| Objective:Although wireless magnetically controlled capsule endoscopy is widely used in clinical practice,it has limitations such as high cost,limited battery life,lower image quality than traditional gastroscopy,incomplete upper gastrointestinal examination and risk of capsule retention.A wired design can help overcome these drawbacks.This study aimed to design and develop a novel wired transmission tethered + magnetically controlled capsule endoscopy system.The feasibility of using a wired transmission tethered + magnetically controlled capsule endoscopy system for upper gastrointestinal examination was further evaluated through in vitro model experiments,ex vivo organ experiments and in vivo animal experiments.Methods:1.Development of novel wired transmission tethered + magnetically controlled capsule endoscopy system: Based on the upper gastrointestinal capsule endoscopy that has been clinically applied and studied,a novel wired transmission tethered +magnetically controlled capsule endoscopy system was designed according to the clinical needs.A prototype machine was made according to the design scheme at Gansu Province Digestive Endoscopy Engineering Research Center.Sample machines were made and upgraded in cooperation with a partner enterprise.2.Experimental study of novel wired transmission tethered + magnetically controlled capsule endoscopy system: Five operators and two observers were included in this study.The operators participated in the experimental operation of the novel wired transmission tethered + magnetically controlled capsule endoscopy and the traditional gastroscopy,and the observers participated in the reading of the endoscopic images and reported the diagnosis.(1)In vitro model experiments: Five operators used the prototype and sample machines of wired transmission tethered + magnetically controlled capsule endoscopy to perform upper gastrointestinal tract examination in a 3D-printed human stomach model and an upper gastrointestinal simulation model respectively.By comparing with conventional gastroscopy,the maneuverability,examination time,visualization of gastric mucosa,image quality and diagnostic accuracy of lesions in the models were evaluated for both prototype and sample machines.(2)Ex vivo organ experiments: Five operators used the sample machine of wired transmission tethered + magnetically controlled capsule endoscopy and conventional gastroscopy to perform upper gastrointestinal examination in the normal excised porcine upper gastrointestinal tract respectively.And the maneuverability,examination time,visualization of gastric mucosa and image quality of the sample machine in the normal excised porcine upper gastrointestinal tract were evaluated.Two operators used the sample machine of wired transmission tethered + magnetically controlled capsule endoscopy system and conventional gastroscopy to perform upper gastrointestinal examination in the excised porcine upper gastrointestinal tract with simulated lesion respectively.And the diagnostic accuracy of the sample machine for lesions in the excised porcine upper gastrointestinal tract with simulated lesion was evaluated compared to conventional gastroscopy.(3)Living animal experiment: Five operators used the sample machine of wired transmission tethered + magnetically controlled capsule endoscopy system and conventional gastroscopy to perform upper gastrointestinal tract examination in three experimental dogs,and evaluated the maneuverability,examination time,visualization of gastric mucosa,image quality and safety of the sample machine in upper gastrointestinal tract of living animal by comparing with conventional gastroscopy.(4)Evaluation index: The maneuverability is evaluated by the operator according to the operation experience,which is divided into three levels: excellent,good and poor.The observer evaluated the visualization of upper gastrointestinal mucosa by analyzing the visualization rates of each anatomical landmark and gastric mucosa.Each anatomical landmark included esophagus,cardia,gastric fundus,gastric body,gastric angle,gastric antrum,pylorus,duodenum,etc.The visualization rate of gastric mucosa was divided into three grades:Ⅰ(> 75%),Ⅱ(50%-75%)and Ⅲ(< 50%).The image quality was evaluated by the observer from four indexes of image sharpness,image brightness,image color and image distortion,which was divided into three levels:excellent,good and poor.The diagnostic accuracy was evaluated using the conventional gastroscopy as the gold standard.(5)Statistical analysis: SPSS 22.0 statistical software was used for statistical analysis,measurement data were expressed as mean ± standard deviation(?