3.0T MR高分辨率成像对直肠癌局部浸润的术前影像学评价

目的 探讨3.0T MR高分辨率成像在直肠癌术前局部浸润的评估价值.方法 回顾性分析经手术病理证实的直肠癌患者168例,术前均行MRI常规盆腔、直肠高分辨成像.评价3.0T MR高分辨成像术前T分期的准确性;探讨T3期直肠癌局部浸润特征性影像学表现.结果 直肠癌累及肠周径程度与病理T分期呈中等正相关(rs=0.530, P=0.003).MRI直肠癌T分期与病理T分期比较,总体诊断准确度为84.52%,各分期MRI征象与病理T分期有较强的相关性(rs=0.837,P=0.001).MRI诊断T3期直肠癌中,各单一征象以肿瘤结节样外凸特异性最高(91.1%),肌层信号中断灵敏度最好(89.7%).而各叠加征象中则以肠壁索条影+肌层信号中断特异性最高(89.3%),灵敏度最好(78.0%).结论 3.0T MR高分辨成像能较好显示直肠癌局部浸润表现,对术前T分期有一定的临床应用价值.     

动态增强MRI在中下段直肠癌T3分期中的应用研究

目的探讨动态增强 MRI 在中下段直肠癌 T3分期中的价值.方法本研究共纳入84例中下段直肠癌病人,包括经病理证实为 T3期直肠癌的66例.所有病人术前均接受动态增强 MRI 检查.分析 T3期直肠癌局部浸润的 MRI 征象,进行影像-病理对照,计算动态增强 MRI 诊断 T3分期的准确度、敏感度、特异度、阳性预测值和阴性预测值.对直肠系膜内癌性与非癌性索条影在边缘和强化形式上的差异进行统计学分析.结果 MRI 对中下段直肠癌 T3分期的诊断准确度、敏感度、特异度、阳性预测值和阴性预测值分别为86.90%、90.91%、72.22%、92.31%和68.42%.直肠系膜内癌性与非癌性索条影在边缘和强化形式上的差异均有统计学意义(P<0.05).在判断 T3期直肠癌局部浸润深度时,将直肠系膜内癌性索条影误判为非癌性索条影是导致分期不足的主要原因.结论通过分析直肠系膜内异常索条影的边缘及强化形式有助于提高中下段直肠癌 T3分期的准确性.     

直肠MRI对直肠癌术前T分期评估的研究进展

直肠MRI是直肠癌术前分期的首选检查方法。高分辨T₂WI可显示直肠癌的位置、形态及信号,通过判别肿瘤的浸润深度来评估直肠癌的T分期;还可以识别直肠癌壁外血管内侵犯、环周切缘阳性等预后不良因素,从而指导选择最佳治疗方案。增强T₁WI可显示病变区是否存在完整的黏膜下强化带,结合形态学特征准确地区分T₁及T₂期肿瘤。基于直肠壁各层及周围结构的MRI征象,对直肠MRI评估直肠癌术前局部T分期的研究进展进行综述。     

薄层MRI直肠癌T3期征象与病理对照研究

目的 探讨薄层MRI直肠癌T分期征象对直肠癌术前分期价值.方法 58例患者行薄层MRI,由两位高年资诊断医师进行T分期及征象评估,最终结果与病理结果对照研究.结果 薄层MRI T分期与病理结果一致性好,Kappa值0.82.直肠癌MRI T分期各级征象与病理分期呈正向线性相关,相关性强(rs =0.874,P＜0.01).壁外索条影、肌层信号中断、肿瘤结节样外凸、系膜脂肪间隙模糊等征象对T3期的准确性分别为67.2％、93.1％、84.5％、72.4％;敏感性分别为64.5％、93.5％、70.9％、77.4％;特异性分别为70.4％、92.6％、100％、66.7％.结论 薄层MRI直肠癌T分期征象用于直肠癌术前T分期有一定的价值.     

