Susumu Kandatsu MD, Presenter: Nothing to Disclose

Riwa Kishimoto MD, PhD, Abstract Co-Author: Nothing to Disclose

Tadashi Kamada MD, PhD, Abstract Co-Author: Nothing to Disclose

Reiko Imai MD, PhD, Abstract Co-Author: Nothing to Disclose

Junnetsu Mizoe MD, Abstract Co-Author: Nothing to Disclose

Hirohiko Tsujii MD, Abstract Co-Author: Nothing to Disclose

We have treated chordoma with heavy ion therapy since 1996. Almost all of the tumors were slowly reduced in size after the therapy, and then, it was difficult to evaluate the effectiveness of the therapy by the change of the tumor size. We studied the change of signal intensities of MR imaging for the evaluation of the effect of the heavy ion therapy for chordoma.

The study was performed with institutional review board approval, and a waiver of individual informed consent was obtained. From April 2005 to March 2007, forty one patients with chordoma underwent heavy ion therapy. Among them, twenty three patients (13 men, 10 women; mean age 66 years; range, 53 - 79 years) underwent follow-up MR imaging for more than 6 months after the therapy. The tumors were located in sacrum in 17 cases, in spine in 5 cases, and in clivus in 1 case. Mean tumor size was 74 mm in maximum diameters ranging from 36 mm to 150 mm. T2 weighted MR imaging, T1 weighted MR imaging, post contrast T1 weighted MR imaging, and diffusion imaging were obtained by a 1.5-T MR imager. The apparent diffusion coefficient (ADC) of the chordomas were calculated using two b factors ( b = 0 and 1,000 sec/mm 2 ).

Mean ADC value before the therapy was 1.31 x 10 -3 mm 2 /sec and the value after the therapy was 1.94 x 10 -3 mm 2 /sec. ADC value was significantly increased more than 6 months after the therapy (P < 0.01). Signal intensities of T2 weighted MR imaging after the therapy were mildly increased and signal intensities of post contrast enhancement were reduced mildly after the therapy.

ADC value is most significant effective value for early evaluation of the effectiveness of heavy ion therapy for chordoma.

By measuring ADC value, we can predict the effectiveness of heavy ion therapy for chordoma and may find the tumor recurrence early.

Kandatsu, S, Kishimoto, R, Kamada, T, Imai, R, Mizoe, J, Tsujii, H, Evaluation of Effectiveness of Heavy Ion Therapy for Chordoma by MR Imaging.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5014117.html