Patients with Syndrome X have normal myocardial oxygenation and perfusion compared to normal volunteers: a 3 Tesla cardiovascular magnetic resonance imaging study by Neubauer Stefan, Robson Matthew D, Howells Ruairidh K, Francis Jane, Pegg Tammy J, Arnold Ranjit, Karamitsos Theodoros D, Jerosch-Herold Michael, Selvanayagam Joseph B