Evaluation of Hybrid PET/MRI for Gross Tumor Volume (GTV) Delineation in Colorectal Cancer Liver Metastases Radiotherapy

Yan-Nan Zhang; Xin Lu; Zhen-Guo Lu; Li-Ping Fu; Jun Zhao; Zuo-Lin Xiang

doi:10.2147/CMAR.S316969

Evaluation of Hybrid PET/MRI for Gross Tumor Volume (GTV) Delineation in Colorectal Cancer Liver Metastases Radiotherapy

Cancer Manag Res. 2021 Jul 6:13:5383-5389. doi: 10.2147/CMAR.S316969. eCollection 2021.

Authors

Yan-Nan Zhang^#¹, Xin Lu^#¹, Zhen-Guo Lu¹, Li-Ping Fu¹, Jun Zhao², Zuo-Lin Xiang¹

Affiliations

¹ Department of Radiation Oncology, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, People's Republic of China.
² Department of Nuclear Medicine, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, People's Republic of China.

^# Contributed equally.

Abstract

Purpose: Hybrid PET/MRI has been increasingly incorporated into the practice of radiation oncologists since it contains both anatomical and biological data and may bring about personalized radiation plans for each patient. The objective of this study was to evaluate the feasibility of GTV delineation from hybrid PET/MRI compared with that from current-practice MRI during radiotherapy planning in patients with colorectal liver metastases.

Patients and methods: Twenty-four patients (thirty lesions) with colorectal liver metastases were prospectively enrolled in this study. Three physicians delineated the target volume with the most popular delineating methods-the visual method. First of all, differences among the three observers were assessed. The difference and correlation of GTV values obtained by MRI, PET, and hybrid PET/MRI were subjected to statistical analysis afterwards. Finally, the dice similarity coefficient (DSC) was calculated to assess the spatial overlap. Based on the value of DSC, we also evaluate the correlation between DSC and tumor size. GTV-MRI was set as a reference.

Results: There was no significant difference among observers in GTV-MRI (F=0.118, p=0.889), GTV-PET (F=0.070, p=0.933) and GTV-PET/MRI (F=0.40, p=0.961). 83.33% of GTV-PET/MRI and 63.33% of GTV-PET were larger than the reference GTV-MRI. Statistical analysis revealed that GTV-PET/MRI (p<0.001) and GTV-PET (p<0.05) diverged statistically significantly from GTV-MRI. GTV-PET (r=0.992, p<0.001) and GTV-PET/MRI (r=0.997, p<0.001) were significantly related to GTV-MRI. The average DSC value between GTV-MRI and GTV-PET was 0.51 (range 0-0.90) and that between GTV-MRI and GTV-PET/MRI was 0.72 (range 0.42-0.90). There was a positive correlation between the DSC and GTV-MRI (r=0.851, p<0.05).

Conclusion: With the database used, there is good agreement among observers. Hybrid PET/MRI in colorectal liver metastases radiotherapy may affect the GTV delineation. Moreover, the overlap degree between GTV-MRI and GTV-PET/MRI is higher and increases with volume.

Keywords: colorectal liver metastases; gross tumor volume; hybrid PET/MRI; radiotherapy.

Grants and funding

This work was supported by the National Natural Science Foundation of China (Grant No. 81960525), the Natural Science Foundation of Shanghai (Grant No. 17ZR1405300), the Science and Technology Supporting Project of Shanghai (Grant No.17411962600), the Science and the Technology Innovation Project of Shanghai (Grant No.19DZ1930900), the Pudong New Area Science and Technology Development Fund (Grant No. PKJ2018-Y02) and the Natural Science Foundation of Jiangxi (Grant No. 20192BAB205071).