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Shayan Moosa, Ching-Jen Chen, Dale Ding, Cheng-Chia Lee, Srinivas Chivukula, Robert M. Starke, Chun-Po Yen, Zhiyuan Xu and Jason P. Sheehan

large AVMs involve the delivery of radiation doses in stages with dose- or volume-staged SRS. Dose staging is described in the literature as either hypofractionated stereotactic radiotherapy (HSRT) or repeat SRS. Hypofractionated stereotactic radiotherapy is typically performed by administering several small doses of radiation to the AVM over a period of a few weeks. Repeat radiosurgery uses a higher initial dose (yet still lower than traditional single-session SRS for small to moderate AVMs), and another dose is administered after several months or years if there is

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Yi-Chieh Hung, Nasser Mohammed, Thomas Jose Eluvathingal Muttikkal, Kathryn N. Kearns, Chelsea Eileen Li, Aditya Narayan, David Schlesinger, Zhiyuan Xu and Jason P. Sheehan

published studies have failed to take into account the de novo volumes of the AVMs when comparing outcomes with embolization and SRS versus SRS alone, leading to inherent matching biases with prior analyses. 15 , 26 , 33 In the current study the case-control method was used in de novo AVM volume-matched cohorts to compare the long-term (10 years) favorable outcome, obliteration rate, and adverse effects of AVMs between 8 ml (approximately 2.5-cm diameter) and 39 ml (approximately 4.2-cm diameter) treated by embolization plus SRS and SRS alone. In addition, the number of

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Mohamed Elsharkawy, Zhiyuan Xu, David Schlesinger and Jason P. Sheehan

had been treated previously with GKS for a posterior fossa ependymoma and a right-sided trigeminal schwannoma, had a right-sided jugular foramen schwannoma. The median age of the patients was 48 years (mean 45.6 years, range 10–72 years). At the time of GKS, the median tumor volume was 2.9 cm 3 (range 0.07–8.8 cm 3 ). Two patients were treated for recurrent tumor growth after prior radiotherapy. Thirteen patients (36%) were treated for residual tumors following resection, while the remaining 23 patients (64%) underwent GKS as an initial treatment on the basis of

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Douglas Kondziolka

been explored. What was once considered heresy 20 years ago when a “focused procedure” was used for an “unfocused disease,” radiosurgery has been shown in initial randomized trials to provide local tumor control benefits in patients with 2, 3, or 4 tumors. In an analysis in patients with more than 4, we found that it was not the number of tumors that was important but the total tumor volume of all brain metastases. If that volume was less than 7.5 cm 3 , the median survival was similar to that typically expected with 1 tumor (12 months). Thus, volume is a much

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Jason P. Sheehan, Gregory Patterson, David Schlesinger and Zhiyuan Xu

32 40 Rück et al., 2008 1 200 28 24 2 200 36 5 3 180 38 28 4 200 35 1 5 200 27 15 6 200 33 1 7 180 39 35 8 180 30 9 Kondziolka et al., 2011 1 140 34 24 2 140 39 8 3 150 39 18 present study 1 140 31 12 2 140 34 13 3 140 33 31 4 160 32 13 5 160 31 12 The precise volume appropriate for a GK capsulotomy remains the subject of debate. In the original study by the Karolinska

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Jason P. Sheehan, Zhiyuan Xu, Britney Popp, Leigh Kowalski and David Schlesinger

small craniectomy (2 × 1 mm) was drilled at a position 3 mm lateral to the midline and 1 mm anterior to the coronal suture. The dura mater was opened. With a Hamilton syringe, a 5-μl volume of 10 5 glioma cells was implanted using stereotactic guidance to a depth of 5 mm below the craniectomy, into the right frontotemporal region. The craniectomy was then sealed with bone wax, and the scalp was closed with sutures. Magnetic Resonance Imaging Technique Two weeks after implantation of the C6 glioma cells, each animal was assessed using a 7-T MRI unit at the

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Dale Ding, Chun-Po Yen, Zhiyuan Xu, Robert M. Starke and Jason P. Sheehan

. Factors analyzed in these analyses included sex, age, preradiosurgery hemorrhage, preradiosurgery embolization, AVM volume, AVM location (superficial vs deep and noneloquent vs eloquent), location of draining veins (superficial vs deep), number of draining veins (single vs multiple), prescription dose, number of isocenters, radiological presence of RIC, SM grade, radiosurgery-based AVM scale (RBAS) score, and Virginia Radiosurgery AVM Scale (Virginia RAS) score. The patient, AVM, and treatment characteristics listed above were initially subjected to univariate

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Dale Ding, Chun-Po Yen, Zhiyuan Xu, Robert M. Starke and Jason P. Sheehan

.6%), III in 163 (36.7%), IV in 30 (6.8%), and V in 3 (0.7%). We also calculated the modified Pittsburgh radiosurgery-based AVM score, which accounts for patient age, deep location, and AVM volume. 36 TABLE 1: Preradiosurgery patient and AVM characteristics in 444 cases Characteristic Value sex  male 222 (50.0%)  female 222 (50.0%) age (yrs)  mean 36.9  median 35.8  range 5–82 preradiosurgery embolization 122 (27.4%) preradiosurgery microsurgical resection 20 (4.5%) location

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Cheng-Chia Lee, Chun-Po Yen, Zhiyuan Xu, David Schlesinger and Jason Sheehan

available for all 109 patients. The study was approved by the institutional review board of the University of Virginia. The median age of these patients was 60.5 years, and the group included 51 males and 58 females. The median tumor volume was 16.8 cm 3 (range 6.0–74.8 cm 3 ). Most patients (68.8%%) had multiple intracranial lesions, and 31.2% of patients had metastasis to other organs. The most common tumor of origin was NSCLC (29.4% of cases), followed by breast cancer (22.9%) and melanoma (21.1%). Of note, those patients included in the current series with SCLC had

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Or Cohen-Inbar, Cheng-Chia Lee, Zhiyuan Xu, David Schlesinger and Jason P. Sheehan

region of the AVM on post-GKRS sequences. A maximum slice thickness of 5 mm or less was required on these MR sequences to perform reliable volumetric analysis of the changes. ARE Volumetric Assessment The volumes of the AVM nidus (estimated using the irradiated volume) and AREs were determined for each imaging data set available for patients in a longitudinal fashion. ARE volume was determined from T2-weighted or FLAIR MRI sequences, and the nidus volume was determined from postcontrast T1-weighted imaging used for the Gamma Knife treatment plan. Volumes were