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。     

超急性期脑内血肿的超低场MRI表现

目的　探讨超急性期脑内血肿的超低场MRIT1 WI表现特点。方法　 160例超急性期脑内血肿行 0 .0 4TWDLMW -4 0 0MR机扫描 ,选用PS3DT1 WI(TR =12 5ms,TE =2 5ms)。结果　基底节出血 14 0例 ,脑叶出血 5例 ,小脑出血 13例 ,脑干出血 2例。 160例在PS3DT1 WI上均呈明显短T1 信号 ,并可见血肿的占位效应及血肿周围的水肿。结论　超急性期脑内血肿在超低场MRI诊断优于中高场MRI。     

MRI多序列扫描技术在乳腺良恶性肿瘤诊断中的应用

目的 探讨磁共振多种检查序列和动态增强技术在乳腺检查中的应用价值.方法 对62例乳腺肿块病灶分别行常规横断位平扫:SE T1WI序列、脂肪抑制FSE T2WI序列、脂肪抑制T1WI SPGR(扰相梯度回波)序列;注射 Gd-DTPA后使用SPGR序列动态增强扫描.比较分析增强前后病灶的形态学特征,强化速率和强化峰值出现时间,时间-信号强度曲线(STC)的类型.结果 良性病变38例,恶性肿瘤24例.良性病变信号均匀35例, T1WI多为等低信号,T2WI为稍高信号或高亮信号.动态增强后绘制病灶感兴趣区的时间-信号强度曲线以无强化型28例、缓慢上升型9例.恶性病变信号不均23例,T1WI多呈低信号,T2WI为高和低信号混杂存在,动态增强后病灶时间-信号强度曲线快进快出型22例、快进平台型1例、快进慢升型1例.结论 MRI多序列及动态增强扫描技术对鉴别乳腺良恶性病变有重要价值.     

3.0T磁敏感加权成像在脊髓出血性病变中的应用价值

目的:探讨磁敏感加权成像在脊髓出血性病变中的应用价值。方法:32例脊髓出血性病变患者(病变组)和16例健康志愿者(对照组)行3.0T磁敏感加权成像(SWI)、二维扰相梯度回波T2*加权(2D-MERGE T2*WI)、FSE T1WI及FSE T2WI扫描。32例病例均经临床随访及病理证实,包括脊髓挫裂伤20例、脊髓动静脉畸形6例、脊髓海绵状血管瘤2例、脊髓星形细胞瘤伴出血4例。比较分析SWI及2D-MERGE T2*WI、常规FSE T2WI对脊髓出血性病变检出的敏感度和特异度。结果:20例脊髓挫裂伤患者常规FSE T2WI均显示水肿征象,其中4例脊髓挫裂伤在SWI、2D-MERGET2*WI、常规FSE T1WI及FSE T2WI均未见出血征象,8例脊髓挫裂伤仅在SWI显示出血征象,另外8例脊髓挫裂伤、6例脊髓动静脉畸形、2例脊髓海绵状血管瘤和4例脊髓星形细胞瘤伴出血在SWI显示低信号出血征象较2D-MERGET2*WI及常规FSE T2WI更敏感。结论:3.0T磁敏感加权成像检出脊髓出血性病变比常规MRI更敏感,可作为脊髓出血性病变MRI检查重要的补充序列。     

磁共振快速T1加权序列在腹部疾病中的应用选择

目的　探讨磁共振快速T1加权序列各成像技术及其在腹部疾病中的应用。方法　对 45例可疑腹部疾病的患者先采用T2 加权快速自旋回波 (T2 WI/TSE)序列扫描 ,再加扫快速多层绕相梯度回波 (DUAL/FFE)、选择水激励梯度回波 (sT1WI/WATS/FFE)及三维超快速梯度回波 (3D/T1WI/TFE)序列进行扫描。结果　 45例中 6例正常 ,3 9例异常。 3种快速T1WI序列中 ,DUAL/FFE(OP)序列对检测腹部含脂质病变较为敏感。sT1WI/WATS/FFE序列对检测胰腺病变较为敏感 ,3D/T1WI/TFE序列对于肝脏结节性病变较为敏感。结论　在MRIT2 WI/TSE序列的基础上合理地结合与DUAL/FFE(OP)、sT1WI/WATS/FFE、3D/T1WI/TFE序列 ,可更好地显示腹部各病变的特征 ,提高诊断准确率。     

