Dynamic contrast-enhanced and diffusion-weighted MR imaging in early prediction of pathologic response to neoadjuvant chemotherapy in locally advanced gastric cancer.

Purpose: To investigate the efficacy of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for the early prediction of the pathologic response to neoadjuvant chemotherapy (NAC) in patients with locally advanced gastric cancer (LAGC).

Methods: Fifty patients with LAGC who were treated with NAC followed by radical gastrectomy were enrolled. Uncontrasted and DCE-MRI were performed within 1 week before NAC. According to tumor regression grading (TRG), patients were labeled as responders (TRG = 0 + 1) and non-responders (TRG = 2 + 3). Apparent diffusion coefficients (ADC) and DCE-MRI kinetics (K, V, and K) were compared between the two groups. Logistic regression analysis was performed to screen independent factors to predict the NAC efficacy. The relationship between MRI parameters and TRG was studied by Spearman's correlation analysis. Receiver-operating characteristic curve analyses were applied to evaluate the efficacy.

Results: ADC, K, and K values were higher in responders than in non-responders (p < 0.05) and correlated with TRG (p < 0.05). The ADC and K values were independent markers for predicting TRG. The area under the curve, sensitivities, specificities of ADC, K, K, and ADC + K were 0.813, 0.699, 0.709, 0.886;73.64%, 65.54%, 63.21%, 70.37%; 86.47%, 54.97%, 79.47%, 95.65%; respectively. ADC + K demonstrated a higher efficacy than K and K (p = 0.012, 0.011), but without improvement compared with ADC (p > 0.05).

Conclusion: Both DWI and DCE-MRI can effectively predict the pathologic response to NAC in LAGC. A combination of ADC and K increased the efficacy, and ADC is the most valuable imaging parameter.