Central Nervous System

PV QA 2 - Poster Viewing Q&A 2

MO_15_2847 - Long-term Outcomes and Imaging Response for Image-Guided Stereotactic Radiosurgery (IG-SRS) of Brain Arteriovenous Malformations (AVM)

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Long-term Outcomes and Imaging Response for Image-Guided Stereotactic Radiosurgery (IG-SRS) of Brain Arteriovenous Malformations (AVM)
J. Trotter, J. P. Kirkpatrick, F. McSherry, A. Rodrigues, M. L. Dworkin, A. Zomorodi, L. F. Gonzalez, J. Herndon, and E. F. Hauck; Duke University Medical Center, Durham, NC

Purpose/Objective(s): While fixed head-frame SRS is an established treatment strategy for AVM, the safety and efficacy of image-guided SRS with relocatable masks is less well-characterized. This study analyzes our long-term experience with IG-SRS in this disease, examining patient and treatment factors as regards outcome and describing serial MRI findings.

Materials/Methods: In this IRB-approved retrospective study, we reviewed all charts of patients with brain AVM who underwent IG-SRS at our institution from March 1, 2008 - July 31, 2017. All patients were treated on a LINAC with a micro-multileaf collimator and orthogonal kV/cone-beam CT imaging using a relocatable face mask. PTV was the nidus volume contoured on T2-weighted MRI expanded 1mm. Patients typically received follow-up MRI’s measuring T2 and T1+C volume 6 months post-SRS and yearly, thereafter. Obliteration was determined via MRI or, preferably, angiography. Adverse events (AE) were determined using CTCAE v4.0. Survival curves were generated via the Kaplan-Meier method. In analyzing dose-volume effect, the LQ model with an α/β of 3 Gy was used to calculate biologically equivalent doses.

Results: 72 patients with adequate information available for analysis were identified. Median patient age at SRS was 41yo (range 4-80) and 28 (38.9%) were female. 35 (48.6%) patients had history of pre-SRS hemorrhage. 40 (55.6%) patients had undergone prior embolization, surgery, or SRS. Median pre-SRS KPS was 90 with 6 patients having KPS ≤60. 57 (79.2%) patients had AVMs in eloquent locations. Median nidal volume was 1.5 ml (range 0.1-36) and median prescribed marginal total dose was 1800 cGy (1200-3000). 57 (79.2%) patients underwent single-fraction SRS, 13 had 2-fraction SRS and 2 received five 6Gy fractions. The median volume of brain receiving 10 Gy was 15.7 ml (2.8-160), 12 Gy was 10.4 ml (2.1-115), and 15 Gy was 6.2 ml (0-85.5). Median follow-up was 47.9 mo (95% CI 37.6, 56.1). The median time to obliteration was 53.9 months (95% CI 46, 73.3); at 7 years post-SRS, the actuarial obliteration rate was 82.4% (95% CI 60.4, 96.1%.) Only 13 patients had severe (≥3) SRS-related AE; 4 Grade-3, 6 Grade-4, and 3 Grade-5. On univariate analysis, there was no significant association between grade ≥3 AE and irradiated volume, AVM volume or location eloquence. Post-SRS hemorrhage was observed in 6 (8.3%) patients. Overall survival was 91.2% 5 years post SRS, with 3 patients each dying from causes related vs. unrelated to AVM. Of 57 patients with >1 follow-up MRI, 37 (64.9%) saw an increase in T1+C volume with median time to peak volume of 11.1 mo (3.1-47.7); 47 (82.5%) patients showed an increase in T2 volume with median time to peak volume of 15.5 mo (2.7-78.3).

Conclusion: IG-SRS appears to be a safe and efficacious method for treatment of brain AVMs. It is important to recognize that most patients experience post-SRS brain changes that seem to peak about one year following SRS. During this time of evolving brain response, patients require thorough and regular follow-up.

Author Disclosure: J. Trotter: None. J.P. Kirkpatrick: Research Grant; Varian Medical System. Partnership; ClearSight RT Products. F. McSherry: None. A. Rodrigues: None. L.F. Gonzalez: None.

Send Email for Jacob Trotter


Assets

MO_15_2847 - Long-term Outcomes and Imaging Response for Image-Guided Stereotactic Radiosurgery (IG-SRS) of Brain Arteriovenous Malformations (AVM)



Attendees who have favorited this

Please enter your access key

The asset you are trying to access is locked. Please enter your access key to unlock.

Send Email for Long-term Outcomes and Imaging Response for Image-Guided Stereotactic Radiosurgery (IG-SRS) of Brain Arteriovenous Malformations (AVM)