Arcuate fasciculus tractography integrated into Gamma Knife surgery

2009 ◽  
Vol 111 (3) ◽  
pp. 520-526 ◽  
Author(s):  
Keisuke Maruyama ◽  
Tomoyuki Koga ◽  
Kyousuke Kamada ◽  
Takahiro Ota ◽  
Daisuke Itoh ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Treatment Planning ◽  
Gamma Knife ◽  
Arteriovenous Malformations ◽  
Diffusion Tensor ◽  
Gamma Knife Surgery ◽  
Arcuate Fasciculus ◽  
Motor Aphasia ◽  
Diffusion Tensor Images ◽  
Temporal Language

Object To prevent speech disturbances after Gamma Knife surgery (GKS), the authors integrated arcuate fasciculus (AF) tractography based on diffusion tensor (DT) MR imaging into treatment planning for GKS. Methods Arcuate fasciculus tractography was retrospectively integrated into planning that had been previously performed by neurosurgeons and radiation oncologists. This technique was retrospectively applied to 12 patients with arteriovenous malformations adjacent to the AF. Diffusion tensor images were acquired before the frame was affixed to the patient's head and DT tractography images of the AF were created using the authors' original software. The data from DT tractography and stereotactic 3D imaging studies obtained after frame fixation were transported to a treatment planning workstation for GKS and coregistered so that the delivered doses and incidence of posttreatment aphasia could be assessed. Results The AF could not be depicted in 2 patients who initially presented with motor aphasia caused by hemorrhaging from arteriovenous malformations. During the median follow-up period of 29 months after GKS, aphasia developed in 2 patients: 30 Gy delivered to the frontal portion of the AF caused conduction aphasia in 1 patient, and 9.6 Gy to the temporal portion led to motor aphasia in the other. Speech dysfunction was not observed after a maximum radiation dose of 10.0–16.8 Gy was delivered to the frontal fibers in 4 patients, and 3.6–5.2 Gy to the temporal fibers in 3. Conclusions The authors found that administration of a 10-Gy radiation dose during GKS was tolerated in the frontal but not the temporal fibers of the AF. The authors recommend confirmation of the dose by integration of AF tractography with GKS, especially in lesions located near the temporal language fibers.

Optic radiation tractography integrated into simulated treatment planning for Gamma Knife surgery

2007 ◽  
Vol 107 (4) ◽  
pp. 721-726 ◽  
Author(s):  
Keisuke Maruyama ◽  
Kyousuke Kamada ◽  
Masahiro Shin ◽  
Daisuke Itoh ◽  
Yoshitaka Masutani ◽  
...  
Keyword(s):  
Visual Field ◽  
Treatment Planning ◽  
Gamma Knife ◽  
Diffusion Tensor ◽  
Maximum Dose ◽  
Gamma Knife Surgery ◽  
Optic Radiation ◽  
Imaging Studies ◽  
Visual Field Deficits ◽  
Neurological Change

Object No definitive method of preventing visual field deficits after stereotactic radiosurgery for lesions near the optic radiation (OR) has been available so far. The authors report the results of integrating OR tractography based on diffusion tensor (DT) magnetic resonance imaging into simulated treatment planning for Gamma Knife surgery (GKS). Methods Data from imaging studies performed in 10 patients who underwent GKS for treatment of arteriovenous malformations (AVMs) located adjacent to the OR were used for the simulated treatment planning. Diffusion tensor images performed without the patient's head being secured by a stereotactic frame were used for DT tractography, and the OR was visualized by means of software developed by the authors. Data from stereotactic 3D imaging studies performed after frame fixation were coregistered with the data from DT tractography. The combined images were transferred to a GKS treatment-planning workstation. Delivered doses and distances between the treated lesions and the OR were analyzed and correlated with posttreatment neurological changes. Results In patients presenting with migraine with visual aura or occipital lobe epilepsy, the OR was located within 11 mm from AVMs. In a patient who developed new quadrantanopia after GKS, the OR had received 32 Gy. A maximum dose to the OR of less than 12 Gy did not cause new visual field deficits. A maximum dose to the OR of 8 Gy or more was significantly related to neurological change (p < 0.05), including visual field deficits and development or improvement of migraine. Conclusions Integration of OR tractography into GKS represents a promising tool for preventing GKS-induced visual disturbances and headaches. Single-session irradiation at a dose of 8 Gy or more was associated with neurological change.

