Radiotherapy for GIST progressing during or after tyrosine kinase inhibitor therapy : A prospective study

Purpose: Gastrointestinal stromal tumor (GIST) has been considered radiation-resistant, and radiotherapy is recommended only for palliation of bone metastases in current treatment guidelines. No registered prospective trial has evaluated GIST responsiveness to radiotherapy. Patients and methods: Patients with GIST progressing at intra-abdominal sites or the liver were entered to this prospective Phase II multicenter study (identifier NCT00515931). Metastases were treated with external beam radiotherapy using either conformal 3D planning or intensity modulated radiotherapy and conventional fractionation to a cumulative planning target volume dose of approximately 40 Gy. Systemic therapy was maintained unaltered during the study. Results: Of the 25 patients entered, 19 were on concomitant tyrosine kinase inhibitor therapy, most often imatinib. Two (8%) patients achieved partial remission, 20 (80%) had stable target lesion size for >= 3 months after radiotherapy with a median duration of stabilization of 16 months, and 3 (12%) progressed. The median time to radiotherapy target lesion progression was 4-fold longer than the median time to GIST progression at any site (16 versus 4 months). Radiotherapy was generally well tolerated. Conclusions: Responses to radiotherapy were infrequent, but most patients had durable stabilization of the target lesions. GIST patients with soft tissue metastases benefit frequently from radiotherapy. (C) 2015 The Authors. Published by Elsevier Ireland Ltd.Peer reviewe

Virtual Reality Glasses and "Eye-Hands Blind Technique" for Microsurgical Training in Neurosurgery

OBJECTIVE: Microsurgical skills and eye-hand coordination need continuous training to be developed and refined. However, well-equipped microsurgical laboratories are not so widespread as their setup is expensive. Herein, we present a novel microsurgical training system that requires a high-resolution personal computer screen, smartphones, and virtual reality glasses. METHODS: A smartphone placed on a holder at a height of about 15-20 cm from the surgical target field is used as the webcam of the computer. A specific software is used to duplicate the video camera image. The video may be transferred from the computer to another smartphone, which may be connected to virtual reality glasses. RESULTS: Using the previously described training model, we progressively performed more and more complex microsurgical exercises. It did not take long to set up our system, thus saving time for the training sessions. CONCLUSION: Our proposed training model may represent an affordable and efficient system to improve eye-hand coordination and dexterity in using not only the operating microscope but also endoscopes and exoscopes.Peer reviewe

Papillary Tumor of the Pineal Region in Children : Presentation of a Case and Comprehensive Literature Review

BACKGROUND: Papillary tumor of the pineal region (PTPR) is a rare grade II-III pineal lesion with peculiar histological and immunohistochemical features. These tumors mostly occur in adults, only rarely in children, with 19 cases reported up to now. CASE DESCRIPTION: We present a 3-year-old boy who underwent reoperation for a recurrent PTPR (grade II). Gross total resection of the lesion through an occipital interhemispheric approach with the patient in a sitting position was followed by adjuvant radiotherapy and chemotherapy. Histological examination revealed tumor progression (grade III) and an MIB-1 proliferation index >25%. The patient continues to do well with no evidence of recurrence more than 3 years following surgery. A comprehensive literature review regarding the PTPR, including the current management in children, is reported. CONCLUSIONS: PTPRs are extremely rare in children, and immunohistochemistry is needed to differentiate them from other pineal tumors. These tumors show a high rate of recurrence, and a multidisciplinary management approach (microsurgical resection followed by radiotherapy and/or chemotherapy) can help achieve a favorable outcome.Peer reviewe

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English summaryPeer reviewe

Extent of Resection and Long-Term Survival of Pineal Region Tumors in Helsinki Neurosurgery

