超短TE成像在肌骨系统中的应用

超短回波时间（UTE）脉冲序列可激发短T2成分并在其衰减之前快速采集其信号，它是直接显示短T2成分的一种成像方法。综述UTE脉冲序列成像的原理及其显示组织内短T2成分的优势，并介绍该脉冲序列成像在肌骨系统中的应用前景。     

正常兔膝关节的三维UTE动态增强MRI实验研究

【摘要】目的：探讨三维超短回波时间（UTE）双回波脉冲序列在主要含短T2成分组织的动态增强MRI中的应用。方法：采用随机数字对照表对6只新西兰大白兔的6个膝关节行MR平扫及UTE动态增强检查。分析正常兔的髌韧带、股骨下段或胫骨上段骨皮质、髓腔的动态增强特点,并与病理结果对照。采用t检验比较未成年兔与成年兔骨皮质的中央管计数。结果：正常兔髌韧带的UTE动态增强信号强度 时间曲线表现为缓慢上升型。未成年兔骨皮质动态增强曲线表现为缓慢上升至峰值时,稍有下降后维持于较高水平;成年兔骨皮质UTE动态增强特点表现为速升速降型。成年兔与未成年兔髓腔的UTE动态增强特点均表现为速升缓降型,组织内对比剂浓度持续较高水平。骨皮质的动态增强曲线差异与组织学所见基本匹配。结论：三维UTE双回波脉冲序列成像可用于主要含短T2成分组织的动态增强检查。     

MRI三维超短回波时间双回波脉冲序列在骨与关节成像中的初步应用

目的 探讨MR三维超短回波时间(UTE)的双回波脉冲序列成像在骨与关节中的应用.方法 分别对7名健康志愿者和1名可疑左膝关节外侧半月板撕裂志愿者的胫骨干、膝关节、踝关节、腕关节及一段离体猪腓骨行MR三维UTE的双回波脉冲序列成像.将原始双回波图及多平面重组后的双回波图的前后2个回波相减获得相减后的差异图,比较2种图像处理方法的信噪比.将踝关节跟腱的UTE双回波成像的第1个回波时间(TE1)分别设置为0.08、0.16、0.24、0.35 ms,对比不同TE1时间2个原始回波相减所得的差异图的图像质量.对踝关节肌腱的TE1为0.08 ms的原始回波图相减后的差异图行最大强度投影获得肌腱的三维空间图.对获取的数据进行单因素方差分析和配对资料t检验.结果 通过对原始回波图相减后的差异图行最大强度投影显示了肌腱的三维空间分布图.8名志愿者的骨皮质、骨膜、肌腱和半月板在超短TE的双回波脉冲序列成像上表现为高信号.将原始双回波图(信噪比为2.82±0.75)行多平面重组后再减影(信噪比为3.76±0.88)可增加图像信噪比(t=-4.851,P<0.01).踝关节跟腱的不同TEl成像的图像质量不同,TE1为0.08 mg的图像质量最高,在TE1分别为0.08、0.16、0.24、0.35 ms时,对比噪声比分别为1.74±0.54、1.35±0.60、1.20±0.48、0.89±0.24,差异有统计学意义(F=3.681,P<0.05).随着成像时间的延长,伪影逐渐增多.结论 三维超短TE的双回波成像能显示传统的临床MR成像序列不能显示的主要含短T2成分的组织,为对这些组织的进一步量化研究奠定了基础.     

UTE的基本原理及在骨关节系统中的应用进展

骨关节系统主要由短T_2组织构成,在常规MRI检查中常表现为低信号或无信号。超短回波时间(UTE)序列是研究短T_2组织最常用的成像技术,短T_2组织在UTE影像上表现为高信号。对UTE成像技术的基本原理进行介绍,并综述其在骨皮质、骨膜、肌腱和韧带、关节软骨和半月板中的具体应用。     

影响短T2成分MR三维超短回波时间双回波脉冲序列成像质量因素的探讨

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.

Abstract：

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.     

磁共振超短回波时间序列在肺部的应用

【摘要】肺磁共振成像(MRI)具有极大的挑战性,因为肺实质的低质子密度,空气软组织交界面的磁化率伪影以及呼吸和心跳伪影的干扰,使用常规磁共振成像序列无法对肺组织进行成像。随着磁共振成像技术的发展,磁共振超短回波时间(UTE)序列的运用能使短T2组织如骨皮质、半月板、肺组织等成像。本文重点陈述UTE序列在肺部的应用进展并分析其在肺部的运用价值和前景。     

