Tuberous sclerosis complex: Imaging characteristics in 11 cases and review of the literature / 华中科技大学学报（医学）（英德文版）

Tuberous sclerosis complex (TSC) is an uncommon multiorgan disorder that may present many and different manifestations on imaging. Radiology plays an important role in diagnosis and management, and can substantially improve the clinical outcome of TSC. Therefore, a comprehensive understanding of this disease is essential for the radiologist. The manifestations of TSC on computer tomography (CT) and magnetic resonance (MR) images were analyzed. Eleven patients with a clinical diagnosis of TSC were retrospectively reviewed. Central nervous system lesions included subependymal nodules (SENs) (11/11), subependymal giant cell astrocytomas (SEGAs) (2/11), cortical and subcortical tuber lesions (5/11), and white matter lesions (4/11). Of the 6 patients with abdominal scans, there were 6 cases of renal angiomyolipomas (AMLs), and one case of hepatic AMLs. Of the 4 patients undergoing chest CT, lung lymhangioleiomyomatosis (LAM) (2/4), and multiple small sclerotic bone lesions (2/4) were observed. Different modalities show different sensitivity to the lesion. Analysis of images should be integrated with patients' history in order to diagnose TSC.

Quantitative Measurement of Cerebral Perfusion with Intravoxel Incoherent Motion in Acute Ischemia Stroke: Initial Clinical Experience / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Intravoxel incoherent motion (IVIM) has the potential to provide both diffusion and perfusion information without an exogenous contrast agent, its application for the brain is promising, however, feasibility studies on this are relatively scarce. The aim of this study is to assess the feasibility of IVIM perfusion in patients with acute ischemic stroke (AIS).</p><p><b>METHODS</b>Patients with suspected AIS were examined by magnetic resonance imaging within 24 h of symptom onset. Fifteen patients (mean age was 68.7 ± 8.0 years) who underwent arterial spin labeling (ASL) and diffusion-weighted imaging (DWI) were identified as having AIS with ischemic penumbra were enrolled, where ischemic penumbra referred to the mismatch areas of ASL and DWI. Eleven different b-values were applied in the biexponential model. Regions of interest were selected in ischemic penumbras and contralateral normal brain regions. Fast apparent diffusion coefficients (ADCs) and ASL cerebral blood flow (CBF) were measured. The paired t- test was applied to compare ASL CBF, fast ADC, and slow ADC measurements between ischemic penumbras and contralateral normal brain regions. Linear regression and Pearson's correlation were used to evaluate the correlations among quantitative results.</p><p><b>RESULTS</b>The fast ADCs and ASL CBFs of ischemic penumbras were significantly lower than those of the contralateral normal brain regions (1.93 ± 0.78 αμm2/ms vs. 3.97 ± 2.49 αμm2/ms, P = 0.007; 13.5 ± 4.5 ml·100 g-1·min-1 vs. 29.1 ± 12.7 ml·100 g-1·min-1, P < 0.001, respectively). No significant difference was observed in slow ADCs between ischemic penumbras and contralateral normal brain regions (0.203 ± 0.090 αμm2/ms vs. 0.198 ± 0.100 αμm2/ms, P = 0.451). Compared with contralateral normal brain regions, both CBFs and fast ADCs decreased in ischemic penumbras while slow ADCs remained the same. A significant correlation was detected between fast ADCs and ASL CBFs (r = 0.416, P < 0.05). No statistically significant correlation was observed between ASL CBFs and slow ADCs, or between fast ADCs and slow ADCs (r = 0.111, P = 0.558; r = 0.200, P = 0.289, respectively).</p><p><b>CONCLUSIONS</b>The decrease in cerebral blood perfusion primarily results in the decrease in fast ADC in ischemic penumbras; therefore, fast ADC can reflect the perfusion situation in cerebral tissues.</p>

Comparative study of DSC-PWI and 3D-ASL in ischemic stroke patients / 华中科技大学学报（医学）（英德文版）

