Biodistribution of Sodium Pertechnetate

What is the abbreviation of Sodium Pertechnetate?

99mTcO4

What is 99mTc-Sodium Pertechnetate produced from?

99Mo/99mTc Generator

What is the chemical behavior?

Mimics halide ions (Especially Iodide)

What is the half life

6 hours

What is the Emission?

Gamma=140 KeV-Ideal for imaging

What is the administration

Intravenous Injection

What is the absorption?

Immediate into the bloodstream

What is the distribution?

Rapid distribution to several organs via blood

What is the metabolism?

Minimal-remains largely unchanged

How is excreted?

Renal (Major), GI Tract (Minor)

What is the main pharmacodynamics of 99mTc-Sodium Pertechnetate?

Mimics iodide and is taken up by sodium-iodide symporters

Where does 99mTc- Sodium Pertechnetate accumulates?

• Thyroid

• Salivary Glands

• Gastric Mucosa

• Choroid Plexus

Does not get organized in the thyroid (unlike iodide)

What is the high uptake organ and what’s its mechanism of action?

Thyroid, Active Transport

What is the salivary glands moderate uptake level and what’s its mechanism of action?

Moderate, active transport

What is the gastric mucosa uptake level and what’s its mechanism of action?

Moderate, Active Transport

What is the Choroid Plexus uptake level and is the mechanism of action?

Low, Passive Diffusion

What is the Kidneys/bladder uptake level and mechanism of action?

High, Excretion

What is the colon’s uptake level and mechanism of action?

Low, delayed excretion

What are the Imaging applications

• Thyroid Imaging

• Meckel’s Diverticulum

• Salivary Gland Imaging

• Brain Imaging (Historical)

What is reason for Thyroid imaging with Sodium Pertechnetate?

Nodules, Hyper/Hypothyroidism

What is the indications for Meckel’s Diverticulum

Detect ectopic gastric mucosa

What is the indication for Salivary Gland Imaging?

Obstruction or Inflammation

What is the indication for Brain Imaging with Sodium Pertechnetate?

Tumor detection (Obsolete)

What is Target Organs

Intended for Imaging

What are Critical Organs

Receive highest radiation dose

What is the Target and critical organ for the thyroid scan?

Target-Thyroid, Critical-Stomach

What is the Target and Critical organ for a Meckel’s scan?

Target-Ectopic Gastric Tissue, Critical-Stomach

What is the target and critical organ for a salivary gland scan?

Target-Salivary glands, Critical- Thyroid

What are the factors affecting biodistribution?

• Patient hydration status

• Renal Function

• Medications

• Pathological changes (e.g., blocked ducts, inflammation)

What is the effective dose for Sodium pertechnetate