Integration of three-dimensional corticospinal tractography into treatment planning for gamma knife surgery

2005 ◽  
Vol 102 (4) ◽  
pp. 673-677 ◽  
Author(s):  
Keisuke Maruyama ◽  
Kyousuke Kamada ◽  
Masahiro Shin ◽  
Daisuke Itoh ◽  
Shigeki Aoki ◽  
...  
Keyword(s):  
Treatment Planning ◽  
Gamma Knife ◽  
Diffusion Tensor ◽  
Three Dimensional ◽  
Spatial Relationship ◽  
Gamma Knife Surgery ◽  
Univariate Logistic Regression Analysis ◽  
Content Type ◽  
Combined Images ◽  
Fine Print

Object. In the radiosurgical treatment of critically located lesions, the effort to minimize the risk of complication is essential. In this study the integration of diffusion-tensor (DT) imaging—based tractography was clinically applied to treatment planning for gamma knife surgery (GKS). Methods. Seven patients with cerebral arteriovenous malformations located adjacent to the corticospinal tract (CST) underwent this technique. Data provided by DT imaging were acquired before the frame was affixed to the patient's head and the CST of the DT tractography was created using our original software. Stereotactic three-dimensional imaging studies were obtained after frame fixation and then coregistered with the data from DT tractography. After image fusion of the two studies, the combined images were transported to a GKS treatment-planning workstation. The spatial relationship between the dose distribution and the CST was clearly demonstrated within the 2 hours it took to complete the entire imaging process. The univariate logistic regression analysis of transient or permanent motor complications revealed a significant independent correlation with the volume of the CST that received 25 Gy or more and with a maximum dose to the CST (p < 0.05). Conclusions. The integration of DT tractography into the GKS treatment planning was highly useful in confirming the dose to the CST during treatment planning.

A simple treatment planning strategy for patients with multiple metastases treated with Gamma Knife surgery

2006 ◽  
Vol 105 (Supplement) ◽  
pp. 2-4 ◽  
Author(s):  
James G. Douglas ◽  
Robert Goodkin
Keyword(s):  
Mr Imaging ◽  
Treatment Planning ◽  
Gamma Knife ◽  
Gamma Knife Surgery ◽  
Planning Method ◽  
Cns Metastases ◽  
Cell Lung Carcinoma ◽  
Dose Volume Histograms ◽  
Number Of Patients ◽  
The Brain

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 trigeminal neuralgia: improved initial response with two isocenters and increasing dose

2005 ◽  
Vol 102 (Special_Supplement) ◽  
pp. 185-188 ◽  
Author(s):  
Tracy E. Alpert ◽  
Chung T. Chung ◽  
Lisa T. Mitchell ◽  
Charles J. Hodge ◽  
Craig T. Montgomery ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Trigeminal Neuralgia ◽  
Gamma Knife ◽  
Linear Regression Analysis ◽  
Initial Response ◽  
Gamma Knife Surgery ◽  
Invasive Treatment ◽  
Content Type ◽  
Improvement Score ◽  
Fine Print

