Нейронна мережа на основі глибокого навчання для отримання зон інтересу на T2*-зважених перфузійних зображеннях МРТ мозку

Brain region segmentation is usually the first step for dynamic susceptibility contrast perfusion analysis. Although manual segmentation is more accurate, it is a time-consuming and not sufficiently reproducible process. Clinicians still rely on manual segmentation especially for cases with abnormal brain anatomy, as removing brain parts or inclusion of non-brain tissues can be a potential source of falsely high or falsely low values of perfusion parameters. This study proposes an effective deep learning-based neural network for fully automatic segmentation of brain from non-brain tissues in T2*-weighted magnetic resonance images with abnormal brain anatomy. Our neural network architecture combines U-Net and ResNet with plugged spatial and channel squeeze and excitation attention modules into the ResNet backbone. The train, validation, and test processes are conducted on 32 three-dimensional volumes of different subjects from the TCGA glioblastoma multiforme collection. Four performance metrics are used in our experiments: Dice coefficient, sensitivity, specificity, and accuracy. Quantitative results (i.e., Dice coefficient of 0.9726 +/- 0.004, sensitivity of 0.9514+/-0.007, specificity of 0.9983+/-0.001, and accuracy of 0.9864+/-0.003) reveal that the proposed neural network architecture is efficient and accurate for brain segmentation. The obtained results also demonstrate that the training model using the proposed U-Net+ResNet architecture of the neural network provides the best Dice coefficient, specificity, and accuracy metric values compared to current methods under the same hardware conditions and using the same test dataset of magnetic resonance images of a human head with abnormal brain anatomy. Moreover, obtained results also indicate that the proposed U-Net+ResNet architecture of deep learning-based neural network could be good enough in a clinical setup to reduce the need for time-consuming and non-reproducible manual segmentation

Сегментація мозку на перфузійних зображеннях магнітно-резонансної томографії

Точне визначення зони дослідження перфузії головного мозку є важливим кроком в отриманні якісних результатів оцінки гемодинамічних параметрів перфузії за допомогою перфузійної динамічно-сприйнятливої контрастної магнітно-резонансної томографії. З метою покращення відтворюваності та надійності визначення зони дослідження перфузії головного мозку були запропоновані різні алгоритми проведення напівавтоматизованої або повністю автоматизованої сегментації ділянки тканин мозку людини. Це дослідження містить огляд поточного стану питання сегментації ділянки тканин мозку людини на перфузійних Т2- і Т2*-зважених МР-зображеннях, а також розгляд алгоритмів, які найчастіше використовуються для повністю автоматизованої процедури сегментації, їхніх переваг та недоліків

Cycle-consistent adversarial networks improves generalizability of radiomics model in grading meningiomas on external validation

The heterogeneity of MRI is one of the major reasons for decreased performance of a radiomics model on external validation, limiting the model's generalizability and clinical application. We aimed to establish a generalizable radiomics model to predict meningioma grade on external validation through leveraging Cycle-Consistent Adversarial Networks (CycleGAN). In this retrospective study, 257 patients with meningioma were included in the institutional training set. Radiomic features (n = 214) were extracted from T2-weighted (T2) and contrast-enhanced T1 (T1C) images. After radiomics feature selection, extreme gradient boosting classifiers were developed. The models were validated in the external validation set consisting of 61 patients with meningiomas. To reduce the gap in generalization associated with the inter-institutional heterogeneity of MRI, the smaller image set style of the external validation was translated into the larger image set style of the institutional training set using CycleGAN. On external validation before CycleGAN application, the performance of the combined T2 and T1C models showed an area under the curve (AUC), accuracy, and F1 score of 0.77 (95% confidence interval 0.63-0.91), 70.7%, and 0.54, respectively. After applying CycleGAN, the performance of the combined T2 and T1C models increased, with an AUC, accuracy, and F1 score of 0.83 (95% confidence interval 0.70-0.97), 73.2%, and 0.59, respectively. Quantitative metrics (by Fréchet Inception Distance) showed that CycleGAN can decrease inter-institutional image heterogeneity while preserving predictive information. In conclusion, leveraging CycleGAN may be helpful to increase the generalizability of a radiomics model in differentiating meningioma grade on external validation.ope

Automatic analysis of skull thickness, scalp-to-cortex distance and association with age and sex in cognitively normal elderly

Personalized neurostimulation has been a potential treatment for many brain diseases, which requires insights into brain/skull geometry. Here, we developed an open source efficient pipeline BrainCalculator for automatically computing the skull thickness map, scalp-to-cortex distance (SCD), and brain volume based on T $_{1}$ -weighted magnetic resonance imaging (MRI) data. We examined the influence of age and sex cross-sectionally in 407 cognitively normal older adults (71.9±8.0 years, 60.2% female) from the ADNI. We demonstrated the compatibility of our pipeline with commonly used preprocessing packages and found that BrainSuite Skullfinder was better suited for such automatic analysis compared to FSL Brain Extraction Tool 2 and SPM12- based unified segmentation using ground truth. We found that the sphenoid bone and temporal bone were thinnest among the skull regions in both females and males. There was no increase in regional minimum skull thickness with age except in the female sphenoid bone. No sex difference in minimum skull thickness or SCD was observed. Positive correlations between age and SCD were observed, faster in females (0.307%/y) than males (0.216%/y) in temporal SCD. A negative correlation was observed between age and whole brain volume computed based on brain surface (females -1.031%/y, males -0.998%/y). In conclusion, we developed an automatic pipeline for MR-based skull thickness map, SCD, and brain volume analysis and demonstrated the sex-dependent association between minimum regional skull thickness, SCD and brain volume with age. This pipeline might be useful for personalized neurostimulation planning