Purpose To evaluate the predictive performance of mean apparent propagator-magnetic resonance imaging(MAP-MRI)combined with habitat analysis for determining O6-methylguanine-DNA methyltransferase(MGMT)promoter methylation status in glioma.Materials and Methods This retrospective study analyzed MRI and clinical data from 55 patients with surgically confirmed glioma at Fujian Medical University Union Hospital from January 2019 to December 2023.All patients underwent structural and diffusion-weighted imaging.Three-dimensional volumes of interest were delineated in the tumor solid region using ImageJ software.The nn-FAE tool was used to segment the tumor solid region into two habitat subregions based on mean diffusivity(MD)maps:high-MD and low-MD habitats.Average diffusion parameter values were extracted from the entire tumor solid region and each habitat subregion.Differences in parameters between methylated and unmethylated groups were compared,and the area under the curve was calculated.Results Among 55 patients,significant differences were observed in all MAP-MRI parameters and MD in the tumor solid region and low-MD habitat,as well as all parameters in the high-MD habitat between methylated and unmethylated groups(t/Z=-3.780-3.153,all P<0.05).The return-to-origin probability(RTOP)in the low-MD habitat demonstrated the highest diagnostic performance,with the area under the curve improving from 0.771 before habitat analysis to 0.827 after habitat analysis.In the high-grade subgroup,significant differences were observed in return-to-axis probability(RTAP)and RTOP in the tumor solid region;RTOP,non-Gaussianity,non-Gaussianity axial,and RTAP in the low-MD habitat;and non-Gaussianity in the high-MD habitat(t/Z=-2.820--1.976,all P<0.05).RTOP in the low-MD habitat again showed optimal diagnostic efficacy(the area under the curve 0.725 before habitat analysis,0.798 after).Multivariate analysis identified RTAP and RTOP in the tumor solid region and low-MD habitat as independent predictors of MGMT methylation.Conclusion MAP-MRI diffusion parameters demonstrate the ability to predict MGMT promoter methylation status in glioma,with superior performance compared with diffusion tensor imaging.Habitat imaging further enhances the predictive efficacy of MAP-MRI parameters for MGMT promoter methylation.

Purpose To evaluate the predictive performance of mean apparent propagator-magnetic resonance imaging(MAP-MRI)combined with habitat analysis for determining O6-methylguanine-DNA methyltransferase(MGMT)promoter methylation status in glioma.Materials and Methods This retrospective study analyzed MRI and clinical data from 55 patients with surgically confirmed glioma at Fujian Medical University Union Hospital from January 2019 to December 2023.All patients underwent structural and diffusion-weighted imaging.Three-dimensional volumes of interest were delineated in the tumor solid region using ImageJ software.The nn-FAE tool was used to segment the tumor solid region into two habitat subregions based on mean diffusivity(MD)maps:high-MD and low-MD habitats.Average diffusion parameter values were extracted from the entire tumor solid region and each habitat subregion.Differences in parameters between methylated and unmethylated groups were compared,and the area under the curve was calculated.Results Among 55 patients,significant differences were observed in all MAP-MRI parameters and MD in the tumor solid region and low-MD habitat,as well as all parameters in the high-MD habitat between methylated and unmethylated groups(t/Z=-3.780-3.153,all P<0.05).The return-to-origin probability(RTOP)in the low-MD habitat demonstrated the highest diagnostic performance,with the area under the curve improving from 0.771 before habitat analysis to 0.827 after habitat analysis.In the high-grade subgroup,significant differences were observed in return-to-axis probability(RTAP)and RTOP in the tumor solid region;RTOP,non-Gaussianity,non-Gaussianity axial,and RTAP in the low-MD habitat;and non-Gaussianity in the high-MD habitat(t/Z=-2.820--1.976,all P<0.05).RTOP in the low-MD habitat again showed optimal diagnostic efficacy(the area under the curve 0.725 before habitat analysis,0.798 after).Multivariate analysis identified RTAP and RTOP in the tumor solid region and low-MD habitat as independent predictors of MGMT methylation.Conclusion MAP-MRI diffusion parameters demonstrate the ability to predict MGMT promoter methylation status in glioma,with superior performance compared with diffusion tensor imaging.Habitat imaging further enhances the predictive efficacy of MAP-MRI parameters for MGMT promoter methylation.

Objective To explore the application of MRI in the differential diagnosis of high-and low-risk thymoma.Methods The data of patients with pathologically confirmed thymoma were collected bidirectionally,and the differences in clinical data,MRI image characteristics of lesions,signal characteristics and apparent diffusion coefficient(ADC)values were compared and analyzed between high-and low-risk thymoma according to the pathological subtype.The receiver operating characteristic(ROC)curve analysis was used to screen out meaningful features,then the diagnostic efficacy and combined prediction probability of indicators were evaluated.Results There was no significant difference in clinical data(P＞0.001).The morphology of high-risk lesions was mainly irregular,while that of low-risk lesions was mainly regular.The edges of high-risk lesions were mostly not smooth,and the edges of low-risk lesions were mostly smooth.The enhancement degree of high-risk lesions was higher than that of low-risk lesions,and the ADC value was lower than that of low-risk lesions,with statistical significance(P＜0.001),in which the ADC value area under the curve(AUC)was higher than other indicators(AUC=0.968),and the combined prediction probability of indicators was the highest(AUC=0.981).Conclusion MRI shows great potential application value in preoperative differential diagnosis of high-and low-risk thymoma.

