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Yayınlar
- MakaleYalnız künye2026Contralateral DTI-ALPS index as a prognostic biomarker in IDH-wildtype glioblastoma: integrating extent of resection and sex-stratified analyses
Aygün, Tayfun; Keskin, Arif; Palanci, Ozgur; Öztanir, Mustafa Namik; Yücel, Nurullah; Hekimoglu, Gulam
Aim This study aimed to evaluate the independent prognostic value of the contralateral DTI-ALPS index in IDH-wildtype glioblastoma, incorporating tumor morphometry, extent of resection, and sex-stratified analyses within a multivariable framework.Methods A retrospective analysis was performed on 153 IDH-wildtype glioblastoma patients from the publicly available UPENN-GBM dataset. Contralateral DTI-ALPS was calculated using DSI Studio via manual ROI placement; tumor morphometry was derived from expert-annotated segmentation labels using 3D Slicer. Survival analyses included Kaplan-Meier estimation, multivariable Cox regression, time-dependent ROC, restricted cubic spline, and sequential C-index comparison with likelihood-ratio testing.Results The contralateral DTI-ALPS index independently predicted overall survival after adjustment for age, sex, tumor volume, and GTR status (HR = 0.405, 95% CI: 0.227-0.725, p = 0.002). Each one standard deviation increase in DTI-ALPS was associated with a 24.2% reduction in mortality risk. GTR >= 90% (HR = 0.651, p = 0.017) and age (HR = 1.021, p = 0.007) also retained independent significance. DTI-ALPS significantly improved model discrimination beyond age alone (C-index: 0.625 -> 0.653 -> 0.668; likelihood-ratio test p = 0.002). Time-dependent AUC reached 0.741 at 6 months. ALPS-based stratification was more pronounced in the subtotal resection subgroup. Sex-stratified analyses showed numerically stronger associations in females, but formal interaction testing did not confirm effect modification. In an exploratory MGMT subset (n = 57), DTI-ALPS did not retain independent significance after MGMT adjustment.Conclusion The contralateral DTI-ALPS index may provide complementary prognostic information beyond established clinical predictors in IDH-wildtype glioblastoma; however, given the incomplete MGMT methylation data and ongoing methodological debate regarding the biological validity of DTI-ALPS, these findings should be considered exploratory. Prospective validation in cohorts with complete molecular and treatment data is required.
- MakaleAçık Erişim2026Cortical thickness and volume alterations in patients with high myopia: a magnetic resonance imaging study
Aydin, Emre; Palanci, Ozgur
Background: The retina and optic nerve are integral components of the visual system and maintain direct anatomical and functional connections with the brain. Both structures are markedly affected in high myopia (HM). Accordingly, characterizing brain structural alterations associated with HM may provide important insights into its underlying neurobiological mechanisms. Using brain magnetic resonance imaging (MRI), this study aimed to evaluate regional gray matter (GM) and white matter (WM) volume changes, their relative percentages, and cortical thickness alterations in individuals with HM. Methods: High-resolution structural MRI, together with visual acuity (VA), intraocular pressure (IOP), refractive error, axial length (AL), and anterior chamber depth (ACD), was used to compare 30 adults with HM and 22 healthy controls (HC). Regional brain volumes and cortical thickness were analyzed in the fusiform gyrus (FuG), inferior temporal gyrus (ITG), middle temporal gyrus (MTG), superior temporal gyrus (STG), and occipital subregions including the calcarine cortex (Calc), cuneus (Cun), lingual gyrus (LiG), inferior occipital gyrus (IOG), middle occipital gyrus (MOG), and superior occipital gyrus (SOG). Results: Compared with HCs, HM patients demonstrated significant volumetric increases in the ITG and MTG regions (all p < 0.05), with the left ITG remaining significant after false discovery rate (FDR) correction. No significant volumetric differences were observed in the fusiform or occipital regions. In contrast, cortical thickness analyses revealed significant thinning in the fusiform gyrus and bilateral occipital subregions, including the calcarine cortex, cuneus, lingual gyrus, and middle occipital gyrus (p = 0.000–0.026, FDR-corrected). Cortical thickness in the fusiform and occipital regions showed negative correlations with AL and ACD and positive correlations with spherical equivalent. Conclusions: High myopia is associated with region-specific brain structural alterations, characterized by volumetric increases in temporal regions and cortical thinning in fusiform and occipital areas, indicating that HM-related neuroanatomical changes extend beyond the ocular system to involve central nervous system structures. Trial registration: Not applicable.
- MakaleYalnız künye2026Comparison of automated subcortical segmentation methods: VolBrain vs. 3D Slicer in brain volumetry
Acer, Niyazi; Palanci, Ozgur; Ipekten, Funda; Erdogan, Furkan Mert; Yarar, Burhan; Ozyasar, Ali Faruk
Objective:Accurate volume measurements of subcortical brain structures are essential in neuroimaging studies. This study aimed to compare two automated segmentation algorithms, 3D Slicer and VolBrain, for subcortical brain volumetry. Method:Subcortical volume measurements obtained using 3D Slicer and VolBrain were compared using the Neurofeedback Skull-stripped (NFBS) dataset. Statistical analyses included the coefficient of determination (R2) and Bland-Altman (B-A) plots. Volumetric measurements from both tools were evaluated across multiple subcortical brain regions. Results:Strong agreement was observed for the caudate nucleus, thalamus, and hippocampus, while notable discrepancies were identified in the amygdala, globus pallidus, and nucleus accumbens. Both constant and proportional systematic errors were detected in certain regions, with greater variability observed in 3D Slicer measurements. Intraclass Correlation Coefficient (ICC) analysis demonstrated weak agreement for the accumbens and amygdala, and moderate agreement for the hippocampus and thalamus, highlighting region-specific differences in performance Conclusion:Both VolBrain and 3D Slicer are effective tools for subcortical brain volumetry. VolBrain provides a fully automated workflow, whereas 3D Slicer allows greater flexibility through detailed corrections. Method selection should be guided by research objectives, regions of interest, and image quality. Further validation across diverse datasets is warranted to improve clinical applicability, particularly in regions showing lower agreement.