Objective:To investigate the feasibility and clinical value of MRI quantitative evaluation technique in detecting sternocleidomastoid muscle fibrosis in patients with nasopharyngeal carcinoma (NPC) after radiotherapy.Methods:From August 2019 to March 2021, 45 patients with clinically confirmed NPC after radiotherapy and 30 healthy controls who underwent physical examination in Lishui Hospital of Zhejiang University were enrolled in our study. According to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer (RTOG/EORTC) classification criteria of late radiation reactions respectively, the sternocleidomastoid muscle injury in the NPC group was divided into grade Ⅰ, Ⅱ and Ⅲ, which included 8, 32 and 5 patients respectively. All patients underwent T 1 mapping and T 2 mapping imaging of the neck. Firstly, the mapping images of sternocleidomastoid muscle between the two groups were analyzed and compared. Using NUMARIS/4 software of Siemens image post-processing workstation, the region of interest was manually drawn along the edge of sternocleidomastoid muscle at the level of laryngeal chamber in axial mapping diagram. Then, T 1 and T 2 values and the long and short diameters of sternocleidomastoid muscle were measured respectively. Finally, the differences of the parameters between the two groups were compared by independent sample t-test, Spearman rank correlation was used to analyze the relationship between the average T 1 and T 2 values of bilateral sternocleidomastoid muscles and the grade of late radiation injury. Results:Compared with the control group, the shape of sternocleidomastoid muscle in the NPC group was smaller in shape, with irregular edge and uneven increase of T 1 mapping color scale. There was no significant difference in muscle signal in T 2 mapping. The T 1 values of left and right sternocleidomastoid muscles in the NPC group were (1 524.7±97.6) and (1 496.5±93.2) ms respectively, which were significantly higher than those in the normal control group [(1 231.5±85.3) and (1 275.9±90.9) ms] ( P<0.05), and the T 2 values of left and right sternocleidomastoid muscles in the NPC group were (28.4±4.8) and (28.4±3.6) ms respectively, which were lower than those in the normal control group [(30.4±3.5) and (30.4±3.5) ms] ( P<0.05). The long and short diameters of bilateral sternocleidomastoid muscles in the NPC group were shorter than those in the control group ( P<0.05). The average T 1 and T 2 values of bilateral sternocleidomastoid muscles in NPC patients after radiotherapy were (1 510.6±95.4) and (28.4±4.2) ms respectively, The T 1 value was positively correlated with the classification of advanced radiation injury ( r=0.78, P<0.001), and T 2 value was negatively correlated with the level of advanced radiation injury ( r=-0.87, P<0.001). Conclusion:Mapping quantitative evaluation technique can noninvasively and objectively detect and evaluate sternocleidomastoid muscle fibrosis after NPC radiotherapy, which has potential clinical application value.

Objective To investigate the relationship between glycoprotein synthase kinase-3 (GSK-3β) and mitochondrial cleavage protein (Drp-1) during diabetes mellitus-caused antagonization of cardioprotection induced by sevoflurane postconditioning in rats.Methods Clean-grade healthy male Sprague-Dawley rats,weighing 250-300 g,were used in this study.Diabetes mellitus was induced by high-fat and high-sucrose diet and intraperitoneal streptozotocin 30 g/kg.Forty rats with diabetes mellitus were divided into 5 groups (n =8 each) using a random number table method:ischemia-reperfusion (I/R) group,sevoflurane postconditioning group (SP group),sevoflurane postconditioning plus Drp1 inhibitor Mivi-1 group (SM group),sevoflurane postconditioning plus GSK-3β inhibitor SB216763 group (SB group) and sevoflurane postconditioning plus Mivi-1 plus SB216763 group (SMB group).Myocardial I/R was induced by 30 min occlusion of the left anterior descending branch of the coronary artery followed by 120 min reperfusion.The rats inhaled 2.5％ sevoflurane for 10 min starting from 5 min before reperfusion in SP,SM,SB and SBM groups.Mivi-1 1.2 mg/kg was injected via the caudal vein at 15 min before reperfusion in group SM.SB216763 0.2 mg/kg was injected via the caudal vein at 5 min before reperfusion in group SB.Mivi-1 1.2 mg/kg and SB216763 0.2 mg/kg were injected via the caudal vein at 15 and 5 min before reperfusion,respectively,in group SMB.Blood samples were collected from the abdominal aorta at 120 min of reperfusion for determination of serum cardiac troponin Ⅰ (cTnⅠ) concentrations.The rats were sacrificed and myocardial specimens were obtained from the apex for determination of the cell apoptosis (by TUNEL) and expression of caspase-3 (by Western blot),and apoptotic index (AI) was calculated.Results Compared with group I/R,no significant change was found in caspase-3 expression,AI or serum cTnⅠ concentrations (P＞0.05),and the pathological changes of myocardium were comparable in group SP,and the expression of caspase-3 was significantly down-regulated,and AI and serum cTnⅠ concentration were decreased (P＜0.05),and the pathological changes of myocardium were significantly attenuated in SM,SB and SMB groups.Compared with group SP,the expression of caspase-3 was significantly down-regulated,AI and serum cTnⅠ concentrations were decreased (P＜0.05),and the pathological changes of myocardium were significantly attenuated in SM,SB and SMB groups.Compared with group SMB or group SB,the expression of caspase-3 was significantly down-regulated,AI and serum cTnI concentrations were decreased (P＜0.05),and the pathological changes of myocardium were significantly attenuated in group SMB.Conclusion It is not a single regulatory relationship between GSK-3β and Drp-1 in the pathophysiological process of diabetes mellitus-caused antagonization of cardioprotection induced by sevoflurane postconditioning in rats.