EJNMMI Research (May 2017)

Optimization of diagnostic performance for differentiation of recurrence from radiation necrosis in patients with metastatic brain tumors using tumor volume-corrected 11C-methionine uptake

  • Tae-Young Jung,
  • In-Young Kim,
  • Sa-Hoe Lim,
  • Ki Seong Park,
  • Dong-Yeon Kim,
  • Shin Jung,
  • Kyung-Sub Moon,
  • Woo-Youl Jang,
  • Sae-Ryung Kang,
  • Sang-Geon Cho,
  • Jung-Joon Min,
  • Hee-Seung Bom,
  • Seong Young Kwon

DOI
https://doi.org/10.1186/s13550-017-0293-0
Journal volume & issue
Vol. 7, no. 1
pp. 1 – 6

Abstract

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Abstract Background Tumor to normal tissue ratio (T/N ratio) on 11C-methionine (11C-MET) positron emission tomography/computed tomography (PET/CT) is affected by variable factors. We investigated whether T/N ratio cutoff values corrected according to metabolic tumor volume (MTV) could improve the diagnostic performance of 11C-MET PET/CT for diagnosis of recurrence in patients with metastatic brain tumor. Forty-eight patients with metastatic brain tumors underwent 11C-MET PET/CT for differential diagnosis between recurrence and radiation necrosis after gamma knife radiosurgery (GKR). Both T/N ratio and MTV were estimated in each lesion on 11C-MET PET/CT. The lesions were classified into three groups based on MTV criteria (≤ 0.5 cm3; > 0.5, ≤ 4.0 cm3; and > 4.0 cm3). The optimal cutoff values of the T/N ratio from receiver operating characteristic (ROC) curve were determined in each group (MTV-corrected) as well as total lesions (non-corrected). Finally, diagnostic performance of 11C-MET PET/CT was compared with the MTV-corrected cutoff values. Results Among 77 lesions, 51 were diagnosed with recurrence. The mean T/N ratio was 2.25 (± 1.12) for recurrent lesions and 1.44 (± 0.22) for radiation necrosis (P 4.0 cm3). In small-sized lesions (MTV ≤ 0.5 cm3), MTV-corrected cutoff values (1.23) could maintain favorable diagnostic performance with sensitivity, specificity, and diagnostic accuracy (70.0, 80.0, and 73.3%, respectively), compared to non-corrected cutoff values. Conclusions MTV-corrected cutoff values of T/N ratio could maintain the diagnostic performance of 11C-MET PET/CT in small sized, metastatic brain tumors. We expect our results to contribute to reproducible and standardized interpretation of 11C-MET PET/CT.

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