We aimed to assess longitudinal changes in quantitative imaging metric values obtained from diffusion-weighted (DW-) and dynamic contrast-enhanced magnetic resonance imaging (DCE)-MRI at pre-treatment (TX[0]), immediately after the first fraction of stereotactic body radiotherapy (D1-TX[1]), and 6 weeks post-TX (Post-TX[2]) in patients with pancreatic ductal adenocarcinoma. Ten enrolled patients (n = 10) underwent DW- and DCE-MRI examinations on a 3.0 T scanner. The apparent diffusion coefficient, ADC (mm
2/s), was derived from DW imaging data using a monoexponential model. The tissue relaxation rate,
R1t, time-course data were fitted with a shutter-speed model, which provides estimates of the volume transfer constant,
Ktrans (min
−1), extravascular extracellular volume fraction,
ve, and mean lifetime of intracellular water protons,
τi (seconds). Wilcoxon rank-sum test compared the mean values, standard deviation, skewness, kurtosis, and relative percentage (r, %) changes (Δ) in ADC,
Ktrans,
ve, and
τi values between the magnetic resonance examinations. rADC
Δ2–0 values were significantly greater than rADC
Δ1-0 values (
P = .009). r
KtransΔ2–0 values were significantly lower than r
Ktrans Δ1-0 values (
P = .048). r
veΔ2-1 and rve
Δ2-0 values were significantly different (
P = .016). r
τiΔ2-1 values were significantly lower than r
τiΔ2-0 values (
P = .008). For group comparison, the pre-TX mean and kurtosis of ADC (
P = .18 and
P = .14), skewness and kurtosis of
Ktrans values (
P = .14 for both) showed a leaning toward significant difference between patients who experienced local control (n = 2) and failed early (n = 4). DW- and DCE-MRI-derived quantitative metrics could be useful biomarkers to evaluate longitudinal changes to stereotactic body radiotherapy in patients with pancreatic ductal adenocarcinoma.
Full article