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
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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,
p < 0.001). M
Vol correlated with the manually-counted lesions (R = 0.61,
p < 0.001) and PSA (R = 0.46,
p < 0.01). PD had a lower counts/voxel in M
Vol than PR/SD (715 ± 190 vs. 975 ± 215 and 1058 ± 255,
p < 0.05 and
p < 0.01) and B
Vol (PD 275 ± 60, PR 515 ± 188 and SD 528 ± 162 counts/voxel,
p < 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.
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