Aquilion PRIME CT scanner for imaging coronary artery disease in adults in whom imaging is difficult

About the technology

Costs and use of the technology

According to the manufacturer, the Aquilion PRIME typically costs between £350,000 and £500,000, excluding VAT, depending on the options added to the core system at the time of purchase or added any time thereafter. The lifespan of a CT scanner is 7–10 years (Clinical Imaging Board 2015). Irrespective of the capital cost, the nationally representative unit cost for a cardiac CT scan including labour time, overheads and consumables is £259 (Department of Health 2014, code RA68Z).

Training to use the Aquilion PRIME system is provided free of charge by the manufacturer.

Other diagnostic procedures used in the chest pain pathway include invasive coronary angiography (ICA), magnetic resonance imaging (MRI), single photon computed emission tomography (SPECT) and stress echocardiography (ECHO). The ICA procedure has a unit cost of £1,241 (NHS 2014/15 National tariff payment system, code EA36A). An outpatient cardiac MRI scan inclusive of contrast medium costs £527 (Department of Health 2014, code RA66Z). The unit cost for SPECT is £220 (NHS 2014/15 National tariff payment system, code RA37Z). The unit cost for stress ECHO is £74 (NHS 2014/15 National tariff payment system, code RA60Z).

CT scanner technologies need specific infrastructure and equipment, as well as suitably trained radiographic and radiological staff. There are no particular practical difficulties in using or adopting the Aquilion PRIME.

Likely place in therapy

The Aquilion PRIME would be used to perform cardiac CT imaging in adults (aged 18 years and over) with suspected CAD in whom imaging with earlier generation CT is difficult and who have an estimated likelihood of CAD of 10–29%, or known CAD in whom imaging with earlier generation CT is difficult and for whom revascularisation is being considered. The scanner may also be used to perform CTCA in people with stable angina whose symptoms are not satisfactorily controlled with medical treatment.

The Aquilion PRIME can also be used for other clinical imaging applications in adults and children.

Specialist commentator comments

One commentator stated that although CTCA is predominantly used to rule out CAD in people with an estimated likelihood of 10–29% of having the disease, it can also be used as a rule‑in test to confirm CAD in people at moderate risk (30–60%). The commentator said that, in practice, people at low, moderate and intermediate risk (10–90%) of CAD have CTCA. People at moderate risk with no sign of disease on CTCA do not have further investigations, whereas people with signs of disease are assessed further using functional imaging, the choice of which will depend on their individual circumstances. The NICE clinical guideline on the assessment and diagnosis of chest pain of recent onset recommended other forms of imaging such as SPECT, ECHO or MRI, or ICA for higher‑risk groups.

Two specialist commentators emphasised the capability of the Aquilion PRIME to scan people with obesity. One stated that the scanner has a larger bore than previous models and has the option of a bariatric table that can support a larger person. Both commentators noted that larger people need higher volumes of contrast medium or higher injection rates. One specialist commentator added that this must be balanced with the advantage of better contrast that can be obtained at lower kV levels, because lowering the kV for people with obesity can result in added image noise and affects the quality of the images. The commentator believed that the ^SUREkV software had the potential to automatically standardise 1 of the imaging parameters based on patient size. Another commentator noted that the automated software tends to use higher kV in people with larger body masses. One commentator did not consider that AIDR 3D iterative reconstruction could reduce the amount of contrast medium or minimise artefacts for people with obesity or grafts.

One specialist commentator stated that the Aquilion PRIME does not have specific features that address the problems posed by people with high coronary calcium.

Because of the range of available CT scanners that are capable of assessing people with bypass grafts, 1 commentator did not believe people with previous bypass grafts were difficult to image. A second commentator noted that non‑invasive imaging of the grafts is often desirable before ICA, because ICA can be challenging in this group.

One specialist commentator said that the arrhythmia detection employed by the Aquilion PRIME, including ^SURECardio software, is useful for people with ectopic beats (extra heartbeats) but does not address the difficulties of scanning people with atrial fibrillation. More advanced CT scanners, such as the Toshiba Aquilion ONE (which only needs a single heartbeat for image acquisition), are preferable for obtaining clear images of people with atrial fibrillation. The commentator also noted that the Aquilion PRIME does not have as high an intrinsic temporal resolution as dual‑source CT scanners or other scanners with higher tube rotation times. They noted that the retrospectively gated mode with segmented reconstruction can be used for high (regular) heart rates, but that the use of beta blockers to lower and control heart rate remains essential for best‑quality images at the lowest radiation doses, as with most coronary CT. They also noted that the optimal temporal resolution is only possible with retrospective ECG‑gating and multi‑segment reconstructions with a higher dose, increasing the possibility of movement artefacts. Finally, the commentator stated that stent visualisation is better in scanners that are more advanced than Aquilion PRIME, particularly where multiple stents may cross acquisition boundaries in prospective scanning. Another specialist commentator noted that using medication to lower heart rate has implications for people who are unable to take or tolerate beta‑blockers.

According to 1 specialist commentator, a scanner lifespan of 7 years is a long time given the rapid rate of technology evolution. The commentator also said that the nationally representative unit cost (which does not account for capital cost) underestimates the cost of advanced cardiac CT scanning in complex cases, which need more advanced (and expensive) hardware.

One specialist commentator noted that the NICE clinical guideline on the assessment and diagnosis of chest pain of recent onset was under review at the time they provided their comments, and that the NICE diagnostics guidance on new generation cardiac CT scanners is out of date because several of the models from the guidance have been superseded and are no longer available.

Two specialist commentators noted that there are currently more advanced scanners on the market that can address clinical challenges for all subgroups of people who are difficult to image. These include the Toshiba Aquilion ONE Vision, Siemens Somatom Force, Philips IQon and the GE Revolution.One of the commentators explained that Aquilion PRIME is a mid‑range scanner, similar to Siemens Definition AS+ and GE Revolution GSI/HD. The same commentator noted that dual‑source scanners have different technological solutions but are not necessarily superior to single‑source scanners for all applications. They stated that their overall impression is that the Toshiba Aquilion PRIME is an excellent general CT scanner that can produce high‑quality cardiac/coronary images, especially in people with low steady heart rates and good breath‑hold capability. It has advantages over previous generation scanners in its ability to scan people with obesity, better image quality and a significant reduction in radiation doses with the advanced iterative reconstruction. However, they added that if the purpose of buying a CT scanner is to scan people who are difficult to image (including those with arrhythmia, poor breath‑hold ability and coronary stents), it would be advisable to buy a more advanced CT scanner that significantly simplifies the scanning procedure and is more robust and 'future‑proof'. The commentator suggested that this might include those with broad detector arrays (16 cm) such as the Toshiba Aquilion ONE series or GE Revolution. This point was reiterated by another specialist commentator, who stated that, in practice, the latest CT technology would offer more image improvement and dose‑saving capability, and thus be suitable for use in everyone, including those in whom imaging is difficult.

Equality considerations

NICE is committed to promoting equality, eliminating unlawful discrimination and fostering good relations between people with particular protected characteristics and others. In producing guidance, NICE aims to comply fully with all legal obligations to:

People with diabetes or obesity may be considered to be disabled under the Equality Act if these conditions have a substantial and long‑term adverse effect on their ability to carry out normal day‑to‑day activities. Disability is a protected characteristic defined in the Equality Act 2010.