PROJECT SUMMARY Coronary Heart Disease (CHD), the leading cause of death among cardiovascular diseases, affects millions of Americans. It is of paramount clinical significance to deliver rapid and accurate CHD diagnosis. Echocardiography provides safe, cost-effective, reproducible, and real-time heart assessment which makes echocardiography a first-line cardiac imaging modality and is routinely used in clinic for CHD evaluation. However, during echocardiography diagnosis, inadequate heart visualization often occurs in obese patients with high Body Mass Index (i.e., BMI ≥ 30 kg/m2). Clinicians commonly employ contrast echocardiography in these patients to improve heart imaging quality. However, contrast echocardiography requires low incident acoustic pressure to avoid contrast microbubble disruption, resulting in unreliable heart assessment in deeper regions. Consequently, CHD can be inaccurately evaluated in obese patients. To fill this gap, a novel long-coded pulse (LCP) sequence has been recently developed by our group with significantly improved contrast and penetration over current state-of-the-art contrast-enhanced ultrasound (CEUS) imaging methods. We will continue this work and propose two specific aims in this study: Specific Aim 1: Advance and optimize the long-coded pulse (LCP) sequence for CEUS echocardiography. Our preliminary work shows significantly improved contrast (+47%) between the left ventricle and the myocardial wall, which allows more accurate endocardial border delineation. This improvement demonstrates the LCP's potential for enhanced heart assessment during CEUS echocardiography. The LCP sequences will be further developed, enhanced, and optimized for CEUS echocardiography to pave the way for clinical study in Aim 2. Specific Aim 2: Conduct a pilot clinical study on coronary heart disease patients using the LCP-CEUS methods. We will recruit 33 CHD patients (BMI ≥ 30 kg/m2) to assess the efficacy of LCP as compared with state-of-the-art CEUS pulse sequences for improving endocardial border delineation in obese patients. Successful completion of the project will lead to a novel contrast echocardiography method for safe, cost-effective, and more reliable assessment for coronary heart disease in obese patients.