Abstract:
Background Prostate-Specifc Membrane Antigen (PSMA) PET/CT and multiparametric MRI (mpMRI) are wellestablished modalities for identifying intra-prostatic lesions (IPLs) in localised prostate cancer. This study aimed to
investigate the use of PSMA PET/CT and mpMRI for biologically targeted radiation therapy treatment planning by: (1)
analysing the relationship between imaging parameters at a voxel-wise level and (2) assessing the performance of
radiomic-based machine learning models to predict tumour location and grade.
Methods PSMA PET/CT and mpMRI data from 19 prostate cancer patients were co-registered with whole-mount
histopathology using an established registration framework. Apparent Difusion Coefcient (ADC) maps were computed from DWI and semi-quantitative and quantitative parameters from DCE MRI. Voxel-wise correlation analysis was
conducted between mpMRI parameters and PET Standardised Uptake Value (SUV) for all tumour voxels. Classifcation
models were built using radiomic and clinical features to predict IPLs at a voxel level and then classifed further into
high-grade or low-grade voxels.
Results Perfusion parameters from DCE MRI were more highly correlated with PET SUV than ADC or T2w. IPLs were
best detected with a Random Forest Classifer using radiomic features from PET and mpMRI rather than either modality alone (sensitivity, specifcity and area under the curve of 0.842, 0.804 and 0.890, respectively). The tumour grading
model had an overall accuracy ranging from 0.671 to 0.992.
Conclusions Machine learning classifers using radiomic features from PSMA PET and mpMRI show promise for predicting IPLs and diferentiating between high-grade and low-grade disease, which could be used to inform biologically targeted radiation therapy planning.
