Low-dose contrast-enhanced time-resolved angiography with stochastic trajectories with iterative reconstruction (IT-TWIST-MRA) in brain arteriovenous shunt

Objectives To assess the feasibility of low-dose contrast-enhanced four-dimensional (4D) time-resolved angiography with stochastic trajectories (TWIST) with iterative reconstruction (hereafter IT-TWIST-MRA) covering the whole brain and to compare IT-TWIST-MRA and TWIST-MRA with reference to digital subtraction angiography (DSA) in the evaluation of arteriovenous shunts (AVS). Methods Institutional Review Board approval was obtained for this observational study, and the requirement for written informed consent was waived. Twenty-nine patients with known AVS underwent TWIST-MRA on a 3-T MRI scanner, using low-dose injection (0.02 mmol/kg) of gadolinium-based contrast agent (GBCA) with each of Fourier and iterative reconstruction between September 2016 and October 2019. Visual evaluation of image quality was conducted for delineation of (a) the normal cerebral arteries and veins and (b) AVS feeder, shunt, and drainer vessels. Region-of-interest evaluation was conducted to evaluate bolus sharpness and baseline signal fluctuation in the signal intensity of the cerebral vessels. We compared the detection of AVS between TWIST-MRA and IT-TWIST-MRA. The paired-samples Wilcoxon test was used to test the differences between TWIST-MRA and IT-TWIST-MRA. Results Visualization scores for normal vasculature and AVS angioarchitecture were significantly better for images produced using IT-TWIST-MRA than those using TWIST-MRA. Peak signal and the enhancement slope of the time-intensity curve were significantly higher for IT-TWIST-MRA than for TWIST-MRA, except for the superior sagittal sinus (SSS). Baseline intensity fluctuation was significantly lower for IT-TWIST-MRA than for TWIST, except for SSS. Conclusions IT-TWIST-MRA yields clinically feasible 4D MR-DSA images and delineates AVS even with low-dose GBCA.

Automated summary

This study assessed the feasibility of low-dose contrast-enhanced four-dimensional time-resolved angiography with stochastic trajectories (TWIST) with iterative reconstruction (IT-TWIST-MRA) for the evaluation of arteriovenous shunts (AVS) in the whole brain. The results showed that IT-TWIST-MRA produced better image quality for visualization of normal vasculature and AVS angioarchitecture compared to TWIST-MRA. The peak signal and enhancement slope were higher for IT-TWIST-MRA, and the baseline intensity fluctuation was lower, indicating better image quality.