Early Changes of Irradiated Parotid Glands Evaluated by T1rho-Weighted Imaging: A Pilot Study.
OBJECTIVE
The aim of the study was to confirm the feasibility of T1rho-weighted imaging to evaluate the dynamic changes of parotid glands in patients with nasopharyngeal carcinoma (NPC) undergoing intensity-modulated radiation therapy.


METHODS
Twenty-six NPC patients (19 men; 7 women; mean [SD] age, 48.9 [13.4] years) underwent the following 3 serial T1rho-weighted imaging: within 2 weeks before radiotherapy (RT, pre-RT), 5 weeks after the beginning of RT (mid-RT), and 4 weeks after RT (post-RT). Parotid volumes, T1rho values, mean radiation doses, and xerostomia degrees were recorded. Change rates of parotid T1rho values were correlated with parotid atrophy rates, mean radiation doses, and xerostomia degrees.


RESULTS
During RT, parotid volume decreased (atrophy rate, 32.7 [8.1%] at mid-RT and 27.9 [10.0%] at post-RT compared with pre-RT; both P < 0.001) and parotid T1rho values increased (change rate, 25.0 [15.8%] at mid-RT and 30.1 [18.0%] at post-RT compared with pre-RT, both P < 0.001) significantly. The change rate of parotid T1rho value correlated with the atrophy rate significantly at post-RT (r = 0.301, P = 0.047). Intraobserver and interobserver reproducibility of parotid T1rho measurements were excellent (intraclass correlation coefficient, 0.974 and 0.956, respectively).


CONCLUSIONS
Dynamic changes of radiation-induced parotid damage in NPC patients who underwent intensity-modulated radiation therapy could be noninvasively evaluated by T1rho-weighted imaging.
From the *Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School; †Department of Radiology, Nanjing Drum Tower Hospital Clinical College of Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine; ‡The Comprehensive Cancer Centre of Drum Tower Hospital, Medical School of Nanjing University & Clinical Cancer Institute of Nanjing University, Nanjing, Jiangsu Province; §Philips Healthcare, Shanghai, China; and ∥Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA.
Nan
N
Zhou
Chen
C
Chu
Xin
X
Dou
Ming
M
Li
Song
S
Liu
Tingting
T
Guo
Lijing
L
Zhu
Baorui
B
Liu
Weibo
W
Chen
Jian
J
He
Jing
J
Yan
Zhengyang
Z
Zhou
Xiaofeng
X
Yang
D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000532:radiotherapy*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D010306:Parotid Gland / Q000000981:diagnostic imaging* / Q000528:radiation effects*; D010865:Pilot Projects; D011446:Prospective Studies; D050397:Radiotherapy, Intensity-Modulated; D015203:Reproducibility of Results; D055815:Young Adult