MR兼容射频消融电极针的研制

目的设计一种能在MRI环境下工作的射频消融电极针。方法采用Inconel 625合金制造一种分体式多极射频消融电极针。与RITA MRI兼容性多极射频电极在1.5T MRI下成像,进行对照,并在MRI环境下完成离体猪肝射频消融。结果与B0分别成角0°、30°、60°、90°时显示的穿刺针直径差异有统计学意义(F=157.914,P=0.000,P<0.05);采用fs FRFSE T_2WI、T_1FSPGR及3D Dyn T_1WI序列获取的穿刺针直径差异有统计学意义(F=13.075,P=0.000,P<0.05);自制MR兼容电极针与RITA MR兼容电极针在MRI成像时显示的穿刺针直径差异无显著统计学意义(F=2.340,P=0.152,P>0.05)。消融灶最大直径平均5.23cm。结论本射频消融电极与RITA MRI兼容性射频消融电极相当,具有临床实用价值。     

前列腺癌的MR诊断

前列腺癌是男性泌尿生殖道最常见的恶性肿瘤之一，介绍了常规MRI、动态增强磁共振成像及磁共振波谱成像在前列腺癌诊断中的应用，以及前列腺癌影像学表现、分期及鉴别诊断。     

前列腺癌的MR诊断

前列腺癌是男性泌尿生殖道最常见的恶性肿瘤之一,介绍了常规MRI、动态增强磁共振成像及磁共振波谱成像在前列腺癌诊断中的应用,以及前列腺癌影像学表现、分期及鉴别诊断.     

门静脉系统的MR血管成像

本文简述了门静脉系统的两种基本ＭＲ血管成像方法（时间飞越法和相位相对法）,并概括介绍了门静脉ＭＲ血管成像的临床应用和局限性。     

MR无创测温的原理及临床应用

间质热消融治疗,需要无创伤性测量温度在体内的分布,多种MR测温技术有望解决这一难题。选择不同的MR温度敏感参数,可产生T1和M0方法、D方法以及PRF方法达到MR无创测温,本文系统阐述其原理并探讨其临床应用价值。     

MR脑功能成像

脑部MR功能成像包括弥散加权成像、弥散张量成像、灌注加权成像、血氧水依赖性成像、脑磁共振波谱分析和磁共振波谱成像等，论述上述各脑功能成像的简单原理以及在临床上的应用。     

肺动脉的MR检查

ＭＲ作为一种安全无创性检查肺动脉的方法,作用日益受到重视。常规的自旋回波技术(ＳＥ)、梯度回波技术(ＧＲＥ)、相位对比技术(ＰＣ)已经普遍应用[1,2],而增强ＭＲ肺动脉造影,尤其是三维对比增强ＭＲ肺动脉造影,以及ＭＲ肺灌注成像等新型技术也越来越引起人们的重视。一、增强ＭＲ肺动脉造影(ＣＥＭＲＰＡ)传统ＭＲ血管造影主要是基于时间飞跃(ｔｉｍｅｏｆｆｌｉｇｈｔ,ＴＯＦ)效应,但它在肺部的应用却受限,主要因为受心脏和呼吸的运动、肺部血管复杂的解剖结构、肺部复杂的血流模式以及空气/组织界面间巨大磁化率伪影等多因素的影响[3]。…     

颅内动脉瘤的MR诊断

目的:探讨MR对颅内动脉瘤的诊断价值,提高颅内动脉瘤MR及临床表现的认识。方法:回顾性分析8例颅内动脉瘤患者的MR及临床表现资料,男3例,女5例,年龄2.5～70岁,平均48.1岁,所有病例均经临床或DSA证实。突发头痛、呕吐4例,双眼视力障碍2例,间歇性头痛、头晕2例。所有患者均行MR平扫及增强扫描。结果:本组8例患者共发现动脉瘤8处,均为单发,位于鞍上池附近,圆形或类圆形,大小约0.7cm×0.5cm×0.6cm～2.2cm×2.4cm×2.5cm不等;信号混杂,T1WI以等、高信号为主,T2WI为低、等或高信号,7例可见附壁血栓;增强扫描病灶信号从内到外表现一定层次感:内部血流强化呈明显高信号,新月形附壁血栓强化不明显或轻度强化,最外层瘤壁成环形强化。结论:作为无创性影像学检查手段,MR对颅内动脉瘤具有重要诊断价值。     

