bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphological redifferentiation in a malignant astrocytic tumor after gamma knife radiosurgery
Authors: Szeifert György T. , Massager Nicolas , Brotchi Jacques , Levivier Marc 
Published: November 2018

Object. The purpose of this study was to demonstrate positron emission tomography (PET), histological, and immunohistochemical data supporting the notion of morphological redifferentiation in a malignant astrocytic tumor after gamma knife radiosurgery (GKS).
Methods. The 11C- methionine-PET activity, Ki-67 labeling index (LI), and p53 protein expression were examined using immunohistochemical methods to assess tumor proliferative capacity. Tissue samples were obtained before and after radiosurgery in a patient with a malignant (Grade III) cerebellar astrocytoma.
Positron emission tomography scans obtained 5.5 months following radiosurgery were suggestive of decreased tumor proliferative capacity and radionecrosis. Histological examination of tumor tissue removed 42 months before GKS was characteristic of a diffuse Grade III astrocytoma in every part of the resected tumor. Similar material removed 6 months after GKS was consistent with a Grade II astrocytoma in the great majority of the resected tumor.
Conclusions. Histopathological examination showed positive phenotypic modification (redifferentiation) consistent with a Grade II astrocytoma in the majority of tumor specimens after radiosurgery. After GKS both the Ki-67 LI and p53 reaction decreased considerably as did 11C methionine uptake. Because p53 is one of the essential genes involved in the radiation response, mutations induced by the ionizing effect of gamma rays might promote partial repair of this gene's tumor suppressor function.
Effect of composite sector collimation on average dose fall-off for Gamma Knife Perfexion
Authors: Ma Lijun , Verhey Lynn , Chuang Cynthia , Descovich Martina , Smith Vernon , Huang Kim , McDermott Michael , Sneed Penny 
Published: November 2018

Object
The new capability of composite sector collimation in Gamma Knife Perfexion produces complex, nonspherical, and nonelliptical dose distributions. In this study, the authors investigated the effect of composite sector collimation on average dose fall-off compared with the previous Gamma Knife model.

Methods
A general formalism was derived to describe the peripheral dose distribution of all Gamma Knife models in the form of (V/V0) = (D/D0)γ, where V is the volume of the peripheral isodose line with the value of D, V0 is the reference prescription isodose volume, D0 is the prescription dose, and γ is the fitting parameter that determines how fast the dose falls off near the target. Based on this formula, the authors compared 40 cases involving patients treated with Gamma Knife Perfexion with 40 similar cases involving patients treated with Gamma Knife model 4C. The cases were grouped based on the use of the sector collimators in the treatment planning process. For each group as well as all cases combined, the mean γ values were compared by means of the Student t-test for varying ranges of the peripheral dose distribution—from 100% of the prescription dose to 75, 50, and 25% of the prescription dose.

Results
The fit of general formula to the data was excellent for both Gamma Knife Perfexion and Gamma Knife 4C with R2> 0.99 for all the cases. The overall γ values (mean ± 2 standard deviations) were as follows: γ = −1.74 ± 0.47 (Model 4C) versus −1.77 ± 0.40 (Perfexion) within 100–75% of the prescription dose; γ = −1.57 ± 0.26 (Model 4C) versus −1.58 ± 0.25 (Perfexion) within 100–50% of the prescription dose; γ = −1.47 ± 0.18 (Model 4C) versus −1.50 ± 0.16 (Perfexion) within 100–25% of the prescription dose. No statistical significance between the mean differences for Gamma Knife Perfexion and Model 4C was found within these ranges. The probability values were 0.65, 0.84, and 0.22, respectively.

Conclusions
The use of composite sector collimators in Gamma Knife Perfexion demonstrated no statistically significant effects on the volume-averaged dose fall-off near a target periphery for typical treatment cases.
Impact of ICP instability and hypotension on outcome in patients with severe head trauma
Authors: Marmarou Anthony , Anderson Randy L. , Ward John D. , Choi Sung C. , Young Harold F. , Eisenberg Howard M. , Foulkes Mary A. , Marshall Lawrence F. , Jane John A. 
Published: November 2018

