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Arnaldo Neves Da Silva, Kazuki Nagayama, David Schlesinger and Jason P. Sheehan

management of patients with brain metastasis. Methods Patient Inclusion From March 2002 to August 2006, 141 patients with brain metastases received staged treatment with GKS (Leksell Gamma Knife, Elekta Instrument AB) at the University of Virginia and had early follow-up MR imaging (< 1 month after GKS). Patients were included in this study if they had follow-up MR imaging within 30 days or less (mean neuroimaging follow-up interval = 13 days) from the initial GKS and had lesions measuring 0.5 cm 3 or greater. The criterion of a minimum tumor volume of 0.5 cm 3

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David Schlesinger, John Snell and Jason Sheehan

pituitary adenoma who underwent GKS between April 2003 and March 2006 at the Lars Leksell Gamma Knife Center at the University of Virginia; in these cases the Model C GK unit (Elekta Instruments AB, Stockholm, Sweden) was used. Thirty-two patients were treated for nonsecretory pituitary adenomas, and 76 for secretory adenomas. Data Collection From Dose Plans Archived dose plans for each of the patients in the study were reviewed using Leksell GammaPlan version 5.34 (Elekta Instruments Inc., Norcross, GA). The volume, maximum orthogonal dimensions of each target, and

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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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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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Claire Olson, Chun-Po Yen, David Schlesinger and Jason Sheehan

volume of the tumors at the time of radiosurgery was 4.6 cm 3 (range 0.3–18.7 cm 3 ). Fifteen of the 28 tumors received a single treatment, 6 were treated twice, 4 were treated 3 times, 2 were treated 4 times, and 1 was treated 5 times ( Table 2 ). The locations of the 28 tumors were as follows: parasellar, 9; posterior fossa, 6; frontal, 4; occipital, 3; temporal, 3; and parietal, 3. TABLE 2: Tumors requiring multiple GKSs * No. of GKSs No. of Cases 2 6 3 4 4 2 5 1 * Thirteen tumors were treated. Two tumors were

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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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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

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Jason Sheehan, Chun Po Yen, Yasser Arkha, David Schlesinger and Ladislau Steiner

Instruments, Inc.). The median tumor volume at the time of GKS was 3.96 cm 3 (range 0.63–8.5 cm 3 ). The median prescription isodose was 50% (range 30–50%) and the median prescription dose was 15 Gy (range 10.2–17 Gy). The mean maximum dose was 35 Gy (range 26–50 Gy). The mean number of isocenters used per patient was six (range two–16). Follow-up Review Clinical follow-up data were obtained by physical examination or through written and verbal communication with the patients and referring physicians. Follow-up MR imaging was performed at 6-month intervals