兔心肌梗塞模型制备方法的改进及其在MRI中的应用

目的　对兔心肌缺血的模型制备方法进行改进 ,并探讨其在 MRI诊断研究中的价值。方法　分别采用高位结扎左冠状动脉前降支 (L AD)和同时低位结扎 L AD及左冠状动脉旋支 (L Cx)建立兔心肌梗塞模型 ,并在术后行 MRI检查 ,对取材后心肌标本行氯化三苯四氮唑 (TTC)及病理检查。结果　 1L AD组 2 0 % (5 / 2 5 )发生心室颤动导致死亡 ,L AD +L Cx组无一例发生室颤死亡。 2 L AD组 EKG改变明显者占 5 6 % (14 / 2 5 ) ,其中 2 1.4 3% (3/14 )在即刻就有 EKG明显改变 ,并在 30分钟后恢复正常 ;EKG改变不明显者占 4 4 % (11/ 2 5 ) ;L AD +L Cx组 10 0 %有 EKG明显改变 ,且 30分钟后亦无明显恢复。 3L AD组心肌梗塞范围较小 ,并均限于左室前壁 ,室间隔前部损害 ;而 L AD+L Cx组心肌梗塞范围较大 ,且累及左室前壁及侧壁 ,无一例有室间隔前部损害。4 L AD组中有 30 % (6 / 2 0 )不能显示小灶缺血局部心肌运动降低 ,16 .6 7% (3/ 18)无法分辨早期小梗塞灶的 MRI信号变化 ;而 L AD+L Cx组均能显示缺血局部心肌运动降低及梗塞灶早期的 MRI信号变化。结论　低位结扎兔心 L AD+L Cx,手术死亡率低 ,EKG改变明显 ,梗塞面积较大 ,是 MRI研究中一种较理想的心肌缺血动物模型制备方法。     

螺旋CT和MRI诊断肝内胆管细胞癌的价值

目的:探讨螺旋CT和MRI诊断肝内胆管细胞癌的价值。材料和方法:回顾性分析经病理证实的18例肝内胆管细胞癌CT平扫和三期增强扫描,9例MRI平扫和动态增强扫描。结果:CT平扫13个病灶呈低密度,2个病灶呈高密度,4个病灶未能显示,病变检出敏感性为78.9%;CT增强扫描动脉期10个病灶表现呈周边薄环状增强,3个病灶呈高密度,4个病灶无增强呈等密度,2个病灶未能检出,病变检出敏感性为89.4%:门脉期11个病灶呈厚环状增强,4个病灶呈等密度,3个病灶均匀增强,呈高密度,1个肿块未见显示,病变检出敏感性为94.7%;延迟期7个病灶呈不定形轻度增强,呈低密度,4个病灶呈等密度,8个病灶明显增强,呈高密度,病变敏感性为100%。9个病灶MR平扫T1WI呈低信号,T2WI呈高或略高信号,病变检出敏感性为100%动态增强扫描6个病灶表现为缓慢增强型:3个病灶表现为快速增强型:病变检出敏感性为100%。结论:肝内胆管细胞癌螺旋CT三期增强扫描及MR动态增强扫描均具有一定的特异性,对于肝内与其它常见病变的鉴别诊断均有重要价值。     

成人纵隔淋巴结结核影像学表现及病理对照分析

目的总结成人纵隔淋巴结结核的影像学表现特点及其与病理改变的关系,探讨影像学诊断价值。方法回顾分析40例纵隔淋巴结结核病例的临床、CT和MRI检查资料,并与17例术后及淋巴结穿刺活检后病理结果进行对照研究。结果40例中多发淋巴结肿大35例,单发淋巴结肿大5例;病变累及右侧纵隔26例,左侧纵隔13例,双侧同时受累11例。CT平扫肿大淋巴结呈等密度或稍低密度,多数密度均匀,少数较大淋巴结可显示内部稍低密度区;MRI平扫肿大淋巴结呈中等T1、中等T2信号,其内可见斑片状稍长T1、稍长T2信号。CT和MRI增强扫描所见淋巴结强化方式相似,分别为结节状、环状、分隔状及不均匀强化,以环状及分隔状强化具特征性及诊断特异性。与手术及活检病理结果对照显示CT和MRI表现与淋巴结结核各期病理改变相一致。结论CT和MRI均可明确显示纵隔淋巴结结核病变大小、形态、范围及其与周围组织关系,增强扫描可充分反映病变不同时期病理改变,影像学检查在该病的诊断和治疗过程中具有极其重要的应用价值。     

In vivo detection of single cells by MRI.

