Longitudinal Assessment of Intravoxel Incoherent Motion Diffusion Weighted Imaging in Evaluating the Radio-sensitivity of Nasopharyngeal Carcinoma Treated with Intensity-Modulated Radiation Therapy.
PURPOSE
Intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI)was evaluated regarding its ability to preliminarily predict the short-term treatment response of nasopharyngeal carcinoma (NPC) following intensity-modulated radiation therapy.


Materials and Methods
IVIM-DWI with 14 b-factors (0-1,000 sec/mm2 ) was performed with a 3T MR system on 47 consecutive NPCs before, during (end of the 5th, 10th, 15th, 20th, and 25th fractions), and after fractional radiotherapy. IVIM parametrics (D, f, and D*) were calculated and compared to the baseline and xth fraction. Patients were categorized into responders and non-responders after radiotherapy. IVIM parametrics were also compared between subgroups.


RESULTS
After fractional radiations, the D (except D5 and D at the end of the 5th fraction) after radiations were larger than the baseline D0 (p < 0.05), and the post-radiation D* (except D*5 and D*10) were smaller than D*0 (p < 0.05). f0 was smaller than f5 and f10 (p < 0.001) but larger than fend (p < 0.05). Furthermore, greater D5, D10, D15, and f10 coupled with smaller f0, D*20, and D*25were observed in responders than non-responders (all p < 0.01). Responders also presented larger ΔD10, Δf10, ΔD*20, and δD*20 than non-responders (p < 0.05). Receiver operating characteristic curve analysis indicated that the D5, D*20, and f10 could better differentiate responders from non-responders.


CONCLUSION
IVIM-DWI could efficiently assess tumor treatment response to fractional radiotherapy and predict the radio-sensitivity for NPCs.
['Xiao|Youping|Y|', 'Chen|Ying|Y|', 'Chen|Yunbin|Y|', 'He|Zhuangzhen|Z|', 'Yao|Yiqi|Y|', 'Pan|Jianji|J|']
D000328:Adult D000368:Aged D038524:Diffusion Magnetic Resonance Imaging D019583:Dose Fractionation, Radiation D005260:Female D006801:Humans D008297:Male D008875:Middle Aged D009038:Motion D000077274:Nasopharyngeal Carcinoma D009303:Nasopharyngeal Neoplasms D012372:ROC Curve D050397:Radiotherapy, Intensity-Modulated D016896:Treatment Outcome
Intravoxel incoherent motion Nasopharyngeal carcinoma Diffusion-weighted imaging Intensity-modulated radiotherapy Radiosensitivity