◥Purpose: Bevacizumab is considered a promising therapy for brain necrosis after radiotherapy, while some patients fail to derive benefit or even worsen. Hence, we developed and validated a radiomics model for predicting the response to bevacizumab in patients with brain necrosis after radiotherapy.Experimental Design: A total of 149 patients (with 194 brain lesions; 101, 51, and 42 in the training, internal, and external validation sets, respectively) receiving bevacizumab were enrolled. In total, 1,301 radiomic features were extracted from the pretreatment MRI images of each lesion. In the training set, a radiomics signature was constructed using the least absolute shrinkage and selection operator algorithm. Multivariable logistic regression analysis was then used to develop a radiomics model incorporated in the radiomics signature and independent clinical predictors. The performance of the model was assessed by its discrimination, calibration, and clinical usefulness with internal and external validation.Results: The radiomics signature consisted of 18 selected features and showed good discrimination performance. The model, which integrates the radiomics signature, the interval between radiotherapy and diagnosis of brain necrosis, and the interval between diagnosis of brain necrosis and treatment with bevacizumab, showed favorable calibration and discrimination in the training set (AUC 0.916). These findings were confirmed in the validation sets (AUC 0.912 and 0.827, respectively). Decision curve analysis confirmed the clinical utility of the model.Conclusions: The presented radiomics model, available as an online calculator, can serve as a user-friendly tool for individualized prediction of the response to bevacizumab in patients with brain necrosis after radiotherapy.

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The Hekou Group, an outcrop at the west margin of the Yangtze Block, consists of volcanic and sedimentary rocks of sodic lava, sodic pyroclastic rocks, coarse to fine-grained siliciclastic rocks and carbonate rocks. These rocks have endured lower to upper greenschist-facies metamorphism. The Hekou Group represents the basement of the late Mesoproterozoic to early Neoproterozoic successions and hosts many Fe-Cu deposits. We conducted zircon U-Pb and Lu-Hf isotope analyses and whole-rock geochemistry analyses on igneous rocks from the Hekou Group to constrain the formation age of the Hekou Group and to understand the genesis of the Fe-Cu deposits. A zircon 207 Pb/ 206 Pb age of 1669 ± 6 Ma was obtained from the tuffaceous schist of the Hekou Group and is considered to represent the deposition age of the group. Most rocks show negative high field strength element (HFSE, e.g., Ta, Nb, P, Zr, Hf and Ti) anomalies, light rare earth element (LREE) enrichment ((La/Yb) n = 12.10-109.01) and positive zircon ε Hf (t) values (+1.5 to +4.5). The geochemical and isotopic compositions indicate that the Hekou Group was formed in a back-arc basin at 1.7 Ga. Our study also implies that Paleoproterozoic tectonic evolution of the western Yangtze Block is correlated with the assembly and fragmentation of the supercontinent Columbia.

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