Changes of F-18 fluorodeoxyglucose positron emission tomography/computed tomography textural features in temporal lobe after radiotherapy for nasopharyngeal carcinoma.

PURPOSE: Treating nasopharyngeal cancer with radiotherapy often causes radiation-induced temporal lobe injury. This study aimed to investigate whether F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) imaging features extracted from the temporal lobe changed after radiotherapy in nasopharyngeal cancer patients.

METHODS

Twenty-two FDG PET textural features were extracted from low-irradiated (less than 20 Gy), 20 Gy-irradiated, 30 Gy-irradiated, and 40 Gy-irradiated areas in the temporal lobe from 24 nasopharyngeal cancer patients who underwent both staging (PET1) and post-radiotherapy (PET2) PET/CT with/without surveillance PET/CT (PET3). Values of FDG PET textural features were compared between PET/CT scan.

RESULTS

On comparison analysis, 30 Gy-irradiated and 40 Gy-irradiated areas on PET2 demonstrated lower values of standardized uptake value (SUV) histogram-based skewness and gray-level co-occurrence matrix (GLCM) correlation, but, significantly higher values of GLCM contrast and neighborhood gray-tone difference matrix (NGTDM) busyness than those on PET1. These four features maintained their differences on PET3 as compared with PET1. The GLCM correlation of the 40 Gy-irradiated area remained statistically significant after false discovery rate correction (adjusted p = .044). On correlation analysis, the volume of the 40 Gy-irradiated area showed significant correlations with changes in SUV histogram-based skewness and NGTDM busyness between PET1 and PET2 (p < .05). Temporal lobe necrosis was found in one patient who showed markedly decreased SUV histogram-based skewness and increased NGTDM busyness on PET2.

CONCLUSIONS

Changes of PET imaging features after RT were found in the temporal lobe areas receiving >30 Gy in nasopharyngeal cancer patients. FDG PET/CT textural features might provide exploratory imaging biomarkers for characterizing radiation-induced temporal lobe injury after radiotherapy.