Purpose: Oligometastatic prostate cancer is a heterogeneous disease. Radium-223 dichloride (Xofigo®) is an FDA approved alpha-particle emitting radiopharmaceutical for treatment of patients with bone metastases in metastatic castrate resistant prostate cancer patients. We are conducting a prospective trial of Radium-223 (NCT03351735) in metastatic castrate sensitive prostate cancer (CSPC). The purpose of this study is to evaluate whether changes in MRI radiomics could be observed in oligometastatic CSPC patients receiving Radium-223 in combination with ADT and SBRT.
Methods: Twelve patients with seventeen lesions were included in this study. All patients received ADT for a total of 36 weeks, concurrent 1 cycle of SBRT treatment with 27Gy delivered in 3 fractions and followed by 6 cycles of radium-223. MRI images including T1-weighted, T2-weighted and T1 post contrast images were acquired before and after treatment. Bone metastases within areas receiving 95% of the prescription dose were evaluated using PyRadiomics (3D-Slicer). Features including first order statistics, gray level cooccurrence matrix (GLCM), gray level run length matrix (GLRLM), gray level size zone matrix (GLSZM), and neighbouring gray tone difference matrix (NGTDM) were analyzed.
Results: Thirty-six features from T1-weighted MRI and eight features from T2-weighted MRI were found significantly different after the treatment. These features were related to image uniformity, entropy, and textures. For example, uniformity from T1-weighted MRI increased from 0.26±0.13 to 0.35±0.15 (P=0.035) after the treatment. Short run emphasis from T1-weighted MRI decreased from 0.76±0.12 to 0.68±0.12 (P=0.018), indicating a coarser texture after the treatment. No significant difference was found in the T1 post contrast images after treatment (P>0.05).
Conclusion: In this study including 12 patients with metastatic CSPC treated with combined therapies of ADT, Radium-223 and SBRT, significant changes related to image uniformity, entropy, and textures were observed in the treated areas with bone metastases from T1- and T2- weighted MR images.
Funding Support, Disclosures, and Conflict of Interest: Savita Dandapani receives funding support from Bayer. Xue Feng is employee of Carina Medical LLC. Quan Chen is shareholder of Carina Medical LLC.