Role of diffusion-weighted magnetic resonance imaging in the differential diagnosis of focal hepatic lesions

AIM:To evaluate the utility of diffusion-weighted im-aging(DWI)in screening and differential diagnosis of benign and malignant focal hepatic lesions.METHODS:Magnetic resonance imaging(MRI)ex-aminations were performed using the Signa Excite Xl Twin Speed 1.5T system(GE Healthcare,Milwaukee,WI,USA).Seventy patients who had undergone MRI of the liver [29 hepatocellular carcinomas(HCC),four cholangiocarcinomas,34 metastatic liver cancers,10 hemangiomas,and eight cysts] between April 2004 and August 2008 were retrospectively evaluated.Visu-alization of lesions,relative contrast ratio(RCR),and apparent diffusion coefficient(ADC)were compared between benign and malignant lesions on DWI.Su-perparamagnetic iron oxide(SPIO)was administered to 59 patients,and RCR was compared pre-and post-administration.RESULTS:DWI showed higher contrast between ma-lignant lesions(especially in multiple small metastatic cancers)and surrounding liver parenchyma than did contrast-enhanced computed tomography.ADCs(mean ± SD × 10-3 mm2/s)were signif icantly lower(P < 0.05)in malignant lesions(HCC:1.31 ± 0.28 and liver me-tastasis:1.11 ± 0.22)and were signifi cantly higher in benign lesions(hemangioma:1.84 ± 0.37 and cyst:2.61 ± 0.45)than in the surrounding hepatic tissues.RCR between malignant lesions and surrounding he-patic tissues signifi cantly improved after SPIO adminis-tration,but RCRs in benign lesions were not improved.CONCLUSION:DWI is a simple and sensitive method for screening focal hepatic lesions and is useful for dif-ferential diagnosis.

Predictor of respiratory disturbances during gastric endoscopic submucosal dissection under deep sedation

BACKGROUND Sedation is commonly performed for the endoscopic submucosal dissection(ESD)of early gastric cancer.Severe hypoxemia occasionally occurs due to the respiratory depression during sedation.AIM To establish predictive models for respiratory depression during sedation for ESD.METHODS Thirty-five adult patients undergoing sedation using propofol and pentazocine for gastric ESDs participated in this prospective observational study.Preoperatively,a portable sleep monitor and STOP questionnaires,which are the established screening tools for sleep apnea syndrome,were utilized.Respiration during sedation was assessed by a standard polysomnography technique including the pulse oximeter,nasal pressure sensor,nasal thermistor sensor,and chest and abdominal respiratory motion sensors.The apnea-hypopnea index(AHI)was obtained using a preoperative portable sleep monitor and polysomnography during ESD.A predictive model for the AHI during sedation was developed using either the preoperative AHI or STOP questionnaire score.RESULTS All ESDs were completed successfully and without complications.Seventeen patients(49%)had a preoperative AHI greater than 5/h.The intraoperative AHI was significantly greater than the preoperative AHI(12.8±7.6 events/h vs 9.35±11.0 events/h,P=0.049).Among the potential predictive variables,age,body mass index,STOP questionnaire score,and preoperative AHI were significantly correlated with AHI during sedation.Multiple linear regression analysis determined either STOP questionnaire score or preoperative AHI as independent predictors for intraoperative AHI≥30/h(area under the curve[AUC]:0.707 and 0.833,respectively)and AHI between 15 and 30/h(AUC:0.761 and 0.778,respectively).CONCLUSION The cost-effective STOP questionnaire shows performance for predicting abnormal breathing during sedation for ESD that was equivalent to that of preoperative portable sleep monitoring.

Development of the nervous system in mouse liver

BACKGROUND The role of the hepatic nervous system in liver development remains unclear.We previously created functional human micro-hepatic tissue in mice by co-culturing human hepatic endodermal cells with endothelial and mesenchymal cells.However,they lacked Glisson’s sheath[the portal tract(PT)].The PT consists of branches of the hepatic artery(HA),portal vein,and intrahepatic bile duct(IHBD),collectively called the portal triad,together with autonomic nerves.AIM To evaluate the development of the mouse hepatic nervous network in the PT using immunohistochemistry.METHODS Liver samples from C57BL/6J mice were harvested at different developmental time periods,from embryonic day(E)10.5 to postnatal day(P)56.Thin sections of the surface cut through the hepatic hilus were examined using protein gene product 9.5(PGP9.5)and cytokeratin 19(CK19)antibodies,markers of nerve fibers(NFs),and biliary epithelial cells(BECs),respectively.The numbers of NFs and IHBDs were separately counted in a PT around the hepatic hilus(center)and the peripheral area(periphery)of the liver,comparing the average values between the center and the periphery at each developmental stage.NF-IHBD and NF-HA contacts in a PT were counted,and their relationship was quantified.SRYrelated high mobility group-box gene 9(SOX9),another BEC marker;hepatocyte nuclear factor 4α(HNF4α),a marker of hepatocytes;and Jagged-1,a Notch ligand,were also immunostained to observe the PT development.RESULTS HNF4αwas expressed in the nucleus,and Jagged-1 was diffusely positive in the primitive liver at E10.5;however,the PGP9.5 and CK19 were negative in the fetal liver.SOX9-positive cells were scattered in the periportal area in the liver at E12.5.The Jagged-1 was mainly expressed in the periportal tissue,and the number of SOX9-positive cells increased at E16.5.SOX9-positive cells constructed the ductal plate and primitive IHBDs mainly at the center,and SOX-9-positive IHBDs partly acquired CK19 positivity at the same period.PGP9.5-positive bodies were first found at E16.5 and HAs were first found at P0 in the periportal tissue of the center.Therefore,primitive PT structures were first constructed at P0 in the center.Along with remodeling of the periportal tissue,the number of CK19-positive IHBDs and PGP9.5-positive NFs gradually increased,and PTs were also formed in the periphery until P5.The numbers of NFs and IHBDs were significantly higher in the center than in the periphery from E16.5 to P5.The numbers of NFs and IHBDs reached the adult level at P28,with decreased differences between the center and periphery.NFs associated more frequently with HAs than IHBDs in PTs at the early phase after birth,after which the number of NF-IHBD contacts gradually increased.CONCLUSION Mouse hepatic NFs first emerge at the center just before birth and extend toward the periphery.The interaction between NFs and IHBDs or HAs plays important roles in the morphogenesis of PT structure.

A Novel Cable-Driven Soft Robot for Surgery

Robot-assisted laparoscopic radical prostatectomy(RARP)is widely used to treat prostate cancer.The rigid instruments primarily used in RARP cannot overcome the problem of blind areas in surgery and lead to more trauma such as more incision for the passage of the instrument and additional tissue damage caused by rigid instruments.Soft robots are relatively fexible and theoretically have infinite degrees of freedom which can overcome the problem of the rigid instrument.A soft robot system for single-port transvesical robot-assisted radical prostatectomy(STvRARP)is developed in this study.The soft manipulator with 10 mm in diameter and a maximum bending angle of 270°has good fexibility and dexterity.The design and mechanical structure of the soft robot are described.The kinematics of the soft manipulator is established and the inverse kinematics is compensated based on the characteristics of the designed soft manipulator.The master-slave control system of soft robot for surgery is built and the feasibility of the designed soft robot is verified.