The prevailing approach for three-dimensional (3D) medical image segmentation is to use convolutional networks. Recently, deep learning methods have achieved human-level performance in several important applied problems, such as volumetry for lung-cancer diagnosis or delineation for radiation therapy planning. However, state-of-the-art architectures, such as U-Net and DeepMedic, are computationally heavy and require workstations accelerated with graphics processing units for fast inference. However, scarce research has been conducted concerning enabling fast central processing unit computations for such networks. Our paper fills this gap. We propose a new segmentation method with a human-like technique to segment a 3D study. First, we analyze the image at a small scale to identify areas of interest and then process only relevant feature-map patches. Our method not only reduces the inference time from 10 min to 15 s but also preserves state-of-the-art segmentation quality, as we illustrate in the set of experiments with two large datasets.

Recent Metal Artifacts Reduction (MAR) methods for Computed Tomography are often based on image-to-image convolutional neural networks for adjustment of corrupted sinograms or images themselves. In this paper, we are exploring the capabilities of a multidomain method, which consists of both sinogram correction (projection domain step) and restored image correction (image-domain step). We formulate the first step problem directly as sinogram inpainting, which allows us to use methods of this specific field, such as partial convolutions. Moreover, we propose a synthetic data generation pipeline to avoid problems with overfitting to metal shapes set and an artifacts formation technique. The proposed method achieves state-of-the-art (−75% MSE) improvement in comparison with a classic benchmark - Li-MAR.

Гамартома гипоталамуса (ГГ) — диспластическое объемное образование, связанное с гипоталамусом, клинически проявляющееся структурной эпилепсией и преждевременным половым развитием. Частота полного регресса эпилептических приступов после хирургического лечения составляет около 50%, но тяжелые осложнения возникают примерно у каждого четвертого из оперированных пациентов. Альтернативой прямому вмешательству являются радиочастотная термокоагуляция, лазерная аблация и стереотаксическая радиохирургия (СРХ) гамартомы. ЦЕЛЬ ИССЛЕДОВАНИЯ На основании собственного опыта уточнить анамнестические, клинические и радиохирургические параметры, влияющие на эффективность СРХ на аппарате Гамма-нож у пациентов с ГГ, определить клинический профиль пациентов-кандидатов на СРХ и оптимальные параметры облучения. МАТЕРИАЛ И МЕТОДЫ В Московском Центре «Гамма-нож» АО «Деловой центр нейрохирургии» СРХ проведена 22 пациентам со структурной эпилепсией, вызванной ГГ. В ретроспективный анализ исходов лечения включено 19 пациентов с достаточной длительностью катамнестического наблюдения. Медиана возраста пациентов на момент СРХ составила 11,5 (1,3—25,8) года. Диаметр облученных ГГ варьировал от 5,5 до 40,9 мм. Объем 8 (36%) гамартом был более 3 см³. Предписанная доза составила в среднем 18±2,0 Гр, предписанная изодоза — 48±4,2%. Медиана длительности наблюдения — 14,8 (3,4–96,1) мес. РЕЗУЛЬТАТЫ У 3 (15,8%) пациентов достигнут полный регресс приступов; у 1 (5,3%) пациента после лечения отсутствовали генерализованные приступы и сохранялись только редкие эмоциональные; у 11 (57,8%) приступы стали значительно реже. Не уменьшилась частота приступов у 4 (21,1%) пациентов. Хорошие результаты чаще удавалось достичь при средней дозе в мишени выше 20–22 Гр, минимальной дозе более 7–10 Гр, покрытии предписанной дозой не менее 70–80%, а также у пациентов с практически полным покрытием всего объема ГГ дозой выше 12 Гр. Ни у одного пациента не было осложнений после СРХ. ВЫВОДЫ Стереотаксическая радиохирургия при корректно установленных показаниях является эффективным методом лечения структурной эпилепсии, обусловленной гамартомой гипоталамуса. Метод безопасен в отношении неврологических, эндокринных, зрительных и гипоталамических функций. Оптимальными кандидатами для стереотаксической радиохирургии на аппарате Гамма-нож являются дети, у которых приступы манифестировали в возрасте старше 1 года, с гамартомой объемом менее 3 см³ и площадью ее контакта с гипоталамусом не более 150 мм².

