Adenosine Stress Myocardial Contrast Echocardiography for the Detection of Coronary Artery Disease

Correlation between abnormal microvascular perfusion and quantitative flow ratio after primary PCI in patients with STEMI

AIMS

Timely assessment of abnormal microvascular perfusion (MVP) may improve prognosis in patients with ST-segment elevation myocardial infarction (STEMI). This study aimed to determine the clinical implications of contrast-flow quantitative flow ratio (cQFR) in evaluating abnormal MVP and subsequent outcomes among STEMI patients after successful primary percutaneous coronary intervention (PPCI).

METHODS

The study population consisted of 2 independent cohorts. The diagnostic cohort was used to evaluate the correlation and diagnostic accuracy of cQFR in predicting abnormal MVP. In this cohort, MVP and cQFR of the culprit vessel (n = 186) were assessed from a prospective consecutive registry. Abnormal MVP was determined using myocardial contrast perfusion echocardiography (MCE) in the culprit vessel after PPCI. The prognostic cohort consisted of STEMI patients undergoing PPCI who were followed for a minimum of 2 years (n = 1931). The primary outcome was all-cause mortality.

RESULTS

In the diagnostic cohort, cQFR exhibited a moderate correlation with abnormal MVP assessed by MCE. Specificity, sensitivity, and area under the curve of post-PPCI cQFR to predict abnormal MVP were 81.6 %, 50.9 % and 0.709 (95 % confidence interval: 0.635-0.783), respectively, with the best cut-off value of 0.875. In the prognostic cohort, patients with cQFR <0.875 showed a significantly higher risk of long-term mortality compared to those with cQFR ≥0.875 (median follow-up: 52 months; mortality: 8.0 % vs. 3.8 %; p < 0.001). Cox-regression analysis revealed that cQFR < 0.875 was an independent predictor of long-term mortality (adjusted HR: 2.132; 95 % CI: 1.358-3.346; p = 0.001) after adjusting for age, gender, diabetes mellitus, hyperlipidemia, symptom to balloon time, culprit vessel.

CONCLUSIONS

We found that cQFR demonstrated a relatively good performance in predicting abnormal MVP in patients with STEMI after successful PPCI. A cQFR value below 0.875 is an independent predictor of both abnormal MVP and long-term mortality. (Prognostic implication of cQFR in STEMI patients; NCT04996901).

Application of apical myocardial perfusion quantitative analysis by contrast-enhanced ultrasound utilizing high-frequency linear probe

BACKGROUND

Due to insufficient near-field resolution and artifacts, it is challenging to evaluate the left ventricular apical perfusion with phased-array probes. By combining high-frequency linear probe and contrast-enhanced ultrasound (CEUS), imaging of apical myocardial perfusion could be improved. The study aims to evaluate the preliminary application of CEUS by high-frequency linear probes to assess the apical perfusion.

METHODS

The study enrolled retrospectively 91 patients to test the feasibility of the novel method. In protocol 1, patients were stratified into a group with left anterior descending artery (LAD) stenosis (N = 40) and a group without LAD stenosis or coronary artery disease (N = 41) based on the degree of coronary artery narrowing, quantified by >50% stenosis in coronary angiography. Receiver operating characteristics (ROC) analysis was performed to test the diagnostic value of perfusion parameters. In protocol 2, the reproducibility of high-frequency linear probe in apical perfusion analysis was compared with the conventional phased-array probe in 30 patients.

RESULTS

(1) The novel method is feasible in 81(89.01%) patients. (2) In protocol 1, to detect LAD stenosis, the best cut-off of β, T, A, and MBF were 10.32, 3.28, 9.39, and 4.99, respectively. Area under the curve of β, T, A, and MBF were .880, .881, .761, and .880, respectively. (3) In protocol 2, compared with phased-array probe, the quantitative analysis of high-frequency linear probe is of high reproducibility and could get good curve fitting (R2 = .29 vs. R2 = .71, P < .01).

CONCLUSION

Observation of apical perfusion using this method is feasible and quantitative analysis allows an accurate and convenient identification of LAD stenosis. This method provides an alternative for patients who have difficulties in visualizing the apical region with a phased-array probe.

