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.     

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.     

A Decrease in Pulmonary Vein Diameter After Radiofrequency Ablation Predicts the Development of Severe Stenosis

A decrease in ostial pulmonary vein (PV) diameter was observed in patients on the day after radiofrequency ablation of atrial fibrillation (AF). This study examined whether a relative reduction in PV diameter on day 1 (RRPVD1) after the procedure predicts the late development of severe PV stenosis (PVS). The study included 104 consecutive patients (mean age = 55 years, range 46–61, 34 women) with drug refractory AF. Pulmonary vein diameter was measured using MR angiography (MRA) on the day before and on day 1 after the ablation procedure. The MRA was repeated every 3 months after the procedure. Severe PVS was defined as a >70% diameter reduction from the initial ostial diameter. The cut-off of RRPVD1 was prespecified as 25% decrease in initial diameter. The data are presented as medians and interquartile range. A total of 357 PV were treated. The RRPVD1 was 0.0% (0.0–11.1%). Severe PVS was found in 18 PV during a follow-up of 12 months (range 6–13). The log-rank analysis confirmed a strong association between a RRPVD1 ≥25% and the development of PVS (hazard ratio: 7.1; 95% confidence interval 3.8–13.5, P < 0.0001). By multivariate Cox regression model, after adjustment of procedure variables, RRPVD1 was the strongest predictor of development of severe PVS. RRPVD1 ≥25% was a strong independent predictor of development of severe PVS.     

Reperfused myocardial infarctions on T1- and susceptibility-enhanced MRI: Evidence for loss of compartmentalization of contrast media

The purpose of this study was to characterize the contrast caused by a susceptibility MRI contrast agents, on spin echo T₂-weighted imaging of reperfused myocardial infarction. Our interest in this model focused on the expected requirement that such agents be compartmentalized in the tissue to cause signal loss on spin echo images, a condition which may not be present in reperfused infarcted myocardium. Accordingly, nine rats were subjected to 2 h of left coronary artery occlusion followed by 3 ± 0.5 h of reperfusion prior to administration of contrast media. Three sets of MR images were acquired: (a) baseline axial images at the midventricle, both T₁-weighted (TR/TE = 300/20) and T₂-weighted (TR/TE = 1500/60); (b) T₁-weighted images after administering a T₁-enhancing agent, Gd-DTPA-BMA (0.2 mmol/kg), to document that contrast media is delivered to the reperfused infarction; and (c) T₂-weighted images after administering the susceptibility agent, Dy-DTPA-BMA (1.0 mmol/kg). Gadolinium-enhanced T₁ images depicted reperfused infarction as regions with greatly enhanced signal intensity compared with unin-farcted myocardium, indicating that contrast agent was delivered to the infarcted zone. Dysprosium-enhanced T₁ images depicted the injury as a region of persistent signal intensity relative to depletion of signal in normal myocardium, consistent with failure of the contrast agent to cause signal loss. Similar infarction sizes were observed for unenhanced T₂-weighted images (33 ± 5%), gadolinium-enhanced T₁ weighted images (36 ± 5%) and postmortem staining (30 ± 6%); strong correlations (r > 0.9) were noted in comparisons of these data. Dysprosium-enhanced images exhibited a smaller region of differential signal presumed to be infarction (20 ± 5%, P < 0.05) and weak correlations (r < 0.75) with the other measurements. We conclude that the smaller infarction depicted on dysprosium-enhanced images is a subregion of the true infarction in which myocardial necrosis is sufficiently advanced that the agent is homogeneously distributed throughout all tissue compartments, preventing T₂*-dependent phase loss on spin echo images.     

椎管内肿瘤磁共振成像增强扫描初步观察

对１１例手术病理证实的椎管内肿瘤进行磁共振成像（ＭＲＩ）增强扫描的前、后分析，并对肿瘤定位、定性和鉴别诊断作了初步探讨。根据肿瘤形态、边界、强化程度，及与脊髓、硬脊膜、神经根等关系，ＭＲＩ的增强扫描对提高其定位、定性诊断均有较大的帮助。