目的分析3 T MRI三维T2加权快速梯度回波(three-dimensional T2-weighted fast field echo,3D-T2*-FFE)序列显示胎儿脊柱解剖及椎体畸形的价值。材料与方法本研究纳入46例产前超声提示胎儿椎体异常或脊柱部分显示不清的中晚期孕妇,所有...目的分析3 T MRI三维T2加权快速梯度回波(three-dimensional T2-weighted fast field echo,3D-T2*-FFE)序列显示胎儿脊柱解剖及椎体畸形的价值。材料与方法本研究纳入46例产前超声提示胎儿椎体异常或脊柱部分显示不清的中晚期孕妇,所有胎儿均行脊柱MRI检查,扫描序列包括:3D-T2*-FFE、二维单次激发快速自旋回波(two-dimensional single shot fast spin echo,2D SSH TSE)和二维平衡式自由稳态进动(two-dimensional balance turbo fast field echo,2D BTFE)。由两名诊断医师对三个序列获得的脊柱各节段图像质量进行评分,采用非参数检验之Friedman检验比较各序列图像之间评分的差异。对所有病例勾画感兴趣区(region of interest,ROI),并分别计算三个序列颈、胸、腰骶段相应的椎体与椎间盘信号差值比,以评价图像对比度,通过单因素方差分析比较三个序列各节段信号差值比的差异是否有统计学意义。结果与2D SSH TSE和2D BTFE序列相比3D-T2*-FFE可以获得更好的胎儿颈椎图像,2D BTFE与3D-T2*-FFE序列在胎儿胸椎及腰骶椎的图像质量均优于2D SSH TSE序列;3D-T2*-FFE和2D BTFE序列的信号差值比高于2D SSH TSE序列,且差异有统计学意义(P<0.05);胎儿胸椎和腰椎在各序列的信号差值比差异无统计学意义(P>0.05)。结论3D-T2*-FFE序列对胎儿椎体成像效果较好,能显示更多脊柱解剖细节,其不受胎儿体位影响,且扫描时间较短,临床MRI扫描时可将其作为胎儿脊柱成像的重要补充序列。展开更多
Background and Purpose -In contrast to platelet-rich white thrombi, red thrombi in the heart are rich in fibrin and trapped erythrocytes. The magnetic susceptibility effect of deoxygenated hemoglobin in red thrombi ma...Background and Purpose -In contrast to platelet-rich white thrombi, red thrombi in the heart are rich in fibrin and trapped erythrocytes. The magnetic susceptibility effect of deoxygenated hemoglobin in red thrombi may result in hypointense signals on T2*-weighted gradient echo imaging (GRE). We tested the hypothesis that a GRE susceptibility vessel sign (SVS) is specific for cardioembolic stroke. Methods -This retrospective study examined data from acute ischemic stroke patients who underwent diffusion-weighted imaging, GRE and magnetic resonance angiography (MRA) within 24 hours of stroke onset and who had symptomatic occl usion of large intracranial arteries in the circle of Willis. Hypointense signals within vascular cisterns on GRE corresponding to symptomatic vascular occlusio n were termed “GRE SVS.”Recanalization was assessed on follow-up MRA performe d within 7 days of onset. The relationships between GRE SVS and stroke subtypes and subsequent recanalization were explored. Results -Of the 95 patients who me t the inclusion criteria, GRE SVS was observed in 45 (47.4%). GRE SVS was more commonly associated with cardioembolic stroke patients (31 of 40, 77.5%) than w ith other stroke subtypes (14 of 55, 25.5%; P < 0.001). In 66 patients who unde rwent follow-up MRA, GRE SVS was associated with subsequent recanalization (P < 0.001). Multivariate analysis showed that GRE SVS was an independent predictor of cardioembolic stroke and subsequent recanalization (odds ratio, 10.75 and 4.2 6; 95%CI, 3.68 to 31.47 and 1.12 to 16.30). Conclusions -GRE SVS may predict c ardioembolic stroke and subsequent recanalization. Identifying clot composition may be important in choosing the optimal treatment based on clot characteristics .展开更多
Gradient echo T2. weighted MRI has high sensitivity in detecting cerebral mic robleeds, which appear as small dot like hypointense lesions. Microbleeds are s trongly associated with intracerebral haemorrhage, hyperten...Gradient echo T2. weighted MRI has high sensitivity in detecting cerebral mic robleeds, which appear as small dot like hypointense lesions. Microbleeds are s trongly associated with intracerebral haemorrhage, hypertension, lacunar stroke and ischaemic small vessel disease, and have generated interest as a marker of b leeding prone microangiopathy. Microbleeds have generally been considered to be clinically silent; however, since they are located in widespread cortical and b asal ganglia regions and are histologically characterized by tissue damage, we h