Fig. 2.

(a) T2-weighted sagittal MR images of sacral spine showing presacral abscess on distal sacral segment; (b) T2-weighted axial MR images on sacral spine (cut on the level of red line in image on the left) showing extension of the abscess to insertion of piriformis; (c) T2-fat suppressed axial images on pelvic showing further lateral extension on the abscess.