Radiomic features from pretreatment biparametric MRI predict prostate cancer biochemical recurrence: Preliminary findings

Background: Radiomics or computer-extracted texture features derived from MRI have been shown to help quantitatively characterize prostate cancer (PCa). Radiomics have not been explored depth in the context of predicting biochemical recurrence (BCR) of PCa.

Purpose: To identify a set of radiomic features derived from pretreatment biparametric MRI (bpMRI) that may be predictive of PCa BCR.

Study type: Retrospective.

Subjects: In all, 120 PCa patients from two institutions, I₁ and I₂ , partitioned into training set D₁ (N = 70) from I₁ and independent validation set D₂ (N = 50) from I₂ . All patients were followed for ≥3 years.

Sequence: 3T, T₂ -weighted (T₂ WI) and apparent diffusion coefficient (ADC) maps derived from diffusion-weighted sequences.

Assessment: PCa regions of interest (ROIs) on T₂ WI were annotated by two experienced radiologists. Radiomic features from bpMRI (T₂ WI and ADC maps) were extracted from the ROIs. A machine-learning classifier (C_BCR ) was trained with the best discriminating set of radiomic features to predict BCR (p_BCR ).

Statistical tests: Wilcoxon rank-sum tests with P < 0.05 were considered statistically significant. Differences in BCR-free survival at 3 years using p_BCR was assessed using the Kaplan-Meier method and compared with Gleason Score (GS), PSA, and PIRADS-v2.

Results: Distribution statistics of co-occurrence of local anisotropic gradient orientation (CoLlAGe) and Haralick features from T₂ WI and ADC were associated with BCR (P < 0.05) on D₁ . C_BCR predictions resulted in a mean AUC = 0.84 on D₁ and AUC = 0.73 on D₂ . A significant difference in BCR-free survival between the predicted classes (BCR + and BCR-) was observed (P = 0.02) on D₂ compared to those obtained from GS (P = 0.8), PSA (P = 0.93) and PIRADS-v2 (P = 0.23).

Data conclusion: Radiomic features from pretreatment bpMRI can be predictive of PCa BCR after therapy and may help identify men who would benefit from adjuvant therapy.

Level of evidence: 4 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018;48:1626-1636.