Objective To investigate the value of MR perfusion-weighted imaging(PWI)in the evaluation of therapeutic effect of brain metastases with gamma knife.Methods Treatment by gamma knife before and after that 3 months or 6 months PWI studies were penformed respectively in 22 patients with brain metastases .Maps of relative regional blood volume(rCBV)and mean transit time(MTT)were obtained.The ratios of rCBV and MTT of lesions were analyzed.Results rCBV of tumors in 22 cases was increased.The ratios of maximum rCBV of the lesions and opposite side were 6.16?3.12 and 1.18?0.17 respectively.The ratios of MTT of the tumors was 1.44?0.53.After gamma knife treatment,9 of 22 cases appeared decreased rCBV,but the ratios of MTT were no changing,of them,3 cases presented cerebral necrosis.13 of 22 cases,the ratios of rCBV were increased in varied degree after treatment by gamma knife,and 6 cases presented brain radionecrosis.Conclusion PWI is a significant method in evaluating the therapeutic effect of brain metastases with gamma knife

Objective : To investigate the application of digital immediate implant and angle screw channel abutment in the aesthetic area and the related influencing factors by reviewing the data of one case of immediate implant repair of the upper anterior teeth and related literature. Methods: One case of refractory chronic apicitis of the upper anterior teeth involved immediate implantation after extraction. The digital information of the patient was obtained by CBCT and intraoral scanning. According to the information from the patients, a preoperative evaluation was performed; a treatment scheme was formulated; a minimally invasive extraction was performed; implants were placed under a digital guide plate; and temporary restoration was immediately performed. Six months after the operation, the patients underwent individualized mold removal, and angle screw channel fixation was completed. We observed the cosmetic effects and soft and hard tissue and gingival contour maintenance effects after restoration and reexamined the patients 6 months after restoration. In addition, the relevant literature was reviewed. Results : The height of the gingival margin and gingival papilla and gingival contour of this patient were well maintained. The red and white aesthetic effect was good. There was no redness or swelling of the gingiva nor obvious changes in the soft and hard tissues around the implant 6 months after restoration, and the patient was satisfied. The results in the literature review show that a preoperative design based on CBCT and intraoral scanning data combined with digital software and a whole digital guide plate make the procedure more accurate and safer. These factors can not only avoid important anatomical structures and serious surgical complications but can also result in implantation in the best three-dimensional position. In addition, the application of digital impression technology and CAD/CAM increases the efficiency, speed, accuracy, simplicity, and comfort of oral impressions and the construction of temporary and final prostheses more precise and faster, greatly improving clinical efficiency. Conclusion Digital immediate implant and angle screw channel abutment is a good method to restore the aesthetics and function of missing teeth and to avoid the complications caused by adhesive residue.