ypothesized that they would cause cognitive dysfunction. We therefore studied pa tients with microbleeds (n = 25) and a nonmicrobleed control group (n = 30) matc hed for age, gender and intelligence quotient. To avoid the confounding effects of coexisting cerebrovascular disease, the groups were also matched for the exte nt of MRI visible white matter changes of presumed ischaemic origin, location o f cortical strokes, and for the proportion of patients with different stroke sub types (including lacunar stroke). A battery of neuropsychological tests was used to assess current intellectual function, verbal and visual memory, naming and p erceptual skills, speed and attention and executive function. Microbleeds were m ost common in the basal ganglia but were also found in frontal, parieto occipit al, temporal and infratentorial regions. There was a striking difference between the groups in the prevalence of executive dysfunction, which was present in 60 %of microbleed patients compared with 30%of non microbleed patients (P = 0.03 ). Logistic regression confirmed that microbleeds (but not white matter changes) were an independent predictor of executive impairment (adjusted odds ratio = 1. 32, 95%confidence interval 1.01 1.70, P = 0.04). Patients with executive dysfu nction had more microbleeds in the frontal region (mean count 1.54 versus 0.03; P = 0.002) and in the basal ganglia (mean 1.17 versus 0.32; P = 0.048). There wa s a modest correlation between the number of microbleeds and the number of cogni tive domains impaired (r = 0.44, P = 0.03). This study provides novel evidence t hat microbleeds are associated with cognitive dysfunction, independent of the ex tent of white matter changes of presumed ischaemic origin, or the presence of is chaemic stroke. The striking effect of microbleeds on executive dysfunction is l ikely to result from associated tissue damage in the frontal lobes and basal gan glia. These findings have implications for the diagnosis of stroke patients with cognitive impairment, and for the appropriate use of antihypertensive and anti platelet treatments in these patients.展开更多
文摘目的分析3 T MRI三维T2加权快速梯度回波(three-dimensional T2-weighted fast field echo,3D-T2*-FFE)序列显示胎儿脊柱解剖及椎体畸形的价值。材料与方法本研究纳入46例产前超声提示胎儿椎体异常或脊柱部分显示不清的中晚期孕妇,所有胎儿均行脊柱MRI检查,扫描序列包括:3D-T2*-FFE、二维单次激发快速自旋回波(two-dimensional single shot fast spin echo,2D SSH TSE)和二维平衡式自由稳态进动(two-dimensional balance turbo fast field echo,2D BTFE)。由两名诊断医师对三个序列获得的脊柱各节段图像质量进行评分,采用非参数检验之Friedman检验比较各序列图像之间评分的差异。对所有病例勾画感兴趣区(region of interest,ROI),并分别计算三个序列颈、胸、腰骶段相应的椎体与椎间盘信号差值比,以评价图像对比度,通过单因素方差分析比较三个序列各节段信号差值比的差异是否有统计学意义。结果与2D SSH TSE和2D BTFE序列相比3D-T2*-FFE可以获得更好的胎儿颈椎图像,2D BTFE与3D-T2*-FFE序列在胎儿胸椎及腰骶椎的图像质量均优于2D SSH TSE序列;3D-T2*-FFE和2D BTFE序列的信号差值比高于2D SSH TSE序列,且差异有统计学意义(P<0.05);胎儿胸椎和腰椎在各序列的信号差值比差异无统计学意义(P>0.05)。结论3D-T2*-FFE序列对胎儿椎体成像效果较好,能显示更多脊柱解剖细节,其不受胎儿体位影响,且扫描时间较短,临床MRI扫描时可将其作为胎儿脊柱成像的重要补充序列。
文摘Background and Purpose -In contrast to platelet-rich white thrombi, red thrombi in the heart are rich in fibrin and trapped erythrocytes. The magnetic susceptibility effect of deoxygenated hemoglobin in red thrombi may result in hypointense signals on T2*-weighted gradient echo imaging (GRE). We tested the hypothesis that a GRE susceptibility vessel sign (SVS) is specific for cardioembolic stroke. Methods -This retrospective study examined data from acute ischemic stroke patients who underwent diffusion-weighted imaging, GRE and magnetic resonance angiography (MRA) within 24 hours of stroke onset and who had symptomatic occl usion of large intracranial arteries in the circle of Willis. Hypointense signals within vascular cisterns on GRE corresponding to symptomatic