What types of scans are performed using Tc labeled red blood cells (RBCs)?

• A. Bone scans
• B. GI bleed and MUGA
• C. Thyroid function tests
• D. Brain imaging

Answer: (B)

Tc labeled red blood cells (RBCs) are primarily used in nuclear medicine for specific imaging purposes, particularly when evaluating certain cardiovascular and gastrointestinal conditions. The correct answer indicates that two key types of scans involving Tc labeled RBCs are the gastrointestinal (GI) bleed scan and the multi-gated acquisition (MUGA) scan.

In the case of a GI bleed scan, Tc labeled RBCs allow for the visualization of active internal bleeding by tracking the flow of blood within the gastrointestinal tract. This is valuable in diagnosing sources of hemorrhage. The use of labeled RBCs is critical here because it enables real-time imaging of blood flow, effectively highlighting areas where blood may be accumulating due to a bleed.

The MUGA scan leverages the properties of Tc labeled RBCs to assess cardiac function. By labeling the patient's own red blood cells with technetium, clinicians can measure the heart's pumping efficiency and determine the ejection fraction. This is essential in diagnosing heart conditions and assessing the effectiveness of certain treatments.

In contrast to the other answer choices: bone scans are typically performed using different radiopharmaceuticals that localize to bone tissue; thyroid function tests utilize iodine isotopes rather than technetium; and brain imaging often employs radiopharmaceuticals