The purpose of this study was to quantitatively analyze the relationship between three dimensional arterial spin labeling (3D-ASL) and dynamic susceptibility contrast-enhanced perfusion weighted imaging (DSC-PWI) in ischemic stroke patients. Thirty patients with ischemic stroke were included in this study. All subjects underwent routine magnetic resonance imaging scanning, diffusion weighted imaging (DWI), magnetic resonance angiography (MRA), 3D-ASL and DSC-PWI on a 3.0T MR scanner. Regions of interest (ROIs) were drawn on the cerebral blood flow (CBF) maps (derived from ASL) and multi-parametric DSC perfusion maps, and then, the absolute and relative values of ASL-CBF, DSC-derived CBF, and DSC-derived mean transit time (MTT) were calculated. The relationships between ASL and DSC parameters were analyzed using Pearson's correlation analysis. Receiver operative characteristic (ROC) curves were performed to define the thresholds of relative value of ASL-CBF (rASL) that could best predict DSC-CBF reduction and MTT prolongation. Relative ASL better correlated with CBF and MTT in the anterior circulation with the Pearson correlation coefficients (R) values being 0.611 (P<0.001) and-0.610 (P<0.001) respectively. ROC curves demonstrated that when rASL ≤0.585, the sensitivity, specificity and accuracy for predicting ROIs with rCBF<0.9 were 92.3%, 63.6% and 76.6% respectively. When rASL ≤0.952, the sensitivity, specificity and accuracy for predicting ROIs rMTT>1.0 were 75.7%, 89.2% and 87.8% respectively. ASL-CBF map has better linear correlations with DSC-derived parameters (DSC-CBF and MTT) in anterior circulation in ischemic stroke patients. Additionally, when rASL is lower than 0.585, it could predict DSC-CBF decrease with moderate accuracy. If rASL values range from 0.585 to 0.952, we just speculate the prolonged MTT.

Frequency-specific alterations of large-scale functional brain networks in patients with Alzheimer's disease / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Previous studies have indicated that the cognitive deficits in patients with Alzheimer's disease (AD) may be due to topological deteriorations of the brain network. However, whether the selection of a specific frequency band could impact the topological properties is still not clear. Our hypothesis is that the topological properties of AD patients are also frequency-specific.</p><p><b>METHODS</b>Resting state functional magnetic resonance imaging data from 10 right-handed moderate AD patients (mean age: 64.3 years; mean mini mental state examination [MMSE]: 18.0) and 10 age and gender-matched healthy controls (mean age: 63.6 years; mean MMSE: 28.2) were enrolled in this study. The global efficiency, the clustering coefficient (CC), the characteristic path length (CpL), and "small-world" property were calculated in a wide range of thresholds and averaged within each group, at three different frequency bands (0.01-0.06 Hz, 0.06-0.11 Hz, and 0.11-0.25 Hz).</p><p><b>RESULTS</b>At lower-frequency bands (0.01-0.06 Hz, 0.06-0.11 Hz), the global efficiency, the CC and the "small-world" properties of AD patients decreased compared to controls. While at higher-frequency bands (0.11-0.25 Hz), the CpL was much longer, and the "small-world" property was disrupted in AD, particularly at a higher threshold. The topological properties changed with different frequency bands, suggesting the existence of disrupted global and local functional organization associated with AD.</p><p><b>CONCLUSIONS</b>This study demonstrates that the topological alterations of large-scale functional brain networks in AD patients are frequency dependent, thus providing fundamental support for optimal frequency selection in future related research.</p>

Observation of post-MCAO cortical inflammatory edema in rats by 7.0 Tesla MRI / 华中科技大学学报（医学）（英德文版）

This study aimed to investigate inflammatory edema after cerebral ischemia through 7.0T MRI and proton magnetic resonance spectroscopy (MRS). All SD rats were randomly divided into sham operated group and middle cerebral artery occlusion (MCAO)-1 day, -3 day and -7 day groups. MRI scan of the brain was performed on a 7.0 Tesla MRI scanner. The volume of positive signals in the ischemic side was detected by using a T2 weighted spinecho multislice sequence; the changes in the height of water-peak were measured with point resolved spectroscopy (PRESS) sequences; cortical edema was detected by using wet-dry weight method; the degrees of nerve injury were evaluated by Bederson neurological score system; double-labeling immunofluorescence technique was used to explore the molecular mechanisms of post-ischemia cerebral edema. The results showed that high T2WI signals were observed in MCAO-1 day, -3 day and -7 day groups, and the water-peak height and water-peak area of MCAO groups were higher than those of sham operated group (P<0.05). Neurological score results were consistent with the degree of brain edema, and a large number of microglia accumulated in the ischemic cortex. Our results suggested that non-invasive MRI technology with the advantage of high spatial resolution and tissue resolution can comprehensively and dynamically observe inflammatory edema after cerebral ischemia from a three-dimensional space, and contribute to evaluation and treatments in clinic.

