Dynamic Contrast-Enhanced MRI–Derived Intracellular Water Lifetime (τ_i): A Prognostic Marker for Patients with Head and Neck Squamous Cell Carcinomas

Representative images from a patient who died 2.12 years after the end of CRT. Axial T2-weighted image (A) demonstrates a heterogeneous hyperintense metastatic left level IIb lymph node (arrow). It appears hypointense on a coregistered T1-weighted image (B) with heterogeneous enhancement on postcontrast T1-weighted image (C). DCE-MRI–derived τ_i (0.031 seconds; [D]) and K^trans (0.135 minutes⁻¹ [E]) maps overlaid on postcontrast T1-weighted images demonstrating lower τ_i and K^trans values from the node compared with the patient with longer survival as shown in Fig 1.

Kaplan-Meier plot for τ_i. Patients with higher pretreatment τ_i (solid curves) demonstrate longer OS compared with patients with lower τ_i (broken curves) for first 2-year (solid vertical line, P = .09), 5-year (dotted vertical line, P = .01), and long-term (median duration, >7 years; P = .006) follow-up periods.

Kaplan-Meier plots for K^trans. Patients with higher pretreatment K^trans (solid curves) demonstrate longer OS compared with patients with lower K^trans (broken curves) at the 2-year (solid vertical line; P = .07), 5-year (dotted vertical line; P = .028), and long-term (median duration, >7 years; P = .06) follow-up periods.

Kaplan-Meier plots for combinations of τ_i and K^trans. Patients with high τ_i/K^trans (thick broken curve) had the longest OS, and patients with low τ_i/K^trans (thin broken curve) had the shortest OS for the first 2-year (solid vertical line; P = .02), 5-year (dotted vertical line; P < .0001), and long-term (median duration, >7 years; P < .0001) follow-up periods. In addition, patients with high τ_i/low K^trans (thick solid curve) exhibited longer OS than patients with low τ_i/high K^trans (thin solid curve) at all clinical end points.