Three-dimensional magnetic resonance imaging of congenital cardiac anomalies 1
We describe a new method of three-dimensional magnetic resonance imaging of the heart that has been used to produce high quality diagnostic images in 274 patients with congenital cardiac disease, ranging in age from 1 day to 66 years. Using a steady state free precession gradient echo technique and parallel imaging, rapid acquisition of the entire cardiac volume is possible during 8 to 15 sequential breath-holds, each lasting between 8 and 15 s. We obtained high-resolution images, with a resolution of 1 mm3, at between 3 and 10 phases of the cardiac cycle.
While images of diagnostic quality were obtained in all cases, in 52 patients there was some degradation due to various factors. Children under 8 years were ventilated, and ventilation was suspended for the breath-holds. For patients breathing spontaneously a novel respiratory navigator technique was developed, using a navigator echo placed over the right hemidiaphragm. This was used successfully in 20 patients, and reduced the misalignment of images obtained during different breath-holds.
Images were analysed using multi-planar reformatting and volume rendering. Image processing took approximately five minutes for each study. End-diastolic images were processed for all patients. Systolic images were also processed in selected cases.
Further improvements in parallel imaging should reduce imaging times further, so that it is possible to obtain the full volume image in a single breath-hold. This will enable imaging of complex anatomy to be obtained using a standard imaging protocol that does not require the operator to understand the cardiac malformation, making the magnetic resonance imaging of congenital cardiac disease faster and more effective.(Accepted May 14 2003)
Key Words: Magnetic resonance imaging; cardiac anomalies; cardiology.
c1 Correspondence to: Dr Reza Razavi, Director of Cardiac MRI, Division of Imaging Sciences, King's College London, 5th Floor Guy's Tower, Guy's Hospital, London SE1 9RT, UK. Tel: +44 20 7955 4531; Fax: +44 20 7955 4532; E-mail: email@example.com
1 Sources of funding: Higher Education Funding Council for England Joint Research Equipment Initiative, Evelina Children's Heart Fund and the Charitable Foundation of Guy's and St Thomas Trust.