目的探讨三维梯度自旋回波(GRASE)序列在老年患者磁共振胆胰管成像(MRCP)中的应用价值。方法纳入MRCP检查的老年患者63例。同时采集屏气2D-FSE、屏气3D-GRASE和呼吸触发3D-FSE序列。计算图像的信噪比、对比噪声比和对比度,并对图像质量...目的探讨三维梯度自旋回波(GRASE)序列在老年患者磁共振胆胰管成像(MRCP)中的应用价值。方法纳入MRCP检查的老年患者63例。同时采集屏气2D-FSE、屏气3D-GRASE和呼吸触发3D-FSE序列。计算图像的信噪比、对比噪声比和对比度,并对图像质量进行主观评价,包括伪影、背景抑制、总体图像质量和胆胰管各分支的显示情况。组间比较采用单因素ANOVA检验或非参数Kruskal-Wallis检验。结果GRASE序列的伪影评分高于2D-FSE序列,差异具有统计学意义(4.24±0.69 vs 3.76±1.03,P<0.05),但与3D-FSE序列之间差异无统计学意义(P>0.05)。GRASE序列背景抑制的评分高于2D-FSE序列(P<0.05)。在图像的总体质量评分中,GRASE序列略高于3D-FSE序列,差异无统计学意义(4.29±0.83 vs 4.16±0.79,P>0.05),两者均高于2D序列,差异均有统计学意义(P<0.05)。GRASE序列的CNR、CR与3D-FSE序列相近,差异无统计学意义(P>0.05),均高于2D-FSE序列,差异均有统计学意义(P均<0.05)。GRASE序列在胆总管、肝总管、右肝管后支、左肝管内、外支的显示的显示能力与3D-FSE序列无差别。GRASE序列在右肝管前支的显示能力不如3D-FSE序列(P<0.05)。结论GRASE获得胆胰管的图像质量与3D-FSE序列接近,高于2D-FSE序列,为老年人疾病诊断提供影像学依据。展开更多
This work investigated the gradient microstructure evolution and tensile property of LPBF fabricated 15-5 precipitation hardening stainless steel in post-process direct ageing(DA)and solution treating&ageing(STA)....This work investigated the gradient microstructure evolution and tensile property of LPBF fabricated 15-5 precipitation hardening stainless steel in post-process direct ageing(DA)and solution treating&ageing(STA).The varied microstructures for austenite and small-sized oxide inclusions at different sample heights in the as-built(AB)condition was generally preserved after DA treatment.However,austenite was almost disappeared,and oxide particle grew significantly after the STA treatment.As a result,the tensile property differences in sample top and bottom for AB and DA conditions did not occur in the STA samples.For the influence of post-process heat treatment,the STA condition had the highest yield strength due to the highest volume fraction of nano-sized Cu precipitates.However,the DA specimen had the highest ultimate tensile strength and elongation owing to the considerable amount of austenite phase and associated transformation induced plasticity effect.展开更多
文摘目的探讨三维梯度自旋回波(GRASE)序列在老年患者磁共振胆胰管成像(MRCP)中的应用价值。方法纳入MRCP检查的老年患者63例。同时采集屏气2D-FSE、屏气3D-GRASE和呼吸触发3D-FSE序列。计算图像的信噪比、对比噪声比和对比度,并对图像质量进行主观评价,包括伪影、背景抑制、总体图像质量和胆胰管各分支的显示情况。组间比较采用单因素ANOVA检验或非参数Kruskal-Wallis检验。结果GRASE序列的伪影评分高于2D-FSE序列,差异具有统计学意义(4.24±0.69 vs 3.76±1.03,P<0.05),但与3D-FSE序列之间差异无统计学意义(P>0.05)。GRASE序列背景抑制的评分高于2D-FSE序列(P<0.05)。在图像的总体质量评分中,GRASE序列略高于3D-FSE序列,差异无统计学意义(4.29±0.83 vs 4.16±0.79,P>0.05),两者均高于2D序列,差异均有统计学意义(P<0.05)。GRASE序列的CNR、CR与3D-FSE序列相近,差异无统计学意义(P>0.05),均高于2D-FSE序列,差异均有统计学意义(P均<0.05)。GRASE序列在胆总管、肝总管、右肝管后支、左肝管内、外支的显示的显示能力与3D-FSE序列无差别。GRASE序列在右肝管前支的显示能力不如3D-FSE序列(P<0.05)。结论GRASE获得胆胰管的图像质量与3D-FSE序列接近,高于2D-FSE序列,为老年人疾病诊断提供影像学依据。
基金Sheng Cao thanks the support from the National Natural Science Foundation of China(No.52204391)the Special Fund Project for Science and Technology Innovation Strategy of Guangdong Province(Nos.STKJ202209021 and STKJ2023040)+1 种基金the Characteristic Innovation Project(Natural Science)for Regular University in Guangdong Province(No.2022KTSCX038)the Shantou University Research Foundation for Talents(No.NTF21013).
文摘This work investigated the gradient microstructure evolution and tensile property of LPBF fabricated 15-5 precipitation hardening stainless steel in post-process direct ageing(DA)and solution treating&ageing(STA).The varied microstructures for austenite and small-sized oxide inclusions at different sample heights in the as-built(AB)condition was generally preserved after DA treatment.However,austenite was almost disappeared,and oxide particle grew significantly after the STA treatment.As a result,the tensile property differences in sample top and bottom for AB and DA conditions did not occur in the STA samples.For the influence of post-process heat treatment,the STA condition had the highest yield strength due to the highest volume fraction of nano-sized Cu precipitates.However,the DA specimen had the highest ultimate tensile strength and elongation owing to the considerable amount of austenite phase and associated transformation induced plasticity effect.