磁共振弥散成像对急性脑梗死的诊断价值

目的探讨磁共振弥散成像对超急性、急性脑梗死的诊断价值。方法对80例疑似急性期脑梗死患者,行磁共振常规T1WI、T2WI、水抑制序列(FLAIR)、弥散加权扫描(DWI)。结果80例中,超急性期脑梗死10例,急性期32例,超急性期、急性期脑梗死在DWI上表现为高信号,T2WI上为等信号或部分稍高信号,ADC图上表现为低信号。MRI扫描未见异常2例。结论磁共振弥散成像对超急性期、急性期脑梗死病变较常规MRI敏感,在多发梗死灶中可以发现责任病灶、为临床选择治疗方案提供依据。     

磁敏感加权成像对脑静脉(窦)血栓形成的诊断价值

目的 探讨磁敏感加权成像(SWI)对脑静脉(窦)血栓形成(CVST)的诊断价值.资料与方法 回顾性分析18例经MR或DSA确诊的CVST患者的影像资料.18例全部行常规MRI、磁共振静脉成像(MRV)及SWI检查.其中15例同时行T2*WI梯度回波(GRE)检查,10例进行了DSA检查.结果 13例急性期CVST,血栓在T1、WI、T2、WI显示不理想,而在T2*WI GRE呈典型低信号.18例CVST,在SWI检查中均可见引流区小静脉数量增多,管径增粗,信号减低,同时发现更多的微小出血灶.但SWI对血栓本身的显示较困难,其他序列如T1WI、T2WI、T2*GRE或MRV具有优势.在全部MRV中,均可见静脉信号缺失.结论 SWI较常规MR序列能发现更多CVST的征象,有更多的诊断价值.     

The value of 3.0T susceptibility weighted imaging (SWI) in detection of spinal hemorrhagic lesion

目的:探讨磁敏感加权成像在脊髓出血性病变中的应用价值.方法:32例脊髓出血性病变患者(病变组)和16例健康志愿者(对照组)行3.0T磁敏感加权成像(SWI)、二维扰相梯度回波T2*加权(2D-MERGE T2*WI)、FSE T1WI及FSE T2WI扫描.32例病例均经临床随访及病理证实,包括脊髓挫裂伤20例、脊髓动静脉畸形6例、脊髓海绵状血管瘤2例、脊髓星形细胞瘤伴出血4例.比较分析SWI及2D-MERGE T2*WI、常规FSE T2WI对脊髓出血性病变检出的敏感度和特异度.结果:20例脊髓挫裂伤患者常规FSE T2WI均显示水肿征象,其中4例脊髓挫裂伤在SWI、2D-MERGE T2*WI、常规FSE T1 WI及FSE T2WI均未见出血征象,8例脊髓挫裂伤仅在SWI显示出血征象,另外8例脊髓挫裂伤、6例脊髓动静脉畸形、2例脊髓海绵状血管瘤和4例脊髓星形细胞瘤伴出血在SWI显示低信号出血征象较2D-MERGET2*WI及常规FSE T2WI更敏感.结论:3.0T磁敏感加权成像检出脊髓出血性病变比常规MRI更敏感.可作为脊髓出血性病变MRI检查重要的补充序列.     

磁共振不同序列对颅内海绵状血管瘤的诊断价值

目的 探讨磁共振成像不同序列对颅内海绵状血管瘤诊断的临床应用价值.方法 应用磁共振梯度回波FLASH T2WI及自旋回波序列SE T1 WI、T2 WI对36例颅内海绵状血管瘤病人进行扫描,分析MRI不同扫描序列图像特征.结果 36例病人中SE T1 WI发现海绵状血管瘤病灶31个,SE T2 WI发现病灶36个,FLASH T2 WI发现病灶38个.结论 在显示颅内海绵状血管瘤方面,MR梯度回波FLASH T2 WI较SE序列更为优越.     

MR不同序列诊断早期脊柱转移瘤的价值

目的:探讨MR不同序列在诊断早期脊椎转移瘤中的价值.方法:25例临床怀疑脊柱转移瘤患者行脊柱磁共振检查,磁共振扫描序列包括自旋回波(SE)T1WI、快速自旋回波(TSE)序列T2WI、快速翻转恢复序列(STIR)、梯度回波(GRE)序列二维多回波聚合(Me-2D).结果:25例均发现脊柱转移瘤病灶,共73个椎体和45个附件受累.椎体的异常在各序列图像显示情况不同,T1WI显示73个异常椎体,T2WI显示55个,STIR显示69个,Me-2D显示73个.在T1WI序列图像有24个椎体表现为弥漫性异常信号,49个椎体局部信号异常.Me-2D序列显示椎体局部受累病灶边缘及骨小梁结构清晰.结论:SE T1WI,TSE T2WI及GRE Me-2D序列结合能够更敏感地发现椎体受累早期改变.     

