Dechun Zheng1, Guojing Lai2, Ying Chen1, Qiuyuan Yue1, Xiangyi Liu1, Xiaodan Chen1, Weibo Chen3, Queenie Chan4, Yunbin Chen1. 1. Department of Radiology, Fujian Cancer Hospital & Fujian Medical University Cancer Hospital, Fuzhou, Fujian Province, P.R. China. 2. Department of Radiation Oncology, Fujian Cancer Hospital & Fujian Medical University Cancer Hospital, Fuzhou, Fujian Province, P.R. China. 3. Philips Healthcare, Shanghai, P.R. China. 4. Philips Healthcare, Hong Kong, China.
Abstract
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/mm2 ). ASSESSMENT: DCE-MRI parameters (Ktrans [the volume transfer constant of Gd-DTPA], kep [rate constant], νe [the extracellular volume fraction of the imaged tissue], and νp [the blood volume fraction]) and DKI parameters (Dapp [apparent diffusion for non-Gaussian distribution] and Kapp [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 Ktrans and Dapp values at baseline and larger <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Δ</mml:mi> <mml:msubsup><mml:mi>K</mml:mi> <mml:mrow><mml:mrow><mml:mo>(</mml:mo> <mml:mrow><mml:mn>0</mml:mn> <mml:mo>-</mml:mo> <mml:mn>4</mml:mn></mml:mrow> <mml:mo>)</mml:mo></mml:mrow> </mml:mrow> <mml:mrow><mml:mtext>trans</mml:mtext></mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> , Δvp(0-4) , and ΔDapp(0-4) 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.
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/mm2 ). ASSESSMENT: DCE-MRI parameters (Ktrans [the volume transfer constant of Gd-DTPA], kep [rate constant], νe [the extracellular volume fraction of the imaged tissue], and νp [the blood volume fraction]) and DKI parameters (Dapp [apparent diffusion for non-Gaussian distribution] and Kapp [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 Ktrans and Dapp values at baseline and larger <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Δ</mml:mi> <mml:msubsup><mml:mi>K</mml:mi> <mml:mrow><mml:mrow><mml:mo>(</mml:mo> <mml:mrow><mml:mn>0</mml:mn> <mml:mo>-</mml:mo> <mml:mn>4</mml:mn></mml:mrow> <mml:mo>)</mml:mo></mml:mrow> </mml:mrow> <mml:mrow><mml:mtext>trans</mml:mtext></mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> , Δvp(0-4) , and ΔDapp(0-4) 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.