Three Dimensional Ultra-short Echo Time MRI Can Depict Cholesterol Components of Gallstones Bright

PurposeNon-calcified cholesterol stones that are small in size are hard to be depicted on CT or magnetic resonance cholangiopancreatography. This institutional review board (IRB)-approved retrospective in vitro study aims to characterize contrast behaviors of 3 main components of the gallstones, i.e., cholesterol component (CC), bilirubin calcium component (BC) and CaCO₃ (CO) on 3D radial scan with ultrashort TE (UTE) MRI, and to test the capability of depicting CC of gallstones as bright signals as compared to background saline.MethodsFourteen representative gallstones from 14 patients, including 15 CC, 6 BC and 4 CO, were enrolled. The gallstones underwent MRI including fat-saturated T1-weighted image (fs-T1WI) and UTE MRI with dual echoes. The contrast-to-noise ratio (CNR) and the chemical analysis for the 25 portions of the stones were compared.ResultsBC was bright on fs-T1WI, which did not change dramatically on UTE MRI and the signal did not remain on UTE subtraction image between dual echoes. Whereas the CC was negative or faintly positive signal on fs-T1WI, bright signal on UTE MRI and the contrast remained even higher on the UTE subtraction, which reflected their short T2 values. Median CNRs and standard errors of the segments on each imaging were as follows: on fs-T1WI, −10.2 ± 4.2 for CC, 149.7 ± 27.6 for BC and 37.9 ± 14.3 for CO; on UTE MRI first echo, 16.7 ± 3.3 for CC, 74.9 ± 21.3 for BC and 17.7 ± 8.4 for CO; on UTE subtraction image, 30.2 ±2.0 for CC, −11.2 ± 5.4 for BC and 17.8 ± 10.7 for CO. Linear correlations between CNRs and cholesterol concentrations were observed on fs-T1WI with r = −0.885, (P < 0.0001), UTE MRI first echo r = −0.524 (P = 0.0072) and UTE subtraction with r = 0.598 (P = 0.0016).ConclusionUTE MRI and UTE subtraction can depict CC bright.     

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.     

急性胰腺炎的MRI诊断

目的　评价MRI在急性胰腺炎诊断中的作用。方法　 77例急性胰腺炎的病人全部采用屏气磁共振序列进行扫描。横断位扫描: 2DFlashT1WI/T1WI+FS,TSET2WI+FSHASTE+FS,部分病人加扫Trufisp序列。冠状位扫描: 2DFlashT1WI+FS;其中 34例病人进行了MRCP检查。所有 77例病人均进行了MRI动态增强扫描。结果　59例诊断为急性水肿性胰腺炎,表现为胰腺肿胀,T1WI稍低信号,T2WI稍高信号。18例诊断为出血坏死性胰腺炎,除前述表现外,还可见T1WI斑片状高信号,胰周渗液明显。结论　MRI对急性胰腺炎的诊断具有重要作用。     

隐性骨折的MRI分析

目的 探讨隐性骨折的MRI诊断价值。方法 16例急性外伤患者均行X线平片检查及MRI检查,3例同时行CT检查,受伤部位分别为股骨髁3例,胫骨近端8例,胸腰段椎体5例。结果 本组16例X线平片均未见骨折征像;11例（11／16）股骨髁及胫骨近端受伤病例中3例（3／16）T1WI见骨皮质下线状信信号带改变,8例（8／16）显示由关节面下向骨干走行的不规则条状、紊乱低信号改变;在T2WI上对应于T1WI低信号区仍表现为相应形状的低信号,且在低信号周围可见高信号水肿改变;T1脂肪抑制序列扫描显示水肿带信号明显增强、增宽。2例股骨髁和1例胫骨近端病例同时行CT检查,示周围软组织肿胀,未见确切骨折征像。5例（5／16）胸腰段椎体MR T1WI、T2WI示椎体中央有水平方向走行的线状低信号带,在T2WI低信号周围可见高信号水肿。结论 MRI能够早期确诊隐性骨折,若患者临床症状、体征不能除外隐性骨折,X线检查后行MRI应为最佳的检查手段。     