成人脊椎结核的MR表现

近年来，脊椎结核的发病率有所上升，因它的致残率较高，应引起我们的高度重视。我们总结了30例经手术病理证实的脊椎结核的MRI表现，结合以往文献总结如下。     

MR-compatible assistance system for punction in a high-field system: device and feasibility of transgluteal biopsies of the prostate gland

We present the first cadavic study results concerning the feasibility of the use of an MR-guided assistance system, Innomotion (Innomedic, Herxheim, Germany), for accurate and consistent placement of percutaneous needles in the prostate gland. The MR-compatible assistance system consists of a C-arch, guiding arm and application module (AMO). T1-weighted fast low angle shot (FLASH) 2-D-GRE sequence (TR/TE=110/4 ms) and T2-weighted turbo spin-echo (TSE)-sequences (TR/TE=3200/97 ms) in transversal orientation were used for the monitoring of the punction of the prostate gland. Planning and control of the intervention is to be made outside the scanner room on a desktop computer that receives DICOM images from the scanner. Servopneumatic drives move the AMO to the insertion point. The physician has to introduce the punction needle manually. The mean deviation of the needle tip to the target in a gel phantom was 0.35 mm. An accurate punction of the prostate gland can easily be performed using this system with a transgluteal access. The T2-weighted images are superior for the evaluation of the prostate anatomy and the needle position during the interventions. In conclusion, our preliminary results indicate that this MR-guided assistance system is suitable for an accurate transgluteal needle placement in the prostate.     

Measurement of temperature changes in cooling dead rats using magnetic resonance thermometry

Magnetic resonance imaging thermometry has been introduced as a technique for measurement of temperature changes in cooling dead rats. Rat pelvic magnetic resonance images were acquired sequentially more than 2 h after euthanasia by halothane overdose. A series of temperature difference maps in cooling dead rats was obtained with calculating imaging phase changes induced by the water proton frequency shift caused by temperature changes. Different cooling processes were monitored by the temperature difference maps in the rats. Magnetic resonance imaging thermometry applied in the study of laboratory animals could theoretically reproduce a variety of causes of death with different environmental conditions. Outcomes from experimental animal studies could be translated into a temperature-based time of death estimation in forensics.     

Emergency MRI utilization trends at a tertiary care academic medical center: baseline data

RATIONALE AND OBJECTIVES: This study evaluates utilization trends of emergency department (ED)-ordered magnetic resonance imaging (MRI) examinations in an adult academic medical center over a 5-year period (2001-2005). MATERIALS AND METHODS: MRI examinations from the ED-ordering location were identified by searching the radiology information system (RIS). Overall MRI volume and ED patient encounters were also assessed during the same period. Each examination was assessed by type of examination, examination completion time, and primary and secondary clinical indications by reviewing the RIS and medical record. RESULTS: During the study period, 1,900 ED-ordered MRI examinations were performed on 1,020 patients. During the same period, 62,823 total MRI examinations were performed, and the total ED patient volume was 420,840. ED-ordered MRI volume increased 391% over the study period (125 to 614 examinations/year), whereas total MRI volume increased only 38.9% and ED patient volume in our institution actually decreased by -9%. MRI examinations of the brain, magnetic resonance angiography of the head and neck, and spinal MRI were the most commonly ordered tests. Clinical indications were analyzed. Peak times of ED-ordered examination completion were between 4:00 PM and 11:00 PM. A total of 15.5% of examinations required overtime or callback of MRI technologists for completion. CONCLUSIONS: Multiple reasons are suggested that may increase utilization (perceived need for diagnostic certainty, as well as medico-legal and patient-driven factors). Whether this increase in MRI utilization resulted in improved patient outcomes is unclear and should be studied further. Implications for radiologist coverage and resident training are discussed.     

