动态对比增强磁共振与扩散加权成像对脑胶质瘤分级诊断的比较研究

目的比较动态对比增强磁共振（DCE-MRI）渗透性参数Ktrans值、ve值及扩散加权成像（DWI）的ADC值对脑胶质瘤分级的诊断价值。方法回顾性分析经病理证实的16例高级别脑胶质瘤（HGG）和12例低级别脑胶质瘤（LGG）患者的磁共振资料,所用序列包括常规平扫、DWI和动态对比增强扫描LAVA序列,分别测量肿瘤感兴趣区域（ROI）DCE-MRI的渗透性参数Ktrans值、ve值和DWI的tADC值、rADC值。t检验比较HGG和LGG两组间参数的统计学差异。采用ROC曲线分析Ktrans值、Ve值、tADC值、rADC值的最佳阈值及其敏感度、特异度和AUC。结果HGGKtrans值、ve值均高于LGG,差异均有统计学意义（均P＜0.01）;而HGGtADC值、rADC值均明显低于LGG,差异均有统计学意义（均P＜0.01）。ve值诊断HGG的AUC最大为0.906,取ve值最佳阈值0.142,对诊断HGG的敏感度和特异度分别为87.5%和91.7%。结论DCE-MRI渗透性参数及DWI的ADC值均有助于高级别和低级别脑胶质瘤的分级诊断,但ve值的价值更高。     

移植骨肉瘤磁共振弥散加权成像特点及价值

目的探讨大鼠骨肉瘤磁共振弥散加权成像(DWI)特点及其判断骨肉瘤坏死区的价值。方法将UMR-106细胞接种于SD大鼠背部皮下成瘤,对肿瘤行MRI常规扫描及DWI成像并做病理对照。结果活肿瘤细胞区血管横断面积百分比与ADC值无相关性。增强扫描确定肿瘤坏死区的敏感性为86.7%(13/15),特异性为38.5%(15/39),准确性为51.9%(28/54)。ADC值确定肿瘤坏死区的敏感性为93.3%(14/15),特异性为94.9%(37/39),准确性为94.4%(51/54)。结论b值较大时,组织微灌注对大鼠骨肉瘤ADC值影响很小。DWI较传统MRI序列及增强扫描能更早期分辨骨肉瘤坏死区。     

High angular resolution diffusion imaging reveals intravoxel white matter fiber heterogeneity.

Magnetic resonance (MR) diffusion tensor imaging (DTI) can resolve the white matter fiber orientation within a voxel provided that the fibers are strongly aligned. However, a given voxel may contain a distribution of fiber orientations due to, for example, intravoxel fiber crossing. The present study sought to test whether a geodesic, high b-value diffusion gradient sampling scheme could resolve multiple fiber orientations within a single voxel. In regions of fiber crossing the diffusion signal exhibited multiple local maxima/minima as a function of diffusion gradient orientation, indicating the presence of multiple intravoxel fiber orientations. The multimodality of the observed diffusion signal precluded the standard tensor reconstruction, so instead the diffusion signal was modeled as arising from a discrete mixture of Gaussian diffusion processes in slow exchange, and the underlying mixture of tensors was solved for using a gradient descent scheme. The multitensor reconstruction resolved multiple intravoxel fiber populations corresponding to known fiber anatomy. Ma     

Transcranial US of preterm neonates: High risk gestational age and birth weight for perinatal asphyxia

Objective

The study aims to determine the high risk gestational week (GW) and/or birth weight (BW) of the preterm neonate, below which perinatal hypoxic cerebral injuries are expected to occur.

Material and methods

Eighty preterm neonates, born at or before 37 GW, were included. Twenty-three of them were <32 GW and 57 >32 GW. Also, 28 of them were <1500 g and 52 >1500 g. Imaging was done by transcranial ultrasound with 4–9 MHz curvilinear probe. CT scan was additionally performed for only 18 candidates. The study protocol was approved by the ethics committee in Al-Mana General Hospital (AGH).

Results

Intraventricular hemorrhage (IVH) was diagnosed in six preterm neonates <32 GW and two >32 GW. Three <32 GW and one >32 GW presented with hypoxic ischemic encephalopathy (HIE) with no hemorrhage. Two preterm neonates <32 GW had both IVH & HIE. All positive cases were below 1500 g BW.

Conclusion

Preterm neonates <32 GW and/or <1500 g are highly susceptible for HIE and/or IVH. Thus, special medical care, including post-labor hospitalization in well equipped special baby care units (SCBU) and routine transcranial ultrasound (TCUS) screening is recommended for those preterm neonates.     

DWI和3D-TOF法MRA在脑梗死中的诊断价值

目的探讨磁共振弥散成像(DWI)和3D-TOF法血管成像(MRA)在脑梗死中临床诊断价值,区分多发梗死灶中急性和非急性方面的能力,尤其是超早期脑梗死诊断和治疗中的作用。方法对72例脑梗死发病不同时间的病例行常规MRI、DWI序列及3D-TOF血管成像扫描,并根据发病时间进行分期比较及分析。结果MRI平扫T2加权像在发病12 h后才能隐约见到稍高信号的病灶,而DWI最早可在发病2 h发现缺血灶,3D-TOF血管成像不仅能显示脑动脉的狭窄、闭塞、动脉硬化还能显示侧枝循环情况。结论DWI可以明确诊断急性,尤其是超早期脑梗死,3D-TOF技术MRA可快速而准确地显示颅内动脉狭窄或闭塞及其相应的脑梗死,2者结合对治疗方案的制定与调整及评价疗效均有重要意义。     

3.0T磁共振DWIBS诊断宫颈癌转移性淋巴结初探

目的探讨3.0T磁共振背景抑制弥散加权成像(DWIBS)在子宫颈癌转移性淋巴结诊断中的应用价值。方法回顾性分析行全宫切除加盆腔淋巴结清扫手术的25例子宫颈癌术前病例。采用方差分析比较子宫颈癌原发病灶及转移性、非转移性淋巴结的ADC值;采用两组随机对照t检验对转移性及非转移性淋巴结的ADC值、长径、短径及短径/长径比分别进行统计学分析。结果 (1)25例子宫颈癌病例中原发病灶25个,转移性淋巴结17个,非转移性淋巴结140个,均经手术病理证实;(2)子宫颈癌原发灶、转移性淋巴结和非转移性淋巴结三者之间的ADC值比较有统计学差异(F=7.93,P=0.001)。子宫颈癌原发灶与转移性淋巴结的ADC值比较无统计学差异(t=-0.75,P=0.456),子宫颈癌原发灶与非转移性淋巴结的ADC值比较有统计学差异(t=4.68,P0.001);(3)转移性及非转移性淋巴结ADC值分别为(0.86±0.36)×10~(-3)mm~2/s和(1.12±0.34)×10~(-3)mm~2/s,长径分别为1.51±0.41cm和1.19±0.36cm,短径分别为1.16±0.35cm和0.77±0.22cm,短径/长径比率分别为0.78±0.17和0.68±0.19,两两比较均有统计学差异。结论 3.0T磁共振DWIBS的ADC值测量能够定量反映转移性及非转移性淋巴结的弥散受限程度,结合淋巴结的短径、长径等综合评价可以提高转移性淋巴结的诊断准确性。