Abstract
662
Objectives: Dynamic 11C-acetate PET/CT can be used to study tissue perfusion and carbon flux simultaneously, but studies in cancer are limited. We investigated the kinetics of 11C-acetate in prostate cancer subjects using parametric images with an image-derived input function (IDIF).
Methods: Twenty-one patients with newly diagnosed low-moderate risk prostate cancer were studied. All underwent pelvic MRI. Dynamic 11C-acetate (5 MBq/kg) PET/CT of the pelvis was acquired for 32 minutes with 32 time frames. An IDIF was acquired from iliac vessels with multiple small regions of interest (ROIs) and a standardized metabolite correction. Parametric images of K1 (extraction), k2 (oxidative metabolism) and Vd (=K1/k2, anabolic metabolism defined as carbon retention) were constructed using a one-tissue compartment model. ROIs of the largest cancer region in each patient and normal prostate tissue were drawn using information from MRI (T2 and DWI images) and from post-surgical histopathology of whole prostate sections (n=7).
Results: Mean PSA was 8.3±3.9. Median Gleason Sum was 6 (range 5-7). K1, Vd and SUVs were higher in cancerous regions compared to normal prostate for all patients (p<0.001). PSA correlated to early SUV (r=0.50, p=0.02) and K1 (r=0.48, p=0.03). Early and late SUVs were correlated to Vd (r>0.76, p<0.001) and K1 (r>0.61, p<0.005).
Conclusion: Parametric images could be used to visualize the 11C-acetate kinetics of the prostate. In this cohort of relatively low-risk cancers, PSA values were related to cancer perfusion. SUV of cancerous regions at any time point is primarily associated with anabolic metabolism. Research Support: Swedish Cancer Foundation (Cancerfonden)