CAJ | 학술논문

目的探讨3D超短回波时间(UTE)舣回波脉冲序列成像的相关成像参数及后处理技术对图像质量的影响.方法对主要含短T2成分的人于燥股骨标本及一组健康志愿者的胫骨、膝关节、踝部肌腱行MR 3D UTE舣回波脉冲序列成像.通过计算、比较图像的信噪比(SNR)或对比噪声比(CNR)及对图像伪影的分析,探讨系统内部不同轨道延迟时间(-6、-3、-2、-1、0、1、2、3 s)、不同反转角(4°、8°、12°、16°、20°、24°)、不同TE1(0.08、0.16、0.24、0.35 ms)及不同后处理技术(超短回波减影差异图、容积超短回波减影差异图)对图像质量的影响.结果骨皮质、骨膜、半月板、肌腱、韧带等在UTE图像上表现为高信号.所设的不同轨道延迟时间中,获得最佳SNR的轨道延迟时阳间为2 s.活体人UTE成像的最佳反转角为8°～12°.不同TE1时间的图像质量不同,TE1为0.08 ms时,图像的CNR最佳.随TE1时阳延长,图像伪影逐渐增多.将原始双回波图经多平面重组后再相减(容积超短回波减影差异图),图像SNR明显增加.结论短T2成分在3D UTE双回波脉冲序列成像上表现为高信号.通过改变反转角和将2次回波图像经MPR后再相减可增加图像SNR.缩短TE1时间可增加图像质量.
목적 탐토3D초단회파시간(UTE)의회파맥충서렬성상적상관성상삼수급후처리기술대도상질량적영향.방법 대주요함단T2성분적인우조고골표본급일조건강지원자적경골、슬관절、과부기건행MR 3D UTE의회파맥충서렬성상.통과계산、비교도상적신조비(SNR)혹대비조성비(CNR)급대도상위영적분석,탐토계통내부불동궤도연지시간(-6、-3、-2、-1、0、1、2、3 s)、불동반전각(4°、8°、12°、16°、20°、24°)、불동TE1(0.08、0.16、0.24、0.35 ms)급불동후처리기술(초단회파감영차이도、용적초단회파감영차이도)대도상질량적영향.결과 골피질、골막、반월판、기건、인대등재UTE도상상표현위고신호.소설적불동궤도연지시간중,획득최가SNR적궤도연지시양간위2 s.활체인UTE성상적최가반전각위8°～12°.불동TE1시간적도상질량불동,TE1위0.08 ms시,도상적CNR최가.수TE1시양연장,도상위영축점증다.장원시쌍회파도경다평면중조후재상감(용적초단회파감영차이도),도상SNR명현증가.결론 단T2성분재3D UTE쌍회파맥충서렬성상상표현위고신호.통과개변반전각화장2차회파도상경MPR후재상감가증가도상SNR.축단TE1시간가증가도상질량.
Objective To investigate the effect of imaging parameters and postprocessing methods on the quality of MR imaging of short T2 components with 3D ultrashort TE (UTE) double echo pulse sequence. Methods 3D UTE double echo pulse sequence was performed on dry human femoral specimen and the tibial diaphyses, knee joints, and tendons of ankles of a group of healthy volunteers. To investigate the effect of different trajectory delays of the imaging system(-6, -3, -2, - 1,0, 1,2, 3 s), different flip angles(4°, 8°, 12°, 16°, 20°, 24°), different TEs (0. 08, 0. 16, 0. 24, 0. 35 ms)and different postprocessing methods(difference imaging of subtracted volume and non-volume UTE)on the 3D UTE MR imaging quality, the SNR and CNR were calculated and compared, and the artifacts of the images were analysed. Results The cortical bone, periosteum, tendon and meniscus showed high signal intensity on the images of UTE pulse sequence. The best SNR was acquired with 2 s trajectory delay. The best flip angle was 8° to 12° for the human UTE imaging in vivo. The highest CNR was obtained from the TE of 0. 08 ms. The longer the TE was, the more artifacts appeared. The SNR of difference imagewas improved when image subtraction was performed afer multiplanar reconstruction (MPR) of the primary double echo images.Conclusions The short T2 components show high signal intensity on the MRI of 3D UTE double echo pulse sequence. The imaging quality can be improved by shortening TE, using appropriate flip angle and performing subtraction for difference image after MPR of the primary double echo images.