Observation of post-MCAO cortical inflammatory edema in rats by 7.0Tesla MRI / 华中科技大学学报（医学）（英德文版）

This study aimed to investigate inflammatory edema after cerebral ischemia through 7.0T MRI and proton magnetic resonance spectroscopy (MRS). All SD rats were randomly divided into sham operated group and middle cerebral artery occlusion (MCAO)-1 day, -3 day and -7 day groups. MRI scan of the brain was performed on a 7.0 Tesla MRI scanner. The volume of positive signals in the ischemic side was detected by using a T2 weighted spinecho multislice sequence; the changes in the height of water-peak were measured with point resolved spectroscopy (PRESS) sequences; cortical edema was detected by using wet-dry weight method; the degrees of nerve injury were evaluated by Bederson neurological score system; double-labeling immunofluorescence technique was used to explore the molecular mechanisms of post-ischemia cerebral edema. The results showed that high T2WI signals were observed in MCAO-1 day, -3 day and -7 day groups, and the water-peak height and water-peak area of MCAO groups were higher than those of sham operated group (P<0.05). Neurological score results were consistent with the degree of brain edema, and a large number of microglia accumulated in the ischemic cortex. Our results suggested that non-invasive MRI technology with the advantage of high spatial resolution and tissue resolution can comprehensively and dynamically observe inflammatory edema after cerebral ischemia from a three-dimensional space, and contribute to evaluation and treatments in clinic.

Experimental study of cell migration and functional differentiation of transplanted neural stem cells co-labeled with superparamagnetic iron oxide and BrdU in an ischemic rat model / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To explore the migration of transplanted neural stem cells co-labeled with superparamagnetic iron oxide (SPIO) and bromodeoxyuridine (Brdu) using the 4.7T MR system and to study the cell differentiation with immuno-histochemical method in ischemic rats.</p><p><b>METHODS</b>Rat neural stem cells (NSCs) co-labelled with SPIO mediated by poly-L-lysine and bromodeoxyuridine (BrdU) were transplanted into the unaffected side of rat brain with middle cerebral artery occlusion (MCAO). At weeks 1, 2, 3, 4, 5, and 6 after MCAO, migration of the labelled cells was monitored by MRI. At week 6, the rats were killed and their brain tissue was cut according to the migration site of transplanted cells indicated by MRI and subjected to Prussian blue staining and immunohistochemical staining to observe the migration and differentiation of the transplanted NSCs.</p><p><b>RESULTS</b>Three weeks after transplantation, the linear hypointensity area derived from the migration of labelled NSCs was observed by MRI in the corpus callosum adjacent to the injection site. Six weeks after the transplantation, the linear hypointensity area was moved toward the midline along the corpus callosum. MRI findings were confirmed by Prussian blue staining and immunohistochemical staining of the specimen at week 6 after the transplantation. Flourescence co-labelled immunohistochemical methods demonstrated that the transplanted NSCs could differentiate into astrocytes and neurons.</p><p><b>CONCLUSION</b>MRI can monitor the migration of SPIO-labelled NSCs after transplantation in a dynamical and non-invasive manner. NSCs transplanted into ischemic rats can differentiate into astrocytes and neurons during the process of migration.</p>

