| Objective：To study the ADC（Apparent Diffusion Coefficient，ADC）variation of salivary glands during non-stimulation and gustatorystimulation of NPC patients treated by intensity modulated radiationtherapy(IMRT) with MR diffusion-weighted imaging(DWI)． Toinvestigate the relationship between radiation dose volume and salivaryglands ability changes.so as to provide the DW MRI can be used to detectthe salivary gland damage.Methods： The study population included20NPC patients treatedwith IMRT in FuJian Tumor Hospital.The ADC variation of salivaryglands during non-stimulation and gustatory stimulation of salivary glandwas examined by DW MRI at the beginning,the2Weeks,the4weeks,andthe e nd (6weeks) after treatment. The index (EX) of salivary gland wasexamined by ECT at the beginning,and the end.Also The grade of xerostomia was examined at the end after the therapy,The relationship among(Ex), the grade of xerostomia and ADC was analyzed according to theRTOG(Radiation Therapy Oncology Group). And to analysis the change of salivary gland volume and dose in intensitymodulated radiotherapywith dose-volume histogram (DVH).Results:1.The ADC of parotid glands during non-stimulation at thebeginning,the2Weeks,the4weeks,and the end (6weeks) were1.13±0.19x10~3mm~2/s、1.28±0.20x10~3mm~2/s、1.41±0.21x10~3mm~2/s、1.48±0.23x10~3mm~2/s，The ADC were raised with the time,There all wereobvious difference between them (p <0.05）respectively.The ADC ofsubmandibular glands during non-stimulation\at the beginning,the2Weeks,the4weeks,and the end (6weeks) were1.33±0.24x10~3mm~2/s、1.42±0.27x10~3mm~2/s、1.61±0.25x10~3mm~2/s、1.70±0.32x10~3mm~2/s，TheADC were raised with the time,There all were obvious differencebetween them (p <0.05）respectively.In the same time.Compare toparotid glands.the the ADC of submandibular glands were obviouslyraised（P<0.05）.2. The ADC of parotid glands during gustatory stimulation at thebeginning,the2Weeks,the4weeks,and the end (6weeks) were1.21±0.17x10~3mm~2/s、1.35±0.24x10~3mm~2/s、1.45±0.22x10~3mm~2/s、1.60±0.21x10~3mm~2/s，The ADC were raised with the time,There all wereobvious difference between them (p <0.05）respectively.The ADC ofsubmandibular glands during gustatory stimulation at the beginning,the2Weeks,the4weeks,and the end (6weeks) were1.33±0.27x10~3mm~2/s、 1.50±0.26x10~3mm~2/s、1.62±0.31x10~3mm~2/s、1.78±0.36x10~3mm~2/s，TheADC were raised with the time,There all were obvious differencebetween them (p <0.05）respectively.In the same time.Compare toparotid glands.the the ADC of submandibular glands were obviouslyraised（P<0.05）.3. The ADC of salivary glands during gustatory stimulation werehigher than the ADC during non-stimulation at the beginning,the2Weeks,tand the end (6weeks)（P<0.05）, except the4weeks.4. By making use of SPECT radioactive dynamic imaging,Thedamage rates of the excretion function (Ex) of parotid glands at thebeginning and the end were44.8%±21.7%and5.4%±25.9%respectively.There were obvious difference between them (p <0.05）Thedamage rates of the excretion function (Ex) of submandibular glands atthe beginning and the end were44.9%±11.8%and7.3%±22.7%respectively.There all were obvious difference between them (p <0.05）.5. After radiotherapy,1patients did not have xerostomia，grade Iwas65.0％，grade11was20.0％，gradeIII was10.0％.There has nocorrelation between the function of salivary glands and the grade ofxerostomia.6. Before and after radiotherapy.The mean value of ADC and the Exof parotid glands was negative correlation （r=-0.567，P<0.01）and The mean value of ADC and the Ex of submandibular glands was negativecorrelation （r=-0.476，P<0.05）during gustatory stimulation.7. By dose-volum e histogram (DVH),The mean dose of left parotid gland was32.75Gy±2.70Gy（28.18Gy—36.99Gy）The mean dose ofright parotid g land was35.10Gy±6.30Gy（28.88Gy—56.83Gy）,Themean dose of left submandibular gland was55.84Gy±3.9Gy（51.39Gy—61.04Gy）， The mean dose of right submandibular glandwas57.3Gy±4．0Gy（50.05Gy—65.23Gy），the function of salivaryglands were damaged with the mean dose,with the Ex were obviouslydecreased （P<0.01）,the ADC were obviously raised（P<0.01）.Conclusion:1. Diffusion-weighted-MRI allows noninvasive evaluation offunctional changes in the major salivary glands after RT and is apromising tool for investigating radiation-induced xerostomia. duringgustatory stimulation the value of Ex and the ADC was nagativrcorrelation.therefore.it proved that DWI allows noninvasive evaluation offunctional changes in the major salivary glands after RT2. The mean dose of parotid gland get25.53Gy—46.41Gy,andsubmandibular gland get50.94Gy—63.13Gy, can lead to thecomposition and function of the salivary glands damaged.and the damagewill be more serious along with the time and the dose,in the samecondition.the damage of the submandibulan glands were more serious.and during gustatory stimulation the decrease of ADC will bemore obviously on account of the damage of the store function of thesalivary glands.3. The mean dose of parotid gland get25.53Gy—46.41Gy,andsubmandibular gland get50.94Gy—63.13Gy, can lead to diffrentextents of xerostomia,There has no correlation between the function ofsalivary glands and the grade of xerostomia.,... |
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