Cardiovascular imaging

Standardised protocol reduces radiation from coronary CT

Non-invasive cardiac computed tomography angiography (CCTA) is increasingly used for the detection of coronary artery disease. However, a significant dose of ionising radiation is used and this has led to concern about the use of this diagnostic modality.

Raff et al introduced a best-practice model for coronary CT scan acquisition for the Advanced Cardiovascular Imaging Consortium (ACIC), a multicentre collaborative quality improvement programme based in Michigan, USA. The model focused on various features of CCTA imaging, including patient instructions, medical history, use of β blockers and several protocol parameters, including cardiac gating, acquisition windows and reduced tube voltage. Primary outcomes included dose–length product and effective radiation dose from all phases of the CCTA scan. Secondary outcomes were image quality assessed on a four-point scale.

Compared with the control period before the introduction of the new model, patients’ estimated median radiation dose in the follow-up period was reduced by 53.3% (p<0.001) and effective dose from 21 mSv to 10 mSv (p<0.001)—the greatest reduction in dose was noted at low-volume sites. There were no significant changes in median image quality noted (p = 0.13) or frequency of diagnostic-quality scans (p = 0.07).

Conclusions

This study shows that simple measures can be used to substantially reduce radiation doses from currently available coronary CT scanners. The majority of changes used here have not been made obsolete by newer CT scanners, and can therefore be used to optimise a coronary CT protocol.

▸ Raff GL, Chinnaiyan KM, Share DA, et al. Radiation dose from cardiac computed tomography before and after implementation of radiation dose-reduction techniques. JAMA 2009;301:2340–8.

General cardiology

Acute stroke surgical targets not being met

Significant carotid atherosclerosis remains the leading cause of transient ischaemic attack and stroke in the UK. Recent data suggest that the risk of major stroke is highest during the first few days and weeks after a transient ischaemic attack or …