Magnetic resonance susceptibility weighted imaging in detecting intracranial calcification and hemorrhage / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Computed tomography (CT) is better than routine magnetic resonance imaging (MRI) in detecting intracranial calcification. This study aimed to assess the value of MR susceptibility weighted imaging (SWI) in the detection and differentiation of intracranial calcification and hemorrhage.</p><p><b>METHODS</b>Enrolled in this study were 35 patients including 13 cases of calcification demonstrated by CT and 22 cases of intracerebral hemorrhage. MR sequences used in all the subjects included axial T1WI, T2WI and SWI. The phase shift (PS) of calcification and hemorrhage on SWI was calculated and their signal features on corrected phase images were compared. The sensitivity of T1WI, T2WI and SWI in detecting intracranial calcification and hemorrhage was analyzed statistically.</p><p><b>RESULTS</b>The detection rate of SWI for cranial calcification was 98.2%, significantly higher than that of T1WI and T2WI. It was not significantly different from that of CT (P > 0.05). There were 49 hemorrhagic lesions at different stages detected on SWI, 30 on T2WI and 18 on T1WI. The average PS of calcification and hemorrhage was +0.734 +/- 0.073 and -0.112 +/- 0.032 respectively (P < 0.05). The PS of calcification was positive and presented as a high signal or the mixed signal dominated by a high signal on the corrected phase images, whereas the PS of hemorrhage was negative and presented as a low signal or the mixed signal dominated by a low signal.</p><p><b>CONCLUSIONS</b>SWI can accurately demonstrate intracranial calcification, not dependant on CT. Being more sensitive than routine MRI in detecting micro-hemorrhage, SWI may play an important role in differentiating cerebral diseases associated with calcification or hemorrhage.</p>

Value of magnetic resonance imaging in the early evaluation of prognosis for hypoxic-ischemic encephalopathy in full-term infants / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To understand the clinical characteristics of hypoxic-ischemic encephalopathy (HIE) in full-term infants and to explore the value of magnetic resonance imaging (MRI) for the early prediction of HIE prognosis.</p><p><b>METHODS</b>The medical data, including histories, clinical manifestations, MRI findings and follow-up outcomes, of 348 full-term infants with HIE between January 2001 and December 2005 were retrospectively reviewed.</p><p><b>RESULTS</b>HIE patients (348 cases) accounted for 8.25% of in-patients (4220 cases) over the five years. The etiology of HIE mainly attributed to birth asphyxia (76.2%), consisting of mild asphyxia (59.2%) and severe asphyxia (40.8%). A poor outcome was confirmed in 10.1% of these patients, including 27.3% in severe HIE, 10.0% in moderate HIE and 1.5% in mild HIE cases. All of patients whose MRI showed diffusion intraparenchymal hemorrhages and cerebral infarctions had poor outcomes. Fourteen (87.5%) out of the 16 cases with basal ganglia and thalamic or internal capsule injury and 9 (81.8%) out of the 11 cases with cytotoxic brain edema diagnosed by diffusion weighted imaging had poor outcomes.</p><p><b>CONCLUSIONS</b>HIE is one of common diseases in newborn infants. The etiology of neonatal HIE mainly attributed to birth asphyxia, mild asphyxia accounting for a greater proportion. MRI findings can be helpful for the early prediction of HIE prognosis.</p>

Correlation between magnetic resonance diffusion weighted imaging and cell density in astrocytoma / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To evaluate the apparent diffusion coefficients (ADC) in magnetic resonance diffusion weighted imaging with echo-planar technique in depicting the tumor cellularity and grading of astrocytoma.</p><p><b>METHODS</b>Thirty-four astrocytoma patients including 18 male and 16 female with age from 10 to 73 years (mean 38.4 years) were examined by MRI and eventually proved by surgical resection and pathological examination. Of them, 26 had low-grade (grade I, II) astrocytoma and 8 high-grade (grade III, IV) astrocytoma. ADC value of astrocytoma was determined on magnetic resonance diffusion weighted images. Cellularity of the astrocytoma was analyzed using Adobe Photoshop 7.0.1 software.</p><p><b>RESULTS</b>The mean ADC value (in units of 10(-4) mm(2)/s) of the high-grade astrocytomas (7.34 +/- 2.95) was significantly lower than that of the low-grade astrocytomas (13.76 +/- 3.31) (t = 4.91, P < 0.001). The mean cellularity of the high-grade astrocytomas (19.81 +/- 9.73)% was significantly higher than that of the low-grade astrocytomas (4.74 +/- 2.96)% (t = 4.32, P = 0.003). ADC value of the astrocytoma was significantly and negatively correlated with its cellularity (r = -0.535, P = 0.001).</p><p><b>CONCLUSION</b>ADC value of astrocytoma is significantly and negatively correlated with its cellularity. Magnetic resonance diffusion weighted imaging may well be highly potential in predicting the degree of astrocytoma.</p>

MRI tracking of transplanted neural stem cells labeled with superparamagnetic iron oxide in ischemic model / 中华器官移植杂志