✓ This study describes the relationship between raised intracranial pressure (ICP), hypotension, and outcome from severe head injury. The study is based on information derived from the Traumatic Coma Data Bank where ICP records from a relatively large number of patients were available to help delineate the major factors influencing outcome. From the total data base of 1030 patients, 428 met minimum monitoring duration criteria for inclusion in the present analysis. Outcome was classified according to the Glasgow Outcome Scale score determined at 6 months postinjury. Arrays of comparably defined summary measures describing the patient's course were considered for ICP, blood pressure (BP), central perfusion pressure, and therapy intensity level. For instance, the array of ICP summary descriptors included the proportion of ICP readings greater than x, for x = 0 to 80 mm Hg by increments of 5 mm Hg. A total of 187 candidate summary descriptors were considered. A stepwise ordinal logistic regression was used to select the subset of candidate summary descriptors that best explained the 6-month outcome.
As established previously, age, admission motor score, and abnormal pupils were each highly significant in explaining outcome. Beyond these factors, the proportion of hourly ICP readings greater than 20 mm Hg was next selected and was also highly significant in explaining outcome (p < 0.0001). In addition to the ICP factor, the cutoff point of 20 mm Hg was selected by the procedure as most indicative of outcome. With these four factors modeled, the next selected factor was the proportion of hourly BP readings less than 80 mm Hg. Again, the BP factor was highly significant in explaining outcome (p < 0.0001). As with the ICP factor, the BP cutoff point of 80 mm Hg was objectively selected as most indicative of outcome. In summary, the incidence of mortality and morbidity resulting from severe head trauma is strongly related to raised ICP and hypotension measured during the course of ICP management. Moreover, these ICP and BP factors provide a better indication of outcome than the similarly defined factors of central perfusion pressure or therapy intensity level.
Tolerance dose in gamma knife surgery of lesions extending to the anterior visual pathway
Authors: Kenai Hiroyuki , Yamashita Masanori , Nakamura Takaharu , Asano Tomoshige , Sainoh Michifumi , Nagatomi Hirofumi 
Published: November 2018

Object. The authors performed a retrospective analysis of the radiation dose to the anterior visual pathway (AVP) to assess its tolerance to gamma knife surgery.
Methods. They examined five cases followed for more than 3 years. The AVP was treated with 10-Gy doses or higher.
The mean maximum delivered dose to the AVP was 14 Gy. Ten gray or more was delivered to 25.5% of the ipsilateral AVP, 12 Gy or more to 12.5% of the ipsilateral AVP, and 14 Gy or more to 5.7% of the ipsilateral AVP. Although the mean follow-up period was 40.8 months (36–51 months), no cases of visual function deterioration developed.
Conclusions. The tolerance dose of the AVP is considered to be less than 8 to 10 Gy; however, although the delivered dose to the AVP definitely exceeded the tolerance dose in all five cases, no visual disturbance has been identified. Longer follow up is required before any final conclusions may be drawn. Nonetheless, it is suggested that a visual disturbance may be avoided by using careful accurate dose planning even if the dose delivered to the AVP is higher than currently believed to be acceptable.
Gamma knife surgery for refractory postherpetic trigeminal neuralgia: targeting in one session both the retrogasserian trigeminal nerve and the centromedian nucleus of the thalamus
Authors: Keep Marcus F. , DeMare Paul A. , Ashby Lynn S. 
Published: November 2018

Object. The authors tested the hypothesis that two targets are needed to treat postherpetic trigeminal neuralgia (TN): one in the trigeminal nerve for the direct sharp pain and one in the thalamus for the diffuse burning pain.
Methods. Three patients with refractory postherpetic TN were treated with gamma knife surgery (GKS) through a novel two-target approach. In a single treatment session, both the trigeminal nerve and centromedian nucleus were targeted. First, the trigeminal nerve, ipsilateral to the facial pain, was treated with 60 to 80 Gy. Second, the centromedian nucleus was localized using standard coordinates and by comparing magnetic resonance images with a stereotactic atlas. A single dose of 120 to 140 Gy was delivered to the target point with a single 4-mm isocenter. Patients were followed clinically and with neuroimaging studies. Pain relief was scored as excellent (75–100%), good (50–75%), poor (25–50%), or none (0–25%). Follow up ranged from 6 to 53 months.
There were no GKS-related complications. Two patients died of unrelated medical illnesses but had good or excellent pain relief until death. One patient continues to survive with 44 months follow up and no decrease in pain intensity, but with a decreased area of pain.
Conclusions. Combined GKS of the centromedian nucleus and trigeminal nerve in a single treatment session is feasible and safe, and the effect was promising. A larger study is required to confirm and expand these results.
Image-guided microradiosurgery for skull base tumors: advantages of using gadolinium-enhanced constructive interference in steady-state imaging
Authors: Hayashi Motohiro , Ochiai Taku , Nakaya Kotaro , Chernov Mikhail , Tamura Noriko , Yomo Shoji , Izawa Masahiro , Hori Tomokatsu , Takakura Kintomo , Regis Jean 
Published: November 2018

