ABSTRACT
Objective:To investigate the application value of oxygen-challenge MRI in the identification of ischemic penumbra in acute middle cerebral artery occlusion (MCAO) model in rats.Methods:Fifty-eight SD rats were received MCAO processing. Ten MCAO rats were randomly selected. MRI scanning was performed and modified neurological severity score mNSS was evaluated before and after oxygen stimulation at the 1st, 3rd, 6th and 12th hour after MCAO model preparation. The scanning data before and after oxygen stimulation were recorded as air group and oxygen group respectively. T 1 values and T 1 change rate of different brain regions were measured. Twenty-four MCAO rats were selected for oxygen stimulation according to the above four time points. At each time point, 3 MCAO rats were randomly selected for HE staining and recorded as oxygen stimulation group 1 ( n=12). Meanwhile, 3 MCAO rats were randomly selected for immunohistochemical examination at each time points to determine the expression of protein kinase C receptor (RACK1), recorded as oxygen stimulation group 2 ( n = 12). Another 24 MCAO rats were selected without oxygen stimulation. Among them, three MCAO rats were randomly selected at each time point for HE staining, recorded as non-oxygen stimulation group 1 ( n=12); and three MCAO rats were randomly selected at each time point for immunohistochemistry to detect the expression of RACK1, recorded as non-oxygen stimulation group 2 ( n=12). Independent sample t-test was used for the comparison between the two groups. One way ANOVA was used for the comparison in T 1 change rate between different brain regions, and repeated measurement ANOVA was used for the comparison of T 1 change rate in the same brain region at different time points. The correlation between the expression of RACK1 protein in oxygen group 2 and non-oxygen group 2, as well as T 1 values in air group and oxygen group was analyzed by Spearman analysis. Results:At the same time point, the difference of mNSS scores between air group and oxygen group was statistically significant ( P<0.05). At different time points, the difference of mNSS between the two groups was also found statistically significant ( P<0.05). There were significant differences in T 1 values and T 1 change rate between air group and oxygen group in ischemic core area, mismatched area and contralateral normal area, among which the difference was statistically significant (all P<0.05). At different time points, the cellular edema or vacuolation in the cerebral ischemic area of 24 MCAO rats in the oxygen challenge group 1 and the non-oxygen challenge group 1 showed an aggravating trend, and the degree of cellular edema or vacuolation in the cerebral ischemic area of the non oxygen challenge group 1 was slightly less degree than that of the non-oxygen challenge group 1. The expression of RACK1 protein in the cerebral ischemia area of 24 MCAO rats in the oxygen challenge group 2 and the non-oxygen challenge group 2 decreased at different time points, and the expression of RACK1 protein in the non-oxygen challenge group 2 was higher than that in the oxygen challenge group 2 ( P<0.05). Conclusions:Oxygen challenge MRI can be used to determine the oxygen metabolism in the brain infarction tissue of MCAO rats. The oxygen challenge MRI T 1 value and T 1 change rate can help to identify the ischemic penumbra of MCAO rats. Oxygen stimulation may delay the development of cerebral ischemia. The expression of RACK1 plays a protective role in acute cerebral ischemia and is related to the development of hypoxia in brain tissue.
ABSTRACT
Objective The purpose of this study was to evaluate whether whole-tumor histogram-based analysis of readout-segmented echo-planar diffusion-weighted imaging (RESOLVE-DWI) ADC map can help in the discrimination of parotid gland tumors(pleomorphic adenoma, Warthin tumor, malignant parotid gland tumor). Methods The MR images(pre / post-contrast enhanced MRI, RESOLVE-DWI, ADC map) of 47 patients with a biopsy-or surgery-proven pleomorphic adenomas, 25 patients with Warthin tumors and 36 patients with malignant parotid gland tumors were retrospectively analyzed. Histogram-based analysis was performed with the software MaZda. ROIs were drawn on every section of the ADC map containing the tumor, then 12 Parameters(Area, MinNorm, MaxNorm, Mean,Variance, Skewness, Kurtosis, Perc.1％, Perc.10％, Perc.50％, Perc.90％, Perc.99％) derived from histogram were calculated. Statistical analysis among the three groups (One-way ANOVA or Kruskal-Wallis test) were performed to find out the statistical significance of each histogram parameter. Then LSD test or Mann-Whitney U test was used for pairwise comparison between groups. And the differential efficiency of each parameter was determined using ROC analysis. Results Overall, 9 parameters (MinNorm, MaxNorm, Mean, Variance, Skewness, Perc. 10％, Perc. 50％, Perc. 90％, Perc. 99％) among three groups were shown to be statistically significant (P<0.05). Between the pleomorphic adenomas and Warthin tumors, these 9 parameters were of statistical significance. Perc.50％revealed the highest diagnostic efficiency, followed by Mean and Perc.10％. Between the pleomorphic adenomas and malignant parotid gland tumors, also all these 9 parameters were of statistical significance. Mean was revealed to have the highest diagnostic efficiency, followed by Perc. 10％ and Perc. 90％. However, between the Warthin tumors and malignant parotid gland tumors, only 5 parameters (MinNorm, Mean, Skewness, Perc. 10％, Perc. 50％) were statistically significant. MinNorm was revealed to have the highest diagnostic efficiency, followed by Perc. 50％ and Perc. 10％. Generally, Mean, Perc. 10％ and Perc. 50％ were more effective in the differential diagnosis of these three types common parotid neoplasms. Conclusion Whole-tumor histogram analysis of ADC maps are effective in differentiating common parotid neoplasms.