Objective: To evaluate the application of laplacian-regularized mean apparent propagator (MAPL)-MRI to brain glioma-induced corticospinal tract (CST) injury. Materials and Methods: This study included 20 patients with glioma adjacent to the CST pathway who had undergone structural and diffusion MRI. The entire CSTs of the affected and healthy sides were reconstructed, and the peritumoral CSTs were manually segmented. The morphological characteristics of the CST (track number, average length, volume, displacement of the affected CST) were examined and the diffusion parameter values, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), mean squared displacement (MSD), q-space inverse variance (QIV), returnto-origin probability (RTOP), return-to-axis probabilities (RTAP), and return-to-plane probabilities (RTPP) along the entire and peritumoral CSTs, were calculated. The entire and peritumoral CST characteristics of the affected and healthy sides as well as those relative CST characteristics of the patients with motor weakness and normal motor function were compared. Results: The track number, volume, MD, RD, MSD, QIV, RTAP, RTOP, and RTPP of the entire and peritumoral CSTs changed significantly for the affected side, whereas the AD and FA changed significantly only in the peritumoral CST (p < 0.05). In patients with motor weakness, the relative MSD of the entire CST, QIV of the entire and peritumoral CSTs, and the AD, MD, RD of the peritumoral CST were significantly higher, whereas the RTPP of the entire and peritumoral CSTs and the RTOP of the peritumoral CST were significantly lower than those in patients with normal motor function (p < 0.05 for all). In contrast, no significant changes were found in the CST morphological characteristics, FA, or RTAP (p > 0.05 for all). Conclusion MAPL-MRI is an effective approach for evaluating microstructural changes after CST injury. Its sensitivity may improve when using the peritumoral CST features.

Objective: To evaluate the application of laplacian-regularized mean apparent propagator (MAPL)-MRI to brain glioma-induced corticospinal tract (CST) injury. Materials and Methods: This study included 20 patients with glioma adjacent to the CST pathway who had undergone structural and diffusion MRI. The entire CSTs of the affected and healthy sides were reconstructed, and the peritumoral CSTs were manually segmented. The morphological characteristics of the CST (track number, average length, volume, displacement of the affected CST) were examined and the diffusion parameter values, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), mean squared displacement (MSD), q-space inverse variance (QIV), returnto-origin probability (RTOP), return-to-axis probabilities (RTAP), and return-to-plane probabilities (RTPP) along the entire and peritumoral CSTs, were calculated. The entire and peritumoral CST characteristics of the affected and healthy sides as well as those relative CST characteristics of the patients with motor weakness and normal motor function were compared. Results: The track number, volume, MD, RD, MSD, QIV, RTAP, RTOP, and RTPP of the entire and peritumoral CSTs changed significantly for the affected side, whereas the AD and FA changed significantly only in the peritumoral CST (p < 0.05). In patients with motor weakness, the relative MSD of the entire CST, QIV of the entire and peritumoral CSTs, and the AD, MD, RD of the peritumoral CST were significantly higher, whereas the RTPP of the entire and peritumoral CSTs and the RTOP of the peritumoral CST were significantly lower than those in patients with normal motor function (p < 0.05 for all). In contrast, no significant changes were found in the CST morphological characteristics, FA, or RTAP (p > 0.05 for all). Conclusion MAPL-MRI is an effective approach for evaluating microstructural changes after CST injury. Its sensitivity may improve when using the peritumoral CST features.

Objective To explore the application of amide proton transfer (APT) imaging in differentiating glioma from treatment effect and to evaluate the diagnostic efficiency of the quantitative APT-related parameters.Methods A total of 23 patients (15 males, 8 females, age: 13-80 years) with 27 lesions who had underwent APT imaging in Tongji Hospital(Wuhan, China) from October 2014 to June 2015 were enrolled in this prospective study.The scan protocols were MRI normal plain scanning, diffusion WI, contrast-enhancement T1WI and APT imaging.Both the magnetization transfer ratio (MTR) and the relative MTR (rMTR) of lesions were manually measured by drawing ROI in the functional post-processing workstation.The results were compared with those of pathologic examinations and radiographic follow-up (≥3 months).Mann-Whitney u test was used to analyze the data.Results Compared with contralateral white matter, the primary gliomas (n=12) and recurrent gliomas (n=8) manifested hyper-intensity, while the treatment induced injuries (n=7) showed iso-or hypo-intensity.The difference of MTR between tumors and treatment effects was significant (102.78(101.93,103.84) vs 100.17(99.94, 100.63);z=-3.76, P<0.01), so was the difference of rMTR between tumors and treatment effects (3.92%(2.69%,4.67%) vs 0.47%(-0.79%,1.11%);z=-3.43, P<0.01).Both those two quantitative parameters exhibited excellent diagnostic performance with the AUC of 0.986 and 0.943.The sensitivity, specificity and accuracy of MTR were 100%(20/20), 6/7 and 96.3%(26/27) in the threshold of 100.68, while those of rMTR were 95.0%(19/20), 6/7 and 92.6%(25/27) in the threshold of 1.66%.Conclusions Combined with the routine MRI images, APT imaging can provide excellent qualitative and quantitative information in differentiating glioma from treatment effect.Both MTR and rMTR are helpful for the differentiation with high sensitivity and specificity and can be used as non-invasive imaging biomarkers in evaluating treatment effect of glioma.