The use of high-relaxivity, intracellular contrast agents has enabled MRI monitoring of cell migration through and homing to various tissues, such as brain, spinal cord, heart, and muscle. Here it is shown that MRI can detect single cells in vivo, homing to tissue, following cell labeling and transplantation. Primary mouse hepatocytes were double-labeled with green fluorescent 1.63-microm iron oxide particles and red fluorescent endosomal labeling dye, and injected into the spleens of recipient mice. This is a common hepatocyte transplantation paradigm in rodents whereby hepatocytes migrate from the spleen to the liver as single cells. One month later the animals underwent in vivo MRI and punctuated, dark contrast regions were detected scattered through the livers. MRI of perfused, fixed samples and labeled hepatocyte phantoms in combination with histological evaluation confirmed the presence of dispersed single hepatocytes grafted into the livers. Appropriate controls were used to determine whether the observed contrast could have been due to dead cells or free particles, and the results confirmed that the contrast was due to disperse, single cells. Detecting single cells in vivo opens the door to a number of experiments, such as monitoring rare cellular events, assessing the kinetics of stem cell homing, and achieving early detection of metastases.     

动态增强MR灌注成像在脑胶质瘤诊断中的价值

目的　探讨动态增强T2 WMR灌注成像在脑胶质瘤术前分级预测及鉴别诊断中的价值。资料与方法　有病理或追踪结果的 4 8例脑病变患者 ,其中胶质瘤 2 5例 (高、低级别胶质瘤分别为 16例和 9例 ) ,非胶质瘤病变 2 3例。全部病例均行常规T1WI、T2 WI和EPI SE序列动态增强MR灌注成像。计算每个病灶的最大相对脑血容量 (rCBV)比值 (病灶最大rCBV/对侧正常脑白质rCBV)。分析胶质瘤的最大rCBV比值与其组织学级别的关系 ,并比较胶质瘤与非胶质瘤的灌注异常及常规MRI强化表现。结果　高级别胶质瘤 ( 16例 )的最大rCBV比值为4 .6 0± 1.98( 2 .5 5～ 9.2 2 ) ,低级别胶质瘤 ( 9例 )的最大rCBV比值为 1.86± 1.5 2 ( 0 .85～ 5 .72 ) ,经t检验 ,两组之间有显著统计学差异 (P <0 .0 1)。脑膜瘤、转移瘤、血管母细胞瘤、淋巴瘤均显示有局部高灌注 ,最大rCBV比值为5 .35± 2 .39( 3.15～ 12 .39) ,而有强化表现的脑梗死、脑炎性灶及放射性脑损伤表现为低、等灌注 ,最大rCBV比值为1.2 7± 0 .36 ( 0 .85～ 1.72 )。结论　MR灌注成像在胶质瘤的术前影像学分级预测上有重要价值 ,在脑胶质瘤的某些鉴别诊断上亦具有一定的参考价值     

Structural white matter abnormalities in patients with idiopathic dystonia

We investigated whether structural white matter abnormalities, in the form of disruption of axonal coherence and integrity as measured with diffusion tensor imaging (DTI), constitute an underlying pathological mechanism of idiopathic dystonia (ID), independent of genotype status. We studied seven subjects with ID: all had cervical dystonia as their main symptom (one patient also had spasmodic dysphonia and two patients had concurrent generalized dystonia, both DYT1‐negative). We compared DTI MR images of patients with 10 controls, evaluating differences in mean diffusivity (MD) and fractional anisotropy (FA). ID was associated with increased FA values in the thalamus and adjacent white matter, and in the white matter underlying the middle frontal gyrus. ID was also associated with increase in MD in adjacent white matter to the pallidum and putamen bilaterally, left caudate, and in subcortical hemispheric regions, including the postcentral gyrus. Abnormal FA and MD in patients with ID indicate that abnormal axonal coherence and integrity contribute to the pathophysiology of dystonia. These findings suggest that ID is not only a functional disorder, but also associated with structural brain changes. Impaired connectivity and disrupted flow of information may contribute to the impairment of motor planning and regulation in dystonia. © 2006 Movement Disorder Society     

Mapping brain size and cortical gray matter changes in elderly depression.

