Brain Perfusion Abnormalities after Radiotherapy Measured by 3-Dimensional Arterial Spin Labeling MRI and Correlations with Cognitive Impairment.

The purpose of this study was to use a 3-dimensional arterial spin labeling (3D ASL) magnetic resonance (MR) method to measure cerebral blood flow (CBF) before and after radiotherapy, and correlate changes with time after receiving radiotherapy and cognitive function. Patients with nasopharyngeal carcinoma receiving radiotherapy at our institution were recruited for the study. Participants were divided into three groups: Pre-radiotherapy control (PC) group, acute reaction period (ARP) group, and delayed reaction period (DRP)group. Thirty-four patients were included in the study. Compared with the PC group, the ARP group exhibited significantly decreased perfusion in the left anterior cingulate cortex (ACC) and right putamen, and increased perfusion in the right cerebellum (Crus 1), right inferior occipital gyrus, left lingual gyrus, left precuneus, and left calcarine gyrus. in the DRP group, increased perfusion was noted in the right cerebellum (Crus 1) and decreased perfusion in the left superior frontal gyrus. CBF differences were observed in several brain areas in the DRP group as compared to the ARP group (P < 0.001). Total Montreal Cognitive Assessment score, and subdomain language and delayed memory recall scores were significantly lower in the ARP and DRP groups than in the PC group (P < 0.05). Data suggest that ASL allows for non-invasive detection of radiation-induced whole-brain CBF changes, which is transient, dynamic and complicated and may be a factor contributing to cognitive impairment induced by radiotherapy for nasopharyngeal carcinoma.

Effects of different irradiators on the establishment of osteoradionecrosis model of rat mandible.

OBJECTIVES: To compare the effects of different irradiators on the establishment of osteoradionecrosis of jaw model (ORNJ) to explore an ideal modeling method. METHODS: A total of 33 adult SD rats were included and randomly divided into three groups according to the radiation equipment, namely, the blank control (CN, 3 rats), group A (linear accelerator irradiation, 15 rats), and group B (small-animal irradiator irradiation, 15 rats). Groups A and B were irradiated with daily fractions of 7, 8, and 9 Gy for 5 days and further divided into three subgroups as follows: group A35/B35, 35 Gy; group A40/B40, 40 Gy; and group A45/B45, 45 Gy. The left mandibular molars of the rats were extracted 1 week after irradiation. The rats were sacrificed 3 weeks after tooth extraction, and the mandible specimens were obtained for gross observation, micro-CT scanning, and histological detection to evaluate the success rate of modeling. RESULTS: At 3 weeks after dental extractions, complete gingival healing was found in the regions of dental extractions in groups A35 and A40. However, failed gingival healing and bone exposure were found in groups A45 and B. Hematoxylin and eosin staining showed necrotic bone of the irradiated mandible in groups A40, A45,and B, with success modeling rates of 40% in group A and 93.3% in group B. CONCLUSIONS: Small-animal irradiator irradiation is an ideal device for establishing ORNJ model.