Contrast Ultrasound, Sonothrombolysis and Sonoperfusion in Cardiovascular Disease: Shifting to Theragnostic Clinical Trials

Contrast ultrasound has a variety of applications in cardiovascular medicine, both in diagnosing cardiovascular disease as well as providing prognostic information. Visualization of intravascular contrast microbubbles is based on acoustic cavitation, the characteristic oscillation that results in changes in the reflected ultrasound waves. At high power, this acoustic response generates sufficient shear that is capable of enhancing endothelium-dependent perfusion in atherothrombotic cardiovascular disease (sonoperfusion). The oscillation and collapse of microbubbles in response to ultrasound also induces microstreaming and jetting that can fragment thrombus (sonothrombolysis). Several preclinical studies have focused on identifying optimal diagnostic ultrasound settings and treatment regimens. Clinical trials have been performed in acute myocardial infarction, stroke, and peripheral arterial disease often with improved outcome. In the coming years, results of ongoing clinical trials along with innovation and improvements in sonothrombolysis and sonoperfusion will determine whether this theragnostic technique will become a valuable addition to reperfusion therapy.

Long-term prognostic value of stress myocardial perfusion echocardiography in patients with coronary artery disease: a meta-analysis

AIMS

To evaluate the prognostic value of myocardial perfusion (MP) imaging during contrast stress echocardiography (cSE) in patients with known or suspected coronary artery disease (CAD).

METHODS AND RESULTS

A search in PubMed, Embase databases, and the Cochrane library was conducted through May 2019. The Cochran Q statistic and the I2 statistic were used to assess heterogeneity, and the results were analysed by RevMan V5.3 and Stata V15.1 software. Twelve studies (seven dipyridamole and five exercise/dobutamine) without evidence of patient overlap (same institution publishing results over a similar time period) enrolling 5953 subjects (47% female, 8-80 months of follow-up) were included in the analysis. In all studies, total adverse cardiovascular events were defined as either cardiac death, non-fatal myocardial infarction (NFMI), or need for urgent revascularization. Hazard ratios (HRs) revealed that a MP abnormality [pooled HR 4.75; 95% confidence interval (CI) 2.47-9.14] was a higher independent predictor of total events than abnormal wall motion (WM, pooled HR 2.39; 95% CI 1.58-3.61) and resting left ventricular ejection fraction (LVEF, pooled HR 1.92; 95% CI 1.44-2.55) with significant subgroup differences (P = 0.002 compared with abnormal WM and 0.01 compared with abnormal LVEF). Abnormal MP was associated with higher risks for death [Risk ratio (RR) 5.24; 95% CI 2.91-9.43], NFMI (RR 3.09; 95% CI 1.84-5.21), and need for coronary revascularization (RR 16.44; 95% CI 6.14-43.99).

CONCLUSION

MP analysis during stress echocardiography is an effective prognostic tool in patients with known or suspected CAD and provides incremental value over LVEF and WM in predicting clinical outcomes.

[Comparison of myocardial contrast stress-echocardiography and standard stress-echocardiography in detecting myocardial ischemia in patients with different severity of coronary artery stenoses]

AIM

To compare diagnostic value between standard stress-echocardiography and myocardial contrast stress echocardiography in detection of myocardial ischemia in patients with different severity of coronary artery stenoses.

MATERIALS AND METHODS

Myocardial contrast stress-echocardiography and standard stress-echocardiography were performed in 38 patients with coronary artery stenoses over 50% by angiography. Of all lesions 39 were intermediate (5075%) and 33 over 75% stenoses. Fractional flow reserve (FFR) was measured in 12 coronary arteries. During myocardial contrast stress-echocardiography wall motion and myocardial perfusion was assessed.

RESULTS

Adequate visualisation increased from 81.6% in unenhanced segments to 96.1% in contrast-enhanced segments. The sensitivity, specificity, and diagnostic accuracy of standard stress-echocardiography and myocardial contrast stress-echocardiography in intermediate (5075%) coronary stenoses were 44%, 83%, 56% and 56%, 94% и 64% respectively compare to angiography. Taking into account the 12 arteries with evaluated FFR, these parameters increased to 52%, 93% и 65% in standard stress-echocardiography and to 68%, 100% and 75% in myocardial contrast stress-echocardiography. In coronary stenoses over 75% the sensitivity, specificity, and diagnostic accuracy of standard stress-echocardiography and myocardial contrast stress-echocardiography were 78%, 88%, 80% and 86%, 100%, 92% respectively Conclusion. Use of contrast-enhanced stress-echorardiography significantly increased the diagnostic value of this method by improving endocardial border visualization and possibilities of myocardial perfusion assessment.

