NMTCB Positron Emission Tomography (PET) Practice Exam

Carcinoid tumors are considered metabolically weak because they tend to have a lower uptake of positron emission tomography (PET) tracer agents like fluorodeoxyglucose (FDG). This lower metabolic rate is characteristic of these endocrine tumors, which are typically slow-growing and have a more indolent behavior compared to other neoplasms.

In patients with carcinoid tumors, the relatively low glycolytic activity means that many of these tumors will not demonstrate distinctly elevated FDG uptake on PET scans, making them challenging to detect using this imaging modality. As a result, carcinoid tumors can often be overlooked during routine PET assessments.

In contrast, tumors such as small cell lung carcinoma, rhabdomyosarcoma, and non-Hodgkin lymphoma typically exhibit higher metabolic activities that are more readily identifiable on PET scans, as they tend to have increased glucose metabolism, which correlates with the PET imaging principles.