Correlation between quantitative DCE-MRI and pathologic complete response in patients with invasive ductal carcinoma undergoing neoadjuvant systemic therapy.

This study aimed to determine the associations between pretreatment quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) pharmacokinetic (PK) parameters, post-neoadjuvant systemic therapy (NST) MRI features, and pathologic complete response (pCR) in patients with invasive ductal carcinoma (IDC). Twenty-eight consecutive IDC patients who received NST were retrospectively reviewed. All patients underwent MRI at 3 time points: before NST; after 2 cycles of NST; and before surgery. Continuous and categorical variables were compared between pCR and non-pCR groups using the Mann-Whitney U test and Fisher exact test, respectively, with HER2 status adjusted in PK parameter analyses. Partial correlation assessed associations between MRI features and pCR. Select PK parameters were further evaluated using Firth's penalized-likelihood regression, controlling for covariates. Receiver operating characteristic (ROC) analysis was performed to evaluate predictive performance. Significant differences were detected between groups regarding HER2-positive, luminal B subtype, Miller-Payne, and postoperative lymph node metastasis (P < .05). Pretreatment peritumoural extravascular extracellular volume (Ve), post-NST shrinkage pattern, and residual disease were significantly different between the groups (P < .05). Partial correlation analysis indicated a positive association between the peritumoural flux rate constant (Kep) and pCR (P < .05). Regression analysis identified the peritumoural Kep as a factor influencing the pCR with an area under the curve of 0.756 (95% CI = 0.564-0.947). Our preliminary findings suggested an association between the pCR and pretreatment peritumoural PK parameters, highlighting the potential value of the peritumoural region. These results require further validation in larger prospective studies.