膝关节软骨缺损性病变的MR成像序列研究

目的　评价各种临床常用MR扫描序列诊断关节软骨病变的价值。方法　实验猪膝关节 5只 ,在股骨内外髁关节面软骨上制成缺损模型 ,分别采用各种常用序列扫描 ,测量各种扫描序列上关节软骨的信噪比 (SNR)、软骨相对周围组织的对比噪声比 (CNR) ,采用一致性评价指标 (ICC)评价软骨缺损MRI测量值与实际测量值的一致性。采用实验中优选的MR序列对 2 3例膝关节病变患者进行检查 ,并与关节镜分级诊断结果比较。结果　实验膝关节软骨SNR良好者有质子和T2 WI快速自旋双回波 (FSEPD/T2 WI)、附加脂肪抑制的三维快速扰相梯度回波 (FS 3DFSPGR)和附加脂肪抑制的质子和T2 WI快速自旋双回波 (FSFSEPD/T2 WI)。CNR表现“极佳”者 ,对骨皮质 :FS 3DFSPGR、FSFSEPD/T2 WI;对关节液 :脂肪抑制快速自旋回波 (FSFSE)T2 WI、FS 3DFSPGR ;对半月板和韧带 :FS 3DFSPGR、FSFSEPD/T2 WI、SET1WI、反转时间为 70 0ms的T1WI反转恢复 (IRTI70 0 )序列 ;对脂肪 :FS 3DFSPGR、SET1WI。ICC只有IRTI70 0序列有统计学上的意义 (P <0 .0 5 ) ,且一致性评价为“极佳”。对2 3例膝关节病变患者MR检查结果 :FS 3DFSPGR序列的敏感性为 86 %、特异性为 96 %、表示准确度的Kappa值为 0 .8;IRTI70 0序列的敏感性为 6 8%、特异性为 99%、Kappa值为 0     

单发型内生软骨瘤影像学表现分析

目的探讨内生软骨瘤的临床与影像学特征。方法对资料完整并经手术病理证实的单发型内生软骨瘤11例的临床与X线平片、CT、MRI资料进行回顾性分析。结果11例中,掌骨3例,指骨4例,肱骨干1例,股骨干骺端2例,胫骨干骺端1例。掌指骨病灶X线平片表现为囊样、类圆形透光区,瘤内钙化,呈膨胀性生长,骨皮质变薄;四肢长骨病灶在CT表现瘤内软组织密度影,内见斑片状钙化;MRI在T1WI为低信号,T2WI为高信号为主的混杂信号,1例股骨病灶T2WI周围见低信号带。结论影像学检查对本病大多数可做出定性诊断与鉴别诊断。     

乳腺黏液腺癌MRI表现特征及其与病理对照研究

目的 探讨乳腺黏液腺癌MR平扫、动态增强(DCE)及DWI表现特征及其与病理表现的相关性.方法 MR枪查采用1.5 T MR扫描仪及乳腺专用线圈,包括MR平扫、3D DCE-MRI以及b值分别为500和1000 s/mm2的DWI.对8例行乳腺MR检查并经手术病理证实的乳腺黏液腺癌,依据乳腺影像报告和数据系统(BI-RADS)MRI标准,回顾性分析病变形态学、T1WI及T2WI信号强度、肿块内部强化特征及动态增强曲线类型、DWI上ADC值表现,并与病理对照,乳腺黏液腺癌病理诊断依据2003年WHO乳腺肿瘤病理学标准.结果 8例乳腺黏液腺癌(5例单纯黏液腺癌,3例混合型黏液腺癌)的黏液含昔为60%～90%.8例在MRI上均表现为肿块,平扫T1WI呈低信号,T2WI呈高和明显高信号.动态增强后,1例表现为不均匀轻微强化,2例表现为内部欠均匀的渐进性强化,其余5例于动态增强早期时相均表现为边缘明显强化,肿块内部结构呈渐进性强化,强化方式呈由边缘强化向中心渗透趋势.于DWI上病变均表现为明显高信号,平均ADC值在b值500 s/mm2时为(2.41±0.28)×10-3mm2/s,b值1000 s/mm2时为(2.06±0.14)×10-3mm2/s,分别高于正常乳腺组织的(1.71±0.32)×10-3和(1.43±0.24)×10-3mm2/s.结论 乳腺黏液腺癌在MR平扫T2WI、DEC及DWI表现均不同于常见的浸润性导管癌,这些特征性表现反映了其特殊的病理类型,MR多种成像序列相结合可对乳腺黏液腺癌在术前作出正确诊断.     

