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Dynamic Contrast Enhanced Magnetic Resonance Imaging-based Assessment of Tumor Response to High-dose Spine Stereotactic Radiosurgery
Volume 84 Number 3S Supplement 2012 compared to 50.4 Gy. In this retrospective study, we report the long term tumor control rate, symptomatic outcome, and hearing preservation rate in patients treated with lower dose FSRT. Materials/Methods: After obtaining IRB approval, we analyzed all patients (pts) diagnosed with AS and treated at our institution from 2002 to 2011. All pts received 46.8 Gy in 1.8 Gy fractions. After treatment, followup audiogram and MRI were performed in 1-year intervals. Tumor control was defined as 1mm increase in tumor size in any dimension on multiple MRIs to allow for operator-dependent differences. Tumor control and hearing preservation were calculated by the Kaplan-Meier (KM) method. Analysis of hearing preservation, defined as Gardner-Robertson value 2, excluded pts with prior surgery, no initial documented hearing test, or non-serviceable hearing. Non-hearing related symptoms were defined by Common Terminology Criteria for Adverse Events (CTCAE) version 4. Symptomatic control was evaluated using descriptive statistics. Results: In total, 127 pts were analyzed. At a median follow-up time of 35 months (range, 4-108 months) tumor control was achieved in 95% of pts (n Z 121/127). Tumor control at 3- and 5-years was 100 and 93%, respectively. For hearing evaluation, 77 pts had a median audiogram follow-up of 28 months (range, 3-90 months). Functional hearing preservation at 3- and 5-years was 83.5 and 64.8%, respectively. Median time to functional hearing loss was 87.5 months. Crude pure tone average at last follow-up was decreased by an average of 12 decibels (db) in all pts and 19 db in pts with over 2 years of follow-up (n Z 42). At last follow-up, 18% (n Z 23) of pts experienced ataxia, vertigo, paresthesia, or pain symptom improvement, 8.7% (n Z 11) had worsening of symptoms, and 81% had no change in symptoms. Of pts with worsening symptoms, 2.4% (n Z 3) experienced cranial nerve dysfunction of the trigeminal or facial nerve (1 Z CTCAE grade 1 and 2 Z CTCAE grade 2 toxicity). There was no grade 3 or higher toxicities. Conclusions: Lower dose FSRT to 46.8 Gy for AS provides excellent local control and functional hearing preservation rates with limited toxicity. The local control rate is similar to reported outcomes for pts receiving radiosurgery. The functional hearing preservation rate appears to compare favorable to pts who received radiosurgery. Future attempts of dose reduction to 45 Gy may potentially increase hearing preservation and warrant prospective evaluation. Author Disclosure: C.E. Champ: None. S. Mayekar: None. M.V. Mishra: None. D.W. Andrews: None. M. Werner-Wasik: None. K. Chapman: None. V. Gunn: None. H. Liu: None. J.J. Evans: None. W. Shi: None.
96 The Role of Proton Radiation Therapy for Multiple Meningiomas E.D. Tanzler, D. Yeung, Z. Li, Z. Su, W.M. Mendenhall, and R. Malyapa; University of Florida Proton Therapy Institute, Jacksonville, FL Purpose/Objective(s): To compare the dose delivered by proton radiation therapy to the dose delivered by intensity modulated radiation therapy (IMRT) for patients presenting with multiple intracranial meningiomas. Materials/Methods: We compared proton radiation therapy and noncoplanar IMRT plans for 4 patients who presented with multiple simultaneous meningiomas. We required that each plan deliver the prescription dose (50.4 Gy at 1.8 Gy per fraction for WHO Grade I meningiomas and 61.2 Gy at 1.8 Gy per fraction for WHO Grade II meningiomas) to 95% of the planning target volume. We compared the dose to 0.1 cc of the critical normal tissue structures (brainstem, optic nerves, and optic chiasm), the mean dose to the brain, the V50, V20, and V30 of the brain, and the integral dose received by each patient. Results: The normal-tissue dose constraints were met for each structure using either IMRT or proton radiation therapy. With the IMRT plans, the integral dose received by each of the 4 patients was 62.3 J, 94.5 J, 66.2 J, and 40.2 J. The integral dose with the proton plan was significantly reduced; the integral dose for each patient was 22.4 J, 26.6 J, 22.1 J, and 16.2 J. The mean dose to the brain delivered by the IMRT plans for each of the 4 patients was 26.92 Gy, 32.71 Gy, 17.58 Gy, and 18.75 Gy. The mean dose delivered to the brain using the proton plans for each of the 4 patients was 12.76 Gy, 8.96 Gy, 11.64 Gy, and 8.92 Gy. In addition, the V20, V30,
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and V50 of the brain were either the same or better when comparing the proton plans to the IMRT plans. Conclusions: Compared to IMRT, proton radiation therapy allows for a significantly lower dose to the brain and optic structures when treating multiple brain lesions because of the proton’s Bragg peak. More specifically, with proton therapy, the integral dose to the brain and optic structures is reduced as is the mean dose to the brain, allowing for fewer toxicities and the safer treatment of patients with multiple meningiomas. Author Disclosure: E.D. Tanzler: None. D. Yeung: None. Z. Li: None. Z. Su: None. W.M. Mendenhall: None. R. Malyapa: None.
