Magnetic Resonance Imaging of the Axial Skeleton for Detecting Bone Metastases in Patients With High-Risk Prostate Cancer: Diagnostic and Cost-Effectiveness and Comparison With Current Detection Strategies

Abstract

Purpose To evaluate the diagnostic performance, costs, and impact on therapy of one-step magnetic resonance imaging (MRI) of the axial skeleton (MRIas) for detecting bone metastases in patients with high-risk prostate cancer (PCa). Patients and Methods Sixty-six consecutive patients with high-risk PCa prospectively underwent MRIas in addition to the standard sequential work-up (SW) of bone metastases (technetium-99m bone scintigraphy [BS] completed with targeted x-rays [TXR] in patients with equivocal BS findings and with MRI obtained on request [MRIor] in patients with inconclusive BS/TXR findings). Panel review of initial and 6-month follow-up MRI findings, BS/TXR, and all available baseline and follow-up clinical and biologic data were used as the best valuable comparator to define metastatic status. Diagnostic effectiveness of MRIas alone was compared with each step of the SW. Impact of MRIas screening on patient management and costs was evaluated. Results On the basis of the best valuable comparator, 41 patients (62%) had bone metastases. Sensitivities were 46% for BS alone, 63% for BS/TXR, 83% for BS/TXR/MRIor, and 100% for MRIas; the corresponding specificities were 32%, 64%, 100%, and 88%, respectively. MRIas was significantly more sensitive than any other approach (P < .05, McNemar). MRIas identified metastases in seven (30%) of 23 patients considered negative and eight (47%) of 17 patients considered equivocal by other strategies, which altered the initially planned therapy. Economic impact was variable among countries, depending on reimbursement rates. Conclusion MRIas is more sensitive than the current SW of radiographically identified bone metastases in high-risk PCa patients, which impacts the clinical management of a significant proportion of patients.