长骨血管瘤的影像诊断

目的 分析长骨血管瘤的影像特征,旨在提高其诊断水平.方法 回顾性分析经手术病理证实的18例长骨血管瘤患者的X线平片(14例)、CT(9例)及MRI(6例).结果 18例长骨血管瘤中髓型10例、骨膜型5例、皮质内型3例.X线表现:髓型8例,其中3例表现为典型的蜂窝状,3例为溶骨性病灶周围骨质硬化明显,单纯溶骨、毛玻璃样密度各1例;骨膜型3例,表现为骨皮质增厚、硬化;皮质内型3例,表现为边界清晰的溶骨性病灶.CT表现:髓型6例,表现为溶骨膨胀型病灶5例,其中3例可见薄厚不一的硬化边,蜂窝状骨嵴影2例,骨皮质呈筛孔状1例,垂直于骨皮质的放射状骨膜增生2例;毛玻璃样密度1例.2例骨膜型表现为骨皮质均匀增厚1例,不规则骨膜增厚1例,局部髓腔狭窄消失.1例皮质内病变表现为病灶呈均匀软组织密度,局部皮质膨胀、增厚.MRI表现:2例显示髓腔内斑片状T1WI稍低信号,T2WI均呈稍高信号,边界清晰;1例T1WI及T2WI均呈等或稍低信号,病灶与正常组织分界不清;1例显示病灶突破局部骨皮质,肿物向外突出,外突肿物及相连髓腔部分T1WI呈稍低信号,T2WI呈高信号;2例显示骨膜增厚,其中1例呈等信号,1例无信号;2例周围肌肉组织内可见不均匀斑片状长T2信号,T1WI与肌肉组织呈等信号.结论 长骨血管瘤的囊性蜂窝状X线表现较为特征型;CT及MRI有助于长骨血管瘤的诊断.

Abstract：

Objective To explore the imaing features of hemangioma in the long bone and improve the diagnostic level of this disease. Methods The X-ray(14 cases), CT(9 cases) and MRI(6 cases)findings of 18 patientswith histologically proven hemangioma in the long bone after surgery were retrospectively reviewed. Results Ten tumors occurred in medullary cavity or bone end(medullary type),6 on the surface of bone (periosteal type) and 3 in cortex (intracortical type). X-ray findings: among 8 cases of medullary type, 3 showed honeycomb appearance, 3 lytic areas with sclerotic borders, one purely osteolyticchanges, and 1 frosted glass; 3 cases of periosteal type showed sclerosis and thickening of the underlying cortex; 3 cases of intracortical type showed well-defined osteolytic foci. CT findings: among 6 cases of medullary type, 5 appeared as expansile lytic lesion with uneven selerotic rim (3 cases)orhoneycomb appearance (2 cases), 1 cribriform appearance in the cortical bone, 2 periostealnew bone formation in vertical radiation pattern; 1 ground-glass appearance; among 2 cases of periosteal typeone showed regular cortical thickening, and the other irregular periosteal proliferation with marrowing of medullarycavity; 1 case of intracorticaltype showed density similar to that of soft tissue, with cortical thickening and expansion . MRI findings: 2 apeared as well-defined lesions with low signal intensity on T1WI and high signal intensity on T2WI; 1 appeared as ill-defined lesion with low to intermediate signal intensity on T1 WI and T2 WI. One showed breakthrogh of cortex and formation of soft tissue mass with low signal intensity on T1 WI and high signal on T2WI. Two showed thickening of periosteumwith intermediate signal intensity in one of them and very low signal intensity in the other. Two showed abnormal signal intensity in surrounding muscles, which was high on T2 WI and intermediate on T1 WI. Conclusions The soap-bubble or honeycomb appearance is the typical radiographic finding of hemangioma in long bone. CT and MRI can provide useful information for the diagnosis of hemangioma in long bone.     

