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. © 2012 Wiley Periodicals, Inc.