The utility of superb microvascular imaging for monitoring low-velocity venous flow following pancreas transplantation: report of a case.

Vascular thrombosis is a major complication after pancreas transplantation. Because delays in detecting thrombosis often result in graft failure, monitoring blood flow is crucial. Periodic evaluation using color Doppler ultrasonography is mostly performed for monitoring blood flow in the grafted pancreas. However, conventional color Doppler imaging has limited capability to visualize low-velocity blood flow. Superb microvascular imaging (SMI) is a novel ultrasound Doppler technique that is especially sensitive in detecting low-velocity flow. Herein, the authors describe the utility of SMI for monitoring splenic venous blood flow not detected by conventional color Doppler ultrasonography after pancreas transplantation. Ultrasonographic evaluation was performed every 4-6 h for 2 weeks after pancreas transplantation. SMI was used for detecting venous blood flow that was not clearly visible by conventional color Doppler imaging. The greater part of venous blood flow was undetectable by conventional color Doppler imaging, especially in the horizontal regions of the splenic vein. However, SMI clearly described venous flow at all points, even immediately after transplantation and when the patient developed hypotension due to massive bleeding complications. SMI is an extremely useful tool for monitoring venous flow after pancreas transplantation and does not require contrast agents.