What is injected during an IVC Gram to measure the IVC?

During an IVC Gram, a specific amount of contrast material, typically around 15-20 ml, is injected into the inferior vena cava (IVC) to visualize its anatomy and assess any potential pathologies. The use of contrast allows for enhanced imaging during fluoroscopy or computed tomography, providing clear delineation of the IVC, including any anomalies, thrombosis, or occlusions.

Contrast agents are radiopaque substances that improve the visibility of internal structures against surrounding tissues, facilitating accurate diagnosis. In this procedure, the contrast material outlines the vessel and can highlight any abnormalities, thereby supporting the interventional radiologist in making informed clinical decisions.

Injecting air or saline would not provide the necessary imaging contrast as effectively as a radiopaque material, and using blood is not a standard practice for this type of examination. Thus, the practice of utilizing contrast material for an IVC Gram aligns well with the standard protocols in interventional radiology, making it the correct answer in this scenario.