Integrating dynamic contrast-enhanced magnetic resonance imaging and diffusion kurtosis imaging for neoadjuvant chemotherapy assessment of nasopharyngeal carcinoma.

Background: Since neoadjuvant chemotherapy (NAC) has proven a benefit for locally advanced nasopharyngeal carcinoma (NPC), early response evaluation after chemotherapy is important to implement individualized therapy for NPC in the era of precision medicine.

Purpose: To determine the combined and independent contribution between dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion kurtosis imaging (DKI) in the early monitoring of NAC response for NPC.

Study Type: Prospective.

Population: Fifty-three locally advanced NPC patients.

Field Strength/sequence: Four examinations before and at 4, 20, and 40 days after NAC initiation were performed at 3T MRI including DCE-MRI and DKI (b values = 0, 500, 1000, 1500 s/mm ).

Assessment: DCE-MRI parameters (K [the volume transfer constant of Gd-DTPA], k [rate constant], ν [the extracellular volume fraction of the imaged tissue], and ν [the blood volume fraction]) and DKI parameters (D [apparent diffusion for non-Gaussian distribution] and K [apparent kurtosis coefficient]) were analyzed using dedicated software.

Statistical Tests: MRI parameters and their corresponding changes were compared between responders and nonresponders after one or two NAC cycles treatment using independent-samples Student's t-test or Mann-Whitney U-test depending on the normality contribution test and then followed by logistic regression and receiver operating characteristic curve (ROC) analyses.

Results: The responder group (RG) patients presented significantly higher mean K and D values at baseline and larger , Δv , and ΔD values after either one or two NAC cycles compared with the nonresponder group (NRG) patients (all P < 0.05). ROC analyses demonstrated the higher diagnostic accuracy of combined DCE-MRI and DKI model to distinguish nonresponders from responders after two NAC cycles than using DCE-MRI (0.987 vs. 0.872, P = 0.033) or DKI (0.987 vs. 0.898, P = 0.047) alone.

Data Conclusion: Combined DCE-MRI and DKI models had higher diagnostic accuracy for NAC assessment compared with either model used independently.

Level Of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1208-1216.