The study purpose was to evaluate the impact of gamma knife radiosurgery (GKRS) alone on the overall survival and rate of intracranial recurrences in brain metastasis patients. Treatment outcomes in 502 patients (211 males and 291 females with 2782 brain metastases (BMs)) were retrospectively reviewed. Most patients (n=142; 28.2%) were diagnosed with breast cancer. Multiple BMs were detected in 259 patients (51.6%). The median of the total tumor volume and ВM number was 5.9 cm3 (0.09-44.5 cm3) and 4 (1-36), respectively. The mean marginal radiation dose was 21 Gy (15-24 Gy). The mean follow-up period was 10.6 months (0.2-47.2 months). The overall survival rate for 12 and 24 months was 37.6 and 19.1%, respectively. The median overall survival after GKRS was 8.6 months (95% confidence interval (CI) 7.0-10.0). Local control of metastatic lesions was achieved in 78.8% of patients. The median local recurrence-free survival was 6.8 months after radiosurgery. The development of new (distant) metastases was observed in 49.5% of patients. The median distant metastasis-free time was 8.8 months. The Karnofsky performance score (KPS) of ≥80 (HR 0.3935, 95% CI 0.2429-0.6376; p=0.0002), BM number of <3 (HR 0.6138, 95% CI 0.3993-0.9943; p=0.0269), and BMs of breast and lung cancers (HR 0.5442, 95% CI 0.3642-0.8071; p=0.0027) are predictors of better survival. In the case of intracranial metastasis recurrence, repeated radiosurgery provides the median overall survival of 19.6 months versus 9.6 months in patients without radiosurgery (HR 0.4026, 95% CI 0.2381-0.6809). Radiosurgical treatment of patients with multiple BMs provides the median overall survival of 8.6 months. A good functional status, non-extensive metastasis of the brain, and radiosensitive morphology of the primary tumor are the predictors of better survival. Repeated radiosurgical treatment for intracranial recurrences provides longer overall survival compared to that in patients without repeated radiosurgical treatment.

Cerebral arteriovenous malformations (AVMs) are the congenital anomalies of development of cerebral vessels during the embryonic period. The conventional therapy for AVMs currently includes endovascular management, microneurosurgical resection, and stereotactic irradiation. A total of 315 patients with brain AVMs were subjected to stereotactic radiotherapy in 2005-2011. 238 (76%) patients had previous subarachnoid hemorrhage (SAH) within different time (6 months to 5 years) before the therapy; 214 (68%) patients had headaches; 113 (36%) patients had focal neurological symptoms caused by localization; and 82 (26%) patients had seizures. Twenty-three patients were subjected to surgical resection of an intracerebral hematoma prior to radiotherapy and 119 (36%) patients received endovascular treatment including partial embolization of the stroma of AVM. 267 patients received single-fraction radiosurgical irradiation. In patients with large AVMs, we used the hypofractionation technique consisting in target irradiation with several (usually 2-7) fractions; the radiation dose per fraction exceeds 2 Gy. Forty-six patients were irradiated in the hypofractionation mode; two patients had a course of stereotactic radiotherapy in the standard fractionation mode. The marginal dose of radiosurgical irradiation was 13-30 Gy (the average dose was 24 Gy). The main group of patients (38 individuals) with large AVMs was treated using hypofractionation of 35 Gy per 5 fractions. Control angiography was carried out in 225 patients who had been followed up for at least 2 years after therapy showed that complete obliteration was achieved in 83% of cases. The rate of symptomatic radiation reactions was less than 10%. The higher risk of developing obliteration was observed for AVMs less than 2 cm3 in size at marginal doses more than 24 Gy. In the hypofractionation group consisting of 27 patients with complete follow-up data, obliteration was observed in 10 (37%) patients. The rate of symptomatic reactions was less than 35%. The radiosurgical method is a minimally invasive choice of treatment for patients with brain AVM, which allows one to achieve sufficiently high degree of obliteration with the minimum complication rate. The hypofractionation procedure is the method of choice for treating large AVMs. Stereotactic irradiation using the Novalis linear accelerator makes it possible to treat patients with AVMs of virtually any location and volume.