TABLE 2.
Tumor Volume and Parameters of Monoexponential, SEM, and IVIM Models Pretreatment, After One Cycle of NACT, and at Mid‐treatment
| Parameter | Pretreatment (a) | After One Cycle of NACT (b) | After Three Cycles of NACT (c) | P | Post hoc** |
|---|---|---|---|---|---|
| Tumor volume (cm3) | 4.67 (2.03, 13.11) | 3.06 (1.63, 8.83) | 2.04 (0.62, 5.27) | <0.001 | a > c |
| ADC (×10−3 mm2 s−1) | 1 (0.9, 1.21) | 1.04 (0.98, 1.21) | 1.2 (1.05, 1.38) | <0.001 | a < c |
| DDC (×10−3 mm2 s−1) | 0.94 (0.82, 1.15) | 1 (0.9, 1.17) | 1.13 (0.99, 1.35) | <0.001 | a < c, b < c |
| α (unitless) | 0.83 (0.79, 0.87) | 0.85 (0.8, 0.9) | 0.84 (0.8, 0.89) | 0.41 | ‐ |
| D t (×10−3 mm2 s−1) | 0.83 (0.73, 0.94) | 0.86 (0.79, 1.01) | 0.95 (0.85, 1.14) | <0.001 | a < c, b < c |
| D p (×10−3 mm2 s−1) | 6.53 (5.3, 7.44) | 6.01 (4.68, 7.31) | 5.87 (4.59, 7.77) | 0.68 | ‐ |
| f (%) | 12.23 (10.07, 15.79) | 14.16 (11.47, 17.13) | 15.51 (13.56, 17.87) | <0.001 | a < c |
| f × D p (×10−3 mm2 s−1) | 0.88 (0.69, 1.05) | 0.83 (0.57, 1.13) | 0.97 (0.7, 1.34) | 0.28 | ‐ |
Data represented by medians (interquartile ranges). P value for a difference between the three visits was found using Friedman's nonparametric test. Pairwise comparisons** (Bonferroni‐corrected) significance at the 0.05 level.
SEM = stretched‐exponential model; IVIM = intravoxel incoherent motion; NACT = neoadjuvant chemotherapy; ADC = apparent diffusion coefficient; DDC = distributed diffusion coefficient; α = diffusion heterogeneity index; D t = tissue diffusion; D p = pseudo‐diffusion coefficient; f = perfusion fraction.