磁共振功能成像观察猫播散性皮层抑制

目的 利用磁共振功能成像(fMRI)研究KCl诱导猫脑模型的播散性脑皮层抑制(SCD)现象.方法 雌猫6只,双侧上侧裂回上方开颅,以备分别注入KCl凝胶和生理盐水凝胶.磁共振检查首先行垂直相交的横断面、矢状面、冠状面T1WI及T2WI扫描,分析各方位图像的解剖特点;然后分别行静息期、KCl刺激期及对侧生理盐水刺激期BOLD采集.最后取局部脑组织行病理学检查.结果 包括双侧上侧裂回和边缘回的冠状面图像能显示脑回的长轴及相邻脑回的关系.脑激活图显示KCl刺激区上侧裂回及邻近边缘回脑皮层出现激活区者5例,同侧边缘回后部出现激活区者5例.时间-信号强度曲线显示注入KCl后,fMRI信号立即显著增高,并持续维持于高水平.病理检查显示KCl刺激局部神经细胞水肿.结论 包括双侧上侧裂回和边缘回的冠状面是磁共振功能成像研究SCD的理想成像层面;fMRI能准确检测出SCD伴发的脑血流量的变化.     

临床用肢端柔性表面线圈和相控阵线圈在小动物磁共振成像中的性能比较

目的对比肢端柔性线圈和相控阵线圈非并行采集及并行采集技术在小动物实验中对图像质量的影响。方法10只Wistar大鼠,分别用西门子标配的临床用正交柔性肢端线圈和相控阵肢端线圈在同一扫描参数的条件下用于头部信号采集,同时在肢端相控阵线圈采集中采用并行采集技术再获得相同的图像,然后对三组图像选择同一层面进行SNR的比较。结果正交柔性线圈和4通道肢端相控阵线圈采集的图像信噪比有明显的差异,正交柔性线圈能获得更高的图像信噪比,而肢端相控阵线圈非并行采集与并行采集技术(R=2)所获得的图像信噪比没有差异,但采用并行采集技术能极大地减少扫描时间。结论小动物实验在线圈的选用上,线圈的填充因数对图像质量的影响更大,但相控阵线圈与并行采集技术合用可以极大地减少成像时间。     

儿童背部纤维瘤病超声表现一例

患儿女,年龄4个月,发现背部肿物1个月,肿物质地较软,移动度差,表面皮肤颜色正常.超声检查显示:背部胸椎(T8~T10水平)后方皮下见一大小为4.9 cm×1.1 cm的混合回声团,似与脊柱相通,近体表侧软组织增厚,较厚处0.8 cm.彩色多普勒血流成像显示肿物内部未见明显血流信号(图1,2).     

磁共振全身弥散成像对胃肠道恶性肿瘤的术后随访价值

目的探讨3.0 T全身磁共振成像的技术对于胃肠道恶性肿瘤性疾病的术后随访价值。材料与方法对19例术后随访的胃肠道恶性肿瘤患者行WBMRI(DWI+T2WI),后处理平台为GE ADW4.6工作站。Functool工具拼接横断面弥散图像,得到HD-MIP图像、黑白反转图像(类"PET"图像)及伪彩色图像;Pasting工具拼接冠状面T2加权图像,得到全身冠状面T2加权图像,再经图像融合得到类"PET-MR"图像。结果 19例患者(其中胃弥漫性大B细胞淋巴瘤2例,胃癌8例,结肠癌7例,直肠癌2例)均获得图像质量良好的全身磁共振图像。发现恶性转移性病例6例,阳性率约32%。结论使用头颈联合线圈及体线圈接收方法可以改善中心频率漂移现象,得到符合诊断需要的全身弥散图像。3.0T MR全身弥散成像可清晰显示胃肠道恶性肿瘤的转移灶,对胃肠道恶性肿瘤的术后随访和辅助诊断具有重要价值。     

