正常成人胼胝体面积磁共振成像定量对比研究

目的:测量磁共振正中矢状位上正常成人胼胝体面积,探讨不同年龄组及不同性别间可能的差异.方法:磁共振检查286例正常成人,其中男性127例,女性159例,年龄由20岁至81岁,分为20～29岁组、30～39岁组、40～49岁组、50～59岁组、60岁以上组共5组;其中20～29岁组男25例、女26例;30～39岁组男26例、女33例;40～49岁组男33例、女50例;50～59岁组男32例、女36例;60岁以上组男11例、女14例.测量磁共振成像T1加权像正中矢状位上胼胝体面积及颅内大脑面积,进行标准化.经统计学处理研究分析.结果:286例正常成人胼胝体面积平均值为(619.01±90.61)mm2;其中男性127例面积平均值为(635.99±85.62)mm2;女性158例面积平均值为(605.37±92.46)mm2;20～29岁组、30～39岁组、40～49岁组、50～59岁组、60岁以上组各年龄组胼胝体面积平均值分别为(627.52±83.34)mm2、(622.13±123.68)mm2、(615.84±85.53)mm2、(621.34±74.32)mm2、(605.81±77.53)mm2.结论:胼胝体面积标准化平均值在20～29岁组、30～39岁组、40～49岁组之间无明显变化,在50岁后逐渐缩小,不同年龄组间无显著性差异(P＜0.05).不同性别胼胝体面积平均值女性大于男性,但无显著差异(P＜0.05).     

正常成人胼胝体膝部及压部磁共振弥散张量成像定量研究

目的 探讨正常成人胼胝体膝部和压部的部分各向异性(FA)值不同年龄及性别间可能存在的差异.方法 连续采集277例健康成人志愿者,其中男119例,女158例,年龄20～81岁,分为20～29岁组(男19例、女19例)、30～39岁组(男26例、女40例)、40～49岁组(男33例、女50例)、50～59岁组(男30例、女35例)及≥60岁组(男10例、女15例)共5组.进行常规磁共振扫描及弥散张量成像,分别测量胼胝体膝部和压部FA值,比较其弥散特征,分析不同年龄和性别间FA值可能的差异.结果 正常成人胼胝体膝部和压部的FA值分别为0.788±0.047、0.796±0.052,膝部显著低于压部(t=-2.148,P=0.033).膝部与压部FA值均为男大于女,膝部FA值男女之间差异无统计学意义(t＝0.346,P＞0.05).压部FA值男女之间差异有统计学意义(t=2.737,P＜0.05).膝部及压部FA值均随年龄的增大逐渐减小,不同年龄组膝部及压部FA值之间差异均无统计学意义(F=0.617,P=0.651;F=1.140,P=0.338).结论 正常成人胼胝体膝部FA值显著低于压部,膝部与压部FA值均随年龄的增大逐渐减小,均为男大于女.     

正常成人胼胝体磁共振轴位及矢状位DTI定量研究

目的:研究正常成人胼胝体磁共振轴位扩散张量成像(DTI)与矢状位DTI各向异性(FA)可能的差异,探讨2种测量方法的可靠性。方法:对68例健康志愿者分别行轴位和矢状位DTI扫描,年龄18～78岁。分别测量胼胝体膝部及压部的FA值。对相同部位的轴位和矢状位测量结果进行比较,并行相关性分析。结果:矢状位上测量的胼胝体膝部FA值大于轴位,且两者之间差异有统计学意义(t=-5.833,P<0.001)。胼胝体压部FA值在矢状位与轴位上差异无统计学意义(t=0.435,P>0.05)。结论:矢状位与轴位DTI测量的胼胝体膝部及压部FA值不同,矢状位DTI能研究胼胝体各个区域各向异性的变化。     