Object. The authors sought to evaluate the initial response of trigeminal neuralgia (TN) to gamma knife surgery (GKS) based on the number of shots delivered and radiation dose. Methods. Between September 1998 and September 2003, some 63 patients with TN refractory to medical or surgical management underwent GKS at Upstate Medical University. Ten patients had multiple sclerosis and 25 patients had undergone prior invasive treatment. Gamma knife surgery was delivered to the trigeminal nerve root entry zone in one shot in 27 patients or two shots in 36 patients. The radiation dose was escalated to less than or equal to 80 Gy in 20 patients, 85 Gy in 21 patients, and greater than or equal to 90 Gy in 22 patients. Pain before and after GKS was assessed using the Barrow Neurological Institute Pain Scale and the improvement score was analyzed as a function of dose grouping and number of shots. Sixty patients were available for evaluation, with an initial overall and complete response rate of 90% and 27%, respectively. There was a greater improvement score for patients who were treated with two shots compared with one shot, mean 2.83 compared with 1.72 (p < 0.001). There was an increased improvement in score at each dose escalation level: less than or equal to 80 Gy (p = 0.017), 85 Gy (p < 0.001), and greater than or equal to 90 Gy (p < 0.001). Linear regression analysis also indicated that there was a greater response with an increased dose (p = 0.021). Patients treated with two shots were more likely to receive a higher dose (p < 0.001). There were no severe complications. Five patients developed mild facial numbness. Conclusions. Gamma knife surgery is an effective therapy for TN. Initial response rates appear to correlate with the number of shots and dose.

scholarly journals Stereotactic diffusion tensor imaging tractography for Gamma Knife radiosurgery

2016 ◽  
Vol 125 (Supplement_1) ◽  
pp. 139-146 ◽  
Author(s):  
Cormac G. Gavin ◽  
H. Ian Sabin
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Stereotactic Radiosurgery ◽  
Treatment Planning ◽  
Vestibular Schwannoma ◽  
Diffusion Tensor ◽  
Gamma Knife Radiosurgery ◽  
Optic Radiation ◽  
Arcuate Fasciculus ◽  
Stereotactic Frame

OBJECTIVEThe integration of modern neuroimaging into treatment planning has increased the therapeutic potential and safety of stereotactic radiosurgery. The authors report their method of integrating stereotactic diffusion tensor imaging (DTI) tractography into conventional treatment planning for Gamma Knife radiosurgery (GKRS). The aim of this study was to demonstrate the feasibility of this technique and to address some of the technical limitations of previously reported techniques.METHODSTwenty patients who underwent GKRS composed the study cohort. They consisted of 1 initial test case (a patient with a vestibular schwannoma), 5 patients with arteriovenous malformations, 9 patients with cerebral metastases, 1 patient with parasagittal meningioma, and 4 patients with vestibular schwannoma. DT images were obtained at the time of standard GKRS protocol MRI (T1 and T2 weighted) for treatment, with the patient's head secured by a Leksell stereotactic frame. All studies were performed using a 1.5-T magnet with a single-channel head coil. DTI was performed with diffusion gradients in 32 directions and coregistered with the volumetric T1-weighted study. DTI postprocessing by means of commercially available software allowed tensor computation and the creation of directionally encoded color–, apparent diffusion coefficient–, and fractional anisotropy–mapped sequences. In addition, the software allowed visualized critical tracts to be exported as a structural volume and integrated into GammaPlan as an “organ at risk” during shot planning. Combined images were transferred to GammaPlan and integrated into treatment planning.RESULTSStereotactic DT images were successfully acquired in all patients, with generation of correct directionally encoded color images. Tract generation with the software was straightforward and reproducible, particularly for axial tracts such as the optic radiation and the arcuate fasciculus. Corticospinal tract visualization was hampered by some artifacts from the base of the stereotactic frame, but this was overcome by a combination of frame/MRI volume adjustment and DTI seeding parameters. Coregistration of the DTI series with the T1-weighted treatment volume at the time of imaging was essential for the generation of correct tensor data. All patients with the exception of the vestibular schwannoma cases had treatment pathology in the vicinity of eloquent tracts and/or the cortex. No new neurological deficits due to radiation were recorded at the short-term follow-up.CONCLUSIONSRecent reports in the medical literature have suggested that white matter tracts (particularly the optic radiation and arcuate fasciculus) are more vulnerable to radiation during stereotactic radiosurgery than previously thought. Integration of stereotactic tractography into GKRS represents a promising tool for preventing GKRS complications by reduction in radiation doses to functional organs at risk, including critical cortical areas and subcortical white matter tracts.