探讨3.0T磁共振UTE序列对肺结节的显示能力:与CT图像对比

目的:通过3.0T MR的超短回波时间(UTE)成像与常规剂量CT平扫进行对比,探讨UTE-MRI对肺结节显示的能力,分析其在肺结节的临床应用价值。方法:搜集本院31例患者,行CT平扫及3.0T磁共振UTE序列扫描。以CT检出结节数量及影像特征作为金标准。2名10年以上工作经验放射诊断医师独立记录CT及UTE肺结节数目及形态特征。结果:31例患者CT共检出41枚结节,UTE序列检出40枚结节(检出率97.6%)。UTE检出分叶征28枚,几乎接近金标准CT图像(29枚),检出率为96.5%,两者间差异无统计学意义。UTE检出病灶中心不均质性(19枚),检出率高于CT(10枚),差异具有统计学意义。UTE显示毛刺征数量(15枚),低于CT显示(20枚),但两者间差异无统计学意义。UTE显示胸膜牵拉数量(11枚),高于CT显示(9枚),差异亦无统计学意义。结论:UTE序列对于肺小结节(≥4 mm)检出有高的敏感性,可媲美CT成像,且可提供接近于CT的影像学特征,具有广阔的临床应用前景。     

MRI超短回波时间序列评价膝关节半月板的研究进展

半月板是膝关节的重要结构,MRI超短回波时间（UTE）序列相比传统MRI序列能够直接采集短T₂/T₂*信号,不仅能够定量测量半月板,还能够显示半月板胶原纤维及钙化成分,区分半月板红白区,以及评估半月板pH值等。简要介绍UTE序列,并就其在半月板中的研究进展予以综述。     

超短回波时间序列在肺部磁共振成像中的研究进展

磁共振成像具有无辐射、软组织分辨力高等特点,但不适用于质子密度低、T2信号衰减迅速的组织器官,因此临床上其在肺部中的应用较为局限。随着超短回波时间（UTE）序列在肺部MRI检查中的应用,MRI对肺部疾病的评估得以拓宽。本文就UTE序列成像技术原理、分类以及其在肺部的临床应用进行综述。     

超短回波脉冲T2加权成像

1．短T2成像的优点 有几种组织在T2加权图像上仅有较弱信号的或没有信号。一个美国的研究小组分析研究了一项课题,注射钆对比剂运用超短脉冲序列成像能否提高这些组织的对比度。     

肿块深度对乳腺超声弹性成像检查结果的影响分析

目的 探究超声弹性成像(UE)中肿瘤深度对于判断乳腺肿物的良、恶性影响.方法 选取本院2017年1月～2018年10月间收治的178例因乳腺肿块行手术切除患者为观察对象,纳入病灶200个.依据肿瘤深度不同分4组.对所有的患者在术前均予以常规超声检查以及超声弹性成像检查,对比不同深度肿瘤的UE成像情况、分析诊断效能(准确...     

Evaluation of the usefulness of the limited cone-beam CT (3DX) in the assessment of the thickness of the roof of the glenoid fossa of the temporomandibular joint

OBJECTIVES: The purpose of this study was to evaluate the usefulness of the limited cone-beam X-ray CT (3DX) (Morita Co., Japan) in measuring the thickness of the roof of the glenoid fossa (RGF) of the temporomandibular joint (TMJ). MATERIALS AND METHODS: Twenty-one TMJs removed at autopsy from 21 cadavers were investigated macroscopically using dissection and 3DX imaging. A Digimatic Outside Micrometer and a 3DX-image tool were used to measure the minimum thickness of the RGF. Multiple measurements were made to identify the thinnest area. Once the thinnest areas had been identified, three linear measurements were made and the average value was used for statistical analysis. RESULTS: The average macroscopic examination measurement was 1.37 mm (range 0.55-3.6 mm) and the average 3DX image measurement was 1.22 mm (range: 0.51-3.0 mm). There was no significant difference between these two groups using the Mann-Whitney U-test (P < 0.05). The Spearman's correlation coefficient by rank between these two groups was r = 0.93(P < 0.001). CONCLUSION: These results suggest that bone thickness measurements of the RGF by 3DX imaging was effective.     

Tendinopathy of the tendon of the long head of the biceps

Pathologies of tendon of the long head of the biceps (LHB) are an important cause of shoulder pain. They include tendinopathy, rupture, superior labrum anterior and posterior lesions, pulley tears, and tendon instability. Conservative management of symptomatic LHB tendinopathy is commonly accepted as the first-line treatment. It consists of rest, nonsteroidal anti-inflammatory drugs, corticosteroid injections, and physical therapy. Biceps tenotomy and tenodesis are the most common surgical procedures to manage both isolated LHB pathology and biceps-glenoid complex tears combined with rotator cuff tears. However, controversy persists about the superiority of one of them because there is no evidence of significant differences in functional scores or patient satisfaction between the 2 techniques. This article provides an overview on biomechanical function of the LHB and current strategies for treatment of LHB disorders.