0.35T磁共振心脏成像技术及其应用

目的 :探索低场磁共振成像系统心脏成像的可行性、技术和方法。方法 :将高场心脏成像序列和技术进行调整和优化 ,用于 0 .3 5T磁共振成像系统 ,进行心脏结构和功能的显示。结果 :在硬件、软件优化设计的低场磁共振成像系统获得的显示心脏结构和功能的图像 ,可满足临床诊断的需求。结论 :低场磁共振成像系统进行心脏检查 ,包括冠状动脉成像和心肌灌注成像等 ,值得进一步探索和期待。     

MRI in central nervous system infections: A simplified patterned approach

Recognition and characterization of central nervous system infections poses a formidable challenge to the neuro-radiologist. Imaging plays a vital role, the lesions typically being relatively inaccessible to tisue sampling. The results of an accurate diagnosis are endlessly rewarding, given the availability of excellent pharmacological regimen. The availability of numerous magnetic resonance (MR) sequences which provide functional and molecular information is a powerful tool in the hands of the radiologist. However, the plethora of sequences and the possibilities on each sequence is also intimidating, and often confusing as well as time consuming. While a large number of reviews have already described in detail the possible imaging findings in each infection, we intend to classify infections based on their imaging characteristics. In this review we describe an algorithm for first classifying the imaging findings into patterns based on basic MR sequences (T1, T2 and enhancement pattern with Gadolinium), and then sub-classify them based on more advanced molecular and functional sequences (Diffusion, Perfusion, Susceptibility imaging, MR Spectroscopy). This patterned approach is intended as a guide to radiologists in-training and in-practice for quickly narrowing their list of differentials when faced with a clinical challenge. The entire content of the article has also been summarised in the form of flow-charts for the purpose of quick reference.     

大鼠活体脑1.5T1H-MRS技术

目的探讨大鼠活体脑1.5T1H-MRS方法及技术参数,并评价其图像质量.方法对25只正常雄性SD大鼠进行单体素1H-MRS采用自制的提高信噪比器具,眼线圈,选用PRESS序列,以大脑胼胝体为中心设定感兴趣区,体素用6mm×6mm×6mm与6mm×10mm×6mm两种,比较NAA、Cho、Cr的信噪比及图像质量.5例大鼠在处死60min后作MRS,观测各谱峰的变化.结果MRS谱图上,脑主要代谢产物NAA、Cho、Cr等谱锋清晰,基线较平.体素6mm×6mm×6mm时主要化合物波谱信噪比显著高于体素6mm×10mm×6mm(P＜0.001),图像质量更好.5例大鼠处死后60min MRS,于1.35ppm处见特征性Lac倒置双峰,NAA、Cho、Cr下降不明显.结论1.5T MR可进行大鼠活体MRS检查,有望用于脑弥漫性病变的实验研究.     

MRI图像传输和处理的初步研究

目的 通过在磁共振成像系统与微机间联网和文件传输、探索建立模型ＰＡＣＳ系统的方法，并进行ＭＲ图像处理的偿试。     

In vivo MR thermometry of frozen tissue using R2* and signal intensity

Cryoablation is one of several minimally invasive treatments that may be suitable for a targeted treatment of prostate cancer. Because efficacy is improved when a sufficiently cold end temperature is reached, the purpose of this work was to demonstrate an image-based thermometry method that could provide temperature maps throughout the frozen tissue. In five in vivo canine prostate cryoablation experiments performed under magnetic resonance imaging guidance, two MR parameters were measured and correlated to temperature: R2* and changes in signal intensity. R2* is elevated approximately linearly as tissue temperature decreases below the freezing point, while the signal intensity decreases exponentially. In vivo temperature maps with isotherms at -5 degrees C, -15 degrees C, and -30 degrees C are demonstrated.