MRI相位对比电影用于儿童脑积水行三脑室底造瘘的疗效评价

目的 了解脑积水患儿行神经内镜下三脑室底造瘘术后的MRI相位对比电影的表现,评价其用于术后疗效判断的价值.方法 12例脑积水患儿行三脑室底造瘘术前后均行MRI常规序列扫描及相位对比电影检查,评估中脑导水管及三脑室造瘘口的脑脊液流动情况,测量脑脊液流动动力学指标(峰值流速、流量及流动波形),比较其前后的差异.结果 12例脑积水患儿造瘘口脑脊液流动在一个心动周期内表现为双向运动,与正常导水管流动波形相似.其中三脑室造瘘术前7例梗阻性脑积水患儿中脑导水管脑脊液双向流动减弱或消失,表现为低动力学改变;5例交通性脑积水患儿三脑室底造瘘术前中脑导水管脑脊液双向流动明显加快,表现为高动力学改变.三脑室底造瘘术后中脑导水管脑脊液流动不规则,循环减慢.12例患儿术后幕上脑室均较术前缩小,其中8例分别于术后半年及术后1年复查见脑室进一步缩小.结论 MRI相位对比电影法为脑积水患儿行三脑室底造瘘术提供可靠的影像学观察手段,可以作为评价三脑室底造瘘术疗效的有效方法.     

Functional analysis of third ventriculostomy patency with phase-contrast MRI velocity measurements

Our purpose was to explore the utility of cine phase-contrast MRI velocity measurements in determining the functional status of third ventriculostomies, and to correlate the quantitative velocity data with clinical follow-up. We examined six patients with third ventriculostomies and 12 normal subjects by phase-contrast MRI. The maximum craniocaudal to maximum caudocranial velocity range was measured at regions of interest near the third ventricular floor, and in cerebrospinal fluid anterior to the upper pons and spinal cord on midline sagittal images. Ratios of the velocities of both the third ventricle and prepontine space to the space anterior to the spinal cord were obtained. The velocities near the third ventricular floor and in the pontine cistern were significantly higher in patients than in normal subjects, but the velocity anterior to the spinal cord was similar between the groups. The velocity ratios, used to normalize individual differences, were also higher in patients than in controls. Two patients had lower velocity ratios than their fellows at the third ventricular floor and in the pontine cistern; one required a shunt 11 months later, while in the other, who had a third ventricular/thalamic tumor, the lower values probably reflect distortion of the third ventricular floor. We conclude that phase-contrast MR velocity measurements, specifically the velocity ratio between the high pontine cistern and the space anterior to the spinal cord, can help determine the functional status of third ventriculostomies. Received: 30 October 1995 Accepted: 28 March 1996     

Constructive interference in steady-state 3D Fourier-transform MRI in the management of hydrocephalus and third ventriculostomy

We describe the use of three-dimensional Fourier transform constructive imaging in the steady state (CISS) MRI in the assessment of patients with hydrocephalus. We have found it of value both as a diagnostic investigation and in the follow-up of patients treated by third ventriculostomy. Received: 30 September 1997 Accepted: 15 July 1998     

国产低场强磁共振设备脂肪抑制技术的应用研究

目的寻找国产低场磁共振设备（ＡＳＭ０．１６Ｔ）脂肪抑制的成像参数，并了解其在临床上的应用效果。方法应用动物组织样本１０块及２０例健康志愿者的头颅和上腹部各进行２次独立的ＳＥ序列扫描，然后行对应区域的脂肪组织信号强度（Ｓ）测量，最后代入Ｔ１值计算公式：Ｓ′／Ｓ″＝（１－ｅＴＲ′／Ｔ１）／（１－ｅＴＲ″／Ｔ１），分别求得标本及志愿者的脂肪组织Ｔ１值为１１３±８毫秒和１３５±１１毫秒。我们以ＴＩ（反转时间）等于６９％Ｔ１作为中心零点时间行短ＴＩ反转恢复序列（ｓｈｏｒｔＴＩｉｎｖｅｒｓｉｏｎｒｅｃｏｖｅｒｙ，ＳＴＩＲ）扫描，同时行ＳＥ序列Ｔ１ＷＩ及Ｔ２ＷＩ。然后通过脂肪信号强度差异及线形灰度曲线进行检测脂肪抑制效果。结果ＳＥＴ１ＷＩ、Ｔ２ＷＩ和ＳＴＩＲ（ＴＩ９０毫秒时）志愿者的脂肪信号强度分别为：３４０８±１６５、２８９９±１８８和３０５±１０６，并且，ＳＴＩＲ（ＴＩ９０毫秒时）的脾／肝和脑灰／白质对比度噪声比较常规ＳＥ序列明显增高（除ＳＥＴ２ＷＩ脾／肝Ｐ＜０．０５外，余Ｐ＜０．０１）。结论ＳＴＩＲ（ＴＩ９０毫秒时）在检测中综合指标最优，从而认定０．１６Ｔ场强下的脂肪抑制零点时间为９０毫秒。     

