The prognostic value of dynamic contrast-enhanced MRI contrast agent transfer constant K(trans) in cervical cancer is explained by plasma flow rather than vessel permeability

BACKGROUND: The microvascular contrast agent transfer constant K(trans) has shown prognostic value in cervical cancer patients treated with chemoradiotherapy. This study aims to determine whether this is explained by the contribution to K(trans) of plasma flow (F(p)), vessel permeability surface-area product (PS), or a combination of both. METHODS: Pre-treatment dynamic contrast-enhanced MRI (DCE-MRI) data from 36 patients were analysed using the two-compartment exchange model. Estimates of F(p), PS, K(trans), and fractional plasma and interstitial volumes (v(p) and v(e)) were made and used in univariate and multivariate survival analyses adjusting for clinicopathologic variables tumour stage, nodal status, histological subtype, patient age, tumour volume, and treatment type (chemoradiotherapy vs radiotherapy alone). RESULTS: In univariate analyses, F(p) (HR=0.25, P=0.0095) and K(trans) (HR=0.20, P=0.032) were significantly associated with disease-free survival while PS, v(p) and v(e) were not. In multivariate analyses adjusting for clinicopathologic variables, F(p) and K(trans) significantly increased the accuracy of survival predictions (P=0.0089). CONCLUSIONS: The prognostic value of K(trans) in cervical cancer patients treated with chemoradiotherapy is explained by microvascular plasma flow (F(p)) rather than vessel permeability surface-area product (PS).