New Applications in Echocardiography for Ultrasound Contrast Agents in the 21st Century

Contrast echocardiography microbubbles are ultrasound-enhancing agents that were originally designed to help improve endocardial border definition, known as left ventricle opacification, and to enhance Doppler signals. Over time, contrast microbubbles are used to assess myocardial perfusion because they travel through the capillaries of the cardiac circulation. Current research provides good evidence that myocardial perfusion echocardiography improves comprehensive echocardiographic evaluations of ischemic heart disease. The approval of regulatory authorities and the availability of quantitative operator-independent analysis software will hopefully prompt physicians and sonographers to implement myocardial perfusion echocardiography into the daily workflow of echo laboratories. New diagnostic and therapeutic applications will result in improved patient care, especially in the area of sonothrombolysis, where preliminary data have already shown utilization in ST elevation myocardial infarction, improving left ventricular systolic function and reducing the need for implantable defibrillators at 6-mo follow-up. This review gives an overview of the applications of myocardial perfusion imaging with ultrasound. Each cited study had institutional review board/institutional animal care and use approval.

Clinical practice of contrast echocardiography: recommendation by the European Association of Cardiovascular Imaging (EACVI) 2017

Contrast echocardiography is widely used in cardiology. It is applied to improve image quality, reader confidence and reproducibility both for assessing left ventricular (LV) structure and function at rest and for assessing global and regional function in stress echocardiography. The use of contrast in echocardiography has now extended beyond cardiac structure and function assessment to evaluation of perfusion both of the myocardium and of the intracardiac structures. Safety of contrast agents have now been addressed in large patient population and these studies clearly established its excellent safety profile. This document, based on clinical trials, randomized and multicentre studies and published clinical experience, has established clear recommendations for the use of contrast in various clinical conditions with evidence-based protocols.

Data on diagnostic performance of stress perfusion cardiac magnetic resonance for coronary artery disease detection at the vessel level

Stress perfusion cardiac magnetic resonance (CMR) has been proposed as an important gatekeeper for invasive coronary angiography (ICA) and percutaneous coronary interventions (PCI) in patients evaluated for possible coronary artery disease (CAD) (Fihn et al., 2012; Montalescot et al., 2013) [1], [2]. Several meta-analyses have evaluated the accuracy of stress perfusion CMR to diagnose CAD at the vessel level (Danad et al., 2017; Dai et al., 2016; Jiang et al., 2016; Takx et al., 2015; Li et al., 2015; Desai and Jha, 2013; Jaarsma et al. 2012; Hamon et al., 2010; Nandalur et al. 2007) [3], [4], [5], [6], [7], [8], [9], [10], [11]. However, they included in the same analysis studies with different definitions of significant CAD (i.e. fractional flow reserve [FFR] < 0.75 and < 0.80 or coronary stenosis ≥ 50% and ≥ 70%), magnetic field strength (1.5 or 3 Tesla [T]), and study protocol (integration or not of late gadolinium enhancement [LGE] into stress perfusion protocol). Data of 34 studies (6091 arteries) have been pooled with the aim of analyzing the accuracy of stress perfusion CMR for the diagnosis of ischemic heart disease at the vessel level according to different definitions of significant CAD, magnetic field strength and study protocol (Arnold et al., 2010; Bettencourt et al., 2013; Cheng et al., 2007; Chiribiri et al., 2013; Cury et al., 2006; De Mello et al., 2012; Donati et al., 2010; Ebersberger et al., 2013; Gebker et al., 2008; Greulich et al., 2015; Hussain et al., 2016; Ishida et al., 2005, 2003; Kamiya et al., 2014; Kitagawa et al., 2008; Klein et al., 2008; Klem et al., 2006; Klumpp et al., 2010; Krittayaphong et al., 2009; Lockie et al., 2011; Ma et al., 2012; Merkle et al., 2007; Meyer et al., 2008; Mor-Avi et al., 2008; Pan et al., 2015; Papanastasiou et al., 2016; Pons Lladó et al., 2004; Sakuma et al., 2005; Salerno et al., 2014; Scheffel et al., 2010; van Werkhoven et al., 2010; Walcher et al., 2013; Watkins et al., 2009; Yun et al., 2015) [12–45]. This article describes data related article titled “Diagnostic Performance of Stress Perfusion Cardiac Magnetic Resonance for the Detection of Coronary Artery Disease” (Kiaos et al., submitted for publication) [46].

