研究目的

To assess evaluability and diagnostic accuracy of a low dose CT angiography (CTA) protocol for carotid arteries using latest Iterative Reconstruction (IR) algorithm in comparison with standard 100 kVp protocol using previous generation CT and IR.

研究成果

In conclusion, our study demonstrates that the combined use of 80 kVp, 160 mm coverage CT scanner and new IR algorithm ASIR-V in CTA of the carotid arteries allows scan protocol with submillisievert effective dose while maintaining good image quality and excellent diagnostic accuracy (compared to DSA as gold standard reference). Furthermore in comparison with previous generation 64-slice CT scanner using standard 100 kVp tube voltage and first generation adaptive statistical iterative reconstruction algorithm, this protocol could lead to an overall mean effective dose reduction up to 86%. Our results suggest that further data about patient safety might be achieved by studies combining dose saving techniques with lower contrast protocols and this could maybe support the revisiting of some aspects of the current guidelines regarding the use of carotid arteries CTA in the management of patients at risk of brain ischemia lowering the problems related to the use of ionizing radiations.

研究不足

First the ASIR-V is only available with this new CT scanner. Thus a retrospective comparison with data regarding image quality parameters of 64-slices MDCT with first generation IR algorithm was done and this could lead to inclusion bias. Second the differences regarding motion and respiratory artifacts during the scan were quite expected due to the significant difference in scan time between the two groups. Third we didn’t perform a comparison with different imaging modalities such as MRI. Fourth a relative a small number of patients underwent DSA and this could limit the diagnostic accuracy assessment. Moreover only in group 1 an accuracy evaluation was performed as well as an evaluation of measurements reproducibility. Fifth the used conversion factors for ED evaluation are calculated for specific body regions or CT scan ranges (e.g. cervical spine) that may not match the clinical scan range used in real life.