MRI导引介入技术临床应用的探讨

目的　评价磁共振成像介入导引技术的初步临床应用经验。方法应用常规0．5T磁共振成像扫描机做了20例MRI引介入诊断和治疗，其中门例活俭，3例肾囊肿硬化剂治疗，用19GMRI兼容的抽吸穿刺针做穿刺。采用快速梯度回波和快速自旋回波技术扫描。结果MRI导引经皮活检刺中率为100％，活检正确率88．2％。本组所有病例无非发症出现。结论MRI导引介入技术是一种安全而有效的技术。     

MRI-guided needle localization of suspicious breast lesions: results of a freehand technique

Magnetic resonance imaging (MRI) can detect clinically and mammographically occult breast lesions. In this study we report the results of MRI-guided needle localization of suspicious breast lesions by using a freehand technique. Preoperative MRI-guided single-needle localization was performed in 220 patients with 304 MRI-only breast lesions at our hospital between January 1997 and July 2004. Procedures were performed in an open 0.5-T Signa-SP imager allowing real-time monitoring, with patient in prone position, by using a dedicated breast coil. MRI-compatible hookwires were placed in a noncompressed breast by using a freehand technique. MRI findings were correlated with pathology and follow-up. MRI-guided needle localization was performed for a single lesion in 150 patients, for two lesions in 56 patients, and for three lesions in 14 patients. Histopathologic analysis of these 304 lesions showed 104 (34%) malignant lesions, 51 (17%) high-risk lesions, and 149 (49%) benign lesions. The overall lesion size ranged from 2.0–65.0 mm (mean 11.2 mm). No direct complications occurred. Follow-up MRI in 54 patients showed that two (3.7%) lesions were missed by surgical biopsy. MRI-guided freehand needle localization is accurate and allows localization of lesions anterior in the breast, the axillary region, and near the chest wall.     

Accuracy of MRI-guided stereotactic thalamic functional neurosurgery

Our goal was to evaluate the accuracy of stereotactic technique using MRI in thalamic functional neurosurgery. A phantom study was designed to estimate errors due to MRI distortion. Stereotactic mechanical accuracy was assessed with the Suetens-Gybels-Vandermeulen (SGV) angiographic localiser. Three-dimensional MRI reconstructions of 86 therapeutic lesions were performed. Their co-ordinates were corrected from adjustments based on peroperative electrophysiological data and compared to those planned. MR image distortion (maximum: 1 mm) and chemical shift of petroleum oil-filled localiser rods (2.2 mm) induced an anterior target displacement of 2.6 mm (at a field strength of 1.5 T, frequency encoding bandwidth of 187.7 kHz, on T1-weighted images). The average absolute error of the stereotactic material was 0.7 mm for anteroposterior (AP), 0.5 mm for mediolateral (ML) and 0.8 mm for dorsoventral (DV) co-ordinates (maximal absolute errors: 1.6 mm, 2.2 mm and 1.7 mm, respectively; mean euclidean error: 1 mm). Three-dimensional MRI reconstructions showed an average absolute error of 0.8 mm, 0.9 mm and 1.9 mm in AP, ML and DV co-ordinates, respectively (maximal absolute errors: 2.4 mm, 2.7 mm and 5.7 mm, respectively; mean euclidean error: 2.3 mm). MRI distortion and chemical-shift errors must be determined by a phantom study and then compensated for. The most likely explanation for an average absolute error of 1.9 mm in the DV plane is displacement of the brain under the pressure of the penetrating electrode. When this displacement is corrected for by microelectrode recordings and stimulation data, MRI offers a high degree of accuracy and reliability for thalamic stereotaxy. Received: 22 September 1998 Accepted: 1 January 1999     

MRI-guided percutaneous nephrostomy: a feasibility study

The purpose of this study was to assess the feasibility and safety of magnetic resonance imaging (MRI)-guided PCN in an open-configuration low-field MRI system. Eight patients were prospectively enrolled in the study. The degree of the dilatation of the renal collecting system varied from minimal to severe. All procedures were performed solely under MRI guidance with a 0.23-T open configuration C-arm-shaped MRI system with interventional optical tracking. In each case, PCN was performed with a MRI-compatible drainage kit using the Seldinger technique. Seven out of eight nephrostomies were successfully performed under MRI guidance. All PCN procedures in dilated renal collection systems were successful; however, nephrostomy catheter could not be placed in a nondilated system. The mean time needed for the MRI-guided PCN was 26 min. No major complications occurred during the procedure or follow-up. MRI-guided PCN in dilated renal collection system is feasible and safe. The presented technique has limitations that necessitate further technical developments before the procedure can be applied to nondilated kidneys and recommended for routine clinical use.     

