in the treatment of acute CHest pain 2–Myocardial CT Perfusion [CATCH2]; NCT02014311)

Coronary autoregulation and assessment of stenosis severity without pharmacological vasodilation.

For identification of myocardial ischaemia by non-invasive imaging or invasive physiological assessment, administration of a vasodilating or positive inotropic agent is often considered indispensable to exhaust the cardiac compensation mechanisms. Indeed, microcirculatory dilatation is needed for assessment of myocardial perfusion or coronary blood flow. However, three different modalities exist that quantify myocardial ischaemia without recourse to pharmacological stress agents, using either myocardial contrast echocardiography, imaging of myocardial blood volume or invasive coronary pressure measurement with the instantaneous wave-free ratio (iFR). The theoretical framework of these vasodilator-free modalities revolves around the two innate mechanisms that protect the myocardium from ischaemia at rest: coronary autoregulation and arteriogenesis. Coronary autoregulation and metabolic dilatation form the putative processes that regulate microvascular tone and constitute of a complex interplay between metabolic factors, myogenic control, and endothelium-based control that each interact with coronary arterioles of a different size. Arteriogenesis describes the development of large calibre collateral arteries from a pre-existing network, triggered by occlusive coronary artery disease. Following these descriptions, the fundamental principles and the existing evidence of these three diagnostic modalities are reviewed. Emphasis is placed on iFR, which is clinically best applicable. Instantaneous wave-free ratio has proven to be an effective method to determine the haemodynamic significance of coronary stenoses in two recent large randomized clinical trials, together enrolling over 4500 patients. Ultimately, this review aims to clarify the theoretical rationale and to describe the clinical implications of functional stenosis assessment under resting conditions.

Diagnostic and prognostic value of myocardial blood flow quantification as non-invasive indicator of cardiac allograft vasculopathy.

Cardiac allograft vasculopathy (CAV) is a leading cause of death in orthotopic heart transplant (OHT) survivors. Effective non-invasive screening methods are needed. Our aim was to investigate the added diagnostic and prognostic value of myocardial blood flow (MBF) to standard myocardial perfusion imaging (MPI) with positron emission tomography (PET) for CAV detection. We studied 94 OHT recipients (prognostic cohort), including 66 who underwent invasive coronary angiography and PET within 1 year (diagnostic cohort). The ISHLT classification was used as standard definition for CAV. Positron emission tomography evaluation included semiquantitative MPI, quantitative MBF (mL/min/g), and left ventricular ejection fraction (LVEF). A PET CAV severity score (on a scale of 0-3) was modelled on the ISHLT criteria. Patients were followed for a median of 2.3 years for the occurrence of major adverse events (death, re-transplantation, acute coronary syndrome, and hospitalization for heart failure). Sensitivity, specificity, positive, and negative predictive value of semiquantitative PET perfusion alone for detecting moderate-severe CAV were 83% [52-98], 82% [69-91], 50% [27-73], and 96% [85-99], respectively {receiver operating characteristic (ROC area: 0.82 [0.70-0.95])}. These values improved to 83% [52-98], 93% [82-98], 71% [42-92], and 96% [97-99], respectively, when LVEF and stress MBF were added (ROC area: 0.88 [0.76-0.99]; P = 0.01). There were 20 major adverse events during follow-up. The annualized event rate was 5%, 9%, and 25% in patients with normal, mildly, and moderate-to-severely abnormal PET CAV grading (P < 0.001), respectively. Multiparametric cardiac PET evaluation including quantification of MBF provides improved detection and gradation of CAV severity over standard myocardial perfusion assessment and is predictive of major adverse events.

