50 years) with occipitocervical pain.

The placement of the flexible ureteroscopic sheath during lithotripsy may injure the ureter. We have developed a double-tube flexible ureteral access sheath. Thirteen patients with renal calculi were treated with double-tube and flexible sheath in one stage. CT examination of 13 cases showed that the ureter was normal. The double-tube flexible ureteral access sheath makes the operation of sheathing easy, safe and effective.

Objective:To explore the clinical application value of MRI-PDFF on different liver segments for the evaluation of non-alcoholic fatty liver disease (NAFLD).Methods:178 volunteers from March 2019 to February 2020 were included. PDFF values ??of all nine segments of the liver were measured using CSE3.0T MRI scan. The obtained average value was used to represent the average liver fat content. PDFF values of each or combined liver segment were equally compared with the average value to observe the representativeness of fat content. Receiver operating characteristic curve was used to analyze the diagnostic performance of each liver segment, and the Youden index was used to calculate the cutoff value. Paired-sample t-test or non-parametric Kruskal-Wallis test were used to compare measurement data among groups.Results:178 volunteers average liver fat content ranged from 0.89% to 42.61% with MRI-PDFF, and 71.35% (127/178) of the volunteers had PDFF > 5%. There was no significant difference between SIII, SIVb, SV, and SVIII liver segments when compared with the average value ( P > 0.05). PDFF values ??of SI, SII, and SIV a liver segments were all lower than the average value, while the PDFF values ??of SVI and SVII liver segments were all higher than the average value ( P ??< 0.05). MRI-PDFF sensitivity value for diagnosing liver steatosis of nine liver segments was 85.8% ~ 94.5%, and the specificity was higher than 96.0%. Among them, the SV liver segment had the highest sensitivity (94.5%), and the corresponding optimal diagnostic threshold value was 5.13%. Compared with single and combined liver segment, the PDFF value of SII, SV, SVI combined liver segment had the highest diagnostic performance for fatty liver, with the sensitivity and specificity of 96.9%, and 100%, respectively, and the corresponding optimal diagnostic threshold value was 5.17%. Conclusion:Compared with single and other combined liver segments, MRI-PDFF values of SII, SV, and SVI combined liver segments have higher sensitivity and specificity for the diagnosis of NAFLD, and it can be used as the first choice for the determination of liver fat content with MRI.