Abstract
There has been a growing interest in exploring the applications of stretched-exponential (SEM) and intravoxel incoherent motion (IVIM) models of diffusion-weighted imaging (DWI) in breast imaging, with the focus on differentiation of breast lesions. However, the use of SEM and IVIM models to predict early response to neoadjuvant chemotherapy (NACT) has received less attention.
To investigate the value of monoexponential, SEM, and IVIM models to predict early response to NACT in patients with primary breast cancer.
Prospective.
Thirty-seven patients with primary breast cancer (aged 46 ± 11 years) due to undergo NACT.
A 1.5-T MR scanner, T
-weighted three-dimensional spoiled gradient-echo, two-dimensional single-shot spin-echo echo-planar imaging sequence (DWI) at six b-values (0-800 s mm
).
Tumor volume, apparent diffusion coefficient, tissue diffusion (D
), pseudo-diffusion coefficient (D
), perfusion fraction (f), distributed diffusion coefficient, and alpha (α) were extracted, following volumetric sampling of the tumors, at three time-points: pretreatment, post one and three cycles of NACT.
Mann-Whitney test, receiver operating characteristic (ROC) curve. Statistical significance level was P < 0.05.
Following NACT, 17 patients were determined to be pathological responders and 20 nonresponders. Tumor volume was significantly larger in nonresponders at each MRI time-point and demonstrated reasonable performance in predicting response (area under the ROC curve [AUC] = 0.83-0.87). No significant differences between groups were found in the diffusion coefficients at each time-point (P = 0.09-1). The parameters α (SEM), f, and f × D
(IVIM) were able to differentiate between response groups after one cycle of NACT (AUC = 0.73, 0.72, and 0.74, respectively).
Diffusion coefficients derived from the monoexponential, SEM, and IVIM models did not predict pathological response. However, the IVIM-derived parameters f and f × D
and the SEM-derived parameter α were able to predict response to NACT in breast cancer patients following one cycle of NACT.
2 TECHNICAL EFFICACY STAGE: 2.