Abstract
PURPOSE: To evaluate the diagnostic performance of quantitative measures derived from [18F]FDG PET/CT, [18F]FEC PET/CT, and DW-MRI in the detection of lymph node metastases in endometrial and cervical cancer with comparison to standard visual PET analysis with histology as the reference standard.
METHODS: Subanalysis of quantitative data from the prospective multicentre MAPPING study. Nodal and tumour SUVmax from [18F]FDG PET/CT and [18F]FEC PET/CT and ADCmean from DW-MRI were documented. Nodal-to-tumour ratios (NTR) and SUVmax-to-ADCmean ratio (STAR) were calculated. Optimal cut-offs of quantitative measures were compared to visual assessment on a regional basis using histopathology as the reference standard.
RESULTS: Scans from 112 patients (36 cervical and 76 endometrial cancers; 340 nodal regions) were eligible for quantitative image analysis. Lower ADCmean on DW-MRI was observed in metastatic nodes for cervical cancer but not for endometrial cancer. Quantitative measures were significantly higher in malignant than benign nodal regions on [18F]FDG PET/CT and [18F]FEC PET/CT in endometrial cancer. SUVmax cut-offs showed similar performance to visual assessment in the diagnosis of metastatic lymph nodes in endometrial cancer whilst ADCmean cut-offs showed significantly lower specificity than visual assessment. Interobserver agreement was excellent for SUVmax measurements on both [18F]FDG PET/CT and [18F]FEC PET/CT, but poor for ADCmean on DW-MRI.
CONCLUSION: Quantitative measures from [18F]FDG PET/CT, [18F]FEC PET/CT, or DW-MRI did not outperform visual assessment in the detection of nodal metastases in endometrial cancer. Therefore, the implementation of these quantitative measures as standalone diagnostic tools in routine clinical practice is not recommended.