Reproducible Computer-Assisted Quantification of Myocardial Perfusion with Contrast-Enhanced Ultrasound

Myocardial perfusion can be quantified by myocardial contrast echocardiography (MCE) and is used for the diagnosis of coronary artery disease (CAD). However, existing MCE quantification software is highly operator dependent and has poor reproducibility and ease of usage. The aim of this study was to develop robust and easy-to-use software that can perform MCE quantification accurately, reproducibly and rapidly. The developed software has the following features: (i) semi-automatic segmentation of the myocardium; (ii) automatic rejection of MCE data with poor image quality; (iii) automatic computation of perfusion parameters such as myocardial blood flow (MBF). MCE sequences of 18 individuals (9 normal, 9 with CAD) undergoing vasodilator stress with dipyridamole were analysed quantitatively using the software. When evaluated against coronary angiography, the software achieved a sensitivity of 71% and a specificity of 91% for hyperemic MBF. With the automatic rejection algorithm, the sensitivity and specificity further improved to 77% and 94%, respectively. For MBF reproducibility, the percentage agreement is 85% (κ = 0.65) for inter-observer variability and 88% (κ = 0.72) for intra-observer variability. The intra-class correlation coefficients are 0.94 (inter-observer) and 0.96 (intra-observer). The time taken to analyse one MCE sequence using the software is about 3 min on a PC. The software has exhibited good diagnostic performance and reproducibility for CAD detection and is rapid and user-friendly.

Cardiac imaging: working towards fully-automated machine analysis & interpretation

INTRODUCTION

Non-invasive imaging plays a critical role in managing patients with cardiovascular disease. Although subjective visual interpretation remains the clinical mainstay, quantitative analysis facilitates objective, evidence-based management, and advances in clinical research. This has driven developments in computing and software tools aimed at achieving fully automated image processing and quantitative analysis. In parallel, machine learning techniques have been used to rapidly integrate large amounts of clinical and quantitative imaging data to provide highly personalized individual patient-based conclusions. Areas covered: This review summarizes recent advances in automated quantitative imaging in cardiology and describes the latest techniques which incorporate machine learning principles. The review focuses on the cardiac imaging techniques which are in wide clinical use. It also discusses key issues and obstacles for these tools to become utilized in mainstream clinical practice. Expert commentary: Fully-automated processing and high-level computer interpretation of cardiac imaging are becoming a reality. Application of machine learning to the vast amounts of quantitative data generated per scan and integration with clinical data also facilitates a move to more patient-specific interpretation. These developments are unlikely to replace interpreting physicians but will provide them with highly accurate tools to detect disease, risk-stratify, and optimize patient-specific treatment. However, with each technological advance, we move further from human dependence and closer to fully-automated machine interpretation.

Qualitative and semi-quantitative evaluation of myocardium perfusion with 3 T stress cardiac MRI

BACKGROUND

3 T MRI has been adopted by some centers as the primary choice for assessment of myocardial perfusion over conventional 1.5 T MRI. However, there is no data published on the potential additional value of incorporating semi-quantitative data from 3 T MRI. This study sought to determine the performance of qualitative 3 T stress magnetic resonance myocardial perfusion imaging (3 T-MRMPI) and the potential incremental benefit of using a semi-quantitative perfusion technique in patients with suspected coronary artery disease (CAD).

METHODS

Fifty eight patients (41 men; mean age: 59 years) referred for elective diagnostic angiography underwent stress 3 T MRMPI with a 32-channel cardiac receiver coil. The MR protocol included gadolinium-enhanced stress first-pass perfusion (0.56 mg/kg, dipyridamole), rest perfusion, and delayed enhancement (DE). Visual analysis was performed in two steps. Ischemia was defined as a territory with perfusion defect at stress study but no DE or a territory with DE but additional peri-infarcted perfusion defect at stress study. Semi-quantitative analysis was calculated by using the upslope of the signal intensity-time curve during the first pass of contrast medium during dipyridamole stress and at rest. ROC analysis was used to determine the MPRI threshold that maximized sensitivity. Quantitative coronary angiography served as the reference standard with significant stenosis defined as >70 % diameter stenosis. Diagnostic performance was determined on a per-patient and per-vessel basis.

