T1-Weighted, Dynamic Contrast-Enhanced MR Perfusion Imaging Can Differentiate between Treatment Success and Failure in Spine Metastases Undergoing Radiation Therapy

Example of a 63-year-old female patient with metastatic thymoma demonstrating an unsuccessful treatment response at T9 and the associated epidural area. The left column shows sagittal T1-weighted MR imaging of the cervical and thoracic spine. The hypointense area corresponds to vertebral lesions. The middle column shows plasma volume (V_p) maps of the lesions. Although tumor size decreased 19.4%, the normalized V_p of the lesion was 5.48 before RT and 9.03 after RT, an increase of 64.8%. The patient experienced progression of disease, particularly in the epidural-associated portion of the tumor. Additional RT therapy was required from T8–T10 14 months after the secondary imaging study. The right column is a T1-weighted MR imaging merged with the perfusion V_p map. The arrows indicate the lesions of interest.

Box-and-whisker plot of the ΔV_p and the change in mean vessel permeability (ΔK^trans) by group. The mean ΔV_p is −57.3% in the clinical response group and +88.2% in the persistent disease group. The mean ΔK^trans is −11.7% in the clinical response group and +51.4% in the persistent disease group. There is a statistically significant difference in ΔV_p between the persistent disease and clinical response groups as evidenced by a Mann-Whitney U test (P < .001). ΔK₁₂ indicates ΔK^trans.

Graphs of the averaged MR signal intensity separated by the clinical outcome group. There is a reduction in averaged signal intensity following RT within the clinical response group. However, averaged signal intensity remains elevated within the persistent disease group.