3.0T MRI在直肠癌术前评估中的应用研究

目的 探讨3.0T MRI在直肠癌术前评估中的应用价值.方法 对41例经病理活检证实为直肠癌的患者进行常规MRI、高分辨MRI及扩散加权成像(DWI)扫描,测量肿瘤最下缘离肛缘的距离及累及环周百分比,评估肿瘤的TN分期、环周切缘(CRM)、系膜血管受侵(EMVI)的状态,与肠镜和手术结果比较.结果 MRI对判断肿瘤下缘距肛缘的距离具有很好的预测价值(P>0.05);T1~T2期、T3期肿瘤累及环周百分比的平均值分别是61%、83%(P>0.05);T、N分期诊断的总准确率分别为80.5%、75.6%,与病理诊断的一致性较好(Kappa值=0.564、0.634);CRM、EMVI诊断的总准确性分别是90.2%、73.2%,与病理诊断的一致性分别是较好、中度一致(Kappa值=0.765、0.461).     

The Application Value of Background Suppression Diffusion Weighted Imaging (DWIBS) in Preoperative Staging of Rectal Cancer

目的 探讨全身磁共振背景抑制扩散加权成像(DWIBS)对直肠癌术前分期的应用价值.资料与方法 对39例经肠镜证实的直肠癌患者,术前行全身磁共振DWIBS检查,以直肠癌原发灶病理结果为标准将本组资料分为T2、T3、T4三组,分析原发灶DWIBS上肿瘤信号强度、表观扩散系数(ADC)值、肠壁病变厚度、肠壁受累长度、肿瘤侵犯肠周径的情况五个指标在各组间的差异,及其与T分期的相关性.通过全身DWIBS图像作出术前NM分期,然后与术后NM病理分期结果进行对照,判断DWIBS对直肠癌NM分期的准确性、特异性及敏感性.结果 全身DWIBS对直肠癌原发灶检出的敏感性为100％,准确性为100％,DWIBS上所显示的肠壁病变厚度和肠周径侵犯程度在各分期间有显著差异(P＜0.05),且两者与T分期均有显著相关性(rs =0.427,P＜0.05;rs =0.384,P＜0.05);原发灶肿瘤信号强度、ADC值、肠壁受累长度在各分期间均无显著差异(P＞0.05).DWIBS对N分期诊断的总体准确性为84.61％;对N0期诊断的敏感性为85.71％,特异性为83.33％,N1期诊断的敏感性为70.00％,特异性为89.66％,N2期诊断的敏感性为100％,特异性为80.65％.对M期诊断的敏感性及准确性均为100％.结论 全身DWIBS对直肠癌NM分期的诊断敏感性较高,是显示转移性淋巴结及远处转移病灶的一种有效检查方法.全身DWIBS对直肠癌原发灶检出的准确性及敏感性很高,但在T分期中的应用有一定的限度,结合常规MRI序列有助于提高T分期的准确性.     

全身磁共振背景抑制扩散成像在直肠癌术前分期中的应用价值

目的探讨全身磁共振背景抑制扩散加权成像(DWIBS)对直肠癌术前分期的应用价值。资料与方法对39例经肠镜证实的直肠癌患者,术前行全身磁共振DWIBS检查,以直肠癌原发灶病理结果为标准将本组资料分为T2、T3、T4三组,分析原发灶DWIBS上肿瘤信号强度、表观扩散系数(ADC)值、肠壁病变厚度、肠壁受累长度、肿瘤侵犯肠周径的情况五个指标在各组间的差异,及其与T分期的相关性。通过全身DWIBS图像作出术前NM分期,然后与术后NM病理分期结果进行对照,判断DWIBS对直肠癌NM分期的准确性、特异性及敏感性。结果全身DWIBS对直肠癌原发灶检出的敏感性为100%,准确性为100%,DWIBS上所显示的肠壁病变厚度和肠周径侵犯程度在各分期间有显著差异(P<0.05),且两者与T分期均有显著相关性(rs=0.427,P<0.05;rs=0.384,P<0.05);原发灶肿瘤信号强度、ADC值、肠壁受累长度在各分期间均无显著差异(P>0.05)。DWIBS对N分期诊断的总体准确性为84.61%;对N0期诊断的敏感性为85.71%,特异性为83.33%,N1期诊断的敏感性为70.00%,特异性为89.66%,N2期诊断的敏感性为100%,特异性为80.65%。对M期诊断的敏感性及准确性均为100%。结论全身DWIBS对直肠癌NM分期的诊断敏感性较高,是显示转移性淋巴结及远处转移病灶的一种有效检查方法。全身DWIBS对直肠癌原发灶检出的准确性及敏感性很高,但在T分期中的应用有一定的限度,结合常规MRI序列有助于提高T分期的准确性。     

直肠癌MRI术前评估价值与术后病理对比研究

目的 探讨MRI对直肠癌术前评估的价值.方法 选取84例行外科手术治疗的直肠癌患者的MRI、病理、临床资料.用卡方检验评价MRI对诊断肿瘤T分期、N分期、环周切缘(CRM)受累情况、壁外血管浸润的准确性,用配对t检验评估MRI分析病灶与齿状线位置关系的准确性.结果 MRI可较准确地评估对诊断肿瘤T分期、N分期、环周切缘...     

