Pretreatment dual-energy CT versus diffusion-weighted imaging for predicting pathologic complete response to neoadjuvant chemotherapy in breast cancer.

BACKGROUND: To explore the feasibility of pretreatment dual-energy CT (DECT) quantitative parameters for predicting pathologic complete response (pCR) after neoadjuvant chemotherapy in breast cancer and to compare their predictive performance with MRI-derived apparent diffusion coefficient (ADC). METHODS: This prospective study enrolled participants with invasive breast cancer receiving NAC between June 2022 and December 2023. All participants underwent pretreatment contrast-enhanced chest DECT and breast MRI. Quantitative DECT parameters (normalized iodine concentration [NIC], normalized effective atomic number [nZeff], slope of the spectral Hounsfield unit curve [λHU] in arterial and venous phases, and interphase differentials [ΔNIC, ΔnZeff, ΔλHU]) and ADC values were measured and compared between pCR and non-pCR groups. Predictive performance was assessed using the area under the receiver operating characteristic curve (AUC). RESULTS: Sixty-five participants (mean age ± SD, 48 ± 10 years) were included; 15 (23.1%) participants achieved pCR. The venous-phase NIC (V-NIC) (0.29 ± 0.10 vs. 0.39 ± 0.13, p = 0.004) and ΔNIC (0.20 ± 0.10 vs. 0.26 ± 0.09, p = 0.03) from DECT were lower, and the ADC (0.89 ± 0.13 vs. 0.77 ± 0.13 × 10− 3 mm2/s, p = 0.004) was higher in the pCR than the non-pCR group. ROC analysis demonstrated no significant difference in AUC between V-NIC and ADC (0.75 [95% CI: 0.51, 0.89] vs. 0.71 [95% CI: 0.58, 0.81], p = 0.69). Combining V-NIC and ADC (AUC: 0.79 [95% CI: 0.65, 0.90]) did not improve predictive performance compared with V-NIC or ADC alone (both p > 0.05). CONCLUSIONS: Pretreatment DECT-derived quantitative parameters may serve as feasible noninvasive indicators for predicting pCR after NAC in breast cancer. In this pilot cohort, the predictive performance of V-NIC was not significantly different from that of ADC; given the limited number of pCR events, these findings are preliminary and require validation in larger, independent cohorts.