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Objective:To analyze the magnetic resonance imaging (MRI) features of diffuse midline gliomas with H3K27M mutation, and to quantitatively analyze the changes of apparent diffusion coefficient (ADC).Methods:The MRI images of 14 cases of diffuse midline gliomas with H3K27M mutation were retrospectively analyzed in the Affiliated Hospital of Qingdao University from April 2017 to November 2019. The location, edge, signal, peritumoral edema and enhancement characteristics of the lesions were observed, and the changes of ADC values were analyzed.Results:The tumors were located in thalamus in four cases, pons in six cases, medulla oblongata in two cases and spinal cord in two cases. In seven cases, the tumor was confined to the midline region, of which six cases had clear boundary, seven cases were located in the midline area, but infiltrated into the non midline area at the same time, and six cases had unclear boundary. Basilar artery entrapment was found in all six patients located in pons. Multiple large cystic changes were found in five cases, multiple small cysts in four cases and no cystic changes in five cases. Cystic changes were found in all seven cases of tumors involving the non midline region, of which six cases were located only in the non midline region, and only two of the seven tumors localized in the midline region had small cysts. Hemorrhage was found in four cases. Five cases showed mild heterogeneous enhancement, six cases showed moderate heterogeneous enhancement, two cases showed obvious enhancement, and one case showed no enhancement. There was no edema around the tumor in nine cases and mild edema in five cases. The average edema index was 1.13. The average ADC value of tumor parenchyma in 12 patients was (7.83±0.88)×10 -4 mm 2/s, which was 15.6% lower than that of the contralateral side [(9.28±0.69)×10 -4 mm 2/s, t=-6.336, P<0.05]. Conclusions:Diffuse midline gliomas with H3K27M mutation have a younger onset age and are more likely to occur in thalamus, brainstem and spinal cord. Most of the tumors have no peritumoral edema or mild peritumoral edema. The tumors confined to the midline region are regular in shape and clear in boundary. The masses involving the non midline area are prone to cystic necrosis. Diffuse midline gliomas with H3K27M mutation in pons are prone to basilar artery entrapment. ADC value can provide a quantitative basis for preoperative tumor grading.
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Objective To investigate the value of intravoxel incoherent motion DWI (IVIM-DWI) in differential diagnosis of high-grade gliomas and brain metastases.Methods Conventional MRI,contrast-enhanced MRI and IVIM-DWI were performed before surgery or chemoradiotherapy in 24 patients with high-grade gliomas and 28 patients with brain metastases.The diffusion constant (D),pseudodiffusion coefficient of perfusion (D*) and the perfusion fraction (f) in the parenchyma and peritumoral edema region within 1 cm and the normal centrum semiovale in the opposite side were measured,then the relative values of all parameters in each region (rD*,rD,rf) were calculated.Independent sample t test was used to analyze the parameters.ROC curve analysis of the parameters statistically different between high grade gliomas and brain metastases were performed,and the diagnostic efficacies were evaluated.Results The D* and rD* values of tumor parenchyma and in peritumoral edema within 1 cm of high-grade gliomas were higher than those of brain metastases (all P＜0.05).The f and rf values of tumor parenchyma and in peritumoral edema within 1 cm of highgrade gliomas were lower than those of brain metastases (all P＜0.01).The AUC of D* value in peritumoral edema within 1 cm was the highest,but there was no statistically different between any two AUC except the rD* value of peritumoral edema within 1 cm (P =0.033).Conclusion IVIM-DWI can distinguish the differences of diffusion and perfusion information in parenchyma and edema area between high-grade gliomas and brain metastases,therefore providing the basis for differential diagnosis of them.
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Objective To explore the values of apparent diffusion coefficients (ADC) in staging the lesions of multiple sclerosis (MS) through analysing the differences of ADC in different types of lesions.Methods 137 lesions identified in 29 patients with MS,were characterized by their enhancement pattern on contrast-enhanced T1-weighted MR images and whether they were changing in appearance, size or signal.The lesions were classified into four groups:homogeneously enhancing lesions (HELs), ring-enhancing lesions (RELs), active nonenhancing lesions (ANELs), and inactive nonenhancing lesions (INELs).The mean ADC values for each type of lesions were calculated and compared.Results The ADC values for HELs, RELs, ANELs and INELs were (91.09±13.63)× 10 5 · m2 · s-1, (105.66±9.92) × 10-5 · m2 · s-1, (136.80±20.31) × 10-5 · m2 · s-1 and (127.46±13.65) ×10-5 · m2 · s-1.There were significant differences between the ADC values of any two groups in the four groups except the ADC values between ANELs and INELs.Conclusion ADC values are useful to differentiate each type of lesion,which can help stage the lesions of MS.