The guidelines, which are currently out for public consultation, recommend the use of Aquilion ONE (Toshiba Medical Systems), Brilliance iCT (Philips Healthcare), Discovery CT750 HD (GE Healthcare), and Somatom Definition Flash (Siemens AG Healthcare) for first-line imaging and evaluation.
Based on a comparison with earlier-generation equipment, the study provides an assessment of diagnostic accuracy, impact on patient outcomes, and cost effectiveness.
The primary focus of this evaluation is to assess the diagnostic accuracy, effect on patient outcomes and cost effectiveness of new-generation CT equipment
Currently there are around 40 of the latest models in use in the NHS England, and the report suggests better optimisation of these existing machines over the coming years, and advises trusts aiming to replace equipment to consider upgrading.
It states: “New-generation CT scanners have a variety of enhancements compared with earlier-generation CT scanners. It is claimed that the new-generation scanners can better detect coronary artery stenosis in people with suspected or known coronary artery disease in whom imaging is difficult with earlier generation equipment. New generation CT scanners can image with greater speed and reduced radiation dose.
“The primary focus of this evaluation is to assess the diagnostic accuracy, effect on patient outcomes and cost effectiveness of new-generation CT equipment in adults with suspected coronary disease in whom imaging with earlier generation CT is difficult and with a 10-29% pre-test likelihood of coronary artery disease; and adults with known coronary artery disease in whom imaging with earlier generation CT is difficult and in whom revascularisation is being considered.”
CT imaging with earlier models can prove particularly challenging where patients are obese, have a calcium score above 400, suffer from arrhythmia, have high heart rates than cannot be lowered with medication, have had stents fitted, or have had previous bypass grafts.< Currently figures estimate that 2.6 million people in the UK have coronary artery disease, with two million showing symptoms of angina. If the estimated number of people with a high heart rate and intolerance to beta blockers is included, the number of people in England alone with coronary artery disease in whom imaging with earlier-generation CT scanners could prove difficult could be as high as 18 million.
It is claimed that the new-generation scanners can better detect coronary artery stenosis in people with suspected or known coronary artery disease in whom imaging is difficult with earlier generation equipment
Based on the findings of the study, the recommendations state: “The health economic analysis showed that in people with suspected coronary artery disease, using new-generation cardiac CT scanners instead of invasive coronary angiography may be considered more appropriate. For investigating suspected coronary artery disease, new-generation CT scanner only was the most cost-effective strategy when compared with new generation CT scan plus invasive coronary angiograph for those with positive CT scans.
“The committee concluded that, based on the results of the assessment carried out by the external assessment group, new-generation cardiac CT scanners should be recommended for first-line imaging of coronary arteries in people with suspected stable coronary artery disease whose estimated likelihood of coronary artery disease is 10-29% and for first-line evaluation in people with known coronary artery disease in whom imaging is difficult.”
ABOUT THE SYSTEMS:
Aquilion ONE: This is a 640-slice CT scanner with 320×0.5mm detector rows giving z-axis coverage of 160mm. This specification allows the imaging of whole organs in a single non-helical rotation. For example, an image of the heart can be captured within a single heartbeat. As well as reducing the examination time, the radiation and the contrast dose are also reduced
Brilliance iCT: This is a new-generation 256-slice multi-detector CT scanner with 128×0.625mm detector rows providing total z-axis coverage of 80mm. Each detector row is double sampled to increase spatial resolution. It is claimed it can capture an image of the heart in two heart beats
Discovery CT750 HD: This is a 2×64-slice dual-energy CT scanner with a single X-ray source that switches between two energy levels, allowing two data sets – high energy and low energy – to be acquired simultaneously. It uses a Gemstone detector that contributes to high image quality, and a prospectively gated axial scanning technique called SnapShot Pulse, which allows a complete picture of the heart to be captured in three or four ‘snapshots’ taken at precise table positions and timed to correspond to a specific phase of the cardiac cycle
Somatom Definition Flash: The Somatom Definition Flash is a second-generation dual-source 128-slice CT scanner designed to provide high resolution images at a fast scanning speed with low dose radiation. It has two X-ray tubes and two detector arrays mounted at 95° to each other. With a maximum scan speed of 458mm/s, it may be of benefit for use with people who cannot remain still or who have difficulty holding their breath. The scanner also uses different strategies to reduce the radiation dose associated with imaging