侵袭性纤维瘤超声表现1例

患者男,45岁,发现右侧背部无痛性包块1年。体格检查:右侧背部可扪及一7.0cm×5.0cm的包块,质中,边界清晰,无压痛,活动度可。超声检查:右侧背部肩胛下方脂肪层深面可见一范围2.94mm×1.25mm的片状减弱回声,前后包膜尚清晰,左右包膜与脂肪层分界欠清(图1),肿块内部未见明显血流信号。超声提示:右侧背部肩胛下方脂肪层深面靠近肌层减弱回声包块。术中所见:包块位于皮下层,与脂肪组织有粘连,与皮肤及肌层表面筋膜无粘连及侵犯,包块边界不清。病理诊断:侵袭性纤维瘤病(图2)。     

颅中窝海绵状血管瘤误诊3例分析

对颅中窝海绵状血管瘤误诊3例分析如下.1 病历摘要例1:女,63岁.间隙性头痛1 a余伴双眼视力减退3个月.查体:神志清,左眼视力0.4右眼视力0.7双颞侧偏盲,双侧视神经原发性萎缩,其他颅神经检查未见异常.内分泌激素水平化验室检查正常.放射学检查:颅骨平片蝶鞍扩大、鞍背鞍底骨质吸收破坏.CT平扫鞍区内可见4.1 cm×5.3 cm之稍高密度团快影,边缘欠清晰,强化后不均匀明显增强.MR扫描显示在鞍区可见占位病灶T1像稍低信号、T2 T1像为高信号,在质子密度像上为高信号,病灶内未见血管流空影,增强扫描,病灶多呈均匀明显强化,病灶部分突入到蝶窦内,冠状位肿瘤向两侧浸润,右侧海绵窦向外推移变形,右侧颈内动脉部分包绕,左侧颈内动脉大部包绕,动脉管径变窄.术前CT及MRI诊断为侵袭性垂体腺瘤.术中所见:肿瘤呈紫红色,有明显搏动,穿刺可抽出动脉血,切开后大出血,部分切除肿瘤,病理检查诊断为海绵状血管瘤.     

MRI对儿童癫痫患者海马硬化的应用价值分析

目的探讨磁共振成像(MRI)对儿童癫痫患者海马硬化的应用价值分析。方法选取2013年11月至2014年11月经手术治疗确诊的癫痫海马硬化患者23例。通过对23例儿童癫痫海马硬化患者进行磁共振成像常规MRI扫描、液体衰减反转恢复序列(FLAIR)薄层扫描、辅助T2W-FLAIR序列、横断位GM-only、三维T1加权成像(3DT1W)与海马单体素磁共振波谱成像(1H-MRS),分析MRI检查对癫痫患者海马硬化的应用价值。结果 MRI检查显示海马结构特征清晰,23例患者在FSET1WI序列图像中海马面积均有萎缩性改变;20例患者出现单侧海马体积缩小(左侧11例,右侧9例);3例患者出现海马体积双侧缩小;FLAIR序列中23例患者海马病变处信号均增高,FSET2WI序列19例患者病变侧海马信号增高,4例无明显变化;海马病变侧头部浅沟明显消失20个,病变侧白质萎缩3个,病变侧颞角增大1个,病变侧颞叶萎缩2个;海马硬化在MRI图像中以表面硬化、颞角增大、T2WI序列中海马信号异常升高、海马体积缩小、病变侧NAA峰下降等为主要特征。结论 MRI各序列的扫描图像对海马硬化区域显示直观,可定量分析脑组织内生化代谢的异常变化,可为深入地了解癫痫灶的病理生理改变及临床手术定位提供丰富的影像学资料。     

