When imaging for LeVeen shunt patency, where are the delayed images taken?

Delayed images for assessing LeVeen shunt patency are taken over the lung fields. The LeVeen shunt is used to treat malignant ascites by redirecting fluid from the peritoneal cavity into the venous system, primarily the inferior vena cava. When the shunt is functioning correctly, any tracer injected into the abdominal cavity will eventually travel through the shunt and into the venous circulation, which is usually first visualized in the lung fields due to the blood flow dynamics.

Monitoring the lung fields specifically allows for the assessment of the tracer's movement and helps confirm that the fluid is adequately draining into the systemic circulation. This is crucial for determining whether the shunt is patent and functioning as intended, as blockage or malfunction would impede this process.

Other areas like the abdominal cavity, heart, or pelvis are less relevant for this type of imaging in the context of the LeVeen shunt, as they do not provide the same level of insight into the shunt’s effectiveness and patency based on the expected pathway of tracer movement post-injection.