MRI辅助腹膜外机器人腹腔镜前列腺根治术镜头孔的定位

目的 探讨利用MRI测量帮助腹膜外途径机器人腹腔镜前列腺根治性切除术(RLRP)中镜头孔定位.资料与方法 前列腺腺癌患者12例,拟采用RLRP治疗.术前在T2WI正中矢状面影像上,以手术视野前列腺尖部为圆心,以腹腔镜最长工作距离25cm为半径画圆,以皮肤表面脐下1cm为起点做垂直皮肤的直线,测量其与圆弧交叉点至皮肤的距离D,作为制造气腹时皮肤抬高的高限.结果 利用MRI测量获得的D值平均为(7.79±0.86) cm,按照上述测定计划,12例患者在完成耻骨后间隙制备后A点升高均小于预测D值.实际操作12例均取A点(脐下1cm处)作为镜头置孔处,12例均顺利完成手术,无一例因穿刺原因而更改术式.结论 这是一种简单的利用MRI图像个体化测量方式,确定做好术前腹腔镜开孔位置计划,可以有效地预判脐下1cm处是否可作为镜头孔的适合位置.     

通过磁共振成像和神经电生理的影像融合实现癫痫的三维立体定位

目的 在完善的医学影像存储与传输系统中使用MR影像输出和神经电生理的数据信息进行结合，从而提高对癫痫病的诊断正确率，并将对病人病情正确判断的信息进人放疗设备的三维立体定向放射治疗计划系统。方法 使用脑电图工作站对脑电图数据进行回放，同时用Brainvoyager软件对病人的MR检查资料进行重建，在Base2000中将重建的影像数据与数字脑电图数据坐标结合，生成适合病人头部的三维模型。对临床诊断确诊的12～54岁的癫痫患者30例（其中男18例，女12例）进行磁共振图像与神经电生理信息融合后获得三维立体定位。结果 对应的数据信息在三维模型中可呈现病人脑部的真实情况，立体直观地呈现病灶的准确位置。三维立体定向引导下手术切除病灶的成功率大幅度提高，30例病人在发病时间上以每周为单位均有不同程度的减少，其中8例病人术后6个月停止发病，手术获得成功。结论 磁共振影像与神经电生理信息的融合，很大程度上提高了癫痫病诊断的整体水平。对于癫痫病的研究及提高手术成功率有着至关重要的意义。     

Targeting difficult accessible breast lesions: MRI-guided needle localization using a freehand technique in a 3.0 T closed bore magnet

PURPOSE: To report the accuracy of magnetic resonance imaging (MRI)-guided needle localization for diagnosis of MRI detected suspicious breast lesions located in difficult accessible regions of the breast, using the freehand method in a 3.0 T closed bore magnet. MATERIALS AND METHODS: In five patients with five MRI-only breast lesions underwent MRI-guided needle localization for histopathologic evaluation of the lesions. All interventional procedures were performed in a 3.0 T MRI system with the patient in prone position and by using a dedicated phased array breast coil. MRI-guided needle localizations were performed by using a freehand technique. In our study, the high-resolution scan allowed preprocedural localization of all lesions without use of contrast enhancement. In all cases contrast-enhanced MRI was performed after insertion of the wire to confirm the tip of the wire in direct contact with the enhancing lesion. RESULTS: Needle localizations were performed in five patients. Histopathologic evaluation of tissue after surgery excision biopsy revealed one lymph node, three invasive ductal carcinoma and one ductal carcinoma in situ. Lesion size varied from 6 to 30 mm. Mean duration time was 25 min. No complications occurred during the intervention method. In the patient with the benign lesion control MRI of the breast after 6 months confirmed lesion removal. CONCLUSIONS: MRI-guided needle localization by using a freehand technique in a 3.0 T closed bore magnet is a safe and accurate method for diagnosis of difficult accessible breast lesions only visible on MRI.