Qualitative and Quantitative Real Time Myocardial Contrast Echocardiography for Detecting Hibernating Myocardium

Enhancing Prediction of Myocardial Recovery After Coronary Revascularization: Integrating Radiomics from Myocardial Contrast Echocardiography with Machine Learning

Introduction

Chronic coronary artery disease (CAD) management often relies on myocardial contrast echocardiography (MCE), yet its effectiveness is limited by subjective interpretations and difficulty in distinguishing hibernating from necrotic myocardium. This study explores the integration of machine learning (ML) with radiomics to predict functional recovery in dyskinetic myocardial segments in CAD patients undergoing revascularization, aiming to overcome these limitations.

Methods

This prospective study enrolled 55 chronic CAD patients, dividing into training (39 patients, 205 segments) and testing sets (16 patients, 68 segments). Dysfunctional myocardial segments were identified by initial wall motion scores (WMS) of ≥2 (hypokinesis or higher). Functional recovery was defined as a decrease of ≥1 grade in WMS during follow-up echocardiography. Radiomics features were extracted from dyssynergic segments in end-systolic phase MCE images across five cardiac cycles post- "flash" impulse and processed through a five-step feature selection. Four ML classifiers were trained and compared using these features and MCE parameters, to identify the optimal model for myocardial recovery prediction.

Results

Functional improvement was noted in 139 out of 273 dyskinetic segments (50.9%) following revascularization. Receiver Operating Characteristic (ROC) analysis determined that myocardial blood flow (MBF) was the most precise clinical predictor of recovery, with an area under the curve (AUC) of 0.770. Approximately 1.34 million radiomics features were extracted, with nine features identified as key predictors of myocardial recovery. The random forest (RF) model, integrating MBF values and radiomics features, demonstrated superior predictive accuracy over other ML classifiers. Validation of the RF model on the testing dataset demonstrated its effectiveness, evidenced by an AUC of 0.821, along with consistent calibration and clinical utility.

Conclusion

The integration of ML with radiomics from MCE effectively predicts myocardial recovery in CAD. The RF model, combining radiomics and MBF values, presents a non-invasive, precise approach, significantly enhancing CAD management.

A novel application of pulmonary transit time to differentiate between benign and malignant pulmonary nodules using myocardial contrast echocardiography

Malignant pulmonary nodules (PNs) are often accompanied by vascular dilatation and structural abnormalities. Pulmonary transit time (PTT) measurement by contrast echocardiograghy has used to assess the cardiopulmonary function and pulmonary vascular status, such as hepatopulmonary syndrome and pulmonary arteriovenous fistula, but has not yet been attempted in the diagnosis and differential diagnosis of PNs. The aim of this work was to evaluate the feasibility and performance of myocardial contrast echocardiography (MCE) for differentiating malignant PNs from benign ones. The study population consisted of 201 participant: 66 healthy participants, 65 patients with benign PNs and 70 patients with malignant PNs. Their clinical and conventional echocardiographic characteristics were collected. MCE with measurements of PTT were performed. There was no difference in age, sex, heart rate, blood pressure, smoking rate, background lung disease, pulmonary function, ECG, myocardial enzymes, cardiac size and function among the healthy participant, patients with benign and malignant PNs (P > 0.05). PTT did not differ significantly in patients with PNs of different sizes, nor did they differ in patients with PNs of different enhancement patterns (P > 0.05). However, the PTT were far shorter (about one half) in patients with malignant PNs than in patients with benign ones (1.88 ± 0.37 vs. 3.73 ± 0.35, P < 0.001). There was no significantly different between patients with benign PNs and healthy participant (3.73 ± 0.35 vs.3.89 ± 0.36, P > 0.05). The area under the receiver operating characteristics curve (AUC) of PTT was 0.99(0.978-1.009) in discriminating between benign and malignant PNs. The optimal cutoff value was 2.78 s, with a sensitivity of 98.52%, a specificity of 97.34%, and a accuracy of 97.69%. MCE had a powerful performance in differentiating between benign and malignant PNs, and a pulmonary circulation time of < 2.78 s indicated malignant PNs.

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.

Value of Low-Dose Dobutamine Stress Real-Time Myocardial Contrast Echocardiography in the Diagnosis of Coronary Heart Disease

To investigate the value of low-dose dobutamine stress real-time myocardial contrast echocardiography (RT-MCE) in the diagnosis of coronary heart disease (CHD). A total of 65 hospitalized patients with suspected or confirmed CHD were detected by RT-MCE combined with low-dose dobutamine stress (0.84 mg/kg). Perfusion curves were quantitatively analyzed using QLAB software. Peak intensity (A), slope of curves (β), and perfusion (A × β) were also calculated. Based on the results of coronary angiography, patients were divided into no obvious stenosis group (<50%), mild stenosis group (50%-74%), moderate stenosis group (75%-89%), and severe stenosis group (≥90%). The A, β, and A × β values before and after low-dose dobutamine stress of each group were compared. In the basal state and after low-dose dobutamine stress, the A, β, and A × β values significantly decreased as the stenosis degree of the myocardial segments increased. The same variation tendency was also found in the A, β, and A × β reserve values, and there was significant difference in these reserve values between moderate and severe stenosis groups and no obvious stenosis and mild stenosis groups. Collateral circulation had marked effects on the values of myocardial perfusion parameters and their reserve values, especially in the segments with severe stenosis. Low-dose dobutamine stress RT-MCE can be a sensitive method for clinical diagnosis and risk assessment of CHD and may provide a basis for further treatment of CHD.