长骨血管瘤的影像诊断

目的 分析长骨血管瘤的影像特征,旨在提高其诊断水平.方法 回顾性分析经手术病理证实的18例长骨血管瘤患者的X线平片(14例)、CT(9例)及MRI(6例).结果 18例长骨血管瘤中髓型10例、骨膜型5例、皮质内型3例.X线表现:髓型8例,其中3例表现为典型的蜂窝状,3例为溶骨性病灶周围骨质硬化明显,单纯溶骨、毛玻璃样密度各1例;骨膜型3例,表现为骨皮质增厚、硬化;皮质内型3例,表现为边界清晰的溶骨性病灶.CT表现:髓型6例,表现为溶骨膨胀型病灶5例,其中3例可见薄厚不一的硬化边,蜂窝状骨嵴影2例,骨皮质呈筛孔状1例,垂直于骨皮质的放射状骨膜增生2例;毛玻璃样密度1例.2例骨膜型表现为骨皮质均匀增厚1例,不规则骨膜增厚1例,局部髓腔狭窄消失.1例皮质内病变表现为病灶呈均匀软组织密度,局部皮质膨胀、增厚.MRI表现:2例显示髓腔内斑片状T1WI稍低信号,T2WI均呈稍高信号,边界清晰;1例T1WI及T2WI均呈等或稍低信号,病灶与正常组织分界不清;1例显示病灶突破局部骨皮质,肿物向外突出,外突肿物及相连髓腔部分T1WI呈稍低信号,T2WI呈高信号;2例显示骨膜增厚,其中1例呈等信号,1例无信号;2例周围肌肉组织内可见不均匀斑片状长T2信号,T1WI与肌肉组织呈等信号.结论 长骨血管瘤的囊性蜂窝状X线表现较为特征型;CT及MRI有助于长骨血管瘤的诊断.     

长骨血管瘤的影像诊断

目的 分析长骨血管瘤的影像特征,旨在提高其诊断水平.方法 回顾性分析经手术病理证实的18例长骨血管瘤患者的X线平片(14例)、CT(9例)及MRI(6例).结果 18例长骨血管瘤中髓型10例、骨膜型5例、皮质内型3例.X线表现:髓型8例,其中3例表现为典型的蜂窝状,3例为溶骨性病灶周围骨质硬化明显,单纯溶骨、毛玻璃样密度各1例;骨膜型3例,表现为骨皮质增厚、硬化;皮质内型3例,表现为边界清晰的溶骨性病灶.CT表现:髓型6例,表现为溶骨膨胀型病灶5例,其中3例可见薄厚不一的硬化边,蜂窝状骨嵴影2例,骨皮质呈筛孔状1例,垂直于骨皮质的放射状骨膜增生2例;毛玻璃样密度1例.2例骨膜型表现为骨皮质均匀增厚1例,不规则骨膜增厚1例,局部髓腔狭窄消失.1例皮质内病变表现为病灶呈均匀软组织密度,局部皮质膨胀、增厚.MRI表现:2例显示髓腔内斑片状T1WI稍低信号,T2WI均呈稍高信号,边界清晰;1例T1WI及T2WI均呈等或稍低信号,病灶与正常组织分界不清;1例显示病灶突破局部骨皮质,肿物向外突出,外突肿物及相连髓腔部分T1WI呈稍低信号,T2WI呈高信号;2例显示骨膜增厚,其中1例呈等信号,1例无信号;2例周围肌肉组织内可见不均匀斑片状长T2信号,T1WI与肌肉组织呈等信号.结论 长骨血管瘤的囊性蜂窝状X线表现较为特征型;CT及MRI有助于长骨血管瘤的诊断.     

软骨母细胞瘤的影像学表现及对比研究

目的分析对比软骨母细胞瘤的X线、CT及MR影像学特征。方法分析经病理证实且于2周内行X线、CT和MR检查的22例软骨母细胞瘤病人的影像学表现。2例同时行CT平扫和增强扫描,7例同时行MR平扫和增强扫描。结果病灶位于胫骨上端11例,股骨下端4例,髌骨2例,肱骨上端、股骨上端、颞骨和下颌骨各1例。1例恶性者发生于髂骨并同时累及骶骨。X线表现为骨质破坏(21),病灶内斑片状、斑点状和(或)条状致密影(5),病灶周围边界不清的斑片状硬化(10)。CT上,病灶呈类圆形分叶状(14),内为软组织密度(7),伴有斑片状、斑点状和(或)结节状钙化(15),病灶周围出现边界不清的斑片状硬化(15),病变周围软组织肿胀(18)。病灶在T2WI和脂肪预饱和T2WI均呈混杂信号(22),病灶周围髓腔内有边界不清的斑片状长T1长T2信号(20)。结论良性软骨母细胞瘤的影像学表现多具有特征性,X线平片、CT和MRI多数征象相互对应。     

