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Temporal Evolution of Parotid Volume and Parotid Apparent Diffusion Coefficient in Nasopharyngeal Carcinoma Patients Treated by Intensity-Modulated Radiotherapy Investigated by Magnetic Resonance Imaging: A Pilot Study.

Juan CJ, Cheng CC, Chiu SC, Jen YM, Liu YJ, Chiu HC, Kao HW, Wang CW, Chung HW, Huang GS, Hsu HH - PLoS ONE (2015)

Bottom Line: A P value less than 0.05 was considered as statistically significant.The parotid ADC was significantly higher at all post-RT stages as compared to pre-RT stage reciprocally (P < .005 at stage 1 and 2, P < .05 at stage 3).The parotid ADC was positively associated with the radiation dose significantly (R(2) = 0.212; P = .0001) and was negatively associated with RMI significantly (R(2) = 0.203; P = .00096) significantly.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, National Defense Medical Center, Taipei, Taiwan, Republic of China; Department of Radiology, Tri-Service General Hospital, Taipei, Taiwan, Republic of China.

ABSTRACT

Purpose: To concurrently quantify the radiation-induced changes and temporal evolutions of parotid volume and parotid apparent diffusion coefficient (ADC) in nasopharyngeal carcinoma (NPC) patients treated by intensity-modulated radiotherapy by using magnetic resonance imaging (MRI).

Materials and methods: A total of 11 NPC patients (9 men and 2 women; 48.7 ± 11.7 years, 22 parotid glands) were enrolled. Radiation dose, parotid sparing volume, severity of xerostomia, and radiation-to-MR interval (RMI) was recorded. MRI studies were acquired four times, including one before and three after radiotherapy. The parotid volume and the parotid ADC were measured. Statistical analysis was performed using SPSS and MedCalc. Bonferroni correction was applied for multiple comparisons. A P value less than 0.05 was considered as statistically significant.

Results: The parotid volume was 26.2 ± 8.0 cm(3) before radiotherapy. The parotid ADC was 0.8 ± 0.15 × 10(-3) mm(2)/sec before radiotherapy. The parotid glands received a radiation dose of 28.7 ± 4.1 Gy and a PSV of 44.1 ± 12.6%. The parotid volume was significantly smaller at MR stage 1 and stage 2 as compared to pre-RT stage (P < .005). The volume reduction ratio was 31.2 ± 13.0%, 26.1 ± 13.5%, and 17.1 ± 16.6% at stage 1, 2, and 3, respectively. The parotid ADC was significantly higher at all post-RT stages as compared to pre-RT stage reciprocally (P < .005 at stage 1 and 2, P < .05 at stage 3). The ADC increase ratio was 35.7 ± 17.4%, 27.0 ± 12.8%, and 20.2 ± 16.6% at stage 1, 2, and 3, respectively. The parotid ADC was negatively correlated to the parotid volume (R = -0.509; P < .001). The parotid ADC was positively associated with the radiation dose significantly (R(2) = 0.212; P = .0001) and was negatively associated with RMI significantly (R(2) = 0.203; P = .00096) significantly. Multiple regression analysis further showed that the post-RT parotid ADC was related to the radiation dose and RMI significantly (R(2) = 0.3580; P < .0001). At MR stage 3, the parotid volume was negatively associated with the dry mouth grade significantly (R(2) = 0.473; P < .0001), while the parotid ADC was positively associated with the dry mouth grade significantly (R(2) = 0.288; P = .015).

Conclusion: Our pilot study successfully demonstrates the concurrent changes and temporal evolution of parotid volume and parotid ADC quantitatively in NPC patients treated by IMRT. Our results suggest that the reduction of parotid volume and increase of parotid ADC are dominated by the effect of acinar loss rather than edema at early to intermediate phases and the following recovery of parotid volume and ADC toward the baseline values might reflect the acinar regeneration of parotid glands.

No MeSH data available.


Related in: MedlinePlus

Parotid ADC at different MR stages in nasopharyngeal carcinoma patients treated by intensity-modulated radiotherapy.Compared to stage 0 (before radiotherapy), parotid ADC increased significantly at all MR stages. After initial elevation at stage 1 (≦100 days), parotid ADC gradually decreased at stage 2 (101 days to 1 year) and stage 3 (>1 year).
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pone.0137073.g005: Parotid ADC at different MR stages in nasopharyngeal carcinoma patients treated by intensity-modulated radiotherapy.Compared to stage 0 (before radiotherapy), parotid ADC increased significantly at all MR stages. After initial elevation at stage 1 (≦100 days), parotid ADC gradually decreased at stage 2 (101 days to 1 year) and stage 3 (>1 year).

Mentions: The parotid ADC before radiotherapy was 0.8 ± 0.15 × 10−3 mm2/sec. Fig 5 showed the quantitative changes of parotid ADC with respect to MR stages. The parotid ADC was significantly higher at stage 1 (P < .005) and stage 2 (P < .005) than at the pre-RT stage, respectively. At stage 3, although the parotid ADC was still higher than that at pre-RT stage, the difference was not significant (P = .153). The post-RT parotid ADC was highest at stage 1 followed by stage 2 and stage 3 in a decreasing order, with significant difference between stage 1 and stage 3 (P < .05). The ADC increase ratio was 35.7 ± 17.4%, 27.0 ± 12.8%, and 20.2 ± 16.6% at stage 1, 2, and 3, respectively.


