Early Changes in Apparent Diffusion Coefficient for Salivary Glands during Radiotherapy for Nasopharyngeal Carcinoma Associated with Xerostomia

OBJECTIVE: To evaluate the early changes in the apparent diffusion coefficient (ADC) of the salivary glands during radiotherapy (RT) and their association with the degree of xerostomia at 6 months after RT in patients with nasopharyngeal carcinoma (NPC). MATERIALS AND METHODS: We enrolled 26 patients with NPC who underwent RT. Each patient underwent diffusion-weighted MRI of the salivary glands at rest and with gustatory stimulation within 1 week before RT and 2 weeks after the beginning of RT. The ADC at rest (ADCR) and increase and increase rate with stimulation (ADCI, ADCIR) of the submandibular and parotid glands were calculated. The differences in the variables' values between 2 weeks after the beginning of RT and baseline (ΔADCR, ΔADCI, and ΔADCIR) were compared to the degree of xerostomia at 6 months after RT. RESULTS: The ADCR of the submandibular and parotid glands were both significantly higher at 2 weeks after the beginning of RT than found at baseline (both p < 0.01). The ADCI and ADCIR for the parotid glands were both significantly lower at 2 weeks after the beginning of RT than found at baseline (both p < 0.01). ΔADCI and ΔADCIR of the parotid glands were associated with the degree of xerostomia at 6 months after RT (r = −0.61 and −0.72, both p < 0.01). CONCLUSION: The ADCs of the salivary glands change early during RT. The differences in the ADC increase and increase rate of the parotid glands between 2 weeks after the beginning of RT and baseline were associated with the degree of xerostomia at 6 months after RT.

Radiosurgery for Cavernous Malformations / 대한뇌혈관학회지

Cavernous malformations (CM) are vascular lesions that comprise the majority of vascular malformations with arteriovenous malformations (AVM). Microsurgical resection of CMs is the preferred management for patients with symptomatic lesion. But in group of patients with hemorrhagic cavernous malformations located in critical brain regions that were thought to pose an excessive risk for microsurgical resection. GKRS has been used as an alternative management approach for this lesions since first application by Karolinska institute in 1985. The favorable results of Gamma Knife radiosurgery (GKRS) for AVMs prompted pilot series in which GKRS was used to treat cavernous malformations. Some authors had suggested that GKRS could reduce the annual rate of hemorrhage, especially after 2-4 years latency interval. The problem with evaluating treatment results in cases of CMs is that, unlike in AVMs, that no imaging modality accurately identifies obliteration of the CM after radiosurgery. To evaluate the potential protection against hemorrhage, the incidence of posttreatment hemorrhage must be compared with the natural course of the disease. Another problem associated with radiosurgical treatment of CMs is that the radiation-induced complication rate appears to be greater than expected compared with that associated with radiosurgery of AVMs. So, radiosurgery for cavernous malformations remains controversial until present time. The clinical application of radiosurgery in CMs needs further investigation, in particular, issues of patient selection, methods of follow-up, long-term risks, and safe dose levels must be addressed.