Early evaluation of irradiated parotid glands with intravoxel incoherent motion MR imaging: correlation with dynamic contrast-enhanced MR imaging.
Radiation-induced parotid damage is one of the most common complications in patients with nasopharyngeal carcinoma (NPC) undergoing radiotherapy (RT). Intravoxel incoherent motion (IVIM) magnetic resonance (MR) imaging has been reported for evaluating irradiated parotid damage. However, the changes of IVIM perfusion-related parameters in irradiated parotid glands have not been confirmed by conventional perfusion measurements obtained from dynamic contrast-enhanced (DCE) MR imaging. The purposes of this study were to monitor radiation-induced parotid damage using IVIM and DCE MR imaging and to investigate the correlations between changes of these MR parameters.



Eighteen NPC patients underwent bilateral parotid T1-weighted, IVIM and DCE MR imaging pre-RT (2 weeks before RT) and post-RT (4 weeks after RT). Parotid volume; IVIM MR parameters, including apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f); and DCE MR parameters, including maximum relative enhancement (MRE), time to peak (TTP), Wash in Rate, and the degree of xerostomia were recorded. Correlations of parotid MR parameters with mean radiation dose, atrophy rate and xerostomia degree, as well as the relationships between IVIM and DCE MR parameters, were investigated.



From pre-RT to post-RT, all of the IVIM and DCE MR parameters increased significantly (p < 0.001 for ADC, D, f, MRE, Wash in Rate; p = 0.024 for D*; p = 0.037 for TTP). Change rates of ADC, f and MRE were negatively correlated with atrophy rate significantly (all p < 0.05). Significant correlations were observed between the change rates of D* and MRE (r = 0.371, p = 0.026) and between the change rates of D* and TTP (r = 0.396, p = 0.017). The intra- and interobserver reproducibility of IVIM and DCE MR parameters was good to excellent (intraclass correlation coefficient, 0.633-0.983).



Early radiation-induced changes of parotid glands could be evaluated by IVIM and DCE MR imaging. Certain IVIM and DCE MR parameters were correlated significantly.
Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.
Nan
N
Zhou
Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.
Chen
C
Chu
Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.
Xin
X
Dou
Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.
Ming
M
Li
Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.
Song
S
Liu
The Comprehensive Cancer Centre of Drum Tower Hospital, Medical School of Nanjing University & Clinical Cancer Institute of Nanjing University, Nanjing, 210008, China.
Lijing
L
Zhu
The Comprehensive Cancer Centre of Drum Tower Hospital, Medical School of Nanjing University & Clinical Cancer Institute of Nanjing University, Nanjing, 210008, China.
Baorui
B
Liu
Department of Radiology, Nanjing Drum Tower Hospital Clinical College of Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210008, China.
Tingting
T
Guo
Philips Healthcare, Shanghai, 200233, China.
Weibo
W
Chen
Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China. hjxueren@126.com.
Jian
J
He
The Comprehensive Cancer Centre of Drum Tower Hospital, Medical School of Nanjing University & Clinical Cancer Institute of Nanjing University, Nanjing, 210008, China. firefreebird@163.com.
Jing
J
Yan
Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China. zyzhou@nju.edu.cn.
Zhengyang
Z
Zhou
Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, 30322, USA.
Xiaofeng
X
Yang
Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, 30322, USA.
Tian
T
Liu
D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000532:radiotherapy; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009038:Motion; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D010306:Parotid Gland / Q000000981:diagnostic imaging* / Q000473:pathology / Q000528:radiation effects*; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D014987:Xerostomia / Q000175:diagnosis / Q000209:etiology; D055815:Young Adult
D003287:Contrast Media
Dynamic contrast-enhanced (DCE) MR imaging; Intravoxel incoherent motion (IVIM) MR imaging; Nasopharyngeal carcinoma (NPC); Parotid glands; Radiotherapy