FIG 1. C2 metastasis in a 60-year-old male patient with renal cell carcinoma.

A, T1-weighted MR image (583/12 [TR/TE]) obtained before radiation therapy shows low signal intensity in the metastatic lesion (arrow).

B, T2-weighted MR image (3800/128) obtained before radiation therapy shows low signal intensity in the metastatic lesion (arrow).

C, Diffusion-weighted MR image (TR, 21.6; diffusion pulse length, 2 ms) obtained before radiation therapy shows slight hyperintensity (arrows) relative to normal vertebral bone marrow.

D, Follow-up T1-weighted MR image reveals persistent hypointensity (arrows) 1 month after therapy.

E, Follow-up T2-weighted MR image reveals persistent hypointensity (arrow) 1 month after therapy.

F, Follow-up diffusion-weighted MR image obtained 1 month after therapy shows iso- to hypointense signal (arrows). In a case of metastasis to the spine with clinical improvement, diffusion-weighted MR image shows decreased signal intensity change whereas conventional spin-echo T1- or T2-weighted MR images are not completely conclusive for monitoring the response.