BACKGROUND: Pineal region tumors represent challenging surgical lesions with wide ranges of survival reported in different surgical series. In this article, we emphasize the role of complete microsurgical resection (CMR) to obtain a favorable long-term outcome of pineal region tumors. METHODS: We report a retrospective study of pineal region tumors operated on in Helsinki Neurosurgery between 1997 and 2015. Information was obtained from the hospital records, and an evaluation of the Finnish population register was conducted in July 2018 to determine the current status of the patients. RESULTS: A total of 76 pineal region tumors were operated on. The survival was 62% at a mean follow-up of 125 +/- 105 months (range, 0-588 months), and the disease-related mortality was limited to 14 patients (18.4%). Up to July 2018, 29 patients had died. Two patients died 1 and 3 months after surgery of delayed thalamic infarctions, 12 patients of disease progression, and 15 had non-disease-related deaths. Only 1 patient was lost in the long-term follow-up. Ten of 14 disease-related deaths occurred during the first 5 years of follow-up: 5 diffuse gliomas, 3 germ cell tumors, 1 grade II-III pineal parenchymal tumor of intermediate differentiation, and 1 meningioma. CMR was linked to better tumor-free survival and long-term survival, with the exception of diffuse gliomas. CONCLUSIONS: CMR, in the setting of a multidisciplinary management of pineal region tumors, correlates with favorable survival and with minimal mortality. Surgically treated grade II-IV gliomas constitute a particular group with high mortality within the first 5 years independently of the microsurgical resection.Peer reviewe

Intensity-based dual model method for generation of synthetic CT images from standard T2-weighted MR images - Generalized technique for four different MR scanners

Background and purpose: Recent studies have shown that it is possible to conduct entire radiotherapy treatment planning (RTP) workflow using only MR images. This study aims to develop a generalized intensity-based method to generate synthetic CT (sCT) images from standard T2-weighted (T2(W)) MR images of the pelvis. Materials and methods: This study developed a generalized dual model HU conversion method to convert standard T2(W) MR image intensity values to synthetic HU values, separately inside and outside of atlas-segmented bone volume contour. The method was developed and evaluated with 20 and 35 prostate cancer patients, respectively. MR images with scanning sequences in clinical use were acquired with four different MR scanners of three vendors. Results: For the generated synthetic CT (sCT) images of the 35 prostate patients, the mean (and maximal) HU differences in soft and bony tissue volumes were 16 +/- 6 HUs (34 HUs) and -46 +/- 56 HUs (181 HUs), respectively, against the true CT images. The average of the PTV mean dose difference in sCTs compared to those in true CTs was -0.6 +/- 0.4% (-1.3%). Conclusions: The study provides a generalized method for sCT creation from standard T2(W) images of the pelvis. The method produced clinically acceptable dose calculation results for all the included scanners and MR sequences. (c) 2017 Elsevier B.V. All rights reserved.Peer reviewe

Pineoblastomas : A long-term follow up study of three cases in Helsinki Neurosurgery

Background Pineoblastomas are very rare malignant lesions with a bad prognosis and high mortality during the first five years from diagnosis. Report of cases We present a retrospective review of three patients with histologically confirmed pineoblastomas consecutively operated on between 1997 and 2015. One of our patients died >14 years after surgery, and the other 2 patients are still alive and in good condition without recurrence of the disease >12 years after surgery. All of them underwent gross total resection and craniospinal radiotherapy. Individualized scheme of chemotherapy was administered in two cases. The cornerstones for the surgical resection of pineoblastomas are reported. Conclusions A proper multidisciplinary management of pineoblastomas, which associates gross total microsurgical resection of the lesion and an adjuvant therapy determined by our neurooncology team based on accurate craniospinal adjuvant radiotherapy with boost of radiation on the tumoral bed, and when needed, an adequate but aggressive medulloblastoma-like chemotherapy, may improve the overall survival of these malignant lesions.Peer reviewe