The myocardial ischemia evaluated by real-time contrast echocardiography may predict the response to cardiac resynchronization therapy: a large animal study

Evidence-based criteria for applying cardiac resynchronization therapy (CRT) in patients with ischemic cardiomyopathy are still scarce. The aim of the present study was to evaluate the predictive value of real-time myocardial contrast echocardiography (RT-MCE) in a preclinical canine model of ischemic cardiomyopathy who received CRT. Ischemic cardiomyopathy was produced by ligating the first diagonal branch in 20 beagles. Dogs were subsequently divided into two groups that were either treated with bi-ventricular pacing (CRT group) or left untreated (control group). RT-MCE was performed at baseline, before CRT, and 4 weeks after CRT. Two-dimensional speckle tracking imaging was used to evaluate the standard deviation of circumferential (Cir12SD), radial (R12SD), and longitudinal (L12SD) strains of left ventricular segments at basal as well as middle levels. Four weeks later, the Cir12SD, R12SD, and myocardial blood flow (MBF) of the treated group were significantly improved compared to their non-CRT counterparts. Furthermore, MBF values measured before CRT were significantly higher in responders than in non-responders to bi-ventricular pacing. Meanwhile, no significant differences were observed between the responder and non-responder groups in terms of Cir12SD, R12SD, and L12SD. A high degree of correlation was found between MBF values before CRT and LVEF after CRT. When MBF value>24.9 dB/s was defined as a cut-off point before CRT, the sensitivity and specificity of RT-MCE in predicting the response to CRT were 83.3% and 100%, respectively. Besides, MBF values increased significantly in the CRT group compared with the control group after 4 weeks of pacing (49.8±15.5 dB/s vs. 28.5±4.6 dB/s, p<0.05). Therefore, we considered that myocardial perfusion may be superior to standard metrics of LV synchrony in selecting appropriate candidates for CRT. In addition, CRT can improve myocardial perfusion in addition to cardiac synchrony, especially in the setting of ischemic cardiomyopathy.

Role of viability imaging in the post-STICH era

PURPOSE OF REVIEW

Recent results from prospective randomized controlled trials examining the management of patients with ischemic cardiomyopathy (ICM) have questioned both the added value of revascularization over contemporary optimal medical therapy (OMT) and the use of viability testing as a gate-keeper to revascularization. The purpose of this review is to summarize recent trial evidence before discussing future perspectives in the field.

RECENT FINDINGS

The Surgical Treatment of Ischemic Heart Failure (STICH) trial, PPAR-2 trial and Heart Failure Revascularisation Trial have all reported their results within the past 5 years. None of these trials found revascularization superior to OMT in improving survival of ICM patients. Additionally, the STICH trial's viability substudy suggested that pretreatment viability testing was not beneficial.

SUMMARY

ICM patients remain a clinical conundrum. The numerous limitations of the recent RCTs have led to uncertainty about optimal management. Revascularization continues to be offered to patients with evidence of myocardial viability. Further studies are required to answer the outstanding questions in the management of patients with ICM.

Effect of graft patency on the prediction of myocardial viability by dobutamine stress and myocardial contrast echocardiography before coronary artery bypass surgery

BACKGROUND

Myocardial functional recovery after revascularization is considered the "gold standard" for myocardial viability (MV) assessment. However, the patency of the revascularized coronary artery affects myocardial functional recovery in patients subjected to coronary artery bypass grafting (CABG). The influence of graft patency on viability results has not been widely studied.

PURPOSE

We evaluated the effect of graft patency on the prediction of MV after CABG by myocardial contrast echocardiography (MCE) and low-dose dobutamine stress echocardiography (LD-DSE).

METHODS

Fifty-three subjects with chronic ischemic heart disease scheduled for CABG were divided randomly into groups A (n = 26) and B (n = 27). They underwent MCE and LD-DSE preoperatively. Patients were followed up 12 months after CABG. Group B patients underwent multislice computed tomography angiography to assess CABG patency, and patients with obstructed grafts were excluded. Group A patients were not subjected to multislice CT angiography. The accuracy of MCE and LD-DSE for assessing MV between the two groups was compared.

RESULTS

The accuracy and positive predictive values of MCE and LD-DSE for predicting MV were higher in group B than in group A (p < 0.05).

CONCLUSIONS

Preoperative LD-DSE and MCE ability to predict MV depends on the patency of CABG.

Quantitative evaluation of contrast-enhanced ultrasonography in the diagnosis of chronic ischemic renal disease in a dog model

Objectives

The aim of this feasibility study was to prospectively explore in a dog model of chronic ischemic renal disease (CIRD) the hypothesis that real-time contrast-enhanced ultrasonography (CEUS) can quantitatively evaluate the early perfusion changes of renal cortex.

Materials and Methods

In this animal care and use committee-approved study, the model of CIRD was carried out in healthy dogs (10.0∼12.0 kg, n = 5), by placing the Ameroid ring constrictors on the distal portion of right renal artery through operation. CEUS monitoring of right kidney perfusion was performed by intravenous bolus injection of 0.6 ml Sulfur hexafluoride filled microbubbles (SonoVue; Bracco S.P.A., Milan, Italy) every week after operation. The slope rate of ascending curve (A) and descending curve (α), area under curve (AUC), derived peak intensity (DPI), and time to peak (TTP) were measured in renal cortex using commercial quantification software (Q-LAB version 6; Philips Medical Systems, Bothell,WA,USA). The sensitivity of CEUS was compared with blood serum urea nitrogen (BUN) and serum creatinine (SCr) level.

Results

With the progression of CIRD, dogs showed delayed enhancement and perfusion in renal CEUS curve. Earliest significant changes happened 4 weeks after operation on DPI and TTP which changed from 13.04±2.71 to 15.58±4.75 dB and 9.03±2.01 to 10.62±6.04 sec, respectively (P<.05).

Conclusions

CEUS can display the perfusion changes of CIRD in the early period.