四肢关节隐性骨损伤的影像学评价

目的 :探讨四肢关节隐性骨损伤的影像学表现并评价X线平片及MRI检查的价值。方法 :搜集 3 4例有外伤史且临床检查提示有四肢关节骨损伤的病例。所有患者外伤后 1天内行X线摄片检查。随后行MRI检查 ,2周内行MRI检查 5例 ,2周后行MRI检查 2 9例。采用矢状位T1WI (TR 45 0msTE 12ms)、矢状位T2 WI加FS (TR 3 0 0 0msTE 96ms)及冠状位ME 2D (TR 775msTE 2 7ms)等序列成像 ,层厚为 4mm ,层间距为 0 .1mm。结果 :所有 3 4例患者 ,常规X线检查结果均为阴性。MRI检查 3 4例患者共发现 44个骨挫伤病灶 ,其中T1WI上 3 1个病灶 ( 70 .5 % )为较低信号 ,T2 WI加FS上 44个病灶 ( 10 0 % )全部表现为高信号 ,ME序列上 44个病灶 ( 10 0 % )全部表现为稍高或高信号。结论 :在隐性骨损伤的诊断中 ,MRI是目前最佳的检查方法。对于外伤后X线平片表现为阴性 ,而临床上仍疑诊为骨损伤者 ,有必要进行MRI检查 ,以T2 WI加FS和ME序列对隐性骨损伤的诊断最具价值。     

MRI对微波固化治疗肝癌疗效的评价

目的评价1.5TMRI平扫和动态增强对肝癌微波固化治疗后表现和疗效随访的价值。方法回顾性分析26例32个病灶肝癌微波固化治疗后MRI表现,并与AFP和DSA结果进行对照。结果微波固化治疗3天后的MRI平扫表现,T1WI呈相对高信号,T2WI呈相对低信号,病灶周围可见长T1,长T2水肿带。微波固化治疗1月后的MRI表现①单独行微波固化治疗的19个病灶以凝固性坏死为主,平扫T1WI呈相对等高信号,T2WI呈相对低信号或等信号,动态增强扫描无强化;②多种介入方法联合应用的5个病灶,特别是与TACE联合治疗的病灶,以凝固性坏死、液化性坏死合并存在,表现为局部T1WI呈相对低信号,T2WI呈相对高信号,但动态增强扫描无强化;③8个病灶不完全坏死:在T1WI上呈相对高信号的病灶周边有低信号结节或同时伴新月形低信号带,在T2WI上则表现为等低信号病灶周边出现相对高信号结节或新月形高信号带,在动态增强扫描时呈快进快出强化表现。结论 MRI平扫和动态增强评价微波固化的疗效可靠、准确,微波固化术后定期MRI随访具有重要意义。     

脑内海绵状血管瘤影像诊断

目的：探讨脑内海绵状血管瘤的CT、MRI影像表现特点及诊断价值。方法：回顾性分析28例脑内海绵状血管瘤的影像资料,经CT检查18例,6例增强扫描,MR检查28例,10例增强扫描,11例经手术病理证实,3例做伽马刀治疗,14例随诊证实。结果：脑内海绵状血管瘤CT平扫表现为稍高或混杂密度影,边界清晰,病灶内可见单发或多发点状或斑片状钙化,少数可表现为血肿密度,增强扫描轻度不均匀强化或无强化。MR典型表现为T2WI及T1WI高低不均匀信号,呈＂爆米花＂样,周边可见低信号环,部分病灶为T2WI中央高、周边低信号,T1WI略低信号,边界模糊;T2WI为高信号,T1WI中央高、周边低信号;少数病灶表现为T2WI、T1WI均为高信号且信号均匀。DWI呈中间混有高信号的不均匀黑色低信号或均匀黑色低信号且较T1WI及T2WI范围加大,增强扫描表现为不均匀强化或无明显强化。结论：脑内海绵状血管瘤以MRI表现更典型,MRI检查T2WI及DWI序列是诊断及随访脑内海绵状血管瘤的最佳方法。     