scholarly journals Gamma Knife surgery for incidental cerebral arteriovenous malformations

2014 ◽  
Vol 121 (5) ◽  
pp. 1015-1021 ◽  
Author(s):  
Chun-Po Yen ◽  
Dale Ding ◽  
Ching-Hsiao Cheng ◽  
Robert M. Starke ◽  
Mark Shaffrey ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Arteriovenous Malformations ◽  
Latency Period ◽  
Invasive Procedure ◽  
Gamma Knife Surgery ◽  
Neurological Deficits ◽  
Cerebral Arteriovenous Malformations ◽  
Long Term Follow Up

Object A relatively benign natural course of unruptured cerebral arteriovenous malformations (AVMs) has recently been recognized, and the decision to treat incidentally found AVMs has been questioned. This study aims to evaluate the long-term imaging and clinical outcomes of patients with asymptomatic, incidentally discovered AVMs treated with Gamma Knife surgery (GKS). Methods Thirty-one patients, each with an incidentally diagnosed AVM, underwent GKS between 1989 and 2009. The nidus volumes ranged from 0.3 to 11.1 cm3 (median 3.2 cm3). A margin dose between 15 and 26 Gy (median 20 Gy) was used to treat the AVMs. Four patients underwent repeat GKS for still-patent AVM residuals after the initial GKS procedure. Clinical follow-up ranged from 24 to 196 months, with a mean of 78 months (median 51 months) after the initial GKS. Results Following GKS, 19 patients (61.3%) had a total AVM obliteration on angiography. In 7 patients (22.6%), no flow voids were observed on MRI but angiographic confirmation was not available. In 5 patients (16.1%), the AVMs remained patent. A small nidus volume was significantly associated with increased AVM obliteration rate. Thirteen patients (41.9%) developed radiation-induced imaging changes: 11 were asymptomatic (35.5%), 1 had only headache (3.2%), and 1 developed seizure and neurological deficits (3.2%). Two patients each had 1 hemorrhage during the latency period (116.5 risk years), yielding an annual hemorrhage rate of 1.7% before AVM obliteration. Conclusions The decision to treat asymptomatic AVMs, and if so, which treatment approach to use, remain the subject of debate. GKS as a minimally invasive procedure appears to achieve a reasonable outcome with low procedure-related morbidity. In those patients with incidental AVMs, the benefits as well as the risks of radiosurgical intervention will only be fully defined with long-term follow-up.

Radiosurgery of isolated cerebral vessels following administration of paclitaxel in the rat

2006 ◽  
Vol 105 (Supplement) ◽  
pp. 214-221 ◽  
Author(s):  
Otto Major ◽  
Lee Walton ◽  
John Goodden ◽  
Matthias Radatz ◽  
Georg Tamas Szeifert ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Gamma Radiation ◽  
Gamma Knife ◽  
Time Course ◽  
Vascular Reactivity ◽  
Gamma Knife Surgery ◽  
Survival Times ◽  
Ki 67 ◽  
Risk Of Hemorrhage

