The Experimental Study Of Fluorescence Imaging System In Intraoperative Real-time Identification Of Ureters

During abdominal surgery,the identification and protection of ureters are essential.In clinical practice,surgeons are often forced to rely on preoperative imaging information and their experience,where they can only palpate and vision inspection the flow of the liquid in the pipeline to identify ureter during abdominal surgery.If the fluid in the pipeline isn't continuous,it should be the ureter.However,there is accidentally still the injury of iatrogenic ureter in practice.Iatrogenic ureteral injury is rare,but when it does occasionally occur,serious complications,such as the urinary tact infections,renal failure,fistulas,etc.will be caused if happened.Therefore,it is an extremely important step to correctly identify the ureters and to protect them.At present,the methods of preventing ureteral injury in clinical practice include gamma detection technology,prophylactic ureteral catheterization(or lighted ureteral stenting),and optical imaging technology.The first two have various defects,such as ionizing radiation,invasive etc.And optical imaging technology can be used for imaging navigation without ionization,non-invasive,non-contact and real-time imaging,especially near infrared fluorescence imaging technology,which is widely used in imaging navigation.The near-infrared fluorescence imaging technology has been favored by scholar for the non-invasive,non-ionizing radiation and visualization tissue anatomical structure.In recent years,scholars have applied near-infrared fluorescence imaging technology combined with methylene blue(MB)successfully to realize real-time visual recognition of ureters in animal or human abdomen.For example,Research on animal experiments conducted by Matsui A et al.in 2010,the first human clinical trial performed by Verbeek F P R et al.In 2013,the related clinical trials conducted by Yeung T M et Al and al-taher M in 2016.Although important progresses have been made,there are still some deficiencies,such as less clinical data,and some need to expose the ureter to detect the fluorescence signal of MB.Therefore,without ionizing radiation,non-invasive,real-time visualiztion ureter during abdominal surgery is still in its primary stage and needs further research and exploration.However,currently the only of the FLARE(the Fluorescence-Assisted resection and exploration)imaging system developed by the John v.Frangioni team can detect the fluorescence of methylene blue.Although the system is capable of multi-spectral fusion imaging,it still has some disadvantages,such as large volume,high cost and unportability.Hence,preliminarily near-infrared fluorescence imaging system based on MB fluorescence characteristics was developed and relevant experimental research was carried out in this paper.In this study,firstly,the basic knowledge of near-infrared fluorescence imaging technology like fluorescence imaging principle and fluorescent group property were described,and iatrogenic ureteral injuries,existing methods and research status of preventing ureteral injury were introduced.The main body of this paper is about the design of the near infrared fluorescence imaging system based on the fluorescence characteristics of methylene blue and the relevant experimental research using the system carried out.The system is composed of two modules including optical module and image reprocessing module.The main function of optical module is the photon generation of excitation light source,optical signal acquisition and conversion of photoelectric signals.The main function of imaging post-processing module includes signal amplification,strengthen,output and storage etc.After the system was built,the system was used to conduct near-infra fluorescent imaging experiments on methylene blue.The results show that the effect of the system imaging is good and meets the expected requirements.At the same time,the research in animal experiments was carried out to verify the performance of the system.It was found that the locational information of ureter was not detected clearly in surgery due to the strong background fluorescence.It is worth mentioning that the near infrared fluorescence imaging system developed in this study has the innovative function of multi-probe compatibility,which has not been reported in the existing literature.In addition to the above,we also carried out related experiments on ZW800-1 to give full play to the advantages of the system's multi-probe compatibility.ZW800-1 developed by Choi,Hak Soo and co-workers in 2011 which is a zwitterionic near-Infrared fluorophores.For the unique physical and chemical properties of ZW800-1,it has high extinction coefficient and quantum yield,and extremely low nonspecific absorption in biological body.Currently,there are few studies on the real-time identification of ureteral ureters using ZW800-1 in abdominal surgery.ZW800-1 near-infrared fluorophore was synthesized reference to Hyun,H S,et al about the synthetic scheme of synthesis of ZW800-1,and combined with near-infrared fluorescence imaging to carry out related experimental research to explore the best recommended dose and minimum visual dose of ZW800-1 for real-time identification of ureters in the abdominal surgery in rat model,and compared with the existing reliable NIR fluorescent groups CW800-CA for comparison research.The experimental results show that the best recommended dose and the lowest dose of CW800-CA and ZW800-1 is 60ug/kg and 7.5ug/kg,which will lay an important theoretical basis for clinical research in the future.