Keywords:
CT, Neuroradiology brain, CT-Quantitative, Computer Applications-Detection, diagnosis, Ischaemia / Infarction, Retrospective, Not applicable, Performed at one institution
Authors:
S. Ichikawa, H. YAMAMOTO; Kurashiki/JP
DOI:
10.26044/ecr2020/C-07900
Conclusion
We simulated low-dose CT perfusion data sets and compared the quantitative perfusion values at low doses with those obtained at the original dose using the Bayesian estimation algorithm. Our results revealed that all quantitative perfusion parameters acquired at 60 and 45 mAs were not different from those at 75 mAs in both affected and contralateral normal regions. Thus, a reduction in the tube current-time product down to 45 mAs can yield sufficient image quality in CT perfusion analysis with the Bayesian estimation algorithm.
A previous simulation study showed that tube current reduction down to 72 mAs did not affect diagnostic accuracy in CT perfusion of acute ischemic stroke [6]. A similar result to ours was described by Murphy et al., in which CBV and CBF were not different at 50 mAs compared to those at 100 mAs, even without the addition of an iterative reconstruction technique [7]. These studies, however, did not refer to the details of a post-processing algorithm for CT perfusion analysis. To our knowledge, our study is the first to demonstrate the effect of radiation dose reduction on quantitative interpretation in CT perfusion using the Bayesian estimation algorithm.
We acknowledge that our study has several limitations. First, the sample size was relatively small. Second, our simulation of CT perfusion data at different dose levels is uncomplicated, although other studies also simply added Gaussian noise to their simulations [8, 9]. Thus, our findings should be validated in a larger group, using dedicated low-dose simulators as described in previous reports [6, 10].
In conclusion, CT perfusion analysis using a Bayesian estimation algorithm may enable radiation dose reduction to 60% of the original dose levels (75 mAs) in patients with acute ischemic stroke.