胼胝体挫伤的磁共振扩散张量成像研究

目的 评价磁共振扩散张量纤维束成像技术在脑外伤所引起的胼胝体纤维损伤中的临床应用价值. 资料与方法 12名健康志愿者和23例脑外伤患者进行常规MRI及扩散张量成像(DTI)检查,通过运算获得大脑白质纤维的各向异性(fractional anisotropy,FA)图、平均扩散系数(average diffusion coefficient,DCavg)图、容积比异向性(volume ratio anisotropy,VrA)图、各向同性(isotropic image,Iso)图等,分别测量经内囊层面胼胝体前部、胼胝体后部的FA、DCavg值,并进行比较. 结果 在FA图像上正常人胼胝体呈均匀高信号显示清晰,23例脑外伤中胼胝体正常7例,FA值正常;局灶胼胝体挫伤14例,FA值下降14例,DCavg下降14例,胼胝体弥漫挫伤2例,T1 FLAIR序列显示胼胝体肿胀变形,FA图胼胝体纤维失去正常结构及形态,类似斑片状,FA值下降. 结论 DTI能精确、直观地显示胼胝体纤维,在评价脑外伤后胼胝体损伤方面有较高的应用价值,尤其对弥漫性轴索损伤及患者预后的评估更有意义.     

胼胝体非出血性挫伤的MRI诊断(附四例报告)

目的报告4例胼胝体非出血性挫伤的MRI表现。材料与方法回顾性分析4例胼胝体非出血性挫伤的MRI资料;3例为车祸伤,1例为坠落伤,都进行了CT和MR非增强检查。结果4例胼胝体挫伤灶2例位于压部、1例位于干部、1例累及胼胝体大部。CT扫描胼胝体区未见异常密度。MR图像上均表现为等或略低T1WI信号与明显高T2WI信号,未见出血信号。SE或FSET2WI(轴位或矢状位)对病变显示清楚,而FLAIR序列则能抑制脑脊液的高信号、使病变显示更加突出。1例4个月后MR检查显示挫伤灶演变为类似脑脊液信号的软化灶。4例中3例还合并颅内多处脑挫伤和血肿。结论胼胝体非出血性挫伤较少见,CT检查难以发现病灶MR是其最佳的影像学检查手段,轴位与矢状位SE或FSET2WI是显示挫伤灶的主要序列,FLAIR序列对病灶的显示更佳。本病典型的MRI表现是胼胝体区T1WI等或略低信号、T2WI高信号,无出血信号;胼胝体非出血性挫伤可合并颅内多发性外伤性改变。     

基于脑白质纤维密度成像研究胼胝体神经纤维密度随年龄变化的规律

目的:利用脑白质纤维密度成像(TDI)研究不同年龄段胼胝体(CC)内纤维数目的分布规律,分析CC随年龄增长变化的复杂性和差异性;对照研究TDI是否能在CC体积变化之前检测到其内纤维数目的变化,以及FA值、胼胝体体积的变化.方法:纳入131名健康志愿者,根据年龄分为6组.通过球面反卷积方法来重建轨道密度图.将CC分割成5...     

急性脑梗死患者胼胝体形态的MRI研究

目的 探讨一侧颞顶叶急性脑梗死时胼胝体形态可能存在的变化.方法 连续采集发生于一侧颞叶、顶叶或2个部位均有的急性脑梗死患者66例,男38例,女28例,年龄40～85岁.选取同期连续采集获得的与病变组匹配的 66例正常成人作为对照分析组.行磁共振扫描,在MRI T1WI 颅脑正中矢状位上分别测量胼胝体膝部厚度、体部前1/3处厚度、中部厚度、体后1/3处厚度、压部厚度及胼胝体面积,进行统计分析研究.结果 所测量的胼胝体膝部厚度、体部前1/3处厚度、中部厚度、体后1/3处厚度、压部厚度及胼胝体面积值,均为正常组大于病变组,且这些指标在正常组和病变组之间差异均存在统计学意义(P＜0.05).结论 当大脑一侧脑叶发生急性脑梗死时,即可引起胼胝体面积及不同区域大小的减小.     

可逆性胼胝体压部病变综合征的磁共振成像诊断及预后评估

目的探讨可逆性胼胝体压部病变综合征的磁共振成像(MRI),分析其预后。方法回顾性分析2014年1月至2017年12月经我院诊断的50例可逆性胼胝体压部病变综合征的MRI影像学资料,分析患者的影像学特征。结果MRI诊断表现胼胝体压部孤立性,圆形或弧形,少数为斑片状,边界清晰。4例T1WI信号改变不明显,其余患者T1WI呈等或稍低信号,T2WI呈稍高信号,FLAIR为稍高信号,信号均匀,病变周围水肿和占位效应不明显,44例T1WI增强扫描病灶无明显强化特征;DWI呈明显高信号且表现扩散系数(ADC)呈低信号;5例行磁敏感加权成像(SWI)检查,4例行MRS检查,5例行MRA检查,结果未见异常特征;3例行扩散张量成像(DTI)检查显示各向异性分数(FA)值减低。45例复查MRI表现为胼胝体压部病变完全消失,无神经系统受累症状,预后效果好;3例DWI信号欠均匀,中央区见稍低信号,预后较差;1例随访发现患有严重神经系统后遗症,四肢无自主运动,长期卧床,预后不良。结论MRI能为RESLES临床诊断提供重要依据,结合其临床症状,为临床诊治提供重要参考依据,一般预后良好。     