In vivo blood T1 measurements at 1.5 T, 3 T,and 7 T

The longitudinal relaxation time of blood is a crucial parameter for quantification of cerebral blood flow by arterial spin labeling and is one of the main determinants of the signal‐to‐noise ratio of the resulting perfusion maps. Whereas at low and medium magnetic field strengths (B₀), its in vivo value is well established; at ultra‐high field, this is still uncertain. In this study, longitudinal relaxation time of blood in the sagittal sinus was measured at 1.5 T, 3 T, and 7 T. A nonselective inversion pulse preceding a Look‐Locker echo planar imaging sequence was performed to obtain the inversion recovery curve of venous blood. The results showed that longitudinal relaxation time of blood at 7 T was ～ 2.1 s which translates to an anticipated 33% gain in the signal‐to‐noise ratio in arterial spin labeling experiments due to T₁ relaxation alone compared with 3 T. In addition, the linear relationship between longitudinal relaxation time of blood and B₀ was confirmed. Magn Reson Med, 70:1082–1086, 2013. © 2012 Wiley Periodicals, Inc.     

Tätertypen bei Tötungsdelikten

Ohne Zusammenfassung     

T1 and T2 relaxivity of intracellular and extracellular USPIO at 1.5T and 3T clinical MR scanning

In this study we evaluated the effects of intracellular compartmentalization of the ultrasmall superparamagnetic iron oxide (USPIO) ferumoxtran-10 on its proton T1 and T2 relaxivities at 1.5 and 3T. Monocytes were labeled with ferumoxtran-10 by simple incubation. Decreasing quantities of ferumoxtran-10-labeled cells (2.5×10⁷-0.3×10⁷ cells/ml) and decreasing concentrations of free ferumoxtran-10 (without cells) in Ficoll solution were evaluated with 1.5 and 3T clinical magnetic resonance (MR) scanners. Pulse sequences comprised axial spin echo (SE) sequences with multiple TRs and fixed TE and SE sequences with fixed TR and increasing TEs. Signal intensity measurements were used to calculate T1 and T2 relaxation times of all samples, assuming a monoexponential signal decay. The iron content in all samples was determined by inductively coupled plasma atomic emission spectrometry and used for calculating relaxivities. Measurements at 1.5T and 3T showed higher T1 and T2 relaxivity values of free extracellular ferumoxtran-10 as opposed to intracellularly compartmentalized ferumoxtran-10, under the evaluated conditions of homogeneously dispersed contrast agents/cells in Ficoll solution and a cell density of up to 2.5×10⁷ cells/ml. At 3T, differences in T1-relaxivities between intra- and extracellular USPIO were smaller, while differences in USPIO T2-relaxivities were similar compared with 1.5T. In conclusion, cellular compartmentalization of ferumoxtran-10 changes proton relaxivity. This work was supported by a seed grant from the Department of Radiology, University of California of San Francisco.     

T1, T2 relaxation and magnetization transfer in tissue at 3T.

T1, T2, and magnetization transfer (MT) measurements were performed in vitro at 3 T and 37 degrees C on a variety of tissues: mouse liver, muscle, and heart; rat spinal cord and kidney; bovine optic nerve, cartilage, and white and gray matter; and human blood. The MR parameters were compared to those at 1.5 T. As expected, the T2 relaxation time constants and quantitative MT parameters (MT exchange rate, R, macromolecular pool fraction, M0B, and macromolecular T2 relaxation time, T2B) at 3 T were similar to those at 1.5 T. The T1 relaxation time values, however, for all measured tissues increased significantly with field strength. Consequently, the phenomenological MT parameter, magnetization transfer ratio, MTR, was lower by approximately 2 to 10%. Collectively, these results provide a useful reference for optimization of pulse sequence parameters for MRI at 3 T.     

T2 quantitation of articular cartilage at 1.5 T

PURPOSE: To evaluate sources of error when using a multiecho sequence for quantitative T2 mapping of articular cartilage at 1.5 T. MATERIALS AND METHODS: Phantom measurements were used to assess the contribution of stimulated echoes to inaccuracy of T2 measurements in cartilage using a multiecho sequence. Five volunteer studies compared in vivo single-echo spin echo results to multiecho, single-slice and multiecho, multislice acquisitions for assessment of both the stimulated echo and magnetization transfer contrast (MTC) contributions to T2 measurement inaccuracy. RESULTS: Phantom experiments demonstrated that substantial inaccuracy (10%-13% longer T2 values) is introduced from stimulated echoes with a multiecho sequence with slice-selective refocusing pulses. The in vivo volunteer studies also demonstrated increases in measured T2 by up to 48% with a multiecho sequence. Use of the multiecho sequence in the multislice mode resulted in T2 values closer to the single-echo standards for the volunteer studies. However, this apparent increased accuracy should be regarded as circumstantial, as it only occurs because the error due to MTC has the opposite sign compared to the error due to the stimulated echo contribution. CONCLUSION: Use of a multiecho, multislice sequence for cartilage T2 measurements should be undertaken with the caution that substantial inaccuracy is introduced from stimulated echoes and MTC.     

