A Comparison Study of Single-Echo Susceptibility Weighted Imaging and Combined Multi-Echo Susceptibility Weighted Imaging in Visualizing Asymmetric Medullary Veins in Stroke Patients

BACKGROUND: Asymmetric medullary veins (AMV) are frequently observed in stroke patients and single-echo susceptibility weighted imaging (SWI(s)) is the main technique in detecting AMV. Our study aimed to investigate which echo time (TE) on single-echo susceptibility is the optimal echo for visualizing AMV and to compare the ability in detecting AMV in stroke patients between SWI(s) and multi-echo susceptibility weighted imaging (SWI(c)). MATERIALS AND METHODS: Twenty patients with middle cerebral artery stroke were included. SWI was acquired by using a multi-echo gradient-echo sequence with six echoes ranging from 5 ms to 35.240 ms. Three different echoes of SWI(s) including SWI(s1) (TE = 23.144 ms), SWI(s2) (TE = 29.192 ms) and SWI(s3) (TE = 35.240 ms) were reconstructed. SWI(c) was averaged using the three echoes of SWI(s). Image quality and venous contrast of medullary veins were compared between SWI(s) and SWI(c) using peak signal-to-noise ratio (PSNR), mean opinion score (MOS), contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). The presence of AMV was evaluated in each SWI(s (1–3)) and SWI(c). RESULTS: SWI(s2) had the highest PSNR, MOS and CNR and SWI(s1) had the highest SNR among three different echoes of SWI(s). No significant difference was found in SNR between SWI(s1) and SWI(s2). PSNR, MOS and CNR in SWI(c) were significantly increased by 27.9%, 28.2% and 17.2% compared with SWI(s2) and SNR in SWI(c) was significantly increased by 32.4% compared with SWI(s1). 55% of patients with AMV were detected in SWI(s2), SWI(s3) and SWI(c), while 50% AMV were found in SWI(s1). CONCLUSIONS: SWI(s) using TE around 29ms was optimal in visualizing AMV. SWI(c) could improve image quality and venous contrast, but was equal to SWI(s) using a relative long TE in evaluating AMV. These results provide the technique basis for further research of AMV in stroke.