Non-invasive coronary imaging: computed tomography or magnetic resonance imaging?
- Correspondence to:
Dr Charles Peebles, Wessex Cardiothoracic Centre, Southampton General Hospital, Tremona Road, Southampton SO16 6YD, UK;
- CT, computed tomography
- EBCT, electron beam computed tomography
- CMR, cardiac magnetic resonance imaging
- IVUS, intravascular ultrasound
- MSCT, multislice computed tomography
Non-invasive coronary artery imaging has taken a significant step forward with the advent of multislice computed tomography
Non-invasive coronary imaging has recently seen a rapid expansion of interest, fuelled largely by technical advances in both computed tomography (CT) and cardiac magnetic resonance imaging (CMR). The race is on for these two modalities to provide routine and robust imaging of coronary arteries in clinical practice.
The rate of this progress has inevitably provided a bewildering array of developments, which are hard to stay abreast of. This article will attempt to clarify the fundamental differences between the available techniques, explore their respective capabilities, and discuss future potentials.
ELECTRON BEAM COMPUTED TOMOGRAPHY (EBCT)
EBCT has been the CT method of choice for imaging the heart for the last 10 years or more. Unlike conventional CT, which uses a rotating x ray tube, EBCT uses a static row of detectors and a moving beam of electrons to produce the x ray photons. The advantage of this is a rapid image acquisition time of 50–100 ms per slice. When combined with ECG triggering this allows imaging of a motion free heart during diastole (usually 80% of the RR interval).1 This technique has been used to quantify coronary calcium burden and more recently to perform contrast enhanced coronary angiography.2,3 The disadvantages of EBCT are the poor signal-to-noise ratio and increased slice thickness compared with conventional CT, the lack of general availability of EBCT, and the radiation dose compared to CMR.
MULTISLICE COMPUTED TOMOGRAPHY (MSCT)
Also known as multidetector CT, these scanners are a development from single slice helical (or spiral) CT. A single rotating x ray tube provides a beam of photons that is then received by several rows of detectors (usually four), effectively giving four axial slices for each tube rotation. There are now scanners available that allow eight or 16 …