Search

Abstract To investigate the diagnostic value of ultra‐small superparamagnetic Fe3O4 nanoparticles as dual modal contrast agent in rabbit orthotopic liver tumor. Twenty‐four New Zealand rabbits with orthotopic liver tumor were randomly divided into experimental group and control group. The experimental group contained 12 rabbits which intravenously injected with Fe3O4 nanoparticles and the control group contained 12 rabbits which intravenously injected with Gd‐DTPA. After injection, the cross‐sectional T1 and T2‐weighted scan images of experimental group and cross‐sectional T1‐weighted scan images of control group were obtained at the different timepoints (including 0, 5, 15, 20, 30, 45, 60, 75, 90, 120, 180, and 240 min) with a clinical 3.0 T MRI scanner. The SNR value of the tumor site and the normal liver site at different time points were calculated, respectively, and then the signal change value (CNR) of the tumor relative to the normal liver tissue was obtained. The r1 value of Fe3O4 nanoparticles was significantly higher than Gd‐DTPA (6.97 mM−1 s−1 for Fe3O4 nanoparticles and 4.75 mM−1 s−1 for Gd‐DTPA and only Fe3O4 nanoparticles exhibited the r2 relaxation rate which was 22.53 mM−1 s−1). In addition, the r2/r1 ratio of Fe3O4 was 3.23 which also demonstrated the strong MR relaxation characteristics of Fe3O4 nanoparticles. Compare with clinical used MRI contrast agent (Gd‐DTPA), the ultra‐small magnetic Fe3O4 nanoparticles not only showed the better T1 contrast enhancement but also exhibited the T1/T2 dual‐modal enhanced contrast ability, which could improve the accuracy and sensitivity of MRI diagnosis and realize the early diagnosis of diseases in prospect.

Robotic drilling through direct cochlear access for cochlear implantation (CI) is currently a prominent area in the field of CI surgery. However, the safety of drilling remains an issue due to the limited space within the facial recess. Estimation and control of drilling force are critical to prevent drill‐bit breakthrough, excessive heat generation, and mechanical damage to the facial nerve. The bone drilling process presents a favorable application scenario for finite element (FE) analysis. In this study, a 3D FE model of temporal bone drilling is established for the first time to predict the drilling force. The self‐developed CI surgical robot validates these findings through experimental drilling. The experimental results show that the drilling process can be divided into three stages, and the corresponding force curve can be divided into six zones. The overall trend of temporal bone drilling is two force peaks and one trough in the middle. The drilling force is positively correlated with the feed rate. The FE results found to be in good agreement with the experimental results. Numerical simulation can be utilized as an invaluable tool for assisting in predicting the position of drilling tools and optimizing drilling parameters in the future. [ABSTRACT FROM AUTHOR]