RESULTS

Qualitative assessment had an overall sensitivity and specificity for detecting significant stenoses of 77 % and 80 %, respectively. By adding MPRI analysis, in cases with negative qualitative assessment, the overall sensitivity increased to 83 %. The impact of MPRI differed depending on the territory; with the sensitivity for detection of left circumflex (LCx) stenosis improving the most after semi-quantification analysis, (66 % versus 83 %).

CONCLUSIONS

Pure qualitative assessment of 3 T MRI had acceptable performance in detecting severe CAD. There is no overall benefit of incorporating semi-quantitative data; however a higher sensitivity can be obtained by adding MPRI, especially in the detection of LCx lesions.

Myocardial perfusion imaging using contrast echocardiography

Microbubbles are an excellent intravascular tracer, and both the rate of myocardial opacification (analogous to coronary microvascular perfusion) and contrast intensity (analogous to myocardial blood volume) provide unique insights into myocardial perfusion. A strong evidence base has been accumulated to show comparability with nuclear perfusion imaging and incremental diagnostic and prognostic value relative to wall motion analysis. This technique also provides the possibility to measure myocardial perfusion at the bedside. Despite all of these advantages, the technique is complicated, technically challenging, and has failed to scale legislative and financial hurdles. The development of targeted imaging and therapeutic interventions will hopefully rekindle interest in this interesting modality.

The dilemma of ischemia testing with different methods

A 52-year-old man presented after one episode of effort angina, normal treadmill electrocardiogram (ECG), and clearly positive adenosine cardiac magnetic resonance (aCMR) for reversible perfusion defects in the left anterior descending (LAD) coronary artery territory. Contrast high-dose dipyridamole (0.84 mg/kg per 6 min) stress echocardiography (cSE) demonstrated normal myocardial perfusion (MP) and wall motion at rest, while perfusion defects were shown in the lateral and apical segments after dipyridamole. Wall motion at stress was completely normal and stress/rest Doppler diastolic velocity ratio on the LAD demonstrated reduced flow reserve. In this case, cSE was the provocative test detecting both the LAD and circumflex obstructive lesions, thanks to MP analysis, while wall motion assessment was negative, not different from treadmill ECG, and aCMR highlighted only the LAD disease.

Combining microbubbles and ultrasound for drug delivery to brain tumors: current progress and overview

Malignant glioma is one of the most challenging central nervous system (CNS) diseases, which is typically associated with high rates of recurrence and mortality. Current surgical debulking combined with radiation or chemotherapy has failed to control tumor progression or improve glioma patient survival. Microbubbles (MBs) originally serve as contrast agents in diagnostic ultrasound but have recently attracted considerable attention for therapeutic application in enhancing blood-tissue permeability for drug delivery. MB-facilitated focused ultrasound (FUS) has already been confirmed to enhance CNS-blood permeability by temporally opening the blood-brain barrier (BBB), thus has potential to enhance delivery of various kinds of therapeutic agents into brain tumors. Here we review the current preclinical studies which demonstrate the reports by using FUS with MB-facilitated drug delivery technology in brain tumor treatment. In addition, we review newly developed multifunctional theranostic MBs for FUS-induced BBB opening for brain tumor therapy.

Integrating anatomical and functional imaging for the assessment of coronary artery disease

Coronary artery disease (CAD) is a leading cause of morbidity and mortality. Invasive cardiac angiography with fractional flow reserve measurement allows for the anatomical and functional assessment of CAD. Given the invasive nature of invasive cardiac angiography and the risks of procedure-related complications, research has focused upon noninvasive methods for anatomical and functional measures of CAD. As such, there is growing interest in the development of hybrid imaging because it may provide incremental diagnostic information over each imaging modality alone. We will provide an overview of the evidence to date on the anatomical and functional stratification of CAD and current hybrid techniques.

Comparison of treadmill exercise stress cardiac MRI to stress echocardiography in healthy volunteers for adequacy of left ventricular endocardial wall visualization: A pilot study

PURPOSE

To compare exercise stress cardiac magnetic resonance (cardiac MR) to echocardiography in healthy volunteers with respect to adequacy of endocardial visualization and confidence of stress study interpretation.

MATERIALS AND METHODS

Twenty-eight healthy volunteers (age 28 ± 11 years, 15 males) underwent exercise stress echo and cardiac MR one week apart assigned randomly to one test first. Stress cardiac MR was performed using an MRI-compatible treadmill; stress echo was performed as per routine protocol. Cardiac MR and echo images were independently reviewed and scored for adequacy of endocardial visualization and confidence in interpretation of the stress study.