磁敏感加权成像对胼胝体损伤的诊断

目的 探讨磁敏感加权成像(susceptibility weighted imaging,SWI)对胼胝体损伤的诊断价值.方法 回顾性分析15例CT检查阴性而MRI检查阳性的胼胝体损伤的MRI图像,所有患者均行高场强1.5T磁共振T1WI、T2WI、FLAIR、SWI横断位及T2WI矢状位扫描,分析各序列胼胝体损伤的信号特征及显示率.结果 胼胝体损伤T1WI为低、略低、稍高信号6例,T2WI、FLAIR为高信号10例,15例SWI均表现为明显低信号,5例患者CT、T1WI、T2WI、FLAIR均未见异常,其中4例SWI诊断为弥漫性轴索损伤,1例诊断为胼胝体等处多发损伤.脑内其他损伤区SWI表现为低信号影.结论 SWI对显示和诊断胼胝体损伤有较高的敏感性和准确性,并能显示常规MRI序列不能显示的微小损伤.     

正常成人大脑胼胝体弥散张量纤维束成像研究

目的 :利用磁共振弥散张量纤维束成像技术 ,研究正常成人大脑胼胝体的形状和结构。方法 :分别对 1 0名正常志愿者 (男 5例 ,女 5例。年龄为 2 4～ 6 5岁 ,平均年龄 4 0 .9岁 )进行弥散张量成像 ,将所得数据输入个人计算机 ,应用日本东京大学附属医院放射科影像计算和分析实验室所研制的软件 :Volume one1 .5 6和diffusionTENSORVisualizer 1 .5 (dTV)进行大脑胼胝体纤维束成像。结果 :本研究成功的在活体显示大脑胼胝体的形状和结构 ,在彩色FA图矢状面上胼胝体呈半月形 ,在弥散张量纤维束图横断面上呈蜈蚣状。结论 :弥散张量纤维束成像可以显示正常人大脑胼胝体 ,为大脑白质纤维束的研究开辟了一新的广阔领域。     

Magnetic resonance elastography of the kidneys: Feasibility and reproducibility in young healthy adults

Purpose:

To evaluate the feasibility and reproducibility of renal magnetic resonance elastography (MRE) in young healthy volunteers.

Materials and Methods:

Ten volunteers underwent renal MRE twice at a 4–5 week interval. The vibrations (45 and 76 Hz) were generated by a speaker positioned beneath the volunteers' back and centered on their left kidney. For each frequency, three sagittal slices were acquired (eight phase offsets per cycle, motion‐encoding gradients successively positioned along the three directions of space). Shear velocity images were reconstructed using the curl operator combined with the local frequency estimation (LFE) algorithm.

Results:

The mean shear velocities measured in the renal parenchyma during the two examinations were not significantly different and exhibited a mean variation of 6% at 45 Hz and 76 Hz. The mean shear velocities in renal parenchyma were 2.21 ± 0.14 m/s at 45 Hz (shear modulus of 4.9 ± 0.5 kPa) and 3.07 ± 0.17 m/s at 76 Hz (9.4 ± 0.8 kPa, P < 0.01). The mean shear velocities in the renal cortex and medulla were respectively 2.19 ± 0.13 m/s and 2.32 ± 0.16 m/s at 45 Hz (P = 0.002) and 3.06 ± 0.16 m/s and 3.10 ± 0.22 m/s at 76 Hz (P = 0.13).

Conclusion:

Renal MRE was feasible and reproducible. Two independent measurements of shear velocities in the renal parenchyma of the same subjects showed an average variability of 6%. J. Magn. Reson. Imaging 2011;. ©2011 Wiley‐Liss, Inc.     