✓Gamma Knife surgery (GKS) is image-guided surgery for brain tumors. Precise tumor visualization is needed in dose planning to control tumor progression. The surrounding vital structures must also be clearly defined to allow the preservation of their function. A special magnetic resonance (MR) imaging sequence was chosen for use with GKS to treat skull base and suprasellar tumors.Gadolinium-enhanced 0.5-mm constructive interference in steady-state (CISS) slices were obtained in skull base and suprasellar tumors. Each structure that was adjacent to the tumor could be visualized more clearly by using this imaging technique because the tumor became transparent even though there was no change in the appearance of the surrounding structures after injection of Gd. Use of this technique in acoustic tumors allowed the seventh and eighth cranial nerves to be visualized in the cisternal and intrameatal portions; both of which were distinguishable from the tumor. Suprasellar tumor could be distinguished from the adjacent optic pathway. The use of Gd-enhanced CISS imaging allowed for optimal dose planning with very high conformity in every tumor. Achieving this high conformity allowed the preservation of adjacent structures and their functions.Establishing optimal dose planning in brain tumors is very important to overcome the problem of producing new neurological deficits in patients who may already be suffering disease-related deficits. The use of this special CISS MR imaging sequence may help accomplish this goal.
Gamma Knife surgery for primary central nervous system lymphoma: usefulness as palliative local tumor control
Authors: Kenai Hiroyuki , Yamashita Masanori , Nakamura Takaharu , Asano Tomoshige , Momii Yasutomo , Nagatomi Hirofumi 
Published: November 2018

ObjectAlthough there is no established treatment for primary central nervous system lymphoma (PCNSL), therapeutic protocols involving high-dose methotrexate therapy followed, in some cases, by whole-brain radiotherapy (WBRT) have generally been adopted, and they have yielded relatively favorable results. Gamma Knife surgery (GKS) is a stopgap measure to treat patients with PCNSL. The authors summarize the results of their cases and evaluate the efficacy and usefulness of GKS.MethodsBetween June 1999, and June 2005, 22 patients suffering from PCNSL were treated with GKS at the authors' institution and were followed up for more than 6 months. Some combination of chemotherapy and/or WBRT and/or microsurgery had been performed in 18 of the 22 patients before GKS. The remaining four patients had not undergone any previous treatment. In these patients, the mean tumor volume was 4.14 cm3, and the tumors were treated with a mean margin dose of 16.5 Gy to the 52.8% isodose line. Magnetic resonance imaging demonstrated the disappearance of the GKS-treated lesions; however, new lesions were observed in other regions of the brain in 10 patients and repeated GKS was performed in some cases. No local recurrences were observed an average of 19.4 months after GKS, and good level of quality of life (QOL) was maintained during this period.Conclusions Gamma Knife surgery should be performed only for local tumor control as a stopgap measure in the treatment of PCNSL. It is noninvasive and safe, and its effects occur rapidly. Its use improves prognosis and enhances the patient's quality of life. Gamma Knife surgery should be considered one of the treatment strategies for patients with PCNSLs.
Preservation of quality of life by preradiotherapy stereotactic radiosurgery for unresectable glioblastoma multiforme
Authors: Kong Doo-Sik , Nam Do-Hyun , Lee Jung-Il , Park Kwan , Kim Jong Hyun 
Published: November 2018