97 Dynamic Contrast Enhanced Magnetic Resonance Imaging-based Assessment of Tumor Response to High-dose Spine Stereotactic Radiosurgery Y. Yamada, S. Karimi, P. Kyung, E. Lis, J. Lyo, M. Bilsky, B. Cox, and A. Holodny; Memorial Sloan-Kettering Cancer Center, New York, NY Purpose/Objective(s): Endothelial damage is thought to be an important mechanism of tumor response to high dose stereotactic radiosurgery (SRS). Dynamic contrast enhanced MRI (DCE) was utilized to assess the changes in blood flow in tumors over time that achieved long term control as well as tumors that eventually failed spine SRS. Materials/Methods: Nineteen spine metastases (19 locally controlled, 2 with local recurrence) treated with SRS (600 cGy x 5 [N Z 4], 900 cGy x 3 [N Z 1], 2,400 cGy x 1 [N Z 14]) who underwent pretreatment and post treatment T1 DCE studies were identified. Plasma volume (Vp), permeability (Ktrans), area under the curve (AUC), and peak enhancement (PE) perfusion parameters were assessed. Images were acquired on 1.5 Tesla scanner with an 8 channel spinal coil. A two-compartment model (intravascular and extra vascular, extracellular space) was assumed. Results: Median follow-up was 17 months (range, 8-48 months). Reduced Vp was the best predictor of response. In lesions that achieved local control, mean Vp was -66% (range, -21% to -99%), whereas the lesions that ultimately recurred were found to have marked increases in Vp (+145% and +207%). The differences in between Vp for locally controlled and local failures was highly significant (p > 0.0001) and the calculated rate of a false positive was 9.38 x 10 9 and a false negative rate of 0.055. The differences in Ktrans, AUC, and PE were not significantly different between locally controlled and locally recurrent lesions. Conclusions: Vp was found to be highly significantly different in lesions that were ultimately locally controlled compared to those that locally progressed. DCE imaging can suggest treatment response even when conventional MRI studies demonstrate minimal or no regression after successful spine SRS. DCE also adds clinical credence to animal experimental data that suggest endothelial effects are an important mechanism of tumor response to very high dose single fraction radiation. Further work may also prove DCE as an important predictive tool of treatment response. Author Disclosure: Y. Yamada: F. Honoraria; Continuing Medical Education Institute. G. Consultant; Varian medical systems. Q. Leadership; American Brachytherapy Society. S. Karimi: None. P. Kyung: None. E. Lis: None. J. Lyo: None. M. Bilsky: None. B. Cox: None. A. Holodny: None.
98 The Risk of Vertebral Compression Fracture (VCF) Postspine Stereotactic Body Radiation Therapy (SBRT) and Evaluation of the Spinal Instability Neoplastic Score (SINS) A. Al-Omair,1 M. da Cunha,2 E. Atenafu,1 D. Letourneau,1 R. Korol,3,4 E. Yu,1 L. Masucci,1 L. Da Costa,4 M. Fehlings,5 and A. Sahgal6; 1Princess Margaret Hospital, Toronto, ON, Canada, 2Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada, 3Sunnybrook Health Sciences Centre, Toronto, ON, Canada, 4Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada, 5Toronto Western Hospital, University of Toronto, Toronto, ON, Canada, 6Princess Margaret Hospital and, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada Purpose/Objective(s): Vertebral compression fracture (VCF) is increasingly being observed post-spine SBRT. A recent SINS classification was
96 The Role of Proton Radiation Therapy for Multiple Meningiomas E.D. Tanzler, D. Yeung, Z. Li, Z. Su, W.M. Mendenhall, and R. Malyapa; University of Florida Proton Therapy Institute, Jacksonville, FL Purpose/Objective(s): To compare the dose delivered by proton radiation therapy to the dose delivered by intensity modulated radiation therapy (IMRT) for patients presenting with multiple intracranial meningiomas. Materials/Methods: We compared proton radiation therapy and noncoplanar IMRT plans for 4 patients who presented with multiple simultaneous meningiomas. We required that each plan deliver the prescription dose (50.4 Gy at 1.8 Gy per fraction for WHO Grade I meningiomas and 61.2 Gy at 1.8 Gy per fraction for WHO Grade II meningiomas) to 95% of the planning target volume. We compared the dose to 0.1 cc of the critical normal tissue structures (brainstem, optic nerves, and optic chiasm), the mean dose to the brain, the V50, V20, and V30 of the brain, and the integral dose received by each patient. Results: The normal-tissue dose constraints were met for each structure using either IMRT or proton radiation therapy. With the IMRT plans, the integral dose received by each of the 4 patients was 62.3 J, 94.5 J, 66.2 J, and 40.2 J. The integral dose with the proton plan was significantly reduced; the integral dose for each patient was 22.4 J, 26.6 J, 22.1 J, and 16.2 J. The mean dose to the brain delivered by the IMRT plans for each of the 4 patients was 26.92 Gy, 32.71 Gy, 17.58 Gy, and 18.75 Gy. The mean dose delivered to the brain using the proton plans for each of the 4 patients was 12.76 Gy, 8.96 Gy, 11.64 Gy, and 8.92 Gy. In addition, the V20, V30,
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and V50 of the brain were either the same or better when comparing the proton plans to the IMRT plans. Conclusions: Compared to IMRT, proton radiation therapy allows for a significantly lower dose to the brain and optic structures when treating multiple brain lesions because of the proton’s Bragg peak. More specifically, with proton therapy, the integral dose to the brain and optic structures is reduced as is the mean dose to the brain, allowing for fewer toxicities and the safer treatment of patients with multiple meningiomas. Author Disclosure: E.D. Tanzler: None. D. Yeung: None. Z. Li: None. Z. Su: None. W.M. Mendenhall: None. R. Malyapa: None.