Magnetic resonance angiography in the head-neck area

Magnetic resonance angiography is a noninvasive method in vascular imaging using non-contrast-enhanced and contrast-enhanced techniques. The contrast media used in contrast-enhanced magnetic resonance angiography are different from the X-ray contrast me-dia and do not affect the thyroid gland or renal function. In detecting hypervascularized lesions in the head and neck, contrast-enhanced magnetic resonance angiography is the method of choice, which provides an acceptable quality in comparison to digital subtraction angiography. Future developments in magnetic resonance imaging techniques will cause a wider use of magnetic resonance angiography, especially in head and neck imaging. Digital subtraction angiography should therefore only be used in problem cases and for preoperative embolization.     

双额叶脑代谢物浓度改变与轻度认知功能障碍的磁共振波谱量化研究

目的:用磁共振频谱(MRS)结合LCModel分析软件定量研究轻度认知功能障碍(MCI)患者双额叶脑代谢物浓度的变化及与脑白质脱髓鞘的关系。方法:前瞻性收集2016年5月至2018年12月于汕头大学医学院第二附属医院就诊的25例神经心理学测试结果为MCI者,记为A组[男12例,女13例,年龄(60.5±5.2)岁],按...     

Renal hemodynamic changes with aging: a preliminary study using CT perfusion in the healthy elderly

ObjectiveTo investigate renal blood flow perfusion parameter changes associated with aging using multislice spiral computed tomography (CT).MethodsThis prospective study was approved by the institute's ethics committee for clinical study and written informed consent was obtained from all subjects. Forty-two consecutive patients who underwent abdominal CT without obvious renal abnormality at plain scanning were enrolled in this study. The renal perfusion scan was carried out using 16-slice spiral CT. The Pearson correlation coefficient was used to examine the correlation between perfusion parameter changes with aging.ResultsIn both the cortex and medulla, blood flow (BF) and blood volume (BV) were negatively correlated with age, while time-to-peak (TTP) value and mean transit time (MTT) showed a positive correlation with age. Changes in BF, TTP, and MTT were found to have a statistically significant correlation with age in both the cortex and medulla, while the correlation between BV and age showed no statistical significance.ConclusionIt is feasible to assess renal hemodynamics changes with aging in the elderly using the current clinically available CT perfusion imaging technology in vivo. It may be helpful in the management of aged patients to familiarize with the renal hemodynamics changes in clinical work-up.     

Magnetic resonance imaging evaluation of bone marrow changes in obstructive sleep apnoea syndrome in adults

PURPOSE: The aim of this study was to evaluate bone marrow reconversion in patients with obstructive sleep apnoea syndrome (OSAS) by means of magnetic resonance imaging (MRI). To our knowledge, no explicit correlation between OSAS and such parameter has been documented in the literature. MATERIALS AND METHODS: During a 35-month period, 33 patients with a clinical diagnosis of OSAS, obese but without restrictive or obstructive ventilatory defects, were evaluated with MRI during wakefulness in all patients with T1-, PD- and T2-weighted sequences in the sagittal and axial plane within 1 week after polysomnography. RESULTS: MRI showed bone marrow reconversion in 33.3% of patients. Patients with bone marrow reconversion showed higher mean haematocrit (HT) values, lower mean nocturnal oxyhaemoglobin saturation, higher percentage of sleep time with oxygen saturation (SaO2) <90%, lower nadir, as well as greater neck adiposity and soft-palate lengthening compared with patients without bone marrow reconversion. Furthermore, in patients with bone marrow reconversion, haematocrit (HT) was negatively correlated with daytime arterial oxygen partial pressure (PaO2) and positively with arterial carbon dioxide partial pressure (PaCO2). CONCLUSIONS: In patients with OSAS, bone marrow reconversion is probably correlated with the severity of nocturnal desaturation. As bone marrow reconversion is, for unknown reasons, greater in adults younger than 40 years, MRI evidence of bone marrow reconversion could be useful in young individuals for the early diagnosis of sleep-disordered breathing and prevention of associated cardiovascular diseases.     

Magnetic resonance imaging in the study of brain changes due to carbon monoxide poisoning

Five cases of carbon monoxide intoxication were studied with MR imaging. The main MR findings were discussed and compared with CT results. MR imaging demonstrated SNC lesions sooner and better than CT--its images corresponding to the anatomic-pathological patterns described in literature. However, severe MR limitations--i.e., the very long execution time and the difficult monitoring of the patients--prevent this methodology from being more extensively employed in this kind of pathology.     

