Objective To investigate the value of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) based on ISHIM sequence in the grading of astrocytic tumor.Methods We collected excised tumors confirmed by histological diagnosis from 42 patients including high-grade astrocytic tumors (10 WHO grade Ⅲ,18 WHO grade Ⅳ),and 14 low-grade astrocytic tumors (1 WHO grade Ⅰ and 13 WHO grade Ⅱ).All patients underwent conventional MR imaging,ISHIM IVIM-DWI,and contrast-enhanced MR imaging.Parameters of tumor parenchyma region,peripheral edema regions and the contralateral normal brain white matter sites were measured,and the statistical analysis was conducted.Results The D value in tumor parenchyma region was significantly lower,but the D* and f values were higher in high-grade astrocytic tumor when compared with lowgrade one and all had statistical significance;in tumor peripheral edema region,D value was lower in high-grade astrocytic tumor than that in low-grade one,and the difference had statistical significance but there was no significant difference in terms of the D* and f values.There was no significant difference of the D,D* and f values in contralateral normal brain white matter sites in both high-and low-grade astrocytic tumor.Conclusion The D,D* and f values measured by ISHIM IVIM-DWI are helpful to the judgment of tumor grade and it has greatapplication value in the differential diagnosis of high-and low-grade astrocytic tumor.

Objective To investigate the value of diffusion kurtosis imaging (DKI) in differential diagnosis of parotid gland disease and diagnosis of parotid adenolymphoma (PAL).Methods DKI and DWI data of 57 patients with parotid gland disease were etrospectively analyzed.Totally 57 cases were divided into infectious lesions group (n=10),pleomorphic adenoma group (n=19),PAL group (n=14),other benign parotid tumor group (n=4) and malignant parotid tumor group (n=10).Contralateral normal parotid glands in 19 patients with unilateral parotid gland lesions were treated as control group.The quantitative parameters including kurtosis concerning parameters (K Krad,Kax),diffusivity concerning parameters (D Drad,Dax),fractional anisotropy (FA) and conventional apparent diffusion coefficient (ADC) values were retrospectively reviewed.The binary Logistic regression method was used to confirm parameters with significant difference in diagnosing PAL.And Logistic regression equation was constructed to diagnose PAL.ROC analysis was conducted to evaluate the diagnostic value of the confirmed parameters and the Logistic regression equation.Results Significant difference of the parameters including K Krad,Kax,D Drad,Dax,FA and ADC values were found among different groups (all P＜0.05).ROC analysis demonstrated a higher area under the curve (AUC) for FA+Kax [0.88±0.06 (0.79-0.94)] than Kax[0.80±0.07 (0.70-0.88)] and FA [0.63±0.10 (0.52-0.73)],respectively (both P＜0.05).The sensitivity,specificity,accuracy,positive predictive value and negative predictive value was 71.43％,95.78％,91.77％,76.92％ and 94.44％.Conclusion DKI showed high diagnostic capacity in differential diagnosis of parotid gland disease.The combination of FA and Kaxcan improve the diagnostic accuracy in diagnosis of PAL.

Objective To evaluate the changes of diffusion kurtosis imaging (DKI) parameters with time in cerebral in farction patients,and contrast with diffusion tensor imaging (DWI).Methods DWI and DKI scans were performed in 95 patients of cerebral infarction.The patients were divided into five groups according to the time of cerebral infarction:Hyperacute phase (n=10),acute phase (n=12),early subacute phase (n =33),late subacute phase (n =20) and chronic phase (n =20).Parameters of DKI were obtained,and the parameters and percentage change of diffusion metrics from normal to ischemic tissue were compared.The evolution rule of parameter with time was analyzed.Results Mean kurtosis (MK),axial kurtosis (K//),radial kurtosis (K⊥) of DKI parameters increased after infarction,and reached the peak at acute phase,and decreased gradually with the prolonging of time.Mean diffusion (MD),axial diffusion (D//),radial diffusion (D⊥) of DTI parameters decreased after infarction,and reached the lowest at the acute phase,and increased gradually with the prolonging of time.The percentage change of MK,K//,K⊥ were higher than those of MD,D//,D⊥,and percent change along the axial direction were significantly larger than that along the radial direction.Conclusion DKI is superior to DTI in evaluating cerebral infarction,and can analyze the changes of microstructure of cerebral infarction comprehensively.

