View ordering for magnetization prepared steady state free precession acquisition: application in contrast-enhanced MR angiography.

Magnetization prepared segmented acquisition requires a view order that maximizes signal contrast during the acquisition of the central portion of k-space. Steady state free precession (SSFP) acquisition further requires a view order that minimizes changes in phase-encoding gradients from one repetition to the next in order to minimize eddy current artifacts. In this article, optimal view ordering schemes satisfying these two requirements are formulated and applied to inversion prepared 3D SSFP contrast-enhanced MR angiography (MRA). Experiments on phantoms and pigs demonstrated improved background suppression and reduced image artifacts.     

正常成人脑外段视神经的MRI研究

目的 评价正常成人视神经-眼平面(NOP)视交叉以外段颅神经的MRI表现,建立正常标准。方法 随机选择正常成人志愿者50例,采用GB1.5T MR/i echo spood plus超导型磁共振成像仪及相控阵头线圈,成像序列包括自旋回波T1加权成像(SET1WI)和自旋回波T2加权成像(SET2WI);扫描方位以NOP平面为基准扫描。分别测量两组视神经眼球后神经膨大段直径、眶内段视神经直径、长度,管内段视神经直径及该段视神经起始至同侧视交叉的长度,后者与眶内段视神经长度之和即代表颅外段视神经的长度。结果 NOP平面上,正常人眼球后神经膨大段直径为4.2±0.56mm,眶内段直径为3.1±0.45mm、长度为24.6±2.88mm,管内段视神经直径为3.2±0.49mm,至同侧视交叉的长度为18.7±2.40mm,颅外段视神经的长度为43.3±3.83mm。统计分析,正常成人组内性别和年龄、双侧视神经之间无显著差异。 结论 NOP平面评价视神经有很大优势,MRI可以很好显示视神经的形态,是研究其解剖和疾病的有效检查手段。     

先天性胆脂瘤的MRI诊断

目的：探讨MRI对先天性胆脂瘤的诊断价值。方珐：回顾性分析7例经手术病理证实的先天性胆脂瘤的MRI表现，7例均为脑外型，其中6例胆脂瘤位于桥小脑角区，l例胆脂瘤位于脊髓内．结果：先天性胆脂瘤的绝大多数MRI表现为T1WI呈低信号,T2WI呈高信号，信号欠均匀，且病灶具有“见缝就钻”的特点。增强扫描，病灶无强化，但如合并感染可有轻度强化。结论：MRI的表现及特殊序列FLAIR、SPIR像的相互补充应用对先天性胆脂瘤的诊断及鉴别诊断具有重要意义。     

Pituitary volume in pediatric obsessive-compulsive disorder.

BACKGROUND: Abnormalities in the limbic-hypothalamic-pituitary-adrenal (LHPA) axis have been implicated in the pathogenesis of obsessive-compulsive disorder (OCD). To our knowledge, however, no prior study has measured pituitary gland volume in OCD. METHODS: Volumetric magnetic resonance imaging studies were conducted in 31 psychotropic drug-na?ve children (10 boys, 21 girls) aged 8-17 years and 31 case-matched healthy comparison subjects. RESULTS: Pituitary volume was significantly smaller in patients with OCD as compared with healthy control subjects (11% smaller). Smaller pituitary volume in patients with OCD was associated with increased compulsive but not obsessive symptom severity. Boys with OCD had smaller pituitary gland volumes compared with control boys (20% smaller). No significant differences in pituitary volume were observed between girls with OCD and control girls. Boys with OCD had significantly smaller pituitary volumes than girls with OCD (31% smaller), whereas control boys also had smaller pituitary gland volumes compared with control girls (21% smaller). CONCLUSIONS: These findings provide new evidence of reduced pituitary volume in pediatric OCD that seems to be more prominent in male patients. The observed alterations in pituitary volume are consistent with neuroendocrine studies that have reported abnormalities in the LHPA axis in OCD.     

Long-term benefit to pallidal deep brain stimulation in a case of dystonia secondary to pantothenate kinase-associated neurodegeneration.

