Author: Sotirios Bisdas

Sotirios Bisdas • Neuroradiology, University of Tuebingen

The Microcirculation in the “Target Node“ as Outcome Prognosticator: Facts and Implications

In the recent paper of Kim et al. [1], the authors attempt for first time to examine the relationship between pharmacokinetic parameters, obtained by dynamic contrast-enhanced (DCE)-MRI, of a metastatic target node and treatment outcome in patients with neck cancer. The paper makes 3 important contributions to the DCE neck imaging: 1) adding to the evidence gained by Cao et al. [2], Kim et al. derived (based on a two-compartment pharmacokinetic model) quantitative perfusion-associated parameters 2) similarly to the work of Bisdas et al. [3] microcirculation parameters (other to blood flow, blood volume, and permeability) such as Ktrans (transfer constant), ve (extravascular extracellular space volume fraction) and τi (intracellular water lifetime) are introduced in the characterization of neck cancer; 3) for first time Kim et al. examine exclusively the pre-treatment microcirculation parameters of nodal disease in neck cancer, trying to evaluate their predictive value. But let’s take a closer look to these 3 important aspects of the paper.

The quantification of the perfusion parameters in neck cancer is valuable as the quantitative results may facilitate an objective disease monitoring in the same institution and, under certain circumstances, an interchangeability across different institutions. Nowadays, theoretical models deliver quantitative information (of course under certain inevitable assumptions concerning the relationship between MR signal and contrast agent concentration) which are obviously superior to heuristic (semi-quantitative) DCE parameters, such as peak enhancement, maximum upslope, time-to-peak enhancement, and washout slope. In the future, DCE-MRI should be besides CT a major player in this field and combined with diffusion-weighted sequences and spectroscopy may face equally the PET/CT.

Kim et al. focused on the nodal disease, which is a rather unattended aspect in the DCE imaging of neck cancer. The authors found significantly elevated baseline Ktrans in responders, which presumably has led to a better distribution of the …