97 Dynamic Contrast Enhanced Magnetic Resonance Imaging-based Assessment of Tumor Response to High-dose Spine Stereotactic Radiosurgery Y. Yamada, S. Karimi, P. Kyung, E. Lis, J. Lyo, M. Bilsky, B. Cox, and A. Holodny; Memorial Sloan-Kettering Cancer Center, New York, NY Purpose/Objective(s): Endothelial damage is thought to be an important mechanism of tumor response to high dose stereotactic radiosurgery (SRS). Dynamic contrast enhanced MRI (DCE) was utilized to assess the changes in blood flow in tumors over time that achieved long term control as well as tumors that eventually failed spine SRS. Materials/Methods: Nineteen spine metastases (19 locally controlled, 2 with local recurrence) treated with SRS (600 cGy x 5 [N Z 4], 900 cGy x 3 [N Z 1], 2,400 cGy x 1 [N Z 14]) who underwent pretreatment and post treatment T1 DCE studies were identified. Plasma volume (Vp), permeability (Ktrans), area under the curve (AUC), and peak enhancement (PE) perfusion parameters were assessed. Images were acquired on 1.5 Tesla scanner with an 8 channel spinal coil. A two-compartment model (intravascular and extra vascular, extracellular space) was assumed. Results: Median follow-up was 17 months (range, 8-48 months). Reduced Vp was the best predictor of response. In lesions that achieved local control, mean Vp was -66% (range, -21% to -99%), whereas the lesions that ultimately recurred were found to have marked increases in Vp (+145% and +207%). The differences in between Vp for locally controlled and local failures was highly significant (p > 0.0001) and the calculated rate of a false positive was 9.38 x 10 9 and a false negative rate of 0.055. The differences in Ktrans, AUC, and PE were not significantly different between locally controlled and locally recurrent lesions. Conclusions: Vp was found to be highly significantly different in lesions that were ultimately locally controlled compared to those that locally progressed. DCE imaging can suggest treatment response even when conventional MRI studies demonstrate minimal or no regression after successful spine SRS. DCE also adds clinical credence to animal experimental data that suggest endothelial effects are an important mechanism of tumor response to very high dose single fraction radiation. Further work may also prove DCE as an important predictive tool of treatment response. Author Disclosure: Y. Yamada: F. Honoraria; Continuing Medical Education Institute. G. Consultant; Varian medical systems. Q. Leadership; American Brachytherapy Society. S. Karimi: None. P. Kyung: None. E. Lis: None. J. Lyo: None. M. Bilsky: None. B. Cox: None. A. Holodny: None.
98 The Risk of Vertebral Compression Fracture (VCF) Postspine Stereotactic Body Radiation Therapy (SBRT) and Evaluation of the Spinal Instability Neoplastic Score (SINS) A. Al-Omair,1 M. da Cunha,2 E. Atenafu,1 D. Letourneau,1 R. Korol,3,4 E. Yu,1 L. Masucci,1 L. Da Costa,4 M. Fehlings,5 and A. Sahgal6; 1Princess Margaret Hospital, Toronto, ON, Canada, 2Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada, 3Sunnybrook Health Sciences Centre, Toronto, ON, Canada, 4Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada, 5Toronto Western Hospital, University of Toronto, Toronto, ON, Canada, 6Princess Margaret Hospital and, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada Purpose/Objective(s): Vertebral compression fracture (VCF) is increasingly being observed post-spine SBRT. A recent SINS classification was