ObjectThe authors conducted a retrospective study to evaluate the efficacy of Gamma Knife surgery (GKS) followed by radiotherapy for the treatment of unresectable glioblastomas multiforme (GBMs) on patient survival and quality of life.MethodsA total of 19 patients with unresectable GBMs located in eloquent areas of the brain were eligible for this study. Beginning in January 2002, 10 patients underwent GKS followed by fractionated radiotherapy. Nine patients who had undergone radiotherapy alone after biopsy-proven diagnosis served as the control group. The mean patient ages were 53 years and 56 years, respectively. Preoperative Karnofsky Performance Scale (KPS) scores were 80 (range 60–100) and 90 (range 50–100), respectively. The median margin dose for GKS was 12 Gy (9–16 Gy), and the total dose for radiotherapy was 60 Gy in 30 fractions. The mean follow-up duration was 7.2 months, the median patient survival time was 52 weeks (95% confidence interval [CI] 22–110.6 weeks) in the GKS group, and the median overall survival time was 28 weeks (95% CI 22.5–33.5 weeks) in the control group. The difference was not statistically significant (p = 0.0758). The estimated progression-free survival rate at 3 months was 75% in the GKS group and 45% in the control group (p = 0.082). The posttreatment KPS scores were either unchanged or improved in the GKS group, whereas it deteriorated by 20 or more points in six of nine patients of the control group (p = 0.004).Conclusions Gamma Knife surgery prior to radiotherapy may be helpful in preserving patients' daily activities in the adjuvant management of unresectable GBM.
Combination of microsurgery and Gamma Knife surgery for the treatment of intracranial chondrosarcomas
Authors: Förander Petter , Rähn Tiit , Kihlström Lars , Ulfarsson Elfar , Mathiesen Tiit 
Published: November 2018

ObjectIntracranial chondrosarcomas have a high risk of recurrence after surgery. This retrospective study of patients with intracranial chondrosarcoma was conducted to determine the long-term results of microsurgery followed by Gamma Knife surgery (GKS) for residual tumor or recurrence.MethodsThe authors treated nine patients whose median age was 36 years. Seven patients had low-grade chondrosarcomas (LGCSs), whereas mesenchymal chondrosarcomas (MCSs) were diagnosed in two. Radiosurgery was performed in eight patients, whereas one patient declined further surgical intervention and tumor-volume reduction necessary for the GKS.The patients were followed up for 15 to 173 months (median 108 months) after diagnosis and 3 to 166 months (median 88 months) after GKS. Seven patients had residual tumor tissue after microsurgery, and two operations appeared radical. In the two latter cases, tumors recurred after 25 and 45 months. Thus, definite tumor control was not achieved after surgery alone in any patient, whereas the addition of radiosurgery allowed tumor control in all six patients with LGCSs. Two of these patients experienced an initial tumor regrowth after GKS; in both cases the recurrences were outside the prescribed radiation field. The patients underwent repeated GKS, and subsequent tumor control was observed. An MCS was diagnosed in the remaining two patients. Complications after microsurgery included diplopia, facial numbness, and paresis. After GKS, one patient had radiation necrosis, which required microsurgery, and two patients had new cranial nerve palsies.Conclusions Tumor control after microsurgery alone was not achieved in any patient, whereas adjuvant radiosurgery provided local tumor control in six of eight GKS-treated patients. Tumor control was not achieved in the two patients with MCS. Similar to other treatments for intracranial chondrosarcoma, morbidity after micro- and radiosurgical combination therapy was high and included severe cranial nerve palsies.
A simple treatment planning strategy for patients with multiple metastases treated with Gamma Knife surgery
Authors: Douglas James G. , Goodkin Robert 
Published: November 2018

ObjectIn a substantial number of patients treated at the authors' facility for brain metastases, additional lesions are identified at the time of Gamma Knife surgery (GKS). These lesions are often widely dispersed and may number over 10, which is the maximal number of matrices that can be currently placed for treatment with Leksell Gamma-Plan 4C. The authors describe a simple planning method for GKS in patients with multiple, widely dispersed central nervous system (CNS) metastases.MethodsTwo patients presented with three to five identified recurrent metastases from non–small cell lung carcinoma and breast carcinoma after having received whole-brain radiotherapy. At the time of treatment with GKS in each patient, spoiled-gradient Gd-enhanced magnetic resonance (MR) imaging revealed substantially more metastases than originally thought, which were widely scattered throughout all regions of the brain. The authors simplified the treatment planning approach by dividing the entire CNS contents into six contiguous, nonoverlapping matrices, which allowed for the planning, calculation, and treatment of all lesions.Two patients were successfully treated with GKS for more than 10 CNS metastases by using this simple planning method. Differing peripheral doses to varied-size lesions were delivered by prescribing to different isodose curves within any given matrix when required. Dose–volume histograms showed brain doses as follows: 10% of the total brain volume received 5 to 6.4 Gy; 25% received 3.8 to 4.8 Gy; 50% received 2.7 to 3.1 Gy; and 75% received 2.2 to 2.5 Gy.Conclusions The delineation of more metastases than appreciated on the diagnostic MR imaging is a common occurrence at the time of GKS at the authors' institution. The treatment of multiple (>10), widely dispersed CNS metastases can be simplified by the placement of multiple, contiguous, non-overlapping matrices, which can be employed to treat lesions in all areas of the brain when separate matrices cannot be utilized.
Gamma Knife surgery for invasive pituitary macroadenoma
Authors: Kim Mooseong , Paeng Sunghwa , Pyo Seyoung , Jeong Yeonggyun , Lee Sunil , Jung Yongtae 
Published: November 2018

