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Presenter: N., Sakata, Sendai, Japan
Authors: N. Sakata, T. Kodama, R. Chen, G. Yoshimatsu, M. Goto, S. Egawa, M. Unno
Ultrasonography examination can visualize transplanted islets and reveal the function of the islets
N. Sakata1, T. Kodama2, R. Chen2, G. Yoshimatsu1, M. Goto3, S. Egawa1, M. Unno1
1 Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Graduate School of Medicine, Tohoku University, Sendai, Japan; 2 Department of Biomedical Engineering, Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan; 3 Innovation of New Biomedical Engineering Center, Tohoku University, Sendai, Japan
Objective: Monitoring transplanted islets is significantly important to perform the proper treatment according to islet condition. Ultrasonography (US) is one of the useful and safe imaging examinations for visualizing subcutaneous body structures. In this study, we attempted to visualize transplanted islets with US exam and evaluate the correlation between US findings and islet function.
Methods: The islets of BALB/c mice (syngeneic) or Sprague Dawley (SD) rats (xenogeneic) were transplanted into the subcapslar space of the left kidney in male mice with streptozotocine-induced diabetes. The numbers of transplanted islets were 0, 200, 500 and 1,000 islet equivalent (IEQ). After transplantation, we underwent B-mode US exam to transplanted mice (VEVO 770 high-frequency ultrasound system: central frequency 35 MHz, axial resolution 50 µm, focal length 10 mm) and measured blood glucose and serum insulin at postoperative day (POD) 3, 7, 14 and 28, and calculated volume of islet mass. We examined the position of islets by US images and evaluated correlation between islet volume and metabolic parameters (blood glucose and serum insulin levels).
Results: While hyperechoic lesions were detected on the surface of kidney in all the times in syngeneic transplantation, hypoechoic mass at renal subcapsule was detected at POD 3 and 7 and the mass was vanished absolutely at POD 28 in xenogeneic transplantation (Figure). While the islet volume in syngeneic transplantation was not changed throughout the study period in syngeneic transplantation, it was temporary increased at POD 7 and decreased to almost zero at POD 28 in xenogeneic transplanation (Figure). Syngeneic islet volume was moderately and significantly correlated with transplanted islet number (R2=0.31, p=0.0003), blood glucose (R2=0.15, p<0.0001) and serum insulin (R2=0.22, p<0.0001).
Conclusions: US can be one of the useful imaging modalities for detecting islets and evaluating islet condition.
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