Automated Definition of Skeletal Disease Burden in Metastatic Prostate Carcinoma: A 3D Analysis of SPECT/CT Images

• Main Authors: Francesco Fiz, Helmut Dittmann, Cristina Campi, Matthias Weissinger, Samine Sahbai, Matthias Reimold, Arnulf Stenzl, Michele Piana, Gianmario Sambuceti, Christian la Fougère
• Format: Article
• Language: English
• Published: MDPI AG 2019-06-01
• Series: Cancers
• Subjects: mCRPC; SPECT/CT; Computer-assisted diagnosis; XOFIGO; Therapy response assessment
• Online Access: https://www.mdpi.com/2072-6694/11/6/869

To meet the current need for skeletal tumor-load estimation in castration-resistant prostate cancer (CRPC), we developed a novel approach based on adaptive bone segmentation. In this study, we compared the program output with existing estimates and with the radiological outcome. Seventy-six whole-body single-photon emission computed tomographies/x-ray computed tomography with 3,3-diphosphono-1,2-propanedicarboxylic acid from mCRPC patients were analyzed. The software identified the whole skeletal volume (S_Vol) and classified the voxels metastases (M_Vol) or normal bone (B_Vol). S_Vol was compared with the estimation of a commercial software. M_Vol was compared with manual assessment and with prostate specific antigen (PSA) levels. Counts/voxel were extracted from M_Vol and B_Vol. After six cycles of ²²³RaCl2-therapy every patient was re-evaluated as having progressive disease (PD), stable disease (SD), or a partial response (PR). S_Vol correlated with that of the commercial software (R = 0.99, <i>p</i> &lt; 0.001). M_Vol correlated with the manually-counted lesions (R = 0.61, <i>p</i> &lt; 0.001) and PSA (R = 0.46, <i>p</i> &lt; 0.01). PD had a lower counts/voxel in M_Vol than PR/SD (715 &#177; 190 vs. 975 &#177; 215 and 1058 &#177; 255, <i>p</i> &lt; 0.05 and <i>p</i> &lt; 0.01) and B_Vol (PD 275 &#177; 60, PR 515 &#177; 188 and SD 528 &#177; 162 counts/voxel, <i>p</i> &lt; 0.001). Segmentation-based tumor load correlated with radiological/laboratory indices. Uptake was linked with the clinical outcome, suggesting that metastases in PD patients have a lower affinity for bone-seeking radionuclides and might benefit less from bone-targeted radioisotope therapies.