Novel Cardiac MRI techniques for the diagnosis of coronary artery disease compared to PET imaging and Invasive Coronary Angiography.

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Coronary artery disease (CAD) is the second most common cause of death in the UK and it is very important to identify patients who have CAD early so that prevention can be started before a heart attack occurs. A wide range of tests are used to detect CAD. Coronary angiography is routinely used in the NHS, and without extra flow measurements, we do not know how important CAD is. Heart scans can be used to detect important CAD including a scan that uses radioactive dye, ultrasound or cardiac MRI (CMR) which are interpreted by simply looking at images on a computer console. This visual interpretation is generally accurate but even with well trained individuals, scan reporters can differ in their interpretation especially in cases where there is such widespread CAD that the test may be appear normal. We can measure the heart's blood flow with heart scans and the best method to do this is with Positron Emission Tomography (PET). This is better than visual inspection in identifying heart disease, can help with predicting the risk of a heart attack and other health hazards and help doctors decide which patients to treat with heart surgery. Unfortunately PET scanning is expensive (over £2,000 per scan), not available widely and uses potential harmful ionising radiation.CMR can be used to measure the heart's blood flow. It has a major advantage over PET because it is much cheaper (around £500), more widely available and is safer as no harmful radiation is used. In previous research studies (the largest one performed at King's College London), blood flow measurements with PET and CMR were compared and found to be similar but not to agree perfectly. This study had some important limitations, as patients were scanned using separate CMR and PET scanners, on different days and separate analysis. Therefore, there has yet to be a conclusive comparison of PET and CMR blood flow measurements.ADVANCES IN TECHNOLOGY- We are privileged to have a 'hybrid PET-MR scanner', only the second one in the UK, which is able to perform PET and CMR scans at the same time. This scanner allows us to perform heart blood flow measurements at exactly the same time with PET and CMR and therefore allows a true head on comparison of the tests. This will help us to determine with more certainty if CMR is as good as PET for measuring the heart's blood flow. - We have developed a new method to measure the heart's blood flow which is very accurate in animal and flow model studies but we need to test this in humans.- Measuring blood flow is cumbersome and time-consuming with CMR and can take several hours even for an expert. We have developed an automated software to perform this which may be used for routine clinical diagnosis at point of care in the NHS.AIMI aim to test if CMR can be a cheaper, more widely available and safer alternative to PET. If proven to be comparable, automated CMR tools can be readily translated to clinical practice across the UK to enhance diagnosis of CAD. I will compare blood flow measured with PET and CMR using a novel hybrid PET-MR scanner and novel CMR techniques in patients with heart disease. We will compare blood flow measurements with novel CMR with findings with coronary angiography. METHODS-10 healthy volunteers without heart disease will undergo a PET-MR scan to measure blood flow with PET and CMR at the same time. This will allow us to test the method in humans.-77 patients who are scheduled for an angiogram will have a PET-MR scan of their heart . We will compare blood flow measurements with CMR, PET and presence of CAD with coronary angiography.We hope to get a better understanding of the heart's blood flow and test if this CMR tool is as good as PET and angiography. This will be helpful to patients as CMR is safe, non-invasive and does not use radiation. This tool may help doctors treat patients better by guiding doctors on which patients needs medications, stents or heart surgery.