利用颅脑射频线圈进行大鼠磁共振成像

目的 研究3.0T磁共振成像系统中大鼠脑部射频线圈.方法 提出一种设计线圈结构的方案,采用高等于直径的鞍型线圈,研究直径为5 cm的大鼠脑部线圈减小电容和分布电容,可使线圈带宽减小,提高线圈品质的因素(Q).将线圈与人体头部线圈和体部线圈分别对自制的模型利用同一序列进行扫描,对三组图像选择同一位置的图像,比较各线圈的信噪比(SNR).观察图像的质量,应用大鼠颅脑模型分别进行轴位、矢状位和冠状位T1W FLAIR或T2W扫描.结果 线圈的SNR比现有的头部线圈高5倍以上.大鼠图像能很好地显示脑室结构,可清楚分辨脑部的灰质和白质.结论 利用所设计的线圈可获得具有很高SNR的图像,在大鼠脑部影像研究中取得了很好的效果.     

猪体外冠状动脉管壁高分辨MR成像

目的 利用1.5T MR扫描仪寻求简单易行的体外冠状动脉管壁成像程序.方法 对10个猪心行冠状动脉MR检查.以3D FIESTA序列行前降支成像,分别选择8通道头部线圈、膝关节线圈、颞下颌关节表面线圈行2D SE T1WI, 成像参数均相同,之后用颞下颌关节表面线圈,采用384×256和512×512的矩阵行T1WI.注入对比剂后,分别使用不同的NEX行SE T1WI、PDWI和frFSE T2WI.测量前降支近段管壁、管腔、前降支周围心外膜下的脂肪结缔组织、前降支邻近的室间隔心肌的信号强度,并测量周围空气的信号强度作为背景噪声,计算图像的信噪比(SNR)和冠状动脉管壁对管腔的对比噪声比(CNR1)及冠状动脉管壁对周围心外膜下脂肪结缔组织的对比噪声比(CNR2).结果 颞下颌关节表面线圈成像前降支管壁SE T1WI的SNR和CNR1、CNR2明显高于8通道头线圈和膝关节线圈.384×256矩阵所得的SE T1WI的SNR和CNR1、CNR2明显高于512×512矩阵.NEX为3时图像的SNR和CNR1、CNR2最高.结论 选择颞下颌关节表面线圈、384×256的矩阵、3个NEX可以得到良好的SNR和CNR.     

超声引导下肝脓肿穿刺治疗1例

1临床资料 患者女,41岁.主诉右上腹疼痛伴高热4天后入院,血常规检查白细胞:26.4×109/1,中性细胞:89.7%.超声检查发现:肝右叶增大,靠近膈面处可见大小约为10.8 cm×7.0 cm的包块,轮廓规整,边界清晰,外周被一内缘较为明亮清晰、外缘模糊不清的回声带所包绕,内部充满密集粗大光点,后壁回声增强.CDFI其内及周边未见明显血流信号.     

Evaluation of a new 1H/31P dual‐tuned birdcage coil for 31P spectroscopy

We introduce a new dual‐tuned hydrogen/phosphorus (¹H/³¹P) birdcage coil, referred to as split birdcage coil, and evaluate its performance using both simulations and magnetic resonance (MR) experiments on a 3 T MR scanner. The proposed coil simplifies the practical matters of tuning and matching, which makes the coil easily reproducible. Simulations were run with the finite difference in time domain method to evaluate the sensitivity and homogeneity of the magnetic field generated by the proposed ¹H coils. Following simulations, MR experiments were conducted using both a phantom and human thigh to compare the proposed design with a currently available commercial dual‐tuned flexible surface coil, referred to as flex surface coil, for signal to noise ratio (SNR) as well as homogeneity for the ³¹P coil. At regions deep within the human thigh, the split birdcage coil was able to acquire spectroscopic signal with a higher average SNR than the flex surface coil. For all regions except those close to the flex surface coil, the split birdcage coil matched or exceeded the performance of the flex surface coil. © 2013 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 43B: 90‐99, 2013     

Contribution of the MR spectroscopic imaging in the diagnosis of prostate cancer in the peripheral zone

