A pilot study of magnetic resonance image fusion technology in the evaluation of anal fistula

Objective To get the fusion image of T2WI and T2WI-FS sequence by applying the image fusion technology, and evaluate the advantages in anal fistulas and surrounding structures. Methods From June 2016 to June 2018, twenty-nine patients with anal fistula were collected prospectively in the First Affiliated Hospital, Sun Yat-sen University. All the patients received anal magnetic resonance imaging (MRI) examination. T2WI and T2WI-FS images were used to generate fusion images (T2WI-Fusion). The discriminability of fistula, perianal sphincter, and perianal fat in T2WI, T2WI-FS, and T2WI-Fusion images was quantified with Fisher’s scoring algorithm. For subjective visual image assessment by researchers, five-point scale scores were determined using a modified double-stimulus continuous quality-scale (DSCQS) test to evaluate T2WI-FS, T2WI, enhanced axial 3D-volumetric interpolated breath-hold examination (3D-VIBE), and T2WI-Fusion sequence images. Results Mean Fisher scores for fistulas vs sphincters obtained from T2WI-Fusion images (value=6.46) were significantly higher than those from T2WI images (value=3.31) (P<0.001). Mean Fisher scores for sphincters vs fat from T2WI-Fusion images (value=10.61) were significantly higher than those from T2WI-FS images (value=2.45) (P<0.001). T2WI-Fusion images showed better whole anal fistula and sphincter discriminability than that of T2WI-FS, T2WI and enhanced 3D-VIBE images (P<0.001). Conclusions MRI fusion technology combines the advantages of the T2WI and T2WI-FS images without increasing scan sequence and scan time. This technology is easy to operate and timesaving, and can significantly increase the anal fistula and sphincter discriminability and improve the imaging quality. Key words: Rectal fistula; Magnetic resonance imaging; Image fusion technology; T2WI; T2WI-FS; Tissue discriminability