Objective To explore the migration of transplanted neural stem cells labeled with SPIO with 4.7T MR system and study cell differentiation by immunohistochemistry in ischemic rats. Methods Rat neural stem cells(NSCs)co-labeled with SPIO mediated by poly-L-lysine and bromode- oxyuridine(BrdU)were transplanted into the middle cerebral artery occlusion(MCAO)rats after 14 days when MCAO model was made successfully.4.7T MR scanner was used to monitor the migration of transplanted cells after 1.2,3,4,5 and 6 weeks post-transplantation.After MRI examination at 6th week,the rats were killed and Prussian blue staining and immunohistochemistric staining were per- formed to study migration and functional differentiation of NSCs.Results Three weeks after trans- plantation,linear hypointensity area derived from migration of labeled NSCs was observed in the corpus callosum adjacent to the injection site.Six weeks after transplantation,linear hypointensity area was moved toward the midline along the corpus callosurn.MRI findings were confirmed by Prussian blue staining and immunohistochemical straining.Co-labeled immunohistochemical methods demonstrated transplanted NSCs could differentiated into astrocytes and neurons.Conclusion MRI is very useful in demonstrating the migration path of labeled NSCs.Transplanted NSCs into ischemic rats can differen- tiated into astrocytes and neurons during the process of migration.

Correlation study between MR spectroscopic findings and cell proliferation in astrocytoma / 中华放射学杂志

Objective To investigate the relationship between findings of proton magnetic resonance spectroscopy(~1H-MRS)and tumor proliferative potential in patents with astrocytoma.Methods Thirty four patients of astrocytomas proved by surgery and pathology were examined by MRI and ~1H-MRS,among them 26 were of grade Ⅰ or Ⅱ(low grade)and 8 of grade Ⅲ or Ⅳ(high grade).Twenty one eases of astrocytomas(17 low-grade and 4 high grade respectively)were homogeneous type.Expression of proliferating cell nuclear antigen(PCNA)was detected by immunohistochemical method of streptavidin- biotin-peroxidase(SP).Results The Cho/NAA and Cho/Cr ratios of high-grade astrocytomas(M=4.895, 4.845 respectively)were significantly higher than those of low-grade astrocytomas(M=2.920, 2.000 respectively)in the 21 homogeneous astrocytomas(Z=-2.597,P=0.009;Z=-2.687,P= 0.007 respectively),and the ratios were found to be significantly correlated to the expression of PCNA(A= 7.880)(r=0.607,P=0.003;r=0.457,P=0.038 respectively).However,the differences of Cho/NAA、 Cho/Cr ratios between the high-grade and low-grade astrocytomas were not significant when 34 cases were included,and no relationship was found between Cho/NAA(M=3.965,2.890 respectively)、Cho/Cr(M= 3.080、1.960 respectively)ratios and the expression of PCNA(A=8.100)(r=0.060,P=0.738;r= 0.125,P=0.480 respectively).Conclusion By measuring the Cho/NAA and Cho/Cr ratios,~1 H-MRS may be a valuable method for presurgical in invo prediction of the malignant degree,tumor proliferative potential and prognosis of homogeneous-type astrocytomas.

Proton MR spectroscopy study in neonates with hypoxic ischemic encephalopathy / 中华放射学杂志

Objective To investigate the metabolic alterations in the brain of neonates with HIE and correlate those alterations with clinical grading and prognosis of HIE.Methods Fourty-six eases of full-term neonates diagnosed as HIE clinically were performed MRI and 1~H-MRS,9 healthy neonates without the evidence of asphyxia were studied as controls,1~H-MRS techniques included single voxel proton MRS and two dimensional muhi-voxel chemical shift spectroscopy imaging,point resolved spectroscopy sequence was used for 1~H-MRS.Metabolic changes in the spectroscopy were analyzed in neonates with HIE,and study the relationgship between MRS findings and prognosis.Results(1)The typical 1~H-MRS manifestations of full- term neonates suffering from HIE were as follows:the peaks of Lac were elevated,GLx-? were elevated and NAA were decreased.(2)GLx-?/Cr ratio in control,mild,moderate and severe HIE group was 0.16, 0.21,0.64,and 1.31,respectively.Lac/Cr ratio in control,mild,moderate and severe HIE group was 0.12,0.14,0.19,and 0.26,respectively.There was a significant difference in the ratio of GLx-? and Lac/Cr between HIE group and control group(t=5.01,P