Chordomas of the skull base: Dynamic MRI

Objective: To investigate the role of dynamic MRI in the diagnosis of chordomas at the skull base. Materials and Methods: Six patients with surgically proven chordomas of the skull base were examined with spin-echo technique (repetition time/echo time 200ms/15ms). Serial imaging was performed every 30 s for 240 s after a rapid injection of gadopenetate dimeglumine (0.1 mmol/kg). The contrast material enhancement ratio (CER) was analyzed. The CER was obtained for each region of interest as follows: (Sn - So) x 100/Smax - So, where Sn indicates signal intensity at each dynamic phase; So, signal intensity on the image obtained before administration of contrast material; and Smax, maximum signal intensity of all dynamic imaging. Results: All chordomas showed very slow but steady increase of contrast enhancement with no peak within 240 s. The CERs of six cases at 30 s are 13 to 40 (mean value +/- standard deviation: 22.8 +/- 10.2). Conclusion: Dynamic MRI may be helpful in differentiating between chordomas and other tumors of the skull base.