Objective To investigate the value of dual-exponential model intravoxel incoherent motion (IVIM) DWI and conventional single-exponential DWI model based on readout segmentation echo-planar (RS-EP) sequence in differential diagnosis of simple rhinitis and chronic hypertrophic rhinitis.Methods Totally,20 patients confirmed by pathology were enrolled in this study and all of them underwent IVIM DWI and conventional DWI.The pure diffusion (D),pseudo-diffusion (D*),perfusion fraction (f) and conventional ADC maps were obtained respectively.The quantitative parameters of anterior,middle,posterior regions of inferior nasal concha mucosa were measured.Comparative statistical analysis was performed for comparing two groups and three regions.ROC analysis was conducted to assess the diagnostic performance.Results The ADC and D values in the simple rhinitis group were (1 938.84 ± 170.46) × 10-6 mm2/s,and (1 698.91 ±145.17) × 10-6 mm2/s.In chronic hypertrophic rhinitis group,the ADC value was (1 681.76± 132.21) × 10-6 mm2/s,and the D value was (1 439.39 ± 101.26)× 10-6 mm2/s.There were significant differences between the two groups (both P＜0.05).No significant differences were found for D* and f values between two groups (both P＞0.05).ADC values increased significantly from anterior region,middle region to posterior region (all P＜0.05).No significant difference was found for D* value among three regions (P＞0.05).ROC analysis demonstrated a higher area under the curve (AUC) for D value than ADC value (0.932±0.044 vs 0.896±0.058) with sensitivity,specificity,accuracy,positive and negative predictive values of 92.31％,93.75％,90.00％,93.75％,85.71％.Conclusion Based on RS-EP sequence,both IVIM DWI model and conventional single-exponential DWI model demonstrated great value in differential diagnosis of simple rhinitis and chronic hypertrophic rhinitis,and the IVIM-derived D value exhibited a higher diagnostic performance than the conventional ADC value.

Objective:To prospectively guide the change of chemotherapy regimen in mouse 5-fluorouracil (5-FU) resistance subcutaneous xenograft tumor model derived from gastric cancer patients by the early changes of MRI apparent diffusion coefficient (ADC), and to compare the difference of tumor load between ADC guided dressing change group and volume guided dressing change group.Methods:From January to June 2020, thirty patient-derived xenografts mouse models were established using 5-FU resistant gastric cancer cells coming from patients, and were randomly divided into experimental group and control group by AdaBoost algorithm, with 15 mice in each group. On the 26th day after transplantation, all mice began chemotherapy with 5-FU as the first-line chemotherapy drug, and underwent MR examination once every two days, including T 2WI and diffusion weighted imaging (DWI). Volumes of tumors were measured using an open-source software ITK-SNAP and values of ADC were measured on ADC maps. According to the change rate of tumor ADC value in the experimental group and the tumor volume growth rate in the control group, the replacement time of chemotherapy drugs was determined, and 5-FU was replaced by paclitaxel. The end point of the experiment was the day that the mice entered the cachexia state. Independent-sample t test was used to compare the difference of tumor load between the two groups. Results:After 5-FU treatment, the ADC value of the two groups both increased. The ADC value began to decline on the 4th day after chemotherapy, and the experimental group continued chemotherapy with paclitaxel instead of 5-FU at this time point. The tumor volume growth rate of the control group increased significantly on the 6th day after chemotherapy (from 8.6% to 16.1%), and the control group used paclitaxel instead of 5-FU chemotherapy at this time point. The observed end point was on the 18th day after chemotherapy. The tumor load of the experimental group [(1.82±0.09) cm 3] was lower than that of the control group [(2.01±0.09) cm 3], and the difference was statistically significant ( t=2.25, P=0.033). On the 16th day after chemotherapy in the experimental group and the 18th day after chemotherapy in the control group, the time of paclitaxel administration in both groups was 12 days. The tumor load in the experimental group [(1.61±0.12) cm 3] was also lower than that in the control group [(2.01±0.09) cm 3], and the difference was statistically significant ( t=2.03, P=0.040). Conclusions:For the subcutaneous transplantation model of 5-FU resistant gastric cancer mice, according to the early changes of tumor ADC value after chemotherapy, the replacement of chemotherapy drugs can obtain a lower tumor load, suggesting that it is a feasible method to optimize the chemotherapy regimen.

