The Optimized Fractional Anisotropy and Apparent Diffusion Coefficient Threshold in Fiber Tracking of Pelvic Floor Muscles

This study aims at finding optimal threshold in diffusion tensor tractography (DTT) of pelvic floor muscles. Twenty healthy adults (ten males and ten females) were included in this study. Conventional MRI sequences(T1WI, FSE-T2WI) and diffusion Tensor Imaging (DTI) were acquired in GE Signa HDxt 3.0T MRI. Then the DTI were post-processed in ADW4.5 workstation. Levator ani muscle, coccygeus and obturtor internus were chosen as seeds to track fibres by regulating different fractional anisotropy (FA) and apparent diffusion coefficient (ADC) threshold. DTT of fiber tracking under FA threshold by every 0.03 from 0.10 to 0.25 and under ADC threshold by every 0.0002 from 0.0015 to 0.0025 were recorded. Then these DTT images and conventional MRI images were evaluated by two radiologists. A four-point Likert scale was used to qualitatively assess the predefined anatomical structure in pelvic floor. The result was that DTT images of levator ani muscle, coccygeus and obturtor internus with FA 0.19 and ADC 0.0021 gained the highest score among all figures. Then we can conclude that DTT of pelvic floor muscles processed with FA 0.19 and ADC 0.0021 were good enough to obtain reliable images.