Abstract：
OBJECTIVE: Xerostomia, caused by radiation-induced parotid damage, is the most commonly reported radiotherapy (RT) complication for nasopharyngeal carcinoma (NPC). The purpose of this study was to evaluate the value of intravoxel incoherent motion (IVIM) MR in monitoring radiation-induced parotid gland damage and predicting the risk of xerostomia.
METHODS: Fifty-four NPC patients were enrolled and underwent at least three IVIM MR scans: before (pre-RT), after 5 fractions of (5th-RT), halfway through (mid-RT), and after RT (post-RT). The degree of xerostomia patients was assessed before each MR examination. Furthermore, the time when patients first reported xerostomia symptoms was recorded. The changes in IVIM parameters throughout RT, as well as the relationships between IVIM parameters and xerostomia, were analysed.
RESULTS: All IVIM parameters increased significantly from pre-RT to post-RT (p < 0.001). The rates of D, D* and f increase increased significantly from pre-RT to mid-RT (p < 0.001), indicating that cell necrosis mainly occurs in the first half of RT. In multivariate analysis, N3 (p = 0.014), pre-D (p = 0.007) and pre-D* (p = 0.003) were independent factors influencing xerostomia. D and f were significantly higher at 5th-RT than at pre-RT (both p < 0.05). IVIM detected parotid gland injury at 5th-RT at an average scanning time of 6.18 ± 1.07 days, earlier than the 11.94 ± 2.61 days when the patient first complained of xerostomia according to the RTOG scale (p < 0.001).
CONCLUSIONS: IVIM MR can dynamically monitor radiation-induced parotid gland damage and assess it earlier and more objectively than RTOG toxicity. Moreover, IVIM can screen people at risk of more severe xerostomia early.
METHODS: Fifty-four NPC patients were enrolled and underwent at least three IVIM MR scans: before (pre-RT), after 5 fractions of (5th-RT), halfway through (mid-RT), and after RT (post-RT). The degree of xerostomia patients was assessed before each MR examination. Furthermore, the time when patients first reported xerostomia symptoms was recorded. The changes in IVIM parameters throughout RT, as well as the relationships between IVIM parameters and xerostomia, were analysed.
RESULTS: All IVIM parameters increased significantly from pre-RT to post-RT (p < 0.001). The rates of D, D* and f increase increased significantly from pre-RT to mid-RT (p < 0.001), indicating that cell necrosis mainly occurs in the first half of RT. In multivariate analysis, N3 (p = 0.014), pre-D (p = 0.007) and pre-D* (p = 0.003) were independent factors influencing xerostomia. D and f were significantly higher at 5th-RT than at pre-RT (both p < 0.05). IVIM detected parotid gland injury at 5th-RT at an average scanning time of 6.18 ± 1.07 days, earlier than the 11.94 ± 2.61 days when the patient first complained of xerostomia according to the RTOG scale (p < 0.001).
CONCLUSIONS: IVIM MR can dynamically monitor radiation-induced parotid gland damage and assess it earlier and more objectively than RTOG toxicity. Moreover, IVIM can screen people at risk of more severe xerostomia early.
摘要：
目的：口干症，由辐射引起的腮腺损伤，是鼻咽癌（NPC）最常报道的放疗（RT）并发症。这项研究的目的是评估体素内不相干运动（IVIM）MR在监测辐射引起的腮腺损伤和预测口干症风险中的价值。
方法：纳入54例NPC患者，接受至少3次IVIMMR扫描：前（RT前），在(5th-RT)的5个分数之后，中途（中期），在RT之后（RT后）。在每次MR检查之前评估口干症患者的程度。此外，记录患者首次报告口干症症状的时间.整个RT期间IVIM参数的变化，以及IVIM参数与口干症之间的关系，进行了分析。
结果：从RT前到RT后，所有IVIM参数均显着增加（p<0.001）。D的比率，从RT前到RT中，D*和f的增加显着增加（p<0.001），说明细胞坏死主要发生在RT的前半部分。在多变量分析中，N3（p=0.014），pre-D(p=0.007)和pre-D*(p=0.003)是影响口干症的独立因素。D和f在第5-RT显著高于在前RT(均p<0.05)。IVIM在第5-RT平均扫描时间为6.18±1.07天检测到腮腺损伤，根据RTOG量表（p<0.001），早于患者首次主诉口干症的11.94±2.61天。
结论：IVIMMR可以动态监测辐射诱导的腮腺损伤，并比RTOG毒性更早，更客观地评估它。此外，IVIM可以早期筛查有更严重口干症风险的人。
方法：纳入54例NPC患者，接受至少3次IVIMMR扫描：前（RT前），在(5th-RT)的5个分数之后，中途（中期），在RT之后（RT后）。在每次MR检查之前评估口干症患者的程度。此外，记录患者首次报告口干症症状的时间.整个RT期间IVIM参数的变化，以及IVIM参数与口干症之间的关系，进行了分析。
结果：从RT前到RT后，所有IVIM参数均显着增加（p<0.001）。D的比率，从RT前到RT中，D*和f的增加显着增加（p<0.001），说明细胞坏死主要发生在RT的前半部分。在多变量分析中，N3（p=0.014），pre-D(p=0.007)和pre-D*(p=0.003)是影响口干症的独立因素。D和f在第5-RT显著高于在前RT(均p<0.05)。IVIM在第5-RT平均扫描时间为6.18±1.07天检测到腮腺损伤，根据RTOG量表（p<0.001），早于患者首次主诉口干症的11.94±2.61天。
结论：IVIMMR可以动态监测辐射诱导的腮腺损伤，并比RTOG毒性更早，更客观地评估它。此外，IVIM可以早期筛查有更严重口干症风险的人。