Role of Cardiac PET in Clinical Practice

Early identification of atherosclerosis and at-risk lesions plays a critical role in reducing the burden of cardiovascular disease. While invasive coronary angiography serves as the gold standard for diagnosing coronary artery disease, non-invasive imaging techniques provide visualization of both anatomical and functional atherosclerotic processes prior to clinical presentation. The development of cardiac positron emission tomography (PET) has greatly enhanced our capability to diagnose and treat patients with early stages of atherosclerosis. Cardiac PET is a powerful, versatile non-invasive diagnostic tool with utility in the identification of high-risk plaques, myocardial perfusion defects, and viable myocardial tissue. Cardiac PET allows for comparisons of myocardial function both at time of rest and stress, providing accurate assessments of both myocardial perfusion and viability. Furthermore, novel PET techniques with unique radiotracers yield clinically relevant data on high-risk plaques in active progressive atherosclerosis. While PET exercise stress tests were previously difficult to perform given short radiotracer half-life, the development of the novel radiotracer Flurpiridaz F-18 provides a promising future for PET exercise stress imaging. In addition, hybrid imaging with computed tomography angiography (CTA) and cardiac magnetic resonance (CMR) provides integration of cardiac function and structure. In this review article, we discuss the principles of cardiac PET, the clinical applications of PET in diagnosing and prognosticating patients at risk for future cardiovascular events, compare PET with other non-invasive cardiac imaging modalities, and discuss future applications of PET in CVD evaluation and management.

Correlation of end tidal carbon dioxide, amplitude spectrum area, and coronary perfusion pressure in a porcine model of cardiac arrest.

Amplitude Spectrum Area (AMSA) values during ventricular fibrillation (VF) correlate with myocardial energy stores and predict defibrillation success. By contrast, end tidal CO2 (ETCO2) values provide a noninvasive assessment of coronary perfusion pressure and myocardial perfusion during cardiopulmonary resuscitation (CPR). Given the importance of the timing of defibrillation shock delivery on clinical outcome, we tested the hypothesis that AMSA and ETCO2 correlate with each other and can be used interchangably to correlate with myocardial perfusion in an animal laboratory preclinical, randomized, prospective investigation. After 6 min of untreated VF, 12 female pigs (32 ± 1 Kg), isoflurane anesthetized pigs received sequentially 3 min periods of standard (S) CPR, S‐CPR+ an impedance threshold device (ITD), and then active compression decompression (ACD) + ITD CPR. Hemodynamic, AMSA, and ETCO2 measurements were made with each method of CPR. The Spearman correlation and Friedman tests were used to compare hemodynamic parameters. ETCO2, AMSA, coronary perfusion pressure, cerebral perfusion pressure were lowest with STD CPR, increased with STD CPR + ITD and highest with ACD CPR + ITD. Further analysis demonstrated a positive correlation between AMSA and ETCO2 (r = 0.37, P = 0.025) and between AMSA and key hemodynamic parameters (P < 0.05). This study established a moderate positive correlation between ETCO2 and AMSA. These findings provide the physiological basis for developing and testing a novel noninvasive method that utilizes either ETCO2 alone or the combination of ETCO2 and AMSA to predict when defibrillation might be successful.

Cardiac stress MRI evaluation of anomalous aortic origin of a coronary artery.

Myocardial ischemia is an insult that is primarily thought of in an adult population. However, there are several congenital and acquired cardiac lesions that may lead to myocardial ischemia in a pediatric population. One of the prominent congenital lesions is anomalous aortic origin of a coronary artery (AAOCA). Anomalous aortic origin of a coronary artery is one of the leading causes sudden cardiac death in pediatric and young adult patients, and thus the assessment of myocardial perfusion is of the utmost importance. Over the past decade, pharmacologic stress MRI has proven to be a highly sensitive and accurate diagnostic examination for qualifying myocardial perfusion in adults with coronary artery disease. This noninvasive imaging modality may be a useful tool in assessing the function impact of AAOCA on myocardial perfusion.

Positron Emission Tomography-Determined Hyperemic Flow, Myocardial Flow Reserve, and Flow Gradient-Quo Vadis?

