Nuclear Medicine & Radiation Therapy

11C-Choline PET-CT Detection of Osseous Metastases versus Bone Scan in Newly Diagnosed High Risk Prostate Cancer Patients-A Pilot Study

Abstract

Nasarachi E Onyeuku, Diandra N Ayala-Peacock, Pradeep Garg and A. William Blackstock

Purpose: Identification of osseous metastatic prostate adenocarcinoma (PCa) is traditionally based on bone scan and computerized tomography (CT) imaging. Positron emission tomography (PET) has been investigated to improve detection of metastatic disease. Given the high number of false positive and false negative results with 18-fluorodeoxyglucose (18F-FDG) PET, novel tracers including 11C-Choline have been investigated for earlier identification metastatic disease. We present a prospective pilot study comparing 11C-Choline PET/CT against traditional bone scan in detecting osseous metastases in newly diagnosed high risk PCa. Methods: High-risk PCa patients underwent a standard initial workup: H&P, transrectal US-guided biopsy, PSA evaluation, CT scan, and bone scan. An experimental 11C-Choline PET/CT scan served to evaluate the extent of disease and predict for occult metastases. Pre-treatment bone scan and 11C-Choline PET/CT interpretations were compared with follow-up imaging, PSA, and clinical assessments to determine the predictive value of pre-treatment 11C-Choline imaging and overall outcomes. Results: Nine patients were successfully enrolled with 11C-Choline PET imaging during the initial workup. Three patients had evidence of osseous metastases on both CT and bone scans. Two of three patients had clinical findings consistent with their imaging, with all three patients exhibiting baseline PSA levels >50. Of the three patients deemed metastatic by conventional radiography, only two of the three corresponding 11C-Choline PET/CT images were in agreement with conventional imaging. The final patient had a negative 11C-Choline study with a T10 sclerotic focus on conventional imaging that was unchanged in follow-up scans despite post-treatment biochemical failure. A fourth patient without evidence of osseous metastatic disease on conventional scans demonstrated a positive 11C-Choline PET/CT scan on initial workup. In follow-up, the patient had evidence of diffuse osseous metastatic disease visualized on conventional imaging. Conclusion: In this limited prospective series, our results suggest an increased sensitivity of 11C-Choline PET/ CT in identifying active lytic lesions and true bony metastasis.