RESULTS

Heart rate at the time of imaging was similar between the studies. Average time from cessation of exercise to start of imaging (21 vs. 31 s, P < 0.001) and time to acquire stress images (20 vs. 51 s, P < 0.001) was shorter for cardiac MR. The number of myocardial segments adequately visualized was significantly higher by cardiac MR at rest (99.8% vs. 96.4%, P = 0.002) and stress (99.8% vs. 94.1%, P = 0.001). The proportion of subjects in whom there was high confidence in the interpretation was higher for cardiac MR than echo (96% vs. 60%, P = 0.005).

CONCLUSION

Exercise stress cardiac MR to assess peak exercise wall motion is feasible and can be performed at least as rapidly as stress echo.

Quantitative myocardial perfusion imaging by cardiovascular magnetic resonance and positron emission tomography

Recent studies have demonstrated that a detailed knowledge of the extent of angiographic coronary artery disease (CAD) is not a prerequisite for clinical decision making, and the clinical management of patients with CAD is more and more focused towards the identification of myocardial ischemia and the quantification of ischemic burden. In this view, non-invasive assessment of ischemia and in particular stress imaging techniques are emerging as preferred and non-invasive options. A quantitative assessment of regional myocardial perfusion can provide an objective estimate of the severity of myocardial injury and may help clinicians to discriminate regions of the heart that are at increased risk for myocardial infarction. Positron emission tomography (PET) has established itself as the reference standard for myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) quantification. Cardiac magnetic resonance (CMR) is increasingly used to measure MBF and MPR by means of first-pass signals, with a well-defined diagnostic performance and prognostic value. The aim of this article is to review the currently available evidence on the use of both PET and CMR for quantification of MPR, with particular attention to the studies that directly compared these two diagnostic methods.

Variability in quantitative cardiac magnetic resonance perfusion analysis

By taking advantage of its high spatial resolution, noninvasive and nontoxic nature first-pass perfusion cardiovascular magnetic resonance (CMR) has rendered an indispensable tool for the noninvasive detection of reversible myocardial ischemia. A potential advantage of perfusion CMR is its ability to quantitatively assess perfusion reserve within a myocardial segment, as expressed semi- quantitatively by myocardial perfusion reserve index (MPRI) and fully- quantitatively by absolute myocardial blood flow (MBF). In contrast to the high accuracy and reliability of CMR in evaluating cardiac function and volumes, perfusion CMR is adversely affected by multiple potential reasons during data acquisition as well as post-processing. Various image acquisition techniques, various contrast agents and doses as well as variable blood flow at rest as well as variable reactions to stress all influence the acquired data. Mechanisms underlying the variability in perfusion CMR post processing, as well as their clinical significance, are yet to be fully elucidated. The development of a universal, reproducible, accurate and easily applicable tool in CMR perfusion analysis remains a challenge and will substantially enforce the role of perfusion CMR in improving clinical care.

MR myocardial perfusion imaging

Contrast material-enhanced myocardial perfusion imaging by using cardiac magnetic resonance (MR) imaging has, during the past decade, evolved into an accurate technique for diagnosing coronary artery disease, with excellent prognostic value. Advantages such as high spatial resolution; absence of ionizing radiation; and the ease of routine integration with an assessment of viability, wall motion, and cardiac anatomy are readily recognized. The need for training and technical expertise and the regulatory hurdles, which might prevent vendors from marketing cardiac MR perfusion imaging, may have hampered its progress. The current review considers both the technical developments and the clinical experience with cardiac MR perfusion imaging, which hopefully demonstrates that it has long passed the stage of a research technique. In fact, cardiac MR perfusion imaging is moving beyond traditional indications such as diagnosis of coronary disease to novel applications such as in congenital heart disease, where the imperatives of avoidance of ionizing radiation and achievement of high spatial resolution are of high priority. More wide use of cardiac MR perfusion imaging, and novel applications thereof, are aided by the progress in parallel imaging, high-field-strength cardiac MR imaging, and other technical advances discussed in this review.