Objective To explore the value of Fast Dixon in improving the quality of thyroid turbo spin echo(TSE)T2WI images via comparing the quality of thyroid MR T2WI images based on Fast Dixon,Dixon,and BLADE sequences.Methods The prospective study included 11 healthy volunteers,who underwent neck MR scanning.The evaluation of image quality was performed via a combination of objective measures and subjective ratings.Objective measures included signal-to-noise ratio(SNR)of bilateral thyroid and muscles,and contrast-to-noise ratio(CNR).Subjective measures included overall image quality,uniformity of fat suppression,sharpness of thyroid margins and muscles surrounding the thyroid,image noise in the neck region,image background noise,and image quality of the nasopharynx.Two diagnostic physicians with over 10 years of thyroid diagnostic experience independently evaluated the images via a 5-point scale.Inter-observer agreement was analyzed via Spearman correlation coefficient.Statistical analysis was performed using SPSS 22.0 software,including normality and homogeneity of variance tests for continuous data.Kruskal-Wallis one-way ANOVA was used for statistical analysis of subjective measures,followed by post hoc pairwise comparisons.A significance level of P<0.05 was considered statistically significant.Results Eleven healthy volunteers,the SNR of bilateral thyroid and muscles was significantly higher in Fast Dixon sequence than that in Dixon and BLADE sequences.For bilateral CNR,Fast Dixon sequence was also significantly higher than that of Dixon and BLADE sequences.Fast Dixon sequence also had significant advantages in seven subjective ratings indicators(P<0.001).Conclusion The Fast Dixon sequence shows the highest image quality and important application value in the display and evaluation of thyroid lesions.

Objective: To explore the value and disadvantage of micro-mirror in the intracranial aneurysm surgery. Methods: Micro-mirror was used to assist microsurgical clipping to 36 intracranial aneurysms in 31 cases, of which 3 were carotid-ophthalmic artery aneurysms, 3 anterior choroidal artery aneurysm, 11 were posterior communicating artery aneurysms, 7 were middle cerebral artery aneurysms, 10 anterior communicating artery or anterior cerebral artery aneurysms, and the others were a posterior cerebral artery aneurysm and a posterior inferior cerebellar artery aneurysm. The micro-mirror was used before and after clipping to observe the anatomic features of necks hidden behind and medial to aneurysms, to visualize surrounding neurovascular structures, and to verify the optimal clipping position. Intraoperative indocyanine green fluorescein angiography confirmed the success of sufficient clipping. Results: All aneurysms were clipped successfully. The parent arteries were occluded temporarily in 26 cases, and 9 aneurysms ruptured during the operation. Postoperative follow-up lasted from 2 weeks to 1 year. After operations digital subtraction angiography (DSA) were repeated in 10 cases, computed tomography angiography(CTA) in 21 cases, and no insufficient clipping or occlusion of parent arteries were revealed. Conclusions Micro-mirror assisting microsurgical clipping to the intracranial aneurysm is conducive to accurate clipping, and is a convenient and practical operation.