Application of a 3D volume 19FMR imaging protocol for mapping oxygen tension (pO2) in perfluorocarbons at low field

A limited flip angle gradient-echo 3D volume acquisition imaging protocol for mapping partial pressure of oxygen (pO₂) in perfluorocarbon compounds (PFCs) at low field (0.14 T) is presented. The pO₂ measurement method is based on the paramagnetic effect of dissolved molecular oxygen (O₂) which reduces the PFC ¹⁹F T_1? Specific objectives related to imaging of PFCs through use of the protocol include improved image signal-to-noise characteristics and elimination of ¹⁹F chemical shift artifacts. A parametric Wiener deconvolution filtering algorithm is used for suppression of ¹⁹F chemical shift artifacts. Application of the protocol is illustrated in a series of calculated pO₂ maps of a gas equilibrated, multi-chamber phantom containing perfluorotributylamine (FC-43). The utility of the protocol is demonstrated in vivo through images of a commercially available perfluorocarbon based blood substitute emulsion containing FC-43 sequestered in the liver and spleen of a rat.     

磁共振胰胆管成像诊断胆系梗阻性疾病的临床评价

目的　探讨磁共振胰胆管成像 (MRCP)对胆道梗阻性疾病的临床诊断价值。方法　对 42例胆道梗阻患者进行MRCP检查 ,并经手术病理或 /和其它影像学和临床资料证实。结果　①本组MRCP定位诊断率为 10 0 % ,定性准确率为 83 % ;②扩张的胆道表现为枯枝状 2 3例、软藤状 15例、腊肠样 4例 ;③梗阻端呈倒杯口状 6例、截断状 5例、杵状 17例、鸟嘴状 9例、鼠尾状 5例。结论　MRCP对胆道梗阻性疾病定位诊断准确 ,结合MRI及源像对胆道梗阻性疾病的定性诊断也具有较高的特异性 ,是一种安全快捷、非创伤性的检查方法 ,能为胆道梗阻的诊治及术后评估提供可靠的依据。     

Cortical Reorganization Allows for Motor Recovery after Crossed Cerebrocerebellar Atrophy

The authors report the case of a 33-year-old woman who exhibited, at the age of 17, a left-sided hemiplegia, which was followed by good motor recovery, though with a permanent deficit in fine finger movements. She had a widespread loss of neural tissue in the right hemisphere (crossed cerebrocerebellar atrophy), including (1) marked atrophy and thinning of the precentral and postcentral gyri; (2) widespread deep white matter destruction, including the corticospinal tract; and (3) crossed cerebellar atrophy. Except over the supplementary motor area (SMA), transcranial magnetic stimulation did not elicit motor evoked potentials in the affected hand. Nevertheless, during opening and closing of the affected hand, functional magnetic resonance imaging showed an activation of the lesioned primary sensorimotor cortex (SMC), as well as of the intact SMA and the parietal areas, but not of the ipsilateral motor areas. The authors speculate that recovery was achieved by a motor command generated in the SMC and the parietal cortex, passing through corticospinal axons originating in the SMA.     

Neurobehavioral effects among subjects exposed to high static and gradient magnetic fields from a 1.5 Tesla magnetic resonance imaging system--a case-crossover pilot study.

The interactive use of magnetic resonance imaging (MRI) techniques is increasing in operating theaters. A study was performed on 17 male company volunteers to assess the neurobehavioral effects of exposure to magnetic fields from a 1.5 Tesla MRI system. The subjects' neurobehavioral performances on a neurobehavioral test battery were compared in four 1-hr sessions with and without exposure to magnetic fields, and with and without additional movements. Adverse effects were found for hand coordination (-4%, P < 0.05; Pursuit Aiming II) and near visual contrast sensitivity (-16% and -15%, P < 0.10; Vistech 6000). The results from the remaining tests were inconclusive due to a strong learning effect. No additional effect from gradient fields was detected. The results indicate that working near a 1.5 Tesla MRI system may lead to neurobehavioral effects. Further research is recommended, especially in members of operating teams using interactive MRI systems.     

质子磁共振波谱在胶质瘤诊断中的应用

目的探讨质子磁共振波谱（^1Hmagnetic resonance spectroscopy，^1HMRS）在胶质瘤诊断及分级中的应用。方法回顾分析我院2003年3月～2005年9月质子磁共振波谱检查并经病理证实的36例胶质瘤的临床资料，根据胶质瘤恶性程度不同分为A、B2组，其中A组为低恶性组（包括星形细胞瘤Ⅰ级和Ⅱ级、室管膜瘤、少突胶质细胞瘤等）21例，B组为高恶性组（包括星形细胞瘤Ⅲ级和Ⅳ级、多形性胶质母细胞瘤、间变型室管膜瘤、髓母细胞瘤）15例。观察氮乙酰门冬氨酸（Nacetylaspartate，NAA）、胆碱（choline，Cho）、肌酸（creatine，Cr）、肌醇（Ins）的共振峰及比值。大脑对侧对应正常脑组织的结果作内对照组。结果2组胶质瘤均表现为异常的。HMRS，与大脑对侧对应正常脑组织相比，A、B2组表现为NAA／Cr含量显著下降，Cho／Cr含量显著增高（P均〈0．05），cr总量变化不大，且无规律性（P〉0．05），Ins含量表现为轻度下降（P〉0．05）。A组NAA／Cr和NAA／Cho均显著高于B组（t=4．235，P=0．011；t=2．832，P=0．031），A组Cho／Cr显著低于B组（t=-2．323，P=0．042）。结论。HMRs可提高对胶质瘤诊断和分级的准确性。     

Intensity-dependent regional cerebral blood flow during 1-Hz repetitive transcranial magnetic stimulation (rTMS) in healthy volunteers studied with H215O positron emission tomography: I. Effects of primary motor cortex rTMS.

BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) affects the excitability of the motor cortex and is thought to influence activity in other brain areas as well. We combined the administration of varying intensities of 1-Hz rTMS of the motor cortex with simultaneous positron emission tomography (PET) to delineate local and distant effects on brain activity. METHODS: Ten healthy subjects received 1-Hz rTMS to the optimal position over motor cortex (M1) for producing a twitch in the right hand at 80, 90, 100, 110, and 120% of the twitch threshold, while regional cerebral blood flow (rCBF) was measured using H(2)(15)O and PET. Repetitive transcranial magnetic stimulation (rTMS) was delivered in 75-pulse trains at each intensity every 10 min through a figure-eight coil. The regional relationship of stimulation intensity to normalized rCBF was assessed statistically. RESULTS: Intensity-dependent rCBF increases were produced under the M1 stimulation site in ipsilateral primary auditory cortex, contralateral cerebellum, and bilateral putamen, insula, and red nucleus. Intensity-dependent reductions in rCBF occurred in contralateral frontal and parietal cortices and bilateral anterior cingulate gyrus and occipital cortex. CONCLUSIONS: This study demonstrates that 1-Hz rTMS delivered to the primary motor cortex (M1) produces intensity-dependent increases in brain activity locally and has associated effects in distant sites with known connections to M1.     

Magnetic resonance imaging - a method of studying the size and asymmetry of the planum temporale

The planum temporale is a triangular region on the upper surface of the temporal lobe. This area of the brain is important for language processing and shows a left-right asymmetry of size in most brains. Particular interest has been focused on the size and asymmetry of the planum temporale in brains of individuals with developmental dyslexia. Magnetic resonance imaging (MRI) is a method that produces excellent morphological details of organic structures. We have developed an MRI method of studying the size and asymmetry of the planum temporale in human brains. Because of considerable variation of anatomical landmarks in this cortical region of the brain, an evaluation of asymmetry is not possible in all brains. Furthermore, our experience with this method indicates that any indirect imaging technique of studying asymmetry of the planum temporale must be evaluated with caution. With this in mind, however, MRI may give valuable anatomical information about the planum temporale in individuals with anomalous language function.     

磁场对家兔急性实验性高血压的影响

目的 :探讨内关穴敷磁的降压效应。方法 :40只清醒家兔和 40只麻醉家兔 (其中 2 0只去减压神经 ) ,静脉注射去甲肾上腺素或苯肾上腺素引起急性实验性高血压 ,并于内关穴敷磁 (0 .1～ 0 .2T) ,记录血压、心率和敷磁前及 1h后的血液粘度的变化。结果 :敷磁 1h后各实验组平均动脉压 (MAP)显著下降 (P <0 .0 1)。麻醉和清醒家兔MAP降幅无差异 (P >0 .0 5 ) ,但显著高于去减压神经家兔MAP的降幅 (P <0 .0 1或 0 .0 5 ) ,各实验组全血比粘度显著下降 (P <0 .0 1或 0 .0 5 ) ,实验组与各自对照组心率敷磁前后无差异 (P >0 .0 5 )。结论 :磁场具有降压作用 ,但对心率无影响 ,其降压效应与减压神经的抑制和全血粘度的降低有关 ,与化学感受性升压反射无关     

旋转强恒磁场对SD大鼠骨骼生长发育及相关激素的影响

目的探讨旋转强恒磁场（RCSMF）对SD大鼠的骨骼生长发育及相关激素的影响，为RCSMF促进人体增高的临床应用奠定基础。方法取25日龄的SD大鼠置RCSMF下，1．5h／d。每5天取血检测大鼠生长激素（GH）、类胰岛素生长因子（IGF-Ⅰ）、雌激素（E2）等与骨骼发育相关的激素，同时测量每组大鼠的身长、体重和尾长，并用骨形态计量学方法研究RCSMF对大鼠骨组织形态学和动态学参数的影响。结果RCSMF处理后大鼠的身长[实验组（25．28±0．41）cm。对照组（24．05±0．35）cm；P〈0．01]、体重[实验组（445．90±16．88）g，对照组（382．22±12．78）g；P〈0．01]、胫骨长[实验组（3．89±0．13）cm，对照组（3．66±0．10）cm；P〈0．01]和股骨长[实验组（3．65±0．08）cm，对照组（3．51±0．06）cm；P〈0．01]，上述多项参数以及骨骺板等相关形态计量学数据实验组明显高于对照组。回归分析身长与相关激素的关系显示：大鼠身长与GH、IGF—I和E2有显著相关性。结论RCSMF有促进骨骼生长发育的作用，其作用机理是通过刺激与骨骼生长发育相关激素的生成、释放，并影响软骨细胞的增殖功能来完成的。     

Multiple pancreatic metastases from clear cell renal carcinoma: Diagnosis with chemical shift magnetic resonance imaging before surgery

We present a case in which multiple pancreatic tumours were diagnosed as metastatic clear cell renal carcinomas with chemical shift MRI (CSI) before surgery. Radiologists may be unable to recognize the loss of intensity on CSI macroscopically. We believe that it is useful to make subtraction images and calculate signal intensity on CSI, even if the lesions are multiple metastatic tumours.