BACKGROUND: In elderly depression, volumetric brain imaging findings suggest abnormalities of the frontal lobe, particularly the orbitofrontal cortex, and the hippocampus. No studies to date have mapped cortical abnormalities over the entire brain surface in major depression. Here, we conducted detailed spatial analyses of brain size and gray matter within the cortical mantle in elderly patients with major depression. METHODS: High-resolution, three-dimensional, structural magnetic resonance imaging data and cortical pattern matching methods were used in 24 depressed elderly patients and 19 group-matched controls to measure local brain size and proportions of gray matter at thousands of homologous cortical surface locations. RESULTS: Prominent brain size reductions were observed in the depressed subjects in the orbitofrontal cortex bilaterally. Cortical gray matter measurements revealed significant gray matter increases in the orbitofrontal cortex, adjacent to focal trend level significant decreases of gray matter in the same region. Depressed patients also exhibited significant gray matter increases in parietal cortices, as well as the left temporal cortex. CONCLUSIONS: Complex cortical changes may contribute to the brain size reduction of the orbitofrontal cortex and to the gray matter abnormalities detected in orbitofrontal cortex and temporoparietal cortices, thereby providing a potentially new window into the pathophysiology of elderly depression.     

咽旁间隙在头颈部肿瘤MRI诊断中的价值

目的探讨咽旁间隙移位方向及肿瘤MRI信号特点对病变定位、定性的价值。方法回顾性分析经病理确诊的累及咽旁间隙肿瘤76例,其中恶性肿瘤51例,良性肿瘤25例。结果扁桃体肿瘤和鼻咽癌使茎突前间隙外移,腮腺肿瘤使茎突前间隙向前内移位,或(和)颈动脉鞘区后移。颈动脉鞘区交感神经鞘瘤使颈内动、静脉向前外侧移位,迷走神经鞘瘤使颈内动、静脉明显分离,颈动脉体瘤使颈内、外动脉分叉角增大,颈静脉球瘤使血管向前外侧移位,转移淋巴结使颈内动、静脉向前内侧移位。25例良性肿瘤边界清楚,其中9例信号均匀;51例恶性肿瘤中,19例边界模糊,15例信号欠均匀。茎突前间隙脂肪消失或不连续6例均为恶性肿瘤,肿瘤边界较清但颈部淋巴结肿大符合淋巴结转移诊断标准2例及颈内动、静脉被肿瘤包绕3例,病理证实亦为恶性肿瘤。结论咽旁间隙移位方向及肿瘤MRI信号特点对头颈部肿瘤的定位、定性具有重要的价值。     

老年性骨质疏松脊柱良性骨折与转移瘤性骨折的MRI鉴别

目的探讨脊椎骨质疏松性压缩骨折的MRI表现及其与转移性压缩骨折的鉴别诊断.资料与方法回顾性分析53例老年性骨质疏松伴压缩性骨折和20例转移性椎体压缩骨折患者的MRI资料.全部病例均行常规MRI检查(矢状位、横轴位).分析两者引起的压缩骨折MRI征象,包括椎体和椎弓根的形态及信号改变、椎间盘增厚、椎体内真空现象和椎旁软组织形态.探讨两者之间的差别.结果两者在椎体和椎弓根形态及信号、椎体内真空现象、椎旁软组织形态上存在非常显著性差异(P＜0.01).结论 MRI能准确显示骨质疏松性压缩骨折的形态及信号,与转移瘤之间有显著差异,大多能对二者做出鉴别诊断.     

MR灌注成像在评估脑胶质瘤放疗效果中的应用

目的探讨MR灌注成像在评估脑胶质瘤放疗疗效中的应用价值。方法对25例脑胶质瘤术后患者于放疗前及放疗后3、6个月行MR灌注成像及常规MRI检查。由灌注数据获取脑血容量（CBV）图和脑血流量（CBF）图。计算出病灶的最大相对局部脑血容量（rCBV）值和最大相对局部脑血流量（rCBF）值。结果25例脑胶质瘤术后放疗前肿瘤区的rCBV值和rCBF值分别为6．32±2．14和5．49±1．98，与正常脑组织的2．58±1．21和2．17±1．19相比，显著升高（P〈0．01）。其中11例放疗后rCBV值和rCBF值与放疗前相比，显著下降（P〈0．01），其中5例证实为放射性脑坏死；另14例放疗后rCBV值和rCBF值与放疗前相比，有不同程度升高，但无统计学意义（P〉9．05）。其中7例证实为肿瘤伴部分放射性坏死组织，2例死亡，5例再次行放射治疗取得较好疗效。结论MR灌注成像可作为评估脑胶质瘤放疗疗效的一项重要指标。并有助于下一步治疗方案的制定。