Temporal averaging angiographic reconstructions from whole-brain CT perfusion for the detection of vasospasm

Purpose: The aim of this study is to evaluate the image quality and diagnostic performance of angiographic images reconstructed from whole-brain CT perfusion (CTP) using temporal averaging compared to CT angi-ography (CTA) for the detection of vasospasm.Materials and methods: 39 CT studies in 28 consecutive patients who underwent brain CTA with CTP for sus-pected vasospasm between September 2020 and May 2021 were retrospectively evaluated. The image qual-ity of these two vascular imaging techniques was assessed either quantitatively (image noise, vascular enhancement, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios,) and qualitatively (4 criteria assessed on a 5-point scale). Intra and interobserver agreements and a diagnostic confidence score on the diagnosis of vasospasm were measured. Radiation dose parameters (volume CT dose index (CTDIvol) and dose-length product (DLP)) were recorded.Results: Both SNR and CNR were significantly higher with temporal averaging compared to CTA, increasing by 104% and 113%, respectively (p<0.001). The qualitative assessment found no significant difference in overall image quality between temporal averag-ing (4.33 +/- 0.48) and brain CTA (4.19 +/- 0.52) (p = 0.12).There was a significant improvement in intravascular noise and arterial contrast enhancement with temporal averaging. The evaluation of intra and interobserver agreements showed a robust concordance in the diagnosis of vaso-spasm between the two techniques. Conclusions: Temporal averaging appeared as a feasible and reliable imaging technique for the detection of vasospasm. The use of temporal averaging, replacing brain CTA, could represent a new strategy of radiation and contrast material doses reduction in these patients.(c) 2022 Elsevier Masson SAS. All rights reserved.