vascular occlusio n were termed “GRE SVS.”Recanalization was assessed on follow-up MRA performe d within 7 days of onset. The relationships between GRE SVS and stroke subtypes and subsequent recanalization were explored. Results -Of the 95 patients who me t the inclusion criteria, GRE SVS was observed in 45 (47.4%). GRE SVS was more commonly associated with cardioembolic stroke patients (31 of 40, 77.5%) than w ith other stroke subtypes (14 of 55, 25.5%; P < 0.001). In 66 patients who unde rwent follow-up MRA, GRE SVS was associated with subsequent recanalization (P < 0.001). Multivariate analysis showed that GRE SVS was an independent predictor of cardioembolic stroke and subsequent recanalization (odds ratio, 10.75 and 4.2 6; 95%CI, 3.68 to 31.47 and 1.12 to 16.30). Conclusions -GRE SVS may predict c ardioembolic stroke and subsequent recanalization. Identifying clot composition may be important in choosing the optimal treatment based on clot characteristics .
文摘Gradient echo T2. weighted MRI has high sensitivity in detecting cerebral mic robleeds, which appear as small dot like hypointense lesions. Microbleeds are s trongly associated with intracerebral haemorrhage, hypertension, lacunar stroke and ischaemic small vessel disease, and have generated interest as a marker of b leeding prone microangiopathy. Microbleeds have generally been considered to be clinically silent; however, since they are located in widespread cortical and b asal ganglia regions and are histologically characterized by tissue damage, we h ypothesized that they would cause cognitive dysfunction. We therefore studied pa tients with microbleeds (n = 25) and a nonmicrobleed control group (n = 30) matc hed for age, gender and intelligence quotient. To avoid the confounding effects of coexisting cerebrovascular disease, the groups were also matched for the exte nt of MRI visible white matter changes of presumed ischaemic origin, location o f cortical strokes, and for the proportion of patients with different stroke sub types (including lacunar stroke). A battery of neuropsychological tests was used to assess current intellectual function, verbal and visual memory, naming and p erceptual skills, speed and attention and executive function. Microbleeds were m ost common in the basal ganglia but were also found in frontal, parieto occipit al, temporal and infratentorial regions. There was a striking difference between the groups in the prevalence of executive dysfunction, which was present in 60 %of microbleed patients compared with 30%of non microbleed patients (P = 0.03 ). Logistic regression confirmed that microbleeds (but not white matter changes) were an independent predictor of executive impairment (adjusted odds ratio = 1. 32, 95%confidence interval 1.01 1.70, P = 0.04). Patients with executive dysfu nction had more microbleeds in the frontal region (mean count 1.54 versus 0.03; P = 0.002) and in the basal ganglia (mean 1.17 versus 0.32; P = 0.048). There wa s a modest correlation between the number of microbleeds and the number of cogni tive domains impaired (r = 0.44, P = 0.03). This study provides novel evidence t hat microbleeds are associated with cognitive dysfunction, independent of the ex tent of white matter changes of presumed ischaemic origin, or the presence of is chaemic stroke. The striking effect of microbleeds on executive dysfunction is l ikely to result from associated tissue damage in the frontal lobes and basal gan glia. These findings have implications for the diagnosis of stroke patients with cognitive impairment, and for the appropriate use of antihypertensive and anti platelet treatments in these patients.
