Cardiac magnetic resonance (MR) is increasingly replacing diagnostic cardiac catheterisation as a method of assessing cardiac anatomy,¹ measuring blood flow,² and quantifying ventricular function,³ particularly in patients with congenital heart disease. However, diagnostic cardiac catheterisation remains important when measurement of cardiac or vascular pressures is required.⁴ Patients with pulmonary hypertension, which is characterised by increased pulmonary vascular resistance (PVR), often undergo multiple x ray guided cardiac catheterisations to assess prognosis and response to medical intervention.⁴ Performing such diagnostic cardiac catheterisation procedures under MR guidance has a number of potential benefits, described by Kuehne and colleagues⁵ in this issue of Heart.⁵ MR guided cardiac catheterisation has been a scientific and technical challenge, with a number of groups trying to demonstrate its feasibility in the last few years. The driving force behind this work comprises the potential benefits of this technique, including reduced x ray dose and acquisition of more accurate physiological information.

MR GUIDED CARDIAC CATHETERISATION

To make MR guided cardiac catheterisation a reality, there is a need to be able to visualise the catheter within cardiovascular structures in real time. This requires fast imaging, which has become possible because of recent developments in MR hardware and software. Cardiac gated steady state free precession (SSFP) sequences, which benefit from high signal to noise ratio, good blood pool myocardial contrast, and high spatiotemporal resolution, have become the mainstay of cardiac MR. Martin and colleagues⁶ showed that using real time, non-gated SSFP endovascular devices could be easily “passively” visualised. Passive catheter visualisation relies on inherent properties of the catheter to provide …