应力性骨折的早期低场强MRI与DR诊断分析

目的：通过对应力性骨折的DR与低场强MRI表现的对比,及分析应力性骨折的解剖学和生物力学特征,提高对应力性骨折早期的低场强MRI诊断的准确性。方法：回顾性分析经临床随访或病理证实29例不同部位应力骨折患者的MRI及DR图像。结果：29例中,胫骨12例（中上段为主）,股骨下段3例,胫骨上段和股骨下段同时发病3例,髂骨、耻骨、坐骨及股骨头颈部、股骨上段各2例,跖骨2例,腓骨中上段2例。MRI均可见骨髓腔内斑片状不均匀长T1、长T2水肿信号,范围远较DR片广泛,边界模糊;7例骨皮质周围见环形或半环形长T1、长T2骨膜水肿信号;6例可见隐匿骨折线;冠、矢状位表现为髓腔内斜形或横形线条状长T1、短T2信号影,其中骨皮质中断4例;10例可见骨皮质增厚,呈长T1、短T2信号;软组织肿胀呈弥漫性长T1、长T2信号。结论：MRI能够更敏感地发现早期应力性骨折,为诊断和判断骨折愈合情况提供更多信息。     

3.0 T MRI不同脉冲序列对胰腺疾病的诊断价值

目的 探讨MRI检查不同脉冲序列对胰腺病变的诊断价值。方法 对87例临床怀疑胰腺病变的病人应用3.0 T MR设备进行检查,扫描序列包括双回波T1WI（同相位与反相位成像）、脂肪抑制T1WI（T1WI+FS）、脂肪抑制T2WI (T2WI+FS)、磁共振胆胰管水成像（MRCP）、快速多层面扰相梯度回波(FSPGR)动态增强扫描。由2名放射科医师分析不同脉冲序列的MRI所见。结果 正常胰腺15例,急性胰腺炎27例,慢性胰腺炎30例,胰腺癌15例。T1WI+FS显示胰腺形态与信号最佳,正常胰腺呈稍高信号。在双回波T1WI上,胰腺与周围组织对比度降低。胰腺病变在T1WI上表现为低信号50例,T2WI+FS显示胰周渗出性病变34例。MRCP显示胰管扩张35例,胆管扩张20例,双管征9例。快速扰相梯度回波（FSPGR）动态增强显示胰腺癌13例,肿块在动脉期表现为相对低信号,延迟期轻度强化,周围血管受侵2例。结论 合理应用MR扫描序列有助于提高胰腺病变的诊断效能。     

磁共振成像在诊断颅内海绵状血管瘤中的应用价值

目的分析颅内海绵状血管瘤(cerebral cavernous malformations,CCMs)常规MRI序列表现及MRI磁敏感加权成像(susceptibility weighted imaging,SWI)的诊断价值。资料与方法回顾性分析50例经病理证实的CCMs患者的MRI资料,比较常规MRI序列(T1WI和T2WI)和SWI表现、检出率和病灶大小,判断其对CCMs的诊断价值。结果 50例共捡出97个病灶,22个病灶可见短T1信号伴出血,常规MRI对出血病灶具有多种表现形式;75个病灶未见短T1信号不伴出血。49个病灶T2WI灶周具有"铁环征";97个病灶中有48个病灶在T1WI或T2WI上呈"网格"状或"桑椹"状高、低混合信号;8个病灶T1WI、T2WI均呈高信号;6个病灶T1WI、T2WI均呈低信号;3个病灶T1WI呈等信号、T2WI呈稍低信号。SWI显示的病灶范围包括瘤体及灶周含铁血黄素区域,病灶信号不均匀性降低;SWI上90个病灶显示均匀或不均匀黑色信号,7个病灶显示混杂信号影。T1WI、T2WI、SWI对出血性病灶的检出率均为100%,SWI对非出血性病灶检出率为100%,显著高于T1WI和T2WI(18.6%和40.0%,P<0.05)。SWI显示出血性瘤体大小为(3.3±1.2)cm,显著大于T1WI和T2WI[(2.0±0.6)cm和(2.6±0.9)cm,P<0.05];SWI显示非出血性瘤体大小为(3.1±1.1)cm,显著大于T1WI和T2WI[(1.7±0.6)cm和(2.3±0.8)cm,P<0.05]。结论 MRI是诊断CCMs的首选方法,常规序列结合SWI序列能提供更准确和更全面的诊断信息。     

Transient Hyperintensity of the Infant Thyroid Gland on T1-Weighted MR Imaging: Correlation with Postnatal Age,Gestational Age,and Signal Intensity of the Pituitary Gland