ObjectProgressive obliteration occurs in arteriovenous malformations (AVMs) after radiosurgery; however, the risk of hemorrhage remains until the obliteration process is complete. The authors sought to enhance the radiation effect and reduce the risk of hemorrhage by facilitating faster vessel obliteration. To that end, a combination of a lower radiation dose with the addition of a radiosensitizing agent was compared with the effect of a higher radiation dose alone.MethodsUsing a method described by Mulvany and Halpern, isometric myography measurements were made on isolated rat middle cerebral artery specimens. The vessels were treated with 200 Gy, 80 Gy, 50 Gy, 25 Gy, 20 Gy, or 15 Gy by using Gamma Knife surgery. Taxol (paclitaxel 3 mg/kg/body weight) was administered intravenously to the animals. Survival times posttreatment were 24 hours, 6 weeks, 12 weeks, 12 months, or 18 months. After dissection, the middle cerebral arteries were mounted on a small-vessel myograph, and contraction and relaxation studies were performed.In a second series of experiments these results were validated in human fibroblast culture. When the cultures were 75 to 80% colonized, the samples were treated in vitro with 60Co gamma radiation in similar doses with or without paclitaxel.Conclusions Constriction responses were generally decreased in the paclitaxel-treated vessels. Differences were significant at 6 weeks (p < 0.05) and at 1 year (p < 0.05). After 1 year, in the paclitaxel-treated groups vascular reactivity was completely abolished in vessels receiving 50 Gy. In comparison, it took 6 months longer (18 months) for this reaction to be abolished in vessels without paclitaxel treatment.In tissue cultures Giemsa staining and immunohistochemical reactions for p53, Ki-67, CD-34, and SMA antigens revealed marked fibroblast hypertrophy in all of the paclitaxel-treated groups. Paclitaxel-treated vessels demonstrated decreased reactivity at significantly earlier stages than vessels that had not been treated. It would appear that paclitaxel causes acceleration in the time course of the late biological effect of gamma radiation. This beneficial effect could be used in Gamma Knife surgery in patients with AVMs, thus reducing the risk of posttreatment hemorrhage.

Long-term complications after gamma knife surgery for arteriovenous malformations

2005 ◽  
Vol 102 (Special_Supplement) ◽  
pp. 34-37 ◽  
Author(s):  
Masahiro Izawa ◽  
Motohiro Hayashi ◽  
Mikhail Chernov ◽  
Koutarou Nakaya ◽  
Taku Ochiai ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Arteriovenous Malformations ◽  
Cyst Formation ◽  
Gamma Knife Surgery ◽  
Content Type ◽  
Delayed Hemorrhage ◽  
Complete Obliteration ◽  
Risk Of Hemorrhage ◽  
Fine Print

Object. The authors analyzed of the long-term complications that occur 2 or more years after gamma knife surgery (GKS) for intracranial arteriovenous malformations (AVMs). Methods. Patients with previously untreated intracranial AVMs that were managed by GKS and followed for at least 2 years after treatment were selected for analysis (237 cases). Complete AVM obliteration was attained in 130 cases (54.9%), and incomplete obliteration in 107 cases (45.1%). Long-term complications were observed in 22 patients (9.3%). These complications included hemorrhage (eight cases), delayed cyst formation (eight cases), increase of seizure frequency (four cases), and middle cerebral artery stenosis and increased white matter signal intensity on T2-weighted magnetic resonance imaging (one case of each). The long-term complications were associated with larger nidus volume (p < 0.001) and a lobar location of the AVM (p < 0.01). Delayed hemorrhage was associated only with incomplete obliteration of the nidus (p < 0.05). Partial obliteration conveyed no benefit. Delayed cyst formation was associated with a higher maximal GKS dose (p < 0.001), larger nidus volume (p < 0.001), complete nidus obliteration (p < 0.01), and a lobar location of the AVM (p < 0.05). Conclusions. Incomplete obliteration of the nidus is the most important factor associated with delayed hemorrhagic complications. Partial obliteration does not seem to reduce the risk of hemorrhage. Complete obliteration can be complicated by delayed cyst formation, especially if high maximal treatment doses have been administered.

scholarly journals Repeat Gamma Knife Surgery for Incompletely Obliterated Cerebral Arteriovenous Malformations

Neurosurgery ◽  
2010 ◽  
Vol 67 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Chun-Po Yen ◽  
Surbhi Jain ◽  
Iftikhar-ul Haq ◽  
Jay Jagannathan ◽  
David Schlesinger ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Gamma Knife ◽  
Arteriovenous Malformations ◽  
Gamma Knife Surgery ◽  
Neurological Deficits ◽  
Resonance Imaging ◽  
Cerebral Arteriovenous Malformations ◽  
Radiation Induced ◽  
Induced Changes

