Gadolinium-enhanced echo-planar T2-weighted MRI of tumors in the extracranial head and neck: Feasibility study and preliminary results using a distributed-parameter tracer kinetic analysis

Purpose: To examine the feasibility of first-pass dynamic contrast-enhanced (DCE) T2-weighted MRI of tumors in the extracranial head and neck by applying a distributed-parameter (DP) tracer kinetic model to quantify the perfusion parameters. Materials and Methods: A total of 16 patients with primary malignant and benign tumors in the head and neck underwent DCE-MR studies. A spin-echo (SE) ecbo-planar-imaging (EPI) MR-sequence was applied for first-pass DCE-T2-weighted imaging. The data were postprocessed applying a DP tracer kinetic model that accounts for capillary-tissue exchange. Region-of-interest (ROI) analysis was performed in the tumor sites and the adjacent normal tissue. Blood flow (F), intravascular blood volume (v(1)), extravascular extracellular volume (v(2)), difference in bolus arrival time between arterial input and tissue (t(0)), intravascular mean transit time (t(1)), permeability (PS), and extraction ratio (E) maps were generated for each patient. Results: All perfusion values in the tumor sites were significantly different (0.000 <= P <= 0.01) than those in the normal muscle tissue. The median perfusion values in the tumor tissue were: F = 150.5 mL/minute/100 g, v(1) = 11.0 mL/100 g, v(2) = 31.5 mL/100 g, t(0) = 4.5 seconds, t(1) = 8.0 seconds, PS = 96.0 mL/minute/100 g, and E = 32.5. Conclusion: EPI-T2-weighted DCE-MR in head and neck tumors as well as quantification of the perfusion values using DP model physiologic imaging was feasible and the promising initial results have encourages further validation studies in the future.