Magnetic resonance in the study of spondylodiscitis

Spondylodiscitis is an uncommon pathologic condition whose diagnosis can be difficult due to its aspecific clinical and radiological signs, especially in its early phase. Seventeen patients were examined in order to evaluate MR diagnostic capabilities. They had cervical (2 cases), thoracic (3 cases) and lumbosacral (12 cases) spondylodiscitis. All patients previously underwent conventional X-ray examination and CT; bone scintigraphy was performed in 9 cases. The final diagnosis was reached by needle aspiration (10 cases), by blood culture (2 cases), or according to clinical evolution (5 cases). MR was highly sensitive in identifying the disease, also in its early stages. Moreover, MR allowed the definition of phlogistic process extent and its relationship with intersomatic disk: signal alterations were limited to the vertebral bodies and to the disk in 3 cases; endocanalar spread of phlogistic process was observed in 8 cases; extravertebral soft tissues were involved in 1 patient; involvement of both canal and paravertebral soft tissue was found in 5 patients. Signal alterations in vertebral bodies and disks, together with the good topographic evaluation obtained with MR imaging, allowed a reliable diagnosis of spondyloscitis to be reached.     

Magnetic resonance imaging in dementia. A study of brain white matter changes

Non-specific white matter changes (WMC) in the brain are common findings in the elderly population. Although they are frequently seen in non-demented persons, WMC seem to be more common in demented patients. The significance of these changes, as well as their pathophysiological background, is incompletely understood. The aim of this thesis was to study different aspects of WMC using MR imaging (MRI) and to investigate the clinical significance of such changes in subjects with mild cognitive impairment or dementia. In study I post-mortem MRI of the brain was compared to corresponding neuropathology slices. WMC were quantified and found to be more extensive on neuropathology. The areas that appeared normal on MRI but not on histopathology represented only minor changes with increased distance between the myelinated fibres but with preserved axonal network and glial cell density. Study II evaluated the blood-brain barrier (BBB) integrity to investigate if an increased permeability could be shown in WMC. A contrast-enhanced MRI technique was used to detect small degrees of enhancement. No general increase in BBB could be detected in the WMC areas. In study III the relation between WMC and apolipoprotein E (APOE) genotype was explored in patients with Alzheimer's disease (AD). Results showed that AD patients, who were homozygous for the APOE epsilon 4 allele had more WMC than patients with other genotypes. This was most significant for changes in the deep white matter. Results also indicated that in AD patients carrying the epsilon 4 allele, WMC are not age-related phenomena, but might be related to the aetiology of the disease. Study IV aimed to investigate if WMC in a specific brain region affect cognitive functions related to that area. Periventricular WMC in the left frontal lobe predicted a decrease in initial word fluency, a test though to reflect left frontal lobe functioning. This indicates that WMC might have specific effects in different brain regions. In study V we evaluated the prognostic significance of WMC in patients with memory impairment, regarding the rate of further global cognitive decline. There was no difference in outcome between patients having extensive WMC and a matched control group, during 2-4 years of follow up, and assessed by the "Mini-Mental State Examination". In conclusion, this work has shown and characterised pathological changes in the white matter not visible on conventional MRI. We have also shown that there is no major general increase in BBB permeability in areas of WMC. In addition, homozygosity with regard to the APOE epsilon 4 gene allele implies an increased extent of WMC in AD patients. In AD patients carrying this gene allele, WMC are not merely age-related phenomena, but might be related to the aetiology of the disease. We also claim that WMC in a specific location might impair cognitive functions that rely on those specific pathways. In contrast, WMC do not seem to have any prognostic value in predicting the rate of global cognitive decline in patients at a memory clinic.     

A quantitative study of physiological cerebral atrophy with aging

Summary A new method of discriminating pathological cerebral atrophy from physiological atrophy during aging is reported. The authors advocate a pixel counting method using a minicomputer for the quantitative measurement of cerebral atrophy. Five hundred cases were studied with this quantitative method and the normal range of the physiological atrophy was determined statistically. In order to estimate the degree of cerebral atrophy easily, the conventional linear measurement methods were compared with the pixel counting method using multivariant analysis, and a simple formula for the calculation of the degree of cerebral atrophy is proposed. Using this formula and the normal range, pathological cerebral atrophy is easily detectable.