BACKGROUND AND PURPOSE:The signal intensity of the thyroid in neonates is high on T1WI. It is affected by gestational and postnatal ages. However, the extent of the influence of these ages is unknown. This study investigated the relationship of signal intensities of the infant thyroid with postnatal and gestational ages and anterior pituitary using 3D gradient-echo T1WI.MATERIALS AND METHODS:This retrospective study included 183 T1-weighted images from 181 infants. Using a multiple linear regression analysis, we evaluated the effects of postnatal and gestational ages on the thyroid–muscle signal intensity ratio. The relationship between the thyroid and anterior pituitary signal intensities on T1WI and the age of the infants was evaluated.RESULTS:Multiple linear regression analysis showed that the thyroid signal intensity was affected negatively by postnatal age at examination and positively by gestational age at birth (P < .01 and P = .04, respectively). According to the standardized partial regression coefficients, the influence of postnatal age at examination was stronger than that of gestational age at birth (−0.72 and 0.13, respectively). The thyroid and anterior pituitary signal intensities reached constant values at 12 weeks'' postnatal age, and the mean thyroid–anterior pituitary signal intensity ratios were almost 1 throughout the entire period.CONCLUSIONS:The signal intensity of the infant thyroid on T1WI was more strongly influenced by the postnatal age at examination than the gestational age at birth, and it was almost equal to that of the anterior pituitary.

Thyroid hormone is essential for prenatal and neonatal neurologic development.¹ The fetal hypothalamic–pituitary–thyroid axis begins to develop by gestational week 6, and thyroid follicular epithelial cells are able to concentrate iodide and synthesize thyroid hormone by 11 weeks of gestation.^2,3 After delivery, serum thyroid-stimulating hormone (TSH) demonstrates a transient increase in the first 24 hours, and this TSH surge stimulates a rise in serum levels of thyroxine and triiodothyronine.⁴ A previous study reported that the fetal thyroid gland showed high signal intensity on 3D gradient-echo (GRE) T1WI, and the fetal thyroid–muscle signal intensity ratio did not correlate with gestational age.⁵In our institution, infants in the neonatal intensive care unit are routinely screened for CNS abnormalities using MR imaging, including 3D GRE T1WI in the head to neck range. Some of these infants display high signal intensity in the thyroid gland on 3D GRE T1WI, especially when the time between birth and the MR examination was short. The anterior pituitary glands of neonates usually show high signal intensity on T1WI, and the relative signal intensity of the anterior pituitary gland to that of the pons was significantly negatively correlated with postnatal age at examination.⁶ A recent study reported that the signal intensity of the infant thyroid and anterior pituitary on 3D GRE T1WI correlated positively with the gestational age at birth and negatively with the postnatal age at examination.⁷ However, the extent of the influence of gestational age at birth and postnatal age at examination on the signal intensities of the infant thyroid and anterior pituitary on T1WI is not known.It was hypothesized that postnatal age at examination might affect the signal intensity changes of the infant thyroid on 3D GRE T1WI more strongly than the gestational age at birth. The change in signal intensity of the infant thyroid on 3D GRE T1WI was thought to be similar to that of the anterior pituitary. In this study, a multiple linear regression analysis was used to evaluate the effects of postnatal age at examination and gestational age at birth on the thyroid–muscle and anterior pituitary–muscle signal intensity ratios. In addition, the change in signal intensity of the infant thyroid gland on 3D GRE T1WI was assessed to clarify the relationship between signal intensities of the infant thyroid and anterior pituitary.     

Magnetic resonance imaging of periosteum with ultrashort TE pulse sequences

PURPOSE: To assess the values of pulse sequences with ultrashort echo times (0.08 msec) for detecting and characterizing periosteum. MATERIALS AND METHODS: Two normal volunteers aged 33 and 58 years and 12 patients aged seven to 55 years were studied. A total of 10 of the patients had contrast enhancement with intravenous Gadodiamide. Two ovine tibias were examined before and after the periosteum was stripped from the bone. RESULTS: High signal regions were observed adjacent to cortical bone in all parts of the skeleton imaged. They were generally more conspicuous after fat suppression and contrast administration. In the ovine tibia there was a reduction in the high signal normally seen at the surface of the bone after periosteal stripping. The detached periosteum produced a high signal. Mean T(2)* values for adult human periosteum ranged from 5.3 to 11.4 msec. After enhancement the signal intensity increased. In two patients with tibial fractures, increased periosteal signal was seen and this showed marked enhancement. Signals from periosteum could be simulated by fat, contrast-enhanced blood and artifacts. CONCLUSION: The periosteum can be visualized with ultrashort echo time pulse sequences in health and disease.