MRI平扫结合扩散加权成像在直肠癌中的临床应用价值

目的:探讨MRI平扫结合扩散加权成像(DWI)在直肠癌中的临床应用价值.方法:对28例直肠癌患者行MRI平扫及DWI检查,评价肿瘤形态、T分期、淋巴结转移、环周切缘(CRM)状态、肿瘤下缘距肛缘的距离,并与术后病理结果进行对照.MRI与病理对T分期、N分期及环周切缘受累评估的一致性采用Kappa检验.结果:MRI平扫及DWI能准确显示肿瘤的部位及形态.MRI平扫结合DWI对28例直肠癌T分期总的诊断符合率为78.57％(22/28),T1～T2期、T3期、T4期的诊断符合率分别为85.71％、78.57％、92.86％,MRI与病理对T分期的诊断具有较高的一致性(Kappa值=0.656).MRI平扫结合DWI对判断N分期的符合率为71.43％ (20/28),判断淋巴结转移的敏感度为66.67％(6/9),特异度为73.68％(14/19),MRI与病理对N分期的诊断具有中度一致性(Kappa值=0.489).MRI判定CRM状态的总体符合率为85.71％ (24/28),敏感度为90.90％(10/11),特异度为82.35％(14/17),阳性预测值为76.92％(10/13),阴性预测值为93.33％(14/15),MRI与病理对环周切缘受累的评估具有较高的一致性(Kappa值=0.710).MRI矢状面图像能测量18例下段直肠癌肿瘤下缘距肛缘的曲线距离.结论:MRI平扫结合DWI对直肠癌、T分期、环周切缘状态的判断及肿瘤下缘距肛缘的距离的测量有重要临床价值.     

FIGOⅠ Ⅱ期子宫内膜癌MRI征象分析与评价

目的:按照FIGO2009分期标准,分析ⅠⅡ期子宫内膜癌的MRI征象及其病理基础,评价MRI对子宫内膜癌肌层和宫颈侵犯的诊断价值。方法:43例ⅠⅡ期子宫内膜癌患者术前均行MRI检查,采用双盲法,描述肿瘤的MRI表现特征,并将MRI术前分期及判断肌层和宫颈浸润结果,与术后病理结果对照分析。结果:Ⅰa 26例,Ⅰb 8例,Ⅱ期9例。Ⅰ期MRI主要表现为子宫内膜增厚、腔内局限型或弥漫性软组织肿块呈中等强化、T2WI低信号结合带中断及肌层侵犯等,其病理基础为癌细胞呈腺样乳突状结构,突破粘膜层,向肌壁间浸润性生长。Ⅱ期以宫颈内出现与宫体肿瘤相连续的异常信号影及宫颈纤维间质破坏为特征。MRI评价肿瘤浸润肌层深度的诊断准确性为86%,判断宫颈侵犯的敏感性、特异性、准确性分别为78%、91%、88%,与病理结果比较无显著性差异(P0.05)。结论:MRI对Ⅰ、Ⅱ期子宫内膜癌的早期诊断、肌层和宫颈侵犯的判断及术前分期准确性高,具有较高的临床应用价值。     

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.     

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 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.     

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。     

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.     

Contrast behavior of high-spatial-resolution T1-weighted MR imaging at 3.0 T vs. 1.5 T

Twenty-four volunteers were examined at T1-weighted images with thin sections using gradient-based sequences with a possible short and same TR at 3.0 and 1.5 T. Pancreas-to-spleen contrast measurements and scores for visual assessments of image contrast were significantly worse at 3.0 T than at 1.5 T on both sequences. The image contrast of high-spatial-resolution T1-weighted images at 3.0 T is decreased compared to that of images with the same and possible short TR at 1.5 T.