Effectiveness of myocardial contrast echocardiography quantitative analysis during adenosine stress versus visual analysis before percutaneous therapy in acute coronary pain: a coronary artery TIMI grading comparing study

The study aim was to compare two different stress echocardiography interpretation techniques based on the correlation with thrombosis in myocardial infarction (TIMI ) flow grading from acute coronary syndrome (ACS) patients. Forty-one patients with suspected ACS were studied before diagnostic coronary angiography with myocardial contrast echocardiography (MCE) at rest and at stress. The correlation of visual interpretation of MCE and TIMI flow grade was significant. The quantitative analysis (myocardial perfusion parameters: A, β, and A × β) and TIMI flow grade were significant. MCE visual interpretation and TIMI flow grade had a high degree of agreement, on diagnosing myocardial perfusion abnormality. If one considers TIMI flow grade <3 as abnormal, MCE visual interpretation at rest had 73.1% accuracy with 58.2% sensitivity and 84.2% specificity and at stress had 80.4% accuracy with 76.6% sensitivity and 83.3% specificity. The MCE quantitative analysis has better accuracy with 100% of agreement with different level of TIMI flow grading. MCE quantitative analysis at stress has showed a direct correlation with TIMI flow grade, more significant than the visual interpretation technique. Further studies could measure the clinical relevance of this more objective approach to managing acute coronary syndrome patient before percutaneous coronary intervention (PCI).

Diagnostic performance of noninvasive myocardial perfusion imaging using single-photon emission computed tomography, cardiac magnetic resonance, and positron emission tomography imaging for the detection of obstructive coronary artery disease: a meta-analysis

OBJECTIVES

This study aimed to determine the diagnostic accuracy of the 3 most commonly used noninvasive myocardial perfusion imaging modalities, single-photon emission computed tomography (SPECT), cardiac magnetic resonance (CMR), and positron emission tomography (PET) perfusion imaging for the diagnosis of obstructive coronary artery disease (CAD). Additionally, the effect of test and study characteristics was explored.

BACKGROUND

Accurate detection of obstructive CAD is important for effective therapy. Noninvasive myocardial perfusion imaging is increasingly being applied to gauge the severity of CAD.

METHODS

Studies published between 1990 and 2010 identified by PubMed search and citation tracking were examined. A study was included if a perfusion imaging modality was used as a diagnostic test for the detection of obstructive CAD and coronary angiography as the reference standard (≥50% diameter stenosis).

RESULTS

Of the 3,635 citations, 166 articles (n = 17,901) met the inclusion criteria: 114 SPECT, 37 CMR, and 15 PET articles. There were not enough publications on other perfusion techniques such as perfusion echocardiography and computed tomography to include these modalities into the study. The patient-based analysis per imaging modality demonstrated a pooled sensitivity of 88% (95% confidence interval [CI]: 88% to 89%), 89% (95% CI: 88% to 91%), and 84% (95% CI: 81% to 87%) for SPECT, CMR, and PET, respectively; with a pooled specificity of 61% (95% CI: 59% to 62%), 76% (95% CI: 73% to 78%), and 81% (95% CI: 74% to 87%). This resulted in a pooled diagnostic odds ratio (DOR) of 15.31 (95% CI: 12.66 to 18.52; I(2) 63.6%), 26.42 (95% CI: 17.69 to 39.47; I(2) 58.3%), and 36.47 (95% CI: 21.48 to 61.92; I(2) 0%). Most of the evaluated test and study characteristics did not affect the ranking of diagnostic performances.

CONCLUSIONS

SPECT, CMR, and PET all yielded a high sensitivity, while a broad range of specificity was observed. SPECT is widely available and most extensively validated; PET achieved the highest diagnostic performance; CMR may provide an alternative without ionizing radiation and a similar diagnostic accuracy as PET. We suggest that referring physicians consider these findings in the context of local expertise and infrastructure.

Diagnostic performance of stress myocardial perfusion imaging for coronary artery disease: a systematic review and meta-analysis

Objectives

To determine and compare the diagnostic performance of stress myocardial perfusion imaging (MPI) for the diagnosis of obstructive coronary artery disease (CAD), using conventional coronary angiography (CCA) as the reference standard.

Methods

We searched Medline and Embase for literature that evaluated stress MPI for the diagnosis of obstructive CAD using magnetic resonance imaging (MRI), contrast-enhanced echocardiography (ECHO), single-photon emission computed tomography (SPECT) and positron emission tomography (PET).