Purpose To establish the additional value of 3D magnetic resonance spectroscopy (3D-MRS) imaging to endorectal MR imaging in the diagnosis of prostrate cancer in the peripheral zone. Materials and methods MR imaging and MRS imaging were performed in 79 patients with suspicion of prostate cancer on the basis of digital rectal exploration, transrectal ultrasound and PSA level. All the examinations were performed with 1.5 T MR scan using an endorectal coil (transverse and coronal FSE T2-weighted sequences, axial SE T1-weighted and PRESS 3D CSI). MR examinations have been evaluated by two Radiologists blind of the clinical data in a “per patients” analysis. MR imaging and MRS imaging findings were compared with the result of histological data from radical prostatectomy in 53 patients and biopsy in 17 patients. Results Nine patients (11.4%) were excluded because of serious artefacts in the MR spectrum. The reported values of sensitivity, specificity, PPV and NPV for MR imaging alone were respectively 84%, 50%, 76% and 63% (LR+ 1.7; LR− 0.3). Instead the reported values of sensitivity, specificity, PPV and NPV for the combination of MR imaging to MRS imaging were respectively 89%, 79%, 89% and 79% (LR+ 4.28; LR− 0.14). We found an incremental benefit of MRS imaging to MR imaging for tumour diagnosis although these results did not show statistically significant differences. Conclusions The MRS imaging improves the accuracy of the endorectal MR imaging in the diagnosis of prostate cancer.     

Design of a quadrature surface coil for hyperpolarized 13C MRS cardiac metabolism studies in pigs

This work describes the design of a quadrature surface coil constituted by a circular loop and a butterfly coil, employed in transmit/receive (TX/RX) mode for hyperpolarized ¹³C studies of pig heart with a clinical 3T scanner. The coil characterization is performed by developing an SNR model for coil performance evaluation in terms of coil resistance, sample‐induced resistance and magnetic field pattern. Experimental SNR‐vs.‐depth profiles, extracted from the [1–13C]acetate phantom chemical shift image (CSI), showed good agreement with the theoretical SNR‐vs.‐depth profiles. Moreover, the performance of the quadrature coil was compared with the single TX/RX circular and TX/RX butterfly coil, in order to verify the advantage of the proposed configuration over the single coils throughout the volume of interest for cardiac imaging in pig. Finally, the quadrature surface coil was tested by acquiring metabolic maps with hyperpolarized [1–13C]pyruvate injected i.v. in a pig. © 2013 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 43B: 69–77, 2013     

相控线圈在上腹部磁共振检查中的作用

目的 选择合适的脉冲线圈以获得清晰的腹部磁共振图像。方法 14例病人采用体线圈和体部相控阵线圈分别进行腹部磁共振扫描，两种线圈 的扫描序列完全一致，比较两种线圈所获图像的质量。结果 用相控阵线圈采集的腹部磁共振图像的平均信噪比明显高于体线圈所获图像（P＜0．05）。结论 利用体部相控阵线圈可明显提高腹部磁共振图像的质量。     

Correction of images in an open-configuration MR imaging system for radiation therapy planning and Interventional MRI

Purpose

In this paper, we present a method to remove system induced geometric distortions in MR images.

Methods

A large 3D phantom with spherical balls was used to characterize geometric distortion on an AIRIS Mate 0.2 T MR Scanner (Hitachi). MR images of the phantom were acquired in axial, sagittal planes. Using 2D Fast Spin Echo (FSE) sequence, distortions were measured at each control point. Two piecewise interpolation methods were then applied to correct distortions and greyvalues.

Results

The distortion was reduced from 16 to 1.2 mm at 180 mm from the magnet center.

Conclusion

Distortions were characterized and corrected in any axial, sagittal or coronal slice within an effective FOV of 330(LR) × 180(AP) × 210(HF) mm³. A fast and accurate method for correction of geometric distortion was performed within large distances from the magnet isocenter.     

