Rubidium Uptake in Chest Tumors on PET/CT

Area of Science:

• Nuclear Medicine
• Radiochemistry
• Oncology

Background:

• Cardiac scans frequently reveal incidental extracardiac tumors.
• Rubidium (Rb) imaging is utilized in cardiac assessments.

Purpose of the Study:

• To characterize Rubidium (Rb) uptake in incidentally discovered extracardiac tumors.
• To compare Rb findings with Fluorodeoxyglucose (FDG) Positron Emission Tomography/Computed Tomography (PET/CT).

Main Methods:

• Retrospective review of cardiac Rb scans over 11 years.
• Identification and measurement of maximum standard uptake value (SUVmax) in tumors and background tissues.
• Comparison of Rb SUVmax with FDG PET/CT in select cases.

Main Results:

• 63 patients with unsuspected extracardiac tumors (17 breast, 36 lung, 10 other) were identified.
• Rb uptake was stable between rest and stress, generally low, and lower than FDG PET/CT.
• A significant correlation was observed between estrogen receptor positivity and Rb uptake in breast tumors.

Conclusions:

• Rb uptake in extracardiac tumors is stable but relatively low compared to FDG PET/CT.
• Potential utility of Rb in molecular imaging, particularly for breast tumors with receptor correlations.
• Background tissue uptake patterns were consistent, with liver > mediastinal blood pool > lung > body wall.