[Imaging of coronary atherosclerotic plaque]

Radiation-reducing planning of cardiac catheterisation

Any radiation exposition for medical purposes should be kept as low as is reasonably achievable. Mean patient radiation exposure of diagnostic cardiac catheterisation is high (16-106 Gy x cm2) and for this reason the International Commission on Radiological Protection (ICRP) recommends credentialing radiation protection training programmes. Twenty cardiologists each documented various dose parameters of 10 cardiac catheterisations, before and after a 90-minute mini-course of the ELICIT study group ("Encourage to Less Irradiating Cardiologic Interventional Techniques"), and could achieve a reduction of the mean dose-area product by 15.9+/-9.0 Gy x cm2, equivalent to 47%. The presented radiation-reducing planning of invasive cardiac catheterisation for this reason is the first one validated in clinical routine and consists of 6 standard runs--one for the left ventricle, 3 and 2 for the left (LCA) and right coronary artery (RCA), respectively--depending on anatomy and findings supplemented by 1...4 special projections. The caudal posteroanterior (PA) view documents the left coronary main stem, proximal and distal left anterior descending artery (LAD), and proximal and mid circumflex segments. The cranial PA view however is suitable for the left coronary orifice, circumflex periphery, LAD, all diagonal bifurcations, and collateral pathways towards the RCA. LCA standard angiography is completed by lateral 90 degrees/0 degrees left anterior oblique (LAO) angulation. The 60 degrees/0 degrees LAO angulation visualises the right posterolateral artery (RPL) and the RCA to its bifurcation. The more proximal one finds the bifurcation, the more the second standard cranial PA view for RCA should vary towards the cranial right anterior oblique (RAO) and finally 30 degrees/0 degrees RAO view. The efficiency of these less-irradiating angulations are improved by radiation-reducing techniques as follows: restriction to essential radiographic frames and runs, consistent collimation to the region of interest--particularly during coronary intubation--, adequate instead of best possible image quality, short skin-to-image-intensifier distance, inspiration during radiography, preference for projections that rotate out the spine, optimisation of fluoroscopy time, well-experienced and well-rested interventionists.