Positron emission tomography/computed tomography (PET/CT) applied with positron-emitting flow tracers such as 13N-ammonia and 82Rubidium enables the quantification of both myocardial perfusion and myocardial blood flow (MBF) in milliliters per gram per minute for coronary artery disease (CAD) detection and characterization. The detection of a regional myocardial perfusion defect during vasomotor stress commonly identifies the culprit lesion or most severe epicardial narrowing, whereas adding regional hyperemic MBFs, myocardial flow reserve (MFR), and/or longitudinal flow decrease may also signify less severe but flow-limiting stenosis in multivessel CAD. The addition of regional hyperemic flow parameters, therefore, may afford a comprehensive identification and characterization of flow-limiting effects of multivessel CAD. The non-specific origin of decreases in hyperemic MBFs and MFR, however, prompts an evaluation and interpretation of regional flow in the appropriate context with the presence of obstructive CAD. Conversely, initial results of the assessment of a longitudinal hyperemic flow gradient suggest this novel flow parameter to be specifically related to increases in CAD caused epicardial resistance. The concurrent assessment of myocardial perfusion and several hyperemic flow parameters with PET/CT may indeed open novel avenues of precision medicine to guide coronary revascularization procedures that may potentially lead to a further improvement in cardiovascular outcomes in CAD patients.

Assessment of myocardial blood flow and coronary flow reserve with positron emission tomography in ischemic heart disease: current state and future directions.

Positron emission tomography (PET) is a versatile imaging technology that allows assessment of myocardial perfusion, both at a spatially relative scale and also in absolute terms, thereby enabling noninvasive evaluation of myocardial blood flow (MBF) and coronary flow reserve (CFR). Assessment of MBF using FDA-approved PET isotopes, such as 82Rb and 13N-ammonia, has been well validated, and several software packages are currently available, thereby allowing for MBF evaluation to be incorporated into routine workflow in contemporary nuclear laboratories. Incremental diagnostic and prognostic information provided with the knowledge of MBF has the potential for widespread applications. Improving the ability to identify the true burden of obstructive epicardial coronary stenoses and allowing for noninvasive assessment of coronary micro circulatory function can be achieved with MBF assessment. On the other hand, attenuated CFR has been shown to predict adverse cardiovascular prognosis in a variety of clinical settings and patient subgroups. With expanding applications of MBF, this tool promises to provide unique insight into the integrity of the entire coronary vascular bed beyond what is currently available with relative perfusion assessment. This review intends to provide an in-depth discussion of technical and clinical aspects of MBF assessment with PET as it relates to patients with ischemic heart disease.

107 The long term prognostic value of dipyridamole stress myocardial contrast echocardiography in comparison with single photon emission tomography in patients with known or suspected coronary artery disease

BackgroundSingle photon emission computed tomography (SPECT) is a well-established method to evaluate patients with coronary artery disease (CAD). Myocardial contrast echocardiography (MCE) is an imaging technique that allows assessment of...

109 The prognostic value of stress cmr in a tertiary centre

BackgroundStress cardiac magnetic resonance imaging (CMR) is increasingly being used in the assessment of myocardial perfusion at rest and in response to exertion. It provides information on the presence or...

Cardiovascular magnetic resonance imaging for the assessment of ischemic heart disease

AbstractCardiovascular magnetic resonance imaging (CMR) offers a broader assessment of cardiac structure and function than any other single imaging modality. In patients with known or suspected ischemic heart disease (IHD), a comprehensive CMR protocol provides an assessment of left ventricular function, myocardial perfusion, edema, and viability in a single sitting. There are applications for this technology in both the acute and chronic IHD settings. CMR is also a valuable tool in the assessment of patients presenting with chest pain, raised troponin levels, and unobstructed coronaries.Answer questions and earn CME: https://wileyhealthlearning.com/Activity2/5430068/Activity.aspx

Recent Advances in Cardiovascular Magnetic Resonance: Techniques and Applications.

Cardiovascular magnetic resonance imaging has become the gold standard for evaluating myocardial function, volumes, and scarring. Additionally, cardiovascular magnetic resonance imaging is unique in its comprehensive tissue characterization, including assessment of myocardial edema, myocardial siderosis, myocardial perfusion, and diffuse myocardial fibrosis. Cardiovascular magnetic resonance imaging has become an indispensable tool in the evaluation of congenital heart disease, heart failure, cardiac masses, pericardial disease, and coronary artery disease. This review will highlight some recent novel cardiovascular magnetic resonance imaging techniques, concepts, and applications.