Objective To explore the methods for the reconstruction of lateral skull base defects after radical tumor resection. Methods Patients who underwent lateral skull base radical tumor resection and reconstruction from January 1, 2012 to December 31, 2019 in the Department of Stomatology and Otorhinolaryngology in Peking Union Medical College Hospital, were enrolled in this retrospective study. These patients were divided into three subgroups depending on the type of defects. Group I, patients without skin defects; Group Ⅱ, patients with skin defects; Group Ⅲ, patients with larger jaw defects. Different reconstructive methods were applied for the three groups. Results Sixty-two patients (63 procedures of defect repair) were enrolled in this study. The survival rate of tissue flap was 98.41%(62/63), and the primary wound healing rate was 90.48% (57/63). There were 34 patients in Group I. Among them, 6 cases received free fat transplantation; 14 cases were repaired with fat transplantation combined with local flaps; 13 cases were repaired with sternocleidomastoid muscle flap or combined temporal muscle flap; 1 case was repaired with temporal muscle flap combined with submandibular gland flap. Among them, two patients had postoperative cerebrospinal fluid leakage and delayed healing after dressing change. All patients had no postoperative infection and fat liquefaction, and the wounds healed by primary intention. The survival rate of tissue flap was 100%, and 94.12% (32/34) of the wounds healed by primary intention. There were 23 patients in Group Ⅱ. Five patients whose skin defects were less than 3 cm were reconstructed with local tissue flaps combined with advancement flaps; all flaps survived completely and the wounds healed by primary intention. The survival rate of tissue flap was 100%, and the primary wound healing rate was 100%. For those skin defects greater than 3 cm, free anterolateral thigh flaps were applied in 8 patients, pedicle flaps such as pectoralis flaps in 6 patients, 2 cases used forearm flap combined with pedicle skin flap or local tissue flap, 2 cases had pectoralis major myocutaneous flap or combined cervical and facial propulsion skin flap and submandibular gland flap, 1 case had rectus abdominis skin flap. One of the patients who had undergone high-dose radiotherapy developed venous embolism 3 days after repair with the anterolateral thigh myocutaneous flap, which was later repaired with pectoralis major myocutaneous flap rescue, and the remaining flaps survived completely; 1 patient with anterolateral thigh flap transplantation developed recipient hematoma on the second postoperative day, and the wound recovered after hematoma evacuation. One patient with rectus abdominis muscle repair developed cerebrospinal fluid leakage after surgery, and the skin lesions had delayed healing after dressing change. Two cases were repaired with pectoralis major myocutaneous flap and other pedicle skin flaps, and there was a small area of necrosis at the distal end. The wounds had delayed healing after dressing change. The wounds of the remaining patients healed at first stage; the first-stage wound-healing rate was 84.21% (16/19), and the flap survival rate was 94.74%(18/19). There were 5 patients in Group Ⅲ; 2 cases were reconstructed with fibular flap; 2 cases were reconstructed with free rib graft combined with temporal flap; 1 patient underwent femur-anterolateral thigh osteomyocutaneous free flap reconstruction. There were 10 patients whose tumors invaded the bones of the skull base and caused intracranial and external communication after surgery. Seven of them had no postoperative complications, and the remaining three had post-operative cerebrospinal fluid leakage, which delayed healing after dressing changes. There were 24 patients received simultaneous facial nerve reconstruction, including 12 cases reconstructed with greater auricular nerve transplantation, 8 cases with hypoglossal nerve, 3 cases with masseter nerve (+/-) greater auricular nerve, and 1 case with lateral femoral cutaneous nerve. Thirteen patients were followed up, and all had varying degrees of recovery of facial nerve function. Conclusions Different reconstruction regimens should be taken according to different types of defects after radical tumor resection. The patients without skin defects can be reconstructed with the temporal muscle flap combined with autologous fat grafting or local tissue flaps. The patients with skin defects smaller than 3 cm can be reconstructed with the cervicofacial advancement flap combined with local tissue flaps. The most reliable free flap for lateral skull base reconstruction is the anterolateral thigh flap for the patients with skin defects larger than 3 cm. For those patients who were not suitable for microsurgical reconstructive operation, the pectoralis major muscle flap repair should be selected. If the defect is above the zygomatic arch, it is better to choose the pectoralis major muscle flap combined with cervicofacial advancement flap or local tissue flaps. The bone defect should be reconstructed appropriately if the patients presented with a large jaw defect. If conditions permit, the facial nerve defect reconstruction should be applied simultaneously.

