What is the fasting requirement for patients before FDG-18 imaging?

The fasting requirement for patients before undergoing FDG-18 imaging is primarily designed to maximize tumor uptake of the radiotracer, which is crucial for obtaining high-quality images. When patients fast for several hours prior to the procedure, their body's glucose levels decrease, which leads to a higher accumulation of FDG in metabolically active tissues, such as tumors. This is important because cancerous cells typically have an increased rate of glucose metabolism compared to normal cells, making them more likely to absorb the FDG when it is administered.

By enhancing tumor uptake, the quality of the images obtained during the imaging process is improved, allowing for more precise detection and evaluation of cancerous lesions. This reduces the background activity from normal tissues, further improving the contrast and clarity of the images received.

While factors such as patient comfort, image clarity, and allergic reactions play roles in overall patient management, the primary rationale for fasting is centered on optimizing the radiotracer's uptake in malignant lesions, making this the correct answer.