Abstract
1664
Objectives The inadequacy of conventional imaging for measuring treatment response in bone metastases is recognised. We aim to develop & evaluate novel multi-modality, multi-parametric functional imaging techniques to improve bone metastasis assessment.
Methods Patients with bone-predominant metastatic prostate cancer (mPC) or breast cancer (mBC) had pre-therapy and 8-12 week post therapy multimodality functional imaging,including whole-body DW-MRI [1.5T, b: 0, 900s/mm2] (n=13 pre-therapy, 10 at repeat); 18F-Fluoride (n=7,5); 11C-Choline (mPC ,n=4,0) and 18F-FDG PET/CT (mBC,n=3,2). Scans were segmented using DW-MRI (extrapolated b=1400s/mm2) or bone-segmented CT from PET/CT, allowing individual lesion & whole-skeleton tumour burden metrics (ADC, SUV, tumour volume).
Results Skeletal metastases were successfully segmented from normal tissues with each modality. Baseline & change in whole-body metrics are presented in table 1. Whilst good correlations were noted between the disease volume defined with each modality, 18F-fluoride PET volumes were generally higher in mPC & lower in mBC than the tumour-specific modalities (DW-MRI, 11C-Choline, 18F-FDG). In mPC an inverse correlation was seen between ADCmean & 11C-choline SUVmean but not 18F-Fluoride. No significant ADC increase or SUV reduction was seen in any mPC patient (all were clinical non-responders).
Conclusions Multi-modality, multi-parametric assessment of metastatic skeletal disease is feasible. Single lesion & whole-skeleton metrics representing differing biological processes can be derived for measuring early treatment response. Variability between functional imaging modalities likely reflects the different tumour & bone-specific biological processes imaged.