Results

All pooled analyses were based on random effects models. Articles on MRI yielded a total of 2,970 patients from 28 studies, articles on ECHO yielded a sample size of 795 from 10 studies, articles on SPECT yielded 1,323 from 13 studies. For CAD defined as either at least 50 %, at least 70 % or at least 75 % lumen diameter reduction on CCA, the natural logarithms of the diagnostic odds ratio (lnDOR) for MRI (3.63; 95 % CI 3.26–4.00) was significantly higher compared to that of SPECT (2.76; 95 % CI 2.28–3.25; P = 0.006) and that of ECHO (2.83; 95 % CI 2.29–3.37; P = 0.02). There was no significant difference between the lnDOR of SPECT and ECHO (P = 0.52).

Conclusion

Our results suggest that MRI is superior for the diagnosis of obstructive CAD compared with ECHO and SPECT. ECHO and SPECT demonstrated similar diagnostic performance.

Key Points

• MRI can assess myocardial perfusion.

• MR perfusion diagnoses coronary artery disease better than echocardiography or SPECT.

• Echocardiography and SPECT have similar diagnostic performance.

• MRI can save coronary artery disease patients from more invasive tests.

• MRI and SPECT show evidence of publication bias, implying possible overestimation.

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-012-2434-1) contains supplementary material, which is available to authorized users.

[State of the art: new developments in cardiac imaging]

Cardiac imaging continues to reveal new anatomical and functional insights into heart disease. In echocardiography, both transesophageal and transthoracic three-dimensional imaging have been fully developed and optimized, and the value of the techniques that have increased our understanding of cardiac mechanics and ventricular function is well established. At the same time, the healthcare industry has released new devices onto the market which, although they are easier to use, have limitations that restrict their use for routine assessment. Tomography's diagnostic and prognostic value in coronary artery disease continues to increase while radiation exposure becomes progressively lower. With cardiac magnetic resonance imaging, myocardial injury and recovery in ischemic heart disease and following acute coronary syndrome can be monitored in exquisite detail. The emergence of new combined tomographic and gamma camera techniques, exclusively developed for nuclear cardiology, have improved the quality of investigations and reduced radiation exposure. The hybrid or fusion images produced by combining different techniques, such as nuclear cardiology techniques and tomography, promise an exciting future.

Rapid Detection of Coronary Artery Stenoses With Real-Time Perfusion Echocardiography During Regadenoson Stress

Background—

Real-time myocardial contrast echocardiography permits the detection of myocardial perfusion abnormalities during stress echocardiography, which may improve the accuracy of the test in detecting coronary artery stenoses. We hypothesized that this technique could be used after a bolus injection of the selective A2A receptor agonist regadenoson to rapidly and safely detect coronary artery stenoses.

Methods and Results—

In 100 patients referred for quantitative coronary angiography, real-time myocardial contrast echocardiography was performed during a continuous intravenous infusion of 3% Definity at baseline and at 2-minute intervals for up to 6 minutes after a regadenoson bolus injection (400 μg). Myocardial perfusion was assessed by examination of myocardial contrast replenishment after brief high mechanical index impulses. A perfusion defect was defined as a delay (>2 seconds) in myocardial contrast replenishment in 2 contiguous segments. Wall motion was also analyzed. The overall sensitivity/specificity/accuracy for myocardial perfusion analysis in detecting a >50% diameter stenosis was 80%/74%/78%, whereas for wall motion analysis it was 60%/72%/66% ( P <0.001 for differences in sensitivity). Sensitivity for myocardial perfusion analysis was highest on images obtained during the first 2 minutes after regadenoson bolus ( P <0.001 compared with wall motion), whereas wall motion sensitivity was highest at the 4-to-6–minute period after the bolus. No significant side effects occurred after regadenoson bolus injection.

Conclusions—

Regadenoson real-time myocardial contrast echocardiography appears to be a feasible, safe, and rapid noninvasive method for the detection of significant coronary artery stenoses.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT0087369.

Ischemic heart disease: comprehensive evaluation by cardiovascular magnetic resonance

Considerable technical advances over the past decade have increased the clinical application of cardiovascular magnetic resonance (CMR) imaging. A comprehensive CMR examination can accurately measure left and right ventricular size and function, identify the presence and extent of reversible versus irreversible myocardial injury, and detect inducible ischemia. Streamlined protocols allow such a CMR examination to be a time-efficient diagnostic tool in patients with coronary artery disease. Moreover, edema imaging with T2-weighted CMR allows the detection of acute coronary syndromes. In this review, we present the relevant CMR methods and discuss practical uses of CMR in acute and chronic ischemic heart disease.