Pantothenate kinase-associated neurodegeneration (PKAN) is a rare autosomal recessive disorder with onset in childhood and rapid progression. There is no causative and insufficient symptomatic drug therapy. Deep brain stimulation (DBS) of the internal pallidum (GPi) has been reported to improve motor function. Most case reports, however, are limited to short observational periods. The impact of DBS on the progression and life expectancy in PKAN is unknown. We present a 5-year outcome and video documentation of bilateral GPi-DBS of an adolescent patient suffering from genetically defined PKAN.     

脑梗死后再发缺血性卒中与脑出血患者微血管病变及预后的比较

【目的】探讨脑梗死后再发缺血性卒中与脑出血患者的临床特点、影像学上微血管病变及预后的异同。【方法】连续收集急性复发性卒中的住院病例（初发事件为脑梗死，复发事件包括脑梗死或脑出血），详细记录临床资料。观察脑内微出血及自质病变的严重程度，随访有无严重血管事件及死亡的发生。【结果】175例再发脑梗死患者。19例复发事件为脑出血的患者进入本研究。155例（88．6％）再发脑梗死患者，以及18例（94．7％）脑出血患者存在自质病变。77例（44％）再发脑梗死患者和16例（84．2％）脑出血患者存在脑内微出血。脑出血组自质病变的严重程度及微出血的数目均明显高于再发脑梗死组（P=0．033，0．016），脑出血组的死亡率及再发脑出血的危险性明显增高（P=0．034，0．036）。【结论】严重的脑自质病变及微出血的出现与脑梗死后再发脑出血有关。多发微出血提示出血风险增高。如复发事件为脑出血，则其死亡率及再次复发脑出血的风险均明显增加。     

磁场对电解铝作业工人免疫功能影响的研究

对某铝厂电解车间采用CT_3-A型交直流特斯拉计测定了电解槽近场区不同高度、不同距离及人体表面不同部位的磁场强度。结果表明作业场所及人体体表的磁场强度为自然界磁场强度的数倍至数十倍。对接触磁场、工龄在20年以上的工人,进行了免疫功能的测定。结果表明该场所的磁场强度对工人免疫功能有抑制作用。由于该作业场所除磁场外,还有其他化学、物理因素的危害,因此,这种免疫功能的改变,可能是磁场等综合因素所造成的。     

Imaging of thoracic aortic dissection

Acute thoracic aortic dissection has a high mortality if untreated, so the diagnosis must be rapidly made if mortality is to be lowered significantly. Multiple imaging techniques are often used. This retrospective study from 1988 to 1993 assesses the usefulness in diagnosis of chest X-rays, computed tomography (CT) scanning, aortography, magnetic resonance imaging (MRI), trans-thoracic (TTE) and trans-oesophageal (TOE) echocardiography. Forty-two patients with a final clinical diagnosis of dissection were studied. The diagnosis was confirmed in 16 (13 at surgery and three at autopsy). Three died with dissection given as the only cause for death. Chest X-ray abnormalities were seen in all 19 patients with surgery or death from dissection, with a widened mediastinum and/or dilated aorta being present in 17. In the group of 16 patients with surgery or autopsy proof, CT scans found dissections in 9 of 12 patients studied and correctly classified the type in only five. Aortography was performed in five, with accurate depiction of dissection and type in all. TTE found dissections in three of eight patients imaged by this method. MRI and TOE were performed each on two patients, with accurate depiction of dissection and type in each. Because of the relatively low sensitivity of CT scanning in defining aortic dissections Westmead Hospital is currently assessing the use of TOE as the prime imaging modality prior to surgical intervention.     

Capacitively coupled electrical stimulation of bovine growth plate chondrocytes grown in pellet form

Pellets formed from isolated bovine growth plate chondrocytes were grown in various capacitively coupled electrical fields. The signals chosen were 0, 10, 100, 250, 500, 750, 1,000, and 1,500 V peak-to-peak, 60 kHz. The effect on cell proliferation and matrix production of these different voltages was determined by [3H]thymidine and [35S]sulfate uptake, respectively, Cyclic AMP assays were done to determine if increases in either thymidine or sulfate uptake were associated with changes in cAMP levels. Significantly increased cell proliferation occurred at 500, 750, and 1,000 V peak to peak. The calculated electric fields were 1.5 to 3.0 x 10(-2) V/cm. Proliferation was significantly inhibited at 1,500 V peak-to-peak with a calculated field of 4.5 x 10(-2) V/cm. Little if any change was seen in cAMP levels at 30 or 60 min following application of the appropriate electric signals.