Dose Planning for Malignant Brain Tumors Using MR and Methionine PET: Fusion or Coregistration?Masaaki Yamamoto1, Takuya Kawabe2, Tadashi Nariai3, Toshiya Momose3, Kiichi Ishiwata4, Kenji Ishii4, Bierta e. Barfod5, Yoichi Urakawa51Ibaraki, Japan 2Hitachi-Naka, Japan 3Department of Neurosurgery, Tokyo Medical and Dental University, Tokyo, Japan 4Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Tokyo, Jap 5Katsuta Hospital Mito GammaHouse, Hitachi-naka, Japan Keywords: gamma knife, brain tumor, Imaging, glioblastoma multiforme, brain metastasis
The utility of L-methyl-11Cmethionine (11C-Met) PET for diagnosing various malignant brain tumors has been demonstrated.
Based on our experiences with malignant brain tumor patients treated undergoing gamma knife radiosurgery (GKRS), we describe how this imaging technique can be applied to dose planning.
The authors present 142 GKRS procedures for malignant brain tumors (malignant glioma; 56, metastatic brain tumor; 77, others; 5), using MR and 11C-Met PET images for dose planning, all conducted between July, 2005 and August, 2011. Before May, 2009 (89 procedures), 11C-Met PET images were fused with stereotactic post-contrast MR images using a personal computer; the application software used for fusing the two images was Dr. View (Asahi Kasei Information Systems, Co., Ltd., Tokyo). The fusion images were transferred into the Leksell GammaPlan System. After June, 2009, when Gamma Plan ver 8.0 became available, the coregistration function of 11C-Met PET images to stereotactic post-contrast MR images was used in 53 procedures.
The earlier fusion technique required meticulous manipulations which could only be performed by highly experienced physicians or technicians. Also, it was time-consuming. However, a threshold level of 11C-Met uptake could be numerically determined the using standardized uptake value (SUV) with this technique. On the other hand, while the coregistration technique is very easy and quick, and does not require experienced personnel, a threshold level of 11C-Met uptake cannot be numerically determined using SUV.
Further advancements in the Gamma Plan System are expected to allow a threshold level of 11C-Met uptake to be numerically determined based on SUV.
Advanced image fusion techniques will be important for radiosurgical planning. Project Roles:
M. Yamamoto (), T. Kawabe (), T. Nariai (), T. Momose (), K. Ishiwata (), K. Ishii (), B. Barfod (), Y. Urakawa ()