磁共振波谱扫描在子宫中的研究进展

MRS是一种通过监测活体组织的代谢物质改变来反映其生物学特性的无创性的影像检查技术。随着MR的发展, 波谱研究已应用到身体不同器官, 国内外也已对子宫波谱进行了一系列的研究、探索。基于不断改进的MR仪器、线圈及扫描方法, 研究者通过对在体及离体子宫波谱的研究发现了正常子宫及部分子宫病变的某些代谢特征, 本文就子宫波谱研究的最新进展进行综述。     

Combined transesophageal and surface MRI provides optimal imaging in aortic atherosclerosis.

OBJECTIVE: Surface magnetic resonance imaging (MRI) for aortic plaque assessment is limited by the trade-off between penetration depth and signal-to-noise ratio (SNR). For imaging the deep seated aorta, a combined surface and transesophageal MRI (TEMRI) technique was developed 1) to determine the individual contribution of TEMRI and surface coils to the combined signal, 2) to measure the signal improvement of a combined surface and TEMRI over surface MRI, and 3) to assess for reproducibility of plaque dimension analysis. METHODS AND RESULTS: In 24 patients six black blood proton-density/T2-weighted fast-spin echo images were obtained using three surface and one TEMRI coil for SNR measurements. Reproducibility of plaque dimensions (combined surface and TEMRI) was measured in 10 patients. TEMRI contributed 68% of the signal in the aortic arch and descending aorta, whereas the overall signal gain using the combined technique was up to 225%. Plaque volume measurements had an intraclass correlation coefficient of as high as 0.97. CONCLUSION: Plaque volume measurements for the quantification of aortic plaque size are highly reproducible for combined surface and TEMRI. The TEMRI coil contributes considerably to the aortic MR signal. The combined surface and TEMRI approach improves aortic signal significantly as compared to surface coils alone. CONDENSED ABSTRACT: Conventional MRI aortic plaque visualization is limited by the penetration depth of MRI surface coils and may lead to suboptimal image quality with insufficient reproducibility. By combining a transesophageal MRI (TEMRI) with surface MRI coils we enhanced local and overall image SNR for improved image quality and reproducibility.     

A Multidisciplinary Approach to Implement Image-Guided Craniospinal Irradiation

PurposePractical considerations dictated a change in the craniospinal irradiation (CSI) technique. We report our experience in developing and refining CSI planning and treatment parameters, using a 3-isocenter image-guided intensity-modulated radiation therapy (IG-IMRT) technique.Methods and MaterialsTwo institutional values guided development: multidisciplinary decision-making and coordinated considerations throughout simulation, planning, and delivery. Patient immobilization and simulation parameters were selected based on treatment delivery system limitations. Commissioning fluence verification maps were acquired to verify dose in regions of overlapping fields. Robustness analysis was performed to assess impact of potential setup errors measured through IGRT verification. Treatment considerations included order of isocenter imaging and treatment and respective IGRT frequency, modality, and image registration thresholds.ResultsOverall film measurements were within 3% of planned dose, confirmed by phantom composite measurements showing all points were within 97% of planned dose. Setup sensitivity analysis suggested a 3-mm setup tolerance was sufficient to ensure confidence in the delivered plan. As the most critical organs at risk were in the superior isocenter, the daily isocenter treatment order was confirmed as superior, middle, and inferior. Daily cone beam computed tomography guidance was chosen for all isocenters (3° rotational threshold). Except for the superior/inferior direction of the middle and inferior isocenters, which were adjusted to 3 mm based on sensitivity analysis, a 1-mm translational threshold was used.ConclusionsAn IG-IMRT CSI technique has been developed and implemented in our institution through a multidisciplinary approach. This process highlights the collaborative, iterative approach used to successfully integrate a new treatment technique in an image-guidance era.     