Clinical advantages of 3.0 T MRI over 1.5 T

Since approval by the FDA in 2000, human MR imaging (MRI) at 3.0 T has been increasingly used in clinical practice. In spite of the potential technical challenges, a number of clinical advantages of 3.0 T MRI over 1.5 T have been identified in the recent years. This article reviews the benefits and the current knowledge of 3.0 T whole-body MRI from an evidence-based perspective and summarizes its clinical applications.     

T2 relaxometry of the hippocampus at 3T

BACKGROUND AND PURPOSE: T2 mapping is useful for identifying and quantifying abnormalities of the hippocampus and amygdala. It is particularly useful in the presurgical evaluation of patients with temporal lobe epilepsy and for the identification of bilateral hippocampal sclerosis (HS). The purpose of this study was to implement and validate a dual-echo method for producing coronal T2 maps with complete coverage of the hippocampus and the rest of the brain on a 3T MR imaging scanner. MATERIALS AND METHODS: T2 relaxation times were estimated on 10 occasions on 3 quality assessment Eurospin II (Diagnostic Sonar, Livingstone, Scotland) test objects with the use of conventional spin-echo (CSE), fast spin-echo, and fast recovery fast spin-echo (FRFSE) sequences on a 3T Excite MR imaging scanner (GE Healthcare, Milwaukee, Wis). Hippocampal T2 relaxation times were then measured in 15 healthy subjects and 20 subjects with clear-cut HS who were scanned at 1.5 T with a previously validated dual-echo CSE sequence and 3T with an FRFSE sequence. RESULTS: 3T FRFSE data were as reliable as CSE data at 1.5 T. Reliability of hippocampal T2 measures was good on healthy volunteers and subjects with HS. FRFSE images were suitable for qualitative radiologic reporting and with complete brain coverage, so no additional T2-weighted sequences were required. There was good correlation between the 3T hippocampal T2 measurements and values obtained with the previously validated technique at 1.5 T, with reliable identification of all of the subjects with HS. CONCLUSIONS: T2 mapping with an FRFSE 30/80 sequence may be readily applied at 3T and can produce reliable T2 values in vivo with contiguous 5-mm sections and in a much reduced scan time of 3 minutes 1 second compared with 10 minutes 30 seconds for the CSE sequence at 1.5 T.     

T—2四醇和T—2五醇的制备

目的：进一步探讨Ｔ－２毒素与其结构效应的关系，制备Ｔ－２毒素的两个衍生物。Ｔ－２和Ｔ－２五醇。     

MR T1 and T2 relaxations in cysts and abscesses measured by 1.5 T MRI

Objectives

The main objective of this study was to make a comparison between the relaxation rates in jaw cysts and abscesses. Such a comparison should provide quantitative information for MR image analysis.

Methods

A phantom containing 20 odontogenic jaw cysts and 11 jaw abscesses was imaged with 1.5 T MR. T₁ measurements were performed by using a mixed sequence of inversion recovery and spin echo, while T₂ measurements were carried out by the Carr–Purcell Meiboom–Gill (CPMG) sequence. Cystic fluids and abscesses were compared statistically.

Results

In cysts and abscesses, respectively, the mean 1/T₁ was 0.9355 s⁻¹ and 0.8245 s⁻¹ and the mean 1/T₂ was 2.4575 s⁻¹ and 4.7073 s⁻¹. The 1/T₂ in cysts was very highly significantly different from that in abscesses (p = 0.0001). Both T₁ and T₂ were linearly proportional to material contents. T₂ relaxivities [26.458 ml (g s)⁻¹ for abscesses and 21.455 ml (g s)⁻¹ for cysts] were higher than T₁ relaxivities [5.4766 ml (g s)⁻¹ for abscesses and 10.075 ml (g s)⁻¹ for cysts].

Discussion

Present T₂ measurements differentiate cysts from abscesses with a confidence interval of 95%. Because in vivo and in vitro image contrasts are changed by the same parameters, the T₂ findings should present valuable information for in vivo MRI. Hence the significant difference and the relaxivities may provide quantitative information for clinicians and researchers making image analyses.

Conclusion

T₂ may differentiate cysts from abscesses. The difference in T₂ is related to the material content of samples.