±),and comparison between groups was conducted by F test or t test.Statistical data were expressed as cases or rates(%),and rates were compared by chi-square test or Fisher exact test.P < 0.05 was considered statistically significant.Results:1.Research and development of novel wired transmission tethered + magnetically controlled capsule endoscopy system: The wired transmission tethered + magnetically controlled capsule endoscopy system mainly includes: wired transmission capsule endoscopy,host machine,imaging device and external guidance magnet.According to the design,the principle machine,first-generation sample machine and secondgeneration sample machine of wired transmission capsule endoscopy were made.The capsule size of the principle machine is 20×11 mm,the weight is 3.6 g,the resolution is 1280×720,the frame rate is 30 fps,the field is more than 120 °,the depth of field is more than 50 mm,the outer diameter of the transmission cable is 1.8 mm,the length is1600 mm,and 6 light-emitting diodes(LEDs)provide the light source with an illuminance more than 8000 lx.The capsule size of the first-generation sample machine is reduced to 15×9 mm,the weight is 2.0 g,the outer diameter of the transmission cable is 1.6 mm,and the other parameters are the same as the principle machine.After upgrading,the capsule size of the second-generation sample machine is adjusted to16.5×16 mm,the weight is 3.2 g,the resolution is upgraded to 1920×1080,the field is140 °,the depth of field is 3-100 mm,and 4 LEDs provide light source with an illuminance more than 20000 lx.Compared with various magnetically controlled capsule endoscopy reported in clinical practice,the second-generation sample machine of the wired transmission tethered + magnetically controlled capsule endoscopy system has the smallest capsule size,the highest resolution and frame rate,the largest depth of field,and unlimited power supply time.2.Experimental results of novel wired transmission tethered + magnetically controlled capsule endoscopy system:(1)In vitro model experiments: In the 3D printed human stomach model experiment,the maneuverability of the principle machine,the first-generation sample machine and the second-generation sample machine was evaluated as "excellent" in 3/5,4/5,5/5,respectively,and the proportion of "excellent + good" is all 100%.The average operation time was 25.01±2.87 minutes、18.51±2.57 minutes and 16.40±1.59 minutes,respectively,the image quality evaluation was all excellent,and the visualization rates of the gastric mucosa were all grade I.In the upper gastrointestinal simulation model experiment,the maneuverability of the principle machine,the firstgeneration sample machine and the second-generation sample machine was evaluated as "excellent" in 3/5,3/5,4/5,respectively,and the proportion of "excellent + good" is all 100%.The average operation time was 30.71±2.44 minutes,23.31±1.50 minutes,and 20.50±1.58 minutes,respectively,the image quality evaluation was all excellent,and the visualization rates of the gastric mucosa were all grade I.All lesions(detection rate 100%)were detected by conventional gastroscopy by 5 operators,including esophageal varices,gastric body ulcer,gastric corner ulcer,gastric foreign body,gastric polyp and duodenal bulb ulcer.Two operators each missed 1 lesion(detection rate93.3%)using the principle machine,and one operator missed 1 lesion(detection rate96.7%)using the first-generation and second-generation sample machines,respectively.There is no statistical difference in the detection rate of lesions between the principle machine,the sample machine and the conventional gastroscopy(P > 0.05).(2)Ex vivo organ experiments: In the normal excised porcine upper gastrointestinal model experiment,the maneuverability of the second-generation sample machine was evaluated as "excellent" in 4/5 without "poor" evaluation.The average operation time was 18.12±1.11 minutes,the image quality evaluation was excellent,and the visualization rate of the gastric mucosa was grade I.In the experiment of excised porcine upper gastrointestinal tract with simulated lesion,the detection rate for simulated lesion was 80% by second generation sample machine and 90% by conventional gastroscopy,and the difference was not statistically significant(P>0.05).(3)Living animal experiment: In the living animal experiment,the maneuverability of the second-generation sample machine was evaluated as "excellent" in 3/5 without "poor" evaluation.The average operation time was 28.06±4.72 minutes and the image quality evaluation was excellent.The visualization rate of the gastric mucosa was grade I in 12/15 and grade Ⅱ in 3/15,and the difference was not statistically significant(P>0.05)compared with conventional gastroscopy.The visualization rates of anatomical landmarks were: esophagus 100%,cardia 80%,gastric fundus 80%,gastric body 100%,gastric angle 73%,gastric antrum 87%,pylorus 87% and duodenum27%.No adverse events occurred during the examination.Conclusion:1.The design of the novel wired transmission tethered + magnetically controlled capsule endoscopy system can help solve the problem of low visibility of traditional magnetically controlled capsule endoscopy for esophagus,dentate line and duodenum,and achieve complete observation of upper gastrointestinal tract.Theoretically,it has advantages such as low cost,small size,portable and convenient,unlimited power supply,high image quality and no risk of capsule retention.The second-generation sample machine manufactured in this study has the highest image resolution,video frame rate,depth of field and smallest capsule size so far.Therefore,it has potential clinical practical value.2.The novel wired transmission tethered + magnetically controlled capsule endoscopy system is feasible for upper gastrointestinal examination in in vitro models,ex vivo organ and living animal,with good maneuverability,high mucosal visualization rate and image quality.The detection rate and diagnostic accuracy is comparable to that of conventional gastroscopy.Further human trials are necessary to evaluate its safety,tolerability and effectiveness. |
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