RT Journal Article SR Electronic T1 Adaptive region-growing - A semi-automatic and highly reproducible method for brain tumor delineation with 11C methionine PET JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 2053 OP 2053 VO 52 IS supplement 1 A1 Kenji Hirata A1 Naoya Hattori A1 Osamu Manabe A1 Tohru Shiga A1 Reiko Usui A1 Keiichi Magota A1 Naoki Kubo A1 Shunsuke Terasaka A1 Nagara Tamaki YR 2011 UL http://jnm.snmjournals.org/content/52/supplement_1/2053.abstract AB 2053 Objectives Surgical resection of cerebral glioma requires highly reproducible size measurement based on preoperative radiological imaging. 11C methionine (MET) PET describes glioma expansion more precisely than MRI, but available automatic methods fail to contour the tumor due to heterogeneity of MET uptake in background brain tissues. The purpose of this study was to investigate reliability of adaptive region-growing (AR) method, a semi-automatic contouring algorism, in comparison with conventional visual thresholding method (VT) and fixed thresholding method (FT). Methods Thirty patients (M:F=20:10, age 51±13 years old) with glioma (n=9,11,10 for WHO grade II,III,IV, respectively) underwent MET PET. In AR, the voxel with the highest intensity in a tumor was chosen as the seed. A neighbor voxel with higher intensity than [mean of current region]*[threshold(%)] was appended to the region. Mean of current region was updated whenever a new voxel joined. An optimal threshold was determined by the sharp point of threshold-volume curve. Two physicians independently measured tumor volume using AR, VT and FT. Contouring was considered as “failed” when the region contained only small parts of the tumor or substantially large parts of normal tissue. Results All the tumors showed higher MET uptake than background with tumor-to-normal ratio ranging from 1.45 to 5.53. AR succeeded to delineate tumor boundary in 25/30 (83%) cases. Unsuccessful 5 cases consisted of 2 underestimations (grade III and IV) and 3 overestimations (grade II, III, and IV). In terms of successful rate, AR was inferior to VT (29/30, 97%) and superior to FT (15/30, 50%). However, semi-automatic AR reproduced tumor volume between two operators (R2 = 1.00), while VT (R2=0.95) and FT (R2=0.93) showed interoperator variations. Conclusions A semi-automatic AR is feasible to evaluate glioma expansion using MET PET with the highest reproducibility among the 3 methods investigated