Temporal Evolution of Parotid Volume and Parotid Apparent Diffusion Coefficient in Nasopharyngeal Carcinoma Patients Treated by Intensity-Modulated Radiotherapy Investigated by Magnetic Resonance Imaging: A Pilot Study.

Juan CJ, Cheng CC, Chiu SC, Jen YM, Liu YJ, Chiu HC, Kao HW, Wang CW, Chung HW, Huang GS, Hsu HH - PLoS ONE (2015)

Parotid ADC at different MR stages in nasopharyngeal carcinoma patients treated by intensity-modulated radiotherapy.Compared to stage 0 (before radiotherapy), parotid ADC increased significantly at all MR stages. After initial elevation at stage 1 (≦100 days), parotid ADC gradually decreased at stage 2 (101 days to 1 year) and stage 3 (>1 year).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556378&req=5

pone.0137073.g005: Parotid ADC at different MR stages in nasopharyngeal carcinoma patients treated by intensity-modulated radiotherapy.Compared to stage 0 (before radiotherapy), parotid ADC increased significantly at all MR stages. After initial elevation at stage 1 (≦100 days), parotid ADC gradually decreased at stage 2 (101 days to 1 year) and stage 3 (>1 year).
Mentions: The parotid ADC before radiotherapy was 0.8 ± 0.15 × 10−3 mm2/sec. Fig 5 showed the quantitative changes of parotid ADC with respect to MR stages. The parotid ADC was significantly higher at stage 1 (P < .005) and stage 2 (P < .005) than at the pre-RT stage, respectively. At stage 3, although the parotid ADC was still higher than that at pre-RT stage, the difference was not significant (P = .153). The post-RT parotid ADC was highest at stage 1 followed by stage 2 and stage 3 in a decreasing order, with significant difference between stage 1 and stage 3 (P < .05). The ADC increase ratio was 35.7 ± 17.4%, 27.0 ± 12.8%, and 20.2 ± 16.6% at stage 1, 2, and 3, respectively.

Bottom Line: A P value less than 0.05 was considered as statistically significant.The parotid ADC was significantly higher at all post-RT stages as compared to pre-RT stage reciprocally (P < .005 at stage 1 and 2, P < .05 at stage 3).The parotid ADC was positively associated with the radiation dose significantly (R(2) = 0.212; P = .0001) and was negatively associated with RMI significantly (R(2) = 0.203; P = .00096) significantly.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, National Defense Medical Center, Taipei, Taiwan, Republic of China; Department of Radiology, Tri-Service General Hospital, Taipei, Taiwan, Republic of China.

ABSTRACT

Purpose: To concurrently quantify the radiation-induced changes and temporal evolutions of parotid volume and parotid apparent diffusion coefficient (ADC) in nasopharyngeal carcinoma (NPC) patients treated by intensity-modulated radiotherapy by using magnetic resonance imaging (MRI).

Materials and methods: A total of 11 NPC patients (9 men and 2 women; 48.7 ± 11.7 years, 22 parotid glands) were enrolled. Radiation dose, parotid sparing volume, severity of xerostomia, and radiation-to-MR interval (RMI) was recorded. MRI studies were acquired four times, including one before and three after radiotherapy. The parotid volume and the parotid ADC were measured. Statistical analysis was performed using SPSS and MedCalc. Bonferroni correction was applied for multiple comparisons. A P value less than 0.05 was considered as statistically significant.

Results: The parotid volume was 26.2 ± 8.0 cm(3) before radiotherapy. The parotid ADC was 0.8 ± 0.15 × 10(-3) mm(2)/sec before radiotherapy. The parotid glands received a radiation dose of 28.7 ± 4.1 Gy and a PSV of 44.1 ± 12.6%. The parotid volume was significantly smaller at MR stage 1 and stage 2 as compared to pre-RT stage (P < .005). The volume reduction ratio was 31.2 ± 13.0%, 26.1 ± 13.5%, and 17.1 ± 16.6% at stage 1, 2, and 3, respectively. The parotid ADC was significantly higher at all post-RT stages as compared to pre-RT stage reciprocally (P < .005 at stage 1 and 2, P < .05 at stage 3). The ADC increase ratio was 35.7 ± 17.4%, 27.0 ± 12.8%, and 20.2 ± 16.6% at stage 1, 2, and 3, respectively. The parotid ADC was negatively correlated to the parotid volume (R = -0.509; P < .001). The parotid ADC was positively associated with the radiation dose significantly (R(2) = 0.212; P = .0001) and was negatively associated with RMI significantly (R(2) = 0.203; P = .00096) significantly. Multiple regression analysis further showed that the post-RT parotid ADC was related to the radiation dose and RMI significantly (R(2) = 0.3580; P < .0001). At MR stage 3, the parotid volume was negatively associated with the dry mouth grade significantly (R(2) = 0.473; P < .0001), while the parotid ADC was positively associated with the dry mouth grade significantly (R(2) = 0.288; P = .015).

Conclusion: Our pilot study successfully demonstrates the concurrent changes and temporal evolution of parotid volume and parotid ADC quantitatively in NPC patients treated by IMRT. Our results suggest that the reduction of parotid volume and increase of parotid ADC are dominated by the effect of acinar loss rather than edema at early to intermediate phases and the following recovery of parotid volume and ADC toward the baseline values might reflect the acinar regeneration of parotid glands.

No MeSH data available.


Related in: MedlinePlus