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Objective To study the value of whole tumors volume based apparent diffusion coefficient histogram analysis in grading diagnosis of ependymoma. Methods Seventy?one patients with ependymal tumors were retrospectively analyzed, including 13 cases of WHOⅠ, 28 cases of WHOⅡ, 30 cases of WHO Ⅲ. Regions of interest (ROI) in the apparent diffusion coefficient maps of three groups on each layer of tumor level were drawn by using MaZda software and were analyzed using the whole tumors gray histogram. The histogram parameters of the three groups all fitted the normal distribution and homogeneity test of variance. The ANOVA analysis was used to compare the three groups. LSD-t test was used to compare the two groups to find out statistical significance of each parameter. Results Through histogram analysis of 9 parameters, three parameters were statistically significant (P<0.05), including variance, perc. 01％ and perc. 10％. The remaining 6 parameters had no significant difference between the three groups (P>0.05). Between the WHOⅠand the WHOⅡ, the sensitivity of perc.10％was 85.7％, the specificity was 87.7％, the area under the curve was 0.835, and the best cut-off value was 131.33. Between the WHOⅠand the WHOⅢ, the sensitivity of perc.10％was 85.7％, the specificity was 100.0％, the area under the curve was 0.872, and the cut-off was 126.5.Between the WHOⅡand the WHOⅢ, the sensitivity of variance was 68.4％, the specificity was 79.6％, the area under the curve was 0.794, and the cut-off was 2645.7. They had a high identification efficiency. Conclusion Whole-tumor histogram analysis of apparent diffusion coefficient maps could provide ancillary diagnostic value in grading diagnosis of ependymoma. Perc.10％and variance had a high diagnostic efficiency.
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Objective To study the value of whole tumors T2WI gray histogram analysis for differential diagnosis of three commonly presented pediatric posterior fossa tumors. Methods A retrospective analysis was conducted to compare brain MRI examination and pathology diagnosis of 133 cases of posterior fossa tumors in pediatric patients in our hospital.Among them, there were 49 cases of ependymoma(there were 25 males and 24 females), 36 cases of astrocytoma(WHO grade Ⅰ)(there were 19 males and 17 females), 48 cases of medulloblastoma(there were 36 males and 12 females),aged 1 to 14 years old, with an average (7±2) years old. Respectively draw the region of interest (ROI) in the T2 MR transaxial images of three groups on each layer of tumor level by using Mazda software and analyze the whole tumors gray histogram, including mean,variance, kurtosis,skewness, perc.01%,perc.10%,perc.50%,perc.90% and perc.99%.The histogram parameters of the three groups were not normally distributed. The Kruskal-Wallis test was used to compare the three groups. Bonferroni test was used to compare the two groups to find out statistical significance of each parameter. Results Through histogram analysis of 9 parameters, these 9 parameters were statistically significant (all P <0.05),including mean,variance,kurtosis,skewness, perc.01%,perc.10%,perc.50%,perc.90% and perc.99%. The sensitivity of skewness to differentiate ependymoma and the astrocytoma was 69.4％, the specificity was 77.8％, the area under the curve was 0.744, and the best cut-off value was-0.08. The sensitivity of kurtosis to differentiate astrocytoma and the medulloblastoma was 95.8％, the specificity was 97.2％ and the area under the curve was 0.972, the cut-off was 1.68. The sensitivity of kurtosis to differentiate ependymoma and the medulloblastoma was 91.7％, the specificity was 89.8％and the area under the curve was 0.932,the cut-off was 1.90.They had a high identification efficiency. Conclusions The T2WI gray histogram analysis based whole tumors is helpful for the dignosis of three types of pediatric posterior fossa tumors. Skewness has a high diagnostic efficiency to differentiate ependymoma and the astrocytoma. Kurtosis has a high diagnostic efficiency to differentiate ependymoma and the medulloblastoma. Kurtosis has a high diagnostic efficiency to differentiate ependymoma and medulloblastoma.