ObjectPituitary adenomas have been treated using a variety of modalities including resection, medication, fractionated radiotherapy, and stereotactic radiosurgery. The policy has been that all adenomas should first be treated with resection to reduce the volume of the tumor. The authors' study was conducted to determine the efficacy of using Gamma Knife surgery (GKS) for pituitary adenomas invading the cavernous sinus.MethodsOf 397 patients with pituitary tumors who underwent GKS between October 1994 and October 2005, 68 patients had pituitary macroadenomas invading the cavernous sinus. Sixty-seven cases were available for follow up. The mean age of the patients in these cases was 42.8 years (range 14–73 years). The male/female ratio was 0.8:1. The mean adenoma volume was 9.3 cm3. A total of 24 patients had undergone craniotomies and resection, and 11 patients had undergone transsphenoidal surgery prior to GKS. The mean follow-up period was 32.8 months. Tumor control was defined as a decrease or no change in tumor volume after GKS. Endocrinological improvement was defined as a decline in hormone levels to below 50% of the pre-GKS level.Tumor control was achieved in 95.5% of the cases. Endocrinological improvement was achieved in 68% of 25 patients. One patient suffered hypopituitarism after GKS.Conclusions Gamma Knife surgery is a safe and effective treatment for invasive pituitary macroadenoma with few complications.
Stereotactic radiosurgery for metastatic tumors in the pituitary gland and the cavernous sinus
Authors: Mori Yoshimasa , Kobayashi Tatsuya , Shibamoto Yuta 
Published: November 2018

ObjectMetastases to the pituitary gland and cavernous sinus occasionally occur. Metastases of this nature are problematic because they are adjacent to eloquent structures such as cranial nerves, including the optic pathways and nerves for extraocular movement and facial sensation. Stereotactic radiosurgery has been reported to be safe and effective for metastases in various sites of brain parenchyma, providing the tumors are not large. Radiosurgery can be performed to treat a precisely defined target, and the risk of radiation side effects on the surrounding structures is reduced. The results of Gamma Knife surgery (GKS) for the treatment of metastases in the pituitary gland and the cavernous sinus are evaluated.MethodsAmong 623 patients with brain metastases treated by GKS, 13 patients (2.1%) had pituitary and/or cavernous metastases. The primary malignancies included lung cancer (five cases), breast cancer (two cases), parotid cancer (two cases), renal cell carcinoma, thyroid cancer, nasal cancer, and gastrointestinal stromal tumor (one case each). The location of the tumors was the pituitary gland (Type 1) in four patients, the cavernous sinus (Type 2) in five patients, and both the cavernous sinus and the sellar region (Type 3) in four patients. The patients' symptoms included dysfunction of the pituitary gland (two patients), visual disturbance (four patients), oculomotor palsy (one patient), abducent palsy (five patients), and trigeminal dysfunction (five patients). A margin dose of 12 to 12.3 Gy was delivered to pituitary metastases. A margin dose of 14.4 to 20 Gy was delivered to cavernous lesions. The dose selection depended on the spatial relationship between tumors and the cranial nerves. Imaging and clinical follow-up data have been obtained in nine of 13 patients for 2 to 12 months (median 4 months) after GKS. Three pituitary and/or cavernous tumors are stable in size, and six tumors have disappeared or decreased in size; full or partial improvement of visual function, extraocular movement, and facial sensation have been achieved in these six patients.Conclusions These preliminary results seem to indicate that GKS is a safe and effective treatment for pituitary and cavernous metastases, as it is effective for parenchymal metastases and promptly improved some patients' symptoms.