Effect of Coronary Revascularization on the Prognostic Value of Stress Myocardial Contrast Wall Motion and Perfusion Imaging.

BackgroundThe assessment of myocardial perfusion (MP) and wall motion (WM) using contrast dipyridamole echocardiography (cSE‐WMP) improves the sensitivity to detect coronary artery disease and the stratification of cardiac events, but its long‐term value for fatal and nonfatal ischemic cardiac events, also with respect to patients undergoing revascularization or not, remains to be determined.Methods and ResultsOne‐thousand three‐hundred and twenty‐nine patients with suspect or known CAD who underwent cSE‐WMP were followed for a median 5.5 years. The independent prognostic value of cSE‐WMP regarding cardiac death or nonfatal myocardial infarction was related to stress WM and MP, rest ejection fraction, clinical risk factors, and medications. Patients revascularized after cSE‐WMP were separately analyzed to determine whether the procedure influenced outcome and whether this depends on cSE‐WMP results. A total of 125 cardiac fatal and nonfatal ischemic events (9.4%) occurred during the follow‐up (61 deaths, 64 myocardial infarctions). The 5‐year event rate with normal MP and WM was 5.9%, 9.9% with isolated MP defects (normal WM), and 15.5% with both MP and WM abnormalities. In patients not undergoing revascularization (n=1111), reversible MP defects added discrimination value over WM response and clinical factors/medication data (P=0.001), while in the cohort undergoing revascularization (n=218), cSE‐WMP results did not influence outcome.Conclusions cSE‐WMP, with both contrast MP and WM assessments, provides independent, incremental prognostic information regarding ischemic cardiac events at 5 years in patients with known or suspected coronary artery disease. Revascularization reduces cardiac events after an abnormal cSE‐WMP, resulting in outcomes not different from those in patients with normal cSE‐WMP.

Detection of Hemodynamically Significant Coronary Artery Stenosis With CT Enhancement Ratio: A Validation Study in a Porcine Model.

Although numerous techniques that are based on CT number analysis have been proposed, the assessment of hemodynamically significant coronary artery stenosis remains a great challenge. The purpose of this study is to validate use of the CT enhancement ratio in the detection of hemodynamically significant coronary artery stenosis in a porcine model. Experiments involving eight closed-chest swine were performed. A balloon catheter was placed into the left anterior descending coronary artery to simulate different degrees of luminal stenosis. The myocardial blood flow (MBF) ratio was measured using the colored microsphere technique. The fractional flow reserve was measured using an invasive pressure wire. CT scans were performed during the first-pass phase, while the pigs were undergoing adenosine stress tests. The CT enhancement ratio and the CT attenuation ratio were calculated using data from the CT images obtained. Results suggested that the CT enhancement ratio had a strong correlation (y = 0.07245 + 0.09963x; r2 = 0.898; p < 0.001) with the MBF ratio measured using the microsphere technique, whereas only moderate correlation (y = -1.5508 + 2.2684x; r2 = 0.498; p < 0.001) was noted between the CT attenuation ratio and the MBF ratio measured using the microsphere technique. In ROC curve analysis, the AUC values of the CT enhancement ratio and the CT attenuation ratio were 0.927 and 0.829, respectively, with regard to the detection of significant ischemia during adenosine stress tests, as defined by the fractional flow reserve. The CT enhancement ratio provides a reliable prediction of the MBF ratio measured using the microsphere technique, indicating that this metric has good diagnostic performance in the detection of hemodynamically significant coronary artery stenosis. The CT enhancement ratio may have potential for use as an imaging biomarker for the relative quantitative assessment of myocardial perfusion.

Spectral detector CT for cardiovascular applications.

