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Grahm Valadie O, Brown SL, Farmer K, Nagaraja TN, Cabral G, Shadaia S, Divine GW, Knight RA, Lee IY, Dolan J, Rusu S, Joiner MC, Ewing JR. Characterization of the Response of 9L and U-251N Orthotopic Brain Tumors to 3D Conformal Radiation Therapy. Radiat Res 2023; 199:217-228. [PMID: 36656561 PMCID: PMC10174721 DOI: 10.1667/rade-22-00048.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 12/21/2022] [Indexed: 01/20/2023]
Abstract
In a study employing MRI-guided stereotactic radiotherapy (SRS) in two orthotopic rodent brain tumor models, the radiation dose yielding 50% survival (the TCD50) was sought. Syngeneic 9L cells, or human U-251N cells, were implanted stereotactically in 136 Fischer 344 rats or 98 RNU athymic rats, respectively. At approximately 7 days after implantation for 9L, and 18 days for U-251N, rats were imaged with contrast-enhanced MRI (CE-MRI) and then irradiated using a Small Animal Radiation Research Platform (SARRP) operating at 220 kV and 13 mA with an effective energy of ∼70 keV and dose rate of ∼2.5 Gy per min. Radiation doses were delivered as single fractions. Cone-beam CT images were acquired before irradiation, and tumor volumes were defined using co-registered CE-MRI images. Treatment planning using MuriPlan software defined four non-coplanar arcs with an identical isocenter, subsequently accomplished by the SARRP. Thus, the treatment workflow emulated that of current clinical practice. The study endpoint was animal survival to 200 days. The TCD50 inferred from Kaplan-Meier survival estimation was approximately 25 Gy for 9L tumors and below 20 Gy, but within the 95% confidence interval in U-251N tumors. Cox proportional-hazards modeling did not suggest an effect of sex, with the caveat of wide confidence intervals. Having identified the radiation dose at which approximately half of a group of animals was cured, the biological parameters that accompany radiation response can be examined.
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Affiliation(s)
- O. Grahm Valadie
- Department of Neurology, Henry Ford Hospital, Detroit, Michigan
- Department of Radiation Oncology, Henry Ford Hospital, Detroit, Michigan
- Department of Radiation Oncology, Wayne State University, Detroit, Michigan
| | - Stephen L. Brown
- Department of Radiation Oncology, Henry Ford Hospital, Detroit, Michigan
- Department of Radiation Oncology, Wayne State University, Detroit, Michigan
- Department of Radiology, Michigan State University College of Human Medicine, East Lansing, Michigan
| | - Katelynn Farmer
- Department of Neurology, Henry Ford Hospital, Detroit, Michigan
| | | | - Glauber Cabral
- Department of Neurology, Henry Ford Hospital, Detroit, Michigan
| | - Sheldon Shadaia
- Department of Neurology, Henry Ford Hospital, Detroit, Michigan
| | - George W. Divine
- Department of Public Health Sciences, Henry Ford Hospital, Detroit Michigan
| | - Robert A. Knight
- Department of Neurology, Henry Ford Hospital, Detroit, Michigan
- Department of Physics, Oakland University, Rochester, Michigan
| | - Ian Y. Lee
- Department of Neurosurgery, Henry Ford Hospital, Detroit Michigan
| | - Jennifer Dolan
- Department of Radiation Oncology, Henry Ford Hospital, Detroit, Michigan
| | - Sam Rusu
- Department of Neurology, Henry Ford Hospital, Detroit, Michigan
| | - Michael C. Joiner
- Department of Radiation Oncology, Wayne State University, Detroit, Michigan
| | - James R. Ewing
- Department of Neurology, Henry Ford Hospital, Detroit, Michigan
- Department of Radiology, Michigan State University College of Human Medicine, East Lansing, Michigan
- Department of Neurosurgery, Henry Ford Hospital, Detroit Michigan
- Department of Physics, Oakland University, Rochester, Michigan
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Adaptation of laser interstitial thermal therapy for tumor ablation under MRI monitoring in a rat orthotopic model of glioblastoma. Acta Neurochir (Wien) 2021; 163:3455-3463. [PMID: 34554269 DOI: 10.1007/s00701-021-05002-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/01/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Laser interstitial thermal therapy (LITT) under magnetic resonance imaging (MRI) monitoring is being increasingly used in cytoreductive surgery of recurrent brain tumors and tumors located in eloquent brain areas. The objective of this study was to adapt this technique to an animal glioma model. METHODS A rat model of U251 glioblastoma (GBM) was employed. Tumor location and extent were determined by MRI and dynamic contrast-enhanced (DCE) MRI. A day after assessing tumor appearance, tumors were ablated during diffusion-weighted imaging (DWI)-MRI using a Visualase LITT system (n = 5). Brain images were obtained immediately after ablation and again at 24 h post-ablation to confirm the efficacy of tumor cytoablation. Untreated tumors served as controls (n = 3). Rats were injected with fluorescent isothiocyanate (FITC) dextran and Evans blue that circulated for 10 min after post-LITT MRI. The brains were then removed for fluorescence microscopy and histopathology evaluations using hematoxylin and eosin (H&E) and major histocompatibility complex (MHC) staining. RESULTS All rats showed a space-occupying tumor with T2 and T1 contrast-enhancement at pre-LITT imaging. The rats that underwent the LITT procedure showed a well-demarcated ablation zone with near-complete ablation of tumor tissue and with peri-ablation contrast enhancement at 24 h post-ablation. Tumor cytoreduction by ablation as seen on MRI was confirmed by H&E and MHC staining. CONCLUSIONS Data showed that tumor cytoablation using MRI-monitored LITT was possible in preclinical glioma models. Real-time MRI monitoring facilitated visualizing and controlling the area of ablation as it is otherwise performed in clinical applications.
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