Quantification of Myocardial Blood Flow Using Dynamic PET/CTA Fused Imagery

Study Overview
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Brief Summary
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This observational prospective clinical study is to develop software tools to fuse coronary anatomy data obtained from CT coronary angiography with dynamic PET data to noninvasively measure absolute myocardial blood flow, flow reserve and relative flow reserve across specific coronary lesions. Results will be compared to those obtained invasively in the catheterization laboratory.

Detailed Description
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This observational prospective clinical study is to develop software tools to fuse coronary anatomy data obtained from CT coronary angiography with dynamic PET data to noninvasively measure absolute myocardial blood flow, flow reserve and relative flow reserve across specific coronary lesions. These results will be compared to those obtained invasively in the catheterization laboratory. The long-term objective of the study is to improve the care of cardiac patients by developing, validating and implementing clinically computer-based methods to noninvasively determine the physiological significance of specific coronary lesions using methods to fuse and quantify multi-modality cardiac imagery.

Official Title
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Quantification of Myocardial Blood Flow Using Dynamic PET/CTA Fused Imagery to Determine the Physiological Significance of Specific Coronary Lesions.

Conditions
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Coronary Artery Disease

Intervention / Treatment
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* Procedure: Invasive Cardiac Catheterization (ICA)
* Procedure: Coronary Computed Tomographic Angiogram (CCTA)
* Procedure: Dynamic Cardiac Positron Emission Tomography (dPET)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult (≥18 years of age) - as the research topic to be studied is irrelevant to children Written consent form Patients with prior dynamic PET or CCTA or ICA for any indications Exclusion Criteria: Previous history of allergy to iodinated contrast Previous CABG Serum creatinine levels >1.8 mg/dl unless patient has end stage kidney disease, not producing any urine and dialysis History of claustrophobia (CT tunnel length of more than 100 cm) Significant arrhythmias or tachycardia History of frequent asthma attacks or acting wheezing Second- and third-degree heart block Systolic blood pressure of < 90 mmHg Heart failure with NYHA class III-IV at the time of the CCTA procedure. If it is deemed that, the heart failure has been resolved or the patient was incorrectly labeled as having heart failure the radiology physician in charge will verify the absence of Heart Failure at the time of CCTA and perform the procedure. Recent myocardial infarction If the patient has been diagnosed with unstable angina within 24 hours prior to CCTA, the patient will not be consented. If the patient does not have the diagnosis of unstable angina and is consented, the radiology physician in charge will verify the absence of unstable angina at the time of CCTA. Patients enrolled and consented for the invasive measurements that at the time of catheterization exhibit severe vessel disease and/or obstructions that prevent the operator from safely conducting the measurements will be removed from the study; further research imaging sessions - if planned - will be canceled and patients indicated as screen failure in our enrollment log.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| CAD detection/risk assessment<br>Patients with angina referred for the assessment of CAD will undergo imaging studies to develop tools to fuse coronary anatomic data obtained from CCTA with dPET data to non-invasively measure absolute MBF, MFR and RFR along vessels centerlines and across coronary lesions. | Procedure: Invasive Cardiac Catheterization (ICA)<br>* Invasive functional measurements will be performed to assess the functional significance of specific lesions by means of FFR and CFR, and to test the presence of microvascular disease by means of IMR in all vessels for which the procedures are feasible. In summary, a 5- to 7-F guide catheter without side holes is used to engage the coronary artery and a pressure-temperature sensor-tipped guidewire introduced. The pressure sensor is positioned at the distal segment of a target vessel, and intracoronary nitroglycerine (100-200 mg) administered before each measurement. The best systolic and diastolic phase (located between 30-50%, and 60-75% of the cardiac cycle) will be selected for successive processing as it allows a relative motion free visualization of the main vessels and the myocardium.<br>Procedure: Coronary Computed Tomographic Angiogram (CCTA)<br>* Fasting patients will undergo a test for coronary calcium by CT; calcium scoring analysis will be done post image data acquisition using the manufacturer's software. Nitroglycerine will be administered in all patients (sublingual administration prior to CCTA initiation). CT acquisitions will be prospectively ECG-gated (30-80% of the cardiac cycle). The acquisition begins with a scout scan to identify the borders of the heart to minimize the field of view and exposure to the patient. A bolus of 60 mL nonionic contrast agent is then injected followed by 60 mL of saline at a rate of 4 mL/s to enhance signal from coronary arteries and blood chambers. In case of irregular heart rate, beta-blockers can be provided to keep optimal heart rate  65-70 bpm. Trans-axial images are reconstructed by means of a filtered back-projection algorithm.<br>Procedure: Dynamic Cardiac Positron Emission Tomography (dPET)<br>* Patients will be asked to fast for 24 hours prior to the test. Before the resting perfusion phase, a single low-dose CT-based transmission scan is acquired for attenuation correction (AC) of all subsequent acquisitions. AC-CT images are automatically registered to the perfusion images, visually verified and manually corrected if necessary. Resting perfusion imaging started with the intravenous injection of a single bolus of 82Rb. Pharmacological stress imaging is obtained after adenosine infusion (140 μg/kg/min) through a peripheral vein, followed by a second dose of 82Rb. Image reconstruction is achieved by means of ordered subset expectation maximization (OSEM) iterative method. The hemodynamic responses to rest/stress tests are collected in terms of mean heart rate, mean blood systolic pressures and diastolic at rest and stress. Dynamic, gated and ungated trans-axial reconstructions are saved in DICOM format for further analysis and processing.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Myocardial blood flow (MBF) measurement comparing non-invasive to the traditional approaches | Myocardial blood flow (MBF) measured in milliliters per minute per gram of tissue is providing unique pathophysiologic and diagnostic information on the function of the coronary macro- and microcirculation. | Up to 3 months | 
| Vessel-specific quantification of myocardial blood flow RFR | Ratio of absolute hyperemic MBFs (abnormal / normal) measured in mL/min/g. | Up to 3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Absolute myocardial blood flow (MBF) measurement comparing non-invasive to the traditional approaches | Absolute myocardial blood flow (MBF) measured in ml/min/gm provides incremental diagnostic and prognostic information over relative perfusion alone. | Up to 3 months | 
| Myocardial flow reserve (MFR) measurement comparing non-invasive to the traditional approaches | Myocardial flow reserve (MFR) provide incremental diagnostic and prognostic information over relative perfusion alone. | Up to 3 months | 
| Fractional Flow Reserve (FFR) measurement comparing non-invasive to the traditional approaches | FFR calculates the maximum flow down a vessel in the presence of stenosis compared to maximum flow in the hypothetical absence of the stenosis. | Up to 3 months | 
| Stress myocardial blood flow (sMBF)/Regional myocardial blood flow (rMBF) ratio | Stress myocardial blood flow (sMBF)/Regional myocardial blood flow (rMBF) ratio will be calculated | Up to 3 months | 
| Distal/proximal pressure ratio | Distal/proximal pressure ratio will be calculated | Up to 3 months | 
| Discriminatory power of dPET/CTA. And FFR(CTA) | Predictive discriminatory power of each technique will be compared to ICA (FFR) | Up to 3 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Fractional flow reserve, Myocardial blood flow, Relative flow reserve, Non-invasive measure, Cardiac catheterization, CT coronary angiography, Dynamic PET, Invasive coronary angiography, 3D fusion dPET/CTA, FFRCT