Abstract OBJECTIVE The causes of failure after an initial Gamma procedure were studied, along with imaging and clinical outcomes, in a series of 140 patients with cerebral arteriovenous malformations (AVMs) treated with repeat Gamma Knife surgery (GKS). METHODS Causes of initial treatment failure included inaccurate nidus definition in 14 patients, failure to fill part of the nidus as a result of hemodynamic factors in 16, recanalization of embolized AVM compartments in 6, and suboptimal dose (&lt; 20 Gy) in 23. Nineteen patients had repeat GKS for subtotal obliteration of AVMs. In 62 patients, the AVM failed to obliterate despite correct target definition and adequate dose. At the time of retreatment, the nidus volume ranged from 0.1 to 6.9 cm3 (mean, 1.4 cm3), and the mean prescription dose was 20.3 Gy. RESULTS Repeat GKS yielded a total angiographic obliteration in 77 patients (55%) and subtotal obliteration in 9 (6.4%). In 38 patients (27.1%), the AVMs remained patent, and in 16 patients (11.4%), no flow voids were observed on magnetic resonance imaging. Clinically, 126 patients improved or remained stable, and 14 experienced deterioration (8 resulting from a rebleed, 2 caused by persistent arteriovenous shunting, and 4 related to radiation-induced changes). CONCLUSION By using repeat GKS, we achieved a 55% angiographic cure rate. Although radiation-induced changes as visualized on magnetic resonance imaging occurred in 48 patients (39%), only 4 patients (3.6%) developed permanent neurological deficits. These findings may be useful in deciding the management of AVMs in whom total obliteration after initial GKS was not achieved.

Clinical and neuroimaging outcome of cerebral arteriovenous malformations after Gamma Knife surgery: analysis of the radiation injury rate depending on the arteriovenous malformation volume

2008 ◽  
Vol 109 (2) ◽  
pp. 191-198 ◽  
Author(s):  
Jung Ho Han ◽  
Dong Gyu Kim ◽  
Hyun-Tai Chung ◽  
Chul-Kee Park ◽  
Sun Ha Paek ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Arteriovenous Malformations ◽  
Radiation Effects ◽  
Radiation Injury ◽  
Injury Rate ◽  
Gamma Knife Surgery ◽  
Cerebral Arteriovenous Malformations ◽  
Bleeding Rate ◽  
Reduced Dose ◽  
The Mean

Object In this paper the authors analyzed the clinical and neuroimaging outcomes of patients with cerebral arteriovenous malformations (AVMs) after Gamma Knife surgery (GKS), focusing on the analysis of the radiation injury rate depending on the AVM volume. Methods Between 1997 and 2004, 277 consecutive patients with cerebral AVMs were treated with GKS. Of these patients, 218 were followed up for ≥ 2 years. The mean age was 31 ± 15 years, the median AVM volume was 3.4 cm3 (range 0.17–35.2 cm3), the median marginal dose was 18.0 Gy (range 10.0–25.0 Gy), and the mean follow-up duration was 44 ± 20 months. The authors reduced the prescription dose by various amounts, depending on the AVM volume and location as prescribed in the classic guideline to avoid irreversible radiation injuries. Results The angiographic obliteration rate was 66.4% overall, and it was 81.7, 53.1, and 12.5% for small, medium, and large AVMs, respectively. The overall annual bleeding rate was 1.9%. The annual bleeding rate was 0.44 and 4.64% for small and large AVMs, respectively. Approximately 20% of the patients showed severe postradiosurgery imaging (PRI) changes. The rate of PRI change was 11.4, 33.3, and 9.5% for small, medium, and large AVM volume groups, respectively, and a permanent radiation injury developed in 5.1% of patients. Conclusions By using the reduced dose from what is usually prescribed, the authors were able to obtain outcomes in small AVMs that were comparable to the outcomes described in previous reports. However, medium AVMs appear to still be at risk for adverse radiation effects. Last, in large AVMs, the authors were able to attain a tolerable rate of radiation injury; however, the clinical outcomes were quite disappointing following administration of a reduced dose of GKS for large AVMs.

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