Objective To summarize the key points of the operation related to the facial nerve function after surgery of paraganglioma involving the jugular foramen in the lateral skull base. Methods We retrospectively analyzed the clinical data of patients with lateral skull base paraganglioma involving jugular foramen that were diagnosed and treated in Peking Union Medical College Hospital from August 2015 to January 2021. According to the relationship between the tumor and the facial nerve, the facial nerve was treated in different ways during the operation. The postoperative facial nerve function of patients with different treatments is summarized. Results A total of 30 patients with lateral skull base paraganglioma in the jugular foramen area were included. The Fisch classification of these patients was as followed: C1(n=3), C2(n=6), C2De1(n=2), C2Di1(n=2), C3De1(n=7), C3Di1(n=5), C3Di2(n=3), C4De1(n=1), C4Di1(n=1). Preoperative facial nerve function assessed by House-Brackmann (HB) grade: grade Ⅰ-Ⅱ (n=22), grade Ⅲ (n=2), grade Ⅳ (n=3), grade Ⅴ(n=2), grade Ⅵ(n=1). All tumors were completely resected, which was verified by post-operational MRI. No recurrence was observed during the medium follow-up of 886 days. All of the postoperative nerve function refers to the results of the last follow-up. Anterior facial nerve rerouting was performed in 15 cases whose tumor did not invade the facial nerve. The postoperative facial nerve function was HB grade Ⅰ-Ⅱ in 13 cases and HB grade Ⅲ in 2 cases. The tumors were adhesive to the facial nerve in 2 cases. The tumors and the facial nerve were successfully separated in both cases; one achieved HB grade Ⅰ-Ⅱ, while the other was HB grade Ⅰ-Ⅱ postoperatively. In 13 cases, the tumor wrapped the facial nerve. Among those patients, the tumor was separated from the facial nerve in 1 case, with the postoperative facial nerve function of HB grade Ⅲ. In the remaining 12 cases, the facial nerve was resected together with the tumor. Facial nerve reconstruction was performed in 3 cases in the same or the second surgery. The postoperative facial nerve function was HB gradeⅠ-Ⅱ in 1 case and HB grade Ⅲ in the other 2 cases. The postoperative facial nerve function in the remaining 9 cases that did not receive facial nerve reconstruction was HB grade Ⅵ. Conclusions In patients with lateral skull base paraganglioma, anterior facial nerve rerouting has a slight effect on the function of facial nerve, if the tumor does not invade the facial nerve. It is difficult to separate the tumor and the facial nerve, if the facial nerve is wrapped by the tumor, and the rate of postoperative facial nerve paralysis is higher in these cases.

Objective To investigate the relationship between the enhanced MRI features of preopera-tive brain volume imaging (BRAVO) and surgical methods in patients with glomus jugulare tumor (GJT). Methods The imaging data of enhanced BRAVO sequence and surgical methods of patients with GJT confirmed by surgery and pathology from February 2015 to March 2021 in Peking Union Medical College Hospital were analyzed retrospectively. According to the surgical mode, the patients were divided into the groups of single infra-temporal fossa approach (IFA) group and combined infratemporal fossa approach (CIFA) group. Both groups of patients underwent MRI examination before operation, and the Fisch classification of tumor was determined based on the characteristics of enhanced BRAVO sequential images, and the consistency was compared with the Fisch classification determined during the operation. The maximum diameter of the tumor in the transverse axis, the longest diameter in the coronal plane, the width diameter of meningeal invasion and the depth diameter of meningeal invasion were measured and compared between two groups. Results A total of 25 patients were included. Among them, 16 cases were in the IFA group (surgical approach was infratemporal fossa type A), and 9 cases in the CIFA group (surgical approach was infratemporal fossa type A + type B). The classification of image C includes 1 case of C1 type, 10 cases of C2 type, 12 cases of C3 type, and 2 cases of C4 type. The classification of image D includes 8 cases of De1 type, 6 cases of Di1 type, and 5 cases of Di2 type. Except for one patient in the IFA group who was evaluated as C3 preoperatively based on imaging, and confirmed as C2 postoperatively, the image classification of C and D of the other patients were consistent with those of surgical classification of C and D (Kappa=0.934, P < 0.001;Kappa=1.000, P < 0.001). Image classification of C (P=0.029) and D (P=0.006) had significant differences between the two groups. The maximum diameter(P=0.013), depth(P=0.003) and width of meningeal invasion(P=0.011) in the CIFA group were greater than those in the IFA group. There was no significant difference in the longest diameter of the coronal plane (P=0.125) between the two groups. Conclusions Enhanced BRAVO sequence can be used for preoperative evaluation of Fisch classification of GJT. The enhanced image features based on BRAVO sequence showed differences between the two different surgical approaches.

The three-degree-of-freedom (3-DoF) parallel mechanism (PM) is widely used due to its simple structure and ability to avoid coupling problems commonly found in high-DoF PMs. The conventional control approach is usually independent control for each branch of the mechanism using a PID controller, without considering the consistency among branches. This paper proposes a novel cooperative control strategy for the 3-DoF PM to achieve both synchronized and differential motion. A pneumatic actuated test rig was constructed to validate the effectiveness of the cooperative controller. The results demonstrate our control approach outperforms the PID controller. Our self-designed platform is functional and intuitive, which can be regarded as a control scheme test bench for a 3-DoF PM. [ABSTRACT FROM AUTHOR]