P14.39 How far should it be removal beyond the Gd-enhanced edge in Glioblastoma cases? -Preoperative removal range identification using Methionine-PET and Thallium-SPECT fusion image

BACKGROUND Mostly, the removal rate of glioblastoma has been discussed in the Gd enhanced area, but tumor cells are surely infiltrated beyond the Gd enhanced edge. Although Methionine-PET (MET) and Thallium-SPECT (Tl) are useful for preoperative tumor invasion range identification, they are off-label use in most countries, and their respective accumulation ranges do not match completely. In this study, Gd-MRI, MET, and Tl were performed, and the accumulation range was compared from the fusion images, and the prediction method of the tumor cell infiltration range was examined. MATERIAL AND METHODS The mean interval period between MET and Tl administration was 16.3 days in 21 cases of glioblastoma (12 male and 9 female, average age 59.1 ± 17.8 years). Fusion images were generated using iPlan Cranial 3.0.The MET-area, Tl-area, Overlap-area where MET and Tl overlap, and Accumulation-area where MET and Tl are maximally accumulated were measured in the same cross section as the Gd-enhanced maximum area (Gd-area, X cm2) in axial view. Each volume was also measured similarly. RESULTS Gd-area was correlated with all of MET-area, Tl-area, Overlap-area, and Accumulation-area (p ≦0.0001).Gd-volume (X’cm3) showed correlation with all of MET-volume, Tl-volume, Overlap-volume, and Accumulation-volume (p ≦0.0001). The linear approximation was calculated as follows. Overlap-area = 1.942X + 1.0208 (R = 0.937), Accumulation-area = 1.3299X + 6.098 (R = 0.889), Overlap-volume = 1.1539X ‘+ 7.0573 (R = 0.927), Accumulation-volume = 1.8668X ‘+30.06 (R = 0.893). CONCLUSION These linear approximations can be used to predict the tumor invasion range from the Gd-enhanced maximum area or Gd-enhanced volume without using off-label use drugs.