Pharmacokinetic analysis based on dynamic contrast-enhanced MRI for evaluating tumor response to preoperative therapy for oral cancer

Purpose: To evaluate whether a pharmacokinetic analysis is useful for monitoring the response of oral cancer to chemoradiotherapy (CRT). Materials and Methods: Twenty-nine patients were included. They underwent dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) before and after CRT. The DCE-MRI data were analyzed using a Tofts and Kermode (TK) model. The histological evaluation of the effects of CRT was performed according to Ohboshi and Shimosato's classification. Results: None of the pre-CRT parameters were significantly different between the responders and nonresponders. The post-CRT volume of the extravascular extracellular space (EES) per unit volume of tissue (v_e) of responders (0.397 ± 0.080) was higher than that of nonresponders (0.281 ± 0.076) (P = 0.01). The change of the v_e between the pre- and post-CRT of the responders (0.154 ± 0.093) was larger than that of the nonresponders (0.033 ± 0.073) (P = 0.001). Therefore, the increase in the v_e strongly suggested a good tumor response to CRT, which reflected an increase of the EES secondary to the destruction of the cancer nest. The changes in the volume transfer constant (K^trans) were significantly different between the responders and nonresponders (P = 0.018). Conclusion: Both the increase of the v_e and the elevation of permeability (K^trans) were indicative of a good tumor response to CRT. The pharmacokinetic analysis had potential for monitoring the histopathological response to CRT. J. Magn. Reson. Imaging 2012;36:589-597.