Measurement of Blood Perfusion in Spinal Metastases With Dynamic Contrast-Enhanced Magnetic Resonance Imaging: Evaluation of Tumor Response to Radiation Therapy

STUDY DESIGN. This was a retrospective study focusing on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to assess treatment response in patients with spinal metastases. OBJECTIVE. To demonstrate DCE-MRI changes before and after radiation treatment and correlating with other imaging and clinical findings. SUMMARY OF BACKGROUND DATA. Currently, conventional imaging is limited in evaluating early treatment success or failure, which impacts patient care. METHODS. Consecutive patients with known spinal metastases underwent DCE-MRI before and after radiotherapy. Perfusion data on 19 lesions were analyzed. Radiotherapy was classified as success (n = 17) or failure (n = 2) on the basis of evidence of tumor contraction (n = 4), negative positron emission tomography (n = 2), or stability for more than 11 months (n = 11). Perfusion parameters blood plasma volume (V(p)), time-dependent leakage (K(trans)), area under the curve, and peak enhancement were derived from the signal intensity-time curves and changes in parameter values from pre- to post-treatment were calculated. Curve morphologies were also qualitatively assessed in 13 pre- and 13 post-treatment scans. RESULTS. V(p) was the strongest predictor of treatment response (false-positive rate = 9.38 × 10(−9) and false-negative rate = 0.055). All successfully treated lesions showed decreases in V(p), and the 2 treatment failures showed drastic increases in V(p). Changes in area under the curve and peak enhancement demonstrated similar relationships to the observed treatment response, whereas changes in K(trans) showed no significant relationship. Signal intensity curve morphologies also demonstrated specificity for active disease (11 of 13) and treated disease (8 of 13). CONCLUSION. Changes in perfusion, particularly V(p), reflect tumor responses to radiotherapy in spinal bone metastases. These changes were able to predict positive outcomes earlier than 6 months after treatment in 16 of 17 tumors. The ability of DCE-MRI to detect early treatment response has the potential to improve patient care and outcome.