Spectral detector computed tomography (SDCT) is a novel technology that uses two layers of detectors to simultaneously collect low and high energy data. Spectral data is used to generate conventional polyenergetic images as well as dedicated spectral images including virtual monoenergetic and material composition (iodine-only, virtual unenhanced, effective atomic number) images. This paper provides an overview of SDCT technology and a description of some spectral image types. The potential utility of SDCT for cardiovascular imaging and the impact of this new technology on radiation and contrast dose are discussed through presentation of initial patient studies performed on a SDCT scanner. The value of SDCT for salvaging suboptimal studies including those with poor contrast-enhancement or beam hardening artifacts through retrospective reconstruction of spectral data is discussed. Additionally, examples of specific benefits for the evaluation of aortic disease, imaging before transcatheter aortic valve implantation, evaluation of pulmonary veins pre- and post-pulmonary radiofrequency ablation, evaluation of coronary artery lumen, assessment of myocardial perfusion, detection of pulmonary embolism, and characterization of incidental findings are presented.

Cardiovascular magnetic resonance myocardial perfusion: methods and applications in patients with coronary artery disease

Perfusion CMR is an attractive imaging modality that is becoming comparable with other clinically diagnostic tests. SPECT and PET are well clinically validated and have good accuracy for detection of significant CAD. However, these techniques have a rather low spatial resolution and are not suitable for the detection of subendocardial perfusion defect. In addition, the radiation burden, the potential for attenuation artefacts (SPECT) and the limited availability (PET) are limitations of these imaging techniques. An integrated assessment of myocardial perfusion, function and viability is feasible with CMR. In addition, compared to other clinically available imaging techniques, CMR perfusion has excellent spatial resolution and no ionising radiation exposure. However, it is not widely available and there is a need of protocol and pulse sequence standardization. Most perfusion analysis remains observer-dependent (“eyeball” analysis) or dependent on bolus dispersion (semi-quantitative analysis). Fully quantitative analysis using CMR perfusion is currently time-consuming for clinical application. Perfusion CMR is an evolving field with numerous future directions.

Takotsubo cardiomyopathy: FDG myocardial uptake pattern in fasting patients. Comparison of PET/CT, SPECT, and ECHO results

BackgroundThe aim of this study was to assess the accumulation pattern of 18F-FDG in fasting patients with takotsubo cardiomyopathy (TTC) and to correlate the results with perfusion scintigraphy and echocardiography. Methods18 consecutive patients with TTC were identified by clinical symptoms, cardiac catheterization, and echocardiography. Coronary angiography (CA) and transthoracic echocardiography (TTE) were performed on the day of the onset of symptoms. An assessment of myocardial perfusion (99mTc-MIBI) and glucose metabolism (18F-FDG) was performed within 18 days. ResultsSPECT showed no regional perfusion abnormalities in 10/18 patients, and a mild perfusion defect was found in 8/18 patients. Perfusion abnormalities were limited to apical and para-apical regions. In 8/18 cases, there was an increased selective apical 18F-FDG accumulation. In 10/18 cases, in spite of the fastened 18F-FDG protocol, slightly inhomogeneous 18F-FDG uptake was present in the entire myocardium: with relatively reduced uptake of 18F-FDG in the apical region and LV mid-segments. ConclusionThis study demonstrated the heterogeneous nature of myocardial 18F-FDG accumulation in patients with TTC. Selective, preferential apical 18F-FDG uptake in almost half of the patients confirms an existing disorder of glucose metabolism, similar to that observed in stunned or hibernated myocardium.

Однофотонная эмиссионная компьютерная томография с коррекцией аттенюации в верификации нарушений микроциркуляции миокарда у пациентов с болевым синдромом в грудной клетке и интактными коронарными артериями

The paper estimated the role of the attenuation correction (AC) for single-photon emission computed tomography combined with computed tomography (SPECT/CT) in the assessment of myocardial perfusion in patients with chest pain and unaffected coronary artery. The study included 31 patients, each of whom had a selective coronary angiography and rest/stress SPECT/CT of the myocardium made with 99mTc -MIBI with- and without CA. Stress-induced myocardial ischemia of varying incidence and severity was detected in all patients according to scintigramm without and with AC on SPECT. However, the perfusion parameters showed the prevalence and severity of stress-induced perfusion deficit which were significantly lower after the correction. The average values of quantitative parameters of perfusion scintigramm on rest were also lower with CA, although not significantly different when compared without CA. Quantitative parameters of myocardial perfusion to assess the functional state of the myocardium by SPECT/CT with attenuation correction are of great diagnostic value.