Microsurgical Management of Vascular Malformations of the Pineal Region

BACKGROUND: Vascular pineal malformations are rare and technically demanding lesions. Because the locations of these lesions, endovascular techniques and radiosurgery have been increasingly used in the recent decades to accomplish safe occlusion. Nevertheless, microsurgical treatment may be required sometimes. METHODS: We present a retrospective review of the vascular pineal malformations operated by the senior author. Moreover, we report illustrative cases for the various types of vascular lesions with a careful analysis of the different microsurgical stages. RESULTS: Eighteen patients with pineal vascular lesions were operated on between 1980 and 2015: 6 patients had vein of Galen malformations, 5 plexiform arteriovenous malformations, 6 cavernous malformations, and 1 patient had a ruptured medial posterior choroidal artery aneurysm. A complete resection and occlusion was possible in all vascular malformations. CONCLUSIONS: The pineal region is an infrequent but challenging location for vascular lesions. A careful and step-wise operative strategy for the different types of vascular lesion is paramount to accomplish an effective and safe microsurgical treatment when other alternatives fail or are not available.Peer reviewe

Retrospective four-dimensional magnetic resonance imaging of liver : Method development

Purpose of our research was to develop a four-dimensional (4D) magnetic resonance imaging (MRI) method of liver. Requirements of the method were to create a clinical procedure with acceptable imaging time and sufficient temporal and spatial accuracy. The method should produce useful planning image sets for stereotactic body radiation therapy delivery both during breath-hold and in free breathing. The purpose of the method was to improve the localization of liver metastasis. The method was validated with phantom tests. Imaging parameters were optimized to create a 4D dataset compressed to one respiratory cycle of the whole liver with clinically reasonable level of image contrast and artifacts. Five healthy volunteers were imaged with T2-weighted SSFSE research sequence. The respiratory surrogate signal was observed by the linear navigator interleaved with the anatomical liver images. The navigator was set on head-feet - direction on the superior surface of the liver to detect the edge of diaphragm. The navigator signal and 2D liver image data were retrospectively processed with a self-developed MATLAB algorithm. A deformable phantom for 4D imaging tests was constructed by combining deformable tissue-equivalent material and a commercial programmable motor unit of the 4D phantom with a clinically relevant range of deformation patterns. 4D Computed Tomography images were used as reference to validate the MRI protocol. The best compromise of reasonable accuracy and imaging time was found with 2D T2-weighted SSFSE imaging sequence using parameters: TR = 500-550 ms, images/slices = 20, slice thickness = 3 mm. Then, image processing with number of respiratory phases = 8 constructed accurate 4D images of liver. We have developed the 4D-MRI method visualizing liver motions three-dimensionally in one representative respiratory cycle. From phantom tests it was found that the spatial agreement to 4D-CT is within 2 mm that is considered sufficient for clinical applications.Peer reviewe

Synthetic computed tomography based dose calculation in prostate cancer patients with hip prostheses for magnetic resonance imaging-only radiotherapy

Background and purpose: Metallic hip prostheses cause substantial artefacts in both computed tomography (CT) and magnetic resonance (MR) images used in radiotherapy treatment planning (RTP) for prostate cancer patients. The aim of this study was to evaluate the dose calculation accuracy of a synthetic CT (sCT) generation workflow and the improvement in implant visibility using metal artefact reduction sequences. Materials and methods: The study included 23 patients with prostate cancer who had hip prostheses, of which 10 patients had bilateral hip implants. An in-house protocol was applied to create sCT images for dose calculation comparison. The study compared prostheses volumes and resulting avoidance sectors against planning target volume (PTV) dose uniformity and organs at risk (OAR) sparing. Results: Median PTV dose difference between sCT and CT-based dose calculation among all patients was 0.1 % (−0.4 to 0.4%) (median(range)). Bladder and rectum differences (V50Gy) were 0.2 % (−0.3 to 1.1%) and 0.1 % (−0.9 to 0.5%). The median 3D local gamma pass rate for partial arc cases using a Dixon MR sequence was Γ20%2mm/2% = 99.9%. For the bilateral full arc cases, using a metal artefact reconstruction sequence, the pass rate was Γ20%2mm/2% = 99.0%. Conclusions: An in-house protocol for generating sCT images for dose calculation provided clinically feasible dose calculation accuracy for prostate cancer patients with hip implants. PTV median dose difference for uni- and bilateral patients with avoidance sectors remained <0.4%. The Outphase images enhanced implant visibility resulting in smaller avoidance sectors, better OAR sparing, and improved PTV uniformity