Magnetic resonance spectroscopy for measuring the biodistribution and in situ in vivo pharmacokinetics of fluorinated compounds: validation using an investigation of liver and heart disposition of tecastemizole

BACKGROUND AND OBJECTIVE: The study of biodistribution and in situ pharmacokinetics is a challenging, but sometimes very important, aspect of premarketing characterization of drugs. We aimed to develop a non-invasive fluorine magnetic resonance (MR) spectroscopic method for the absolute quantitation of a mono-fluorinated compound and of its metabolites in the heart and liver of healthy subjects for this purpose. METHOD: We used fluorine MR spectroscopy (MRS) at 4 T (Tesla) and external standardization in an open label multiple-dose study. Twenty-three healthy adult subjects were enrolled in the study. The surface coil localized fluorine MR spectrum was monitored in the heart and liver at baseline and after oral administration of multiple doses of tecastemizole. Steady-state measurements were made at set time points that depended upon dose, and washout measurements were made only on subjects in which in vivo fluorine signal was observed. RESULTS AND DISCUSSION: At 4 T, under the given experimental conditions, the method had a lower limit of quantitation (LLOQ) of about 2.6 microm and a limit of detection (LOD) of about 0.3 microm for solution state samples (linewidth approximately 15 Hz). The measurement reproducibility was 6.4% using a 50 microm phantom. The effect of MR operator and spectral analyst on the calculated calibration curve slope was small, with inter-rater correlation coefficients of 0.999 and 0.998 respectively. MR signal from fluorine-containing tecastemizole-related moieties was observed in situ only at day 8 in the liver of three of five subjects dosed at 270 mg/day. The average in situ concentration was estimated to be 58+/-22 microm, with an average test-retest reproducibility of 216%. Extrapolating the in vitro results to human measurements, with an approximate linewidth of 250 Hz, predicts in situ LOD and LLOQ values of approximately 6 and 44 microm respectively. However, the human study had a fluorine MRS LOD of approximately 20 microm. The decrease in sensitivity and the increase in variability of the in vivo, in situ measurements compared with the validation study most likely arose from coil placement and incomplete rephasing of the MR signal by the respiratory phase compensation method. CONCLUSION: The measured concentrations were the lowest ever recorded for a multi-dose exogenous mono-fluorinated compound in the human liver using a validated fluorine MR quantitation method. The proposed non-invasive MR method for studying the biodistribution and in situ pharmacokinetics of mono-fluorinated compounds in the liver and heart should have broader application to the development of non-invasive biomarkers.     

前列腺癌的MRI诊断：T2WI、DWI、MRS及其综合应用

目的以病理结果为参照,探讨T2WI、DWI及MRS三种成像方法及其综合应用对前列腺癌定性诊断的价值。方法 42例患者在1.5T磁共振仪上采用体部矩阵线圈结合脊柱矩阵线圈行T2WI、DWI及3DCSI1H-MRS扫描,所有病例均经直肠穿刺活检证实。按照前列腺6分区法将所得图像数据分区评估测量,采用5分制针对各分区评分,并与病理结果对照。对三种扫描方法各自所得数据以及三种方法综合评分分别做ROC曲线分析比较,计算各组方法诊断的敏感性、特异性及准确性等。结果 42例病例中15例经穿刺证实为前列腺癌,27例为前列腺良性病变。252个分区均得到病理证实,其中201个为良性,51个为恶性。各组诊断方法的敏感性、特异性及ROC曲线下面积（Az）如下：T2WI：88.2%、67.2%和0.848±0.030,最佳诊断界值为3;DWI：82.4%、81.6%和0.860±0.033,最佳诊断界值为4;MRS：84.3%、98.0%和0.961±0.016,最佳诊断界值为5;三者综合：96.1%、96.5%和0.978±0.009,最佳诊断界值为4。结论 T2WI、DWI及MRS三种方法均可以独立有效诊断前列腺癌。三种成像方法结合诊断前列腺癌的准确性显著高于三种成像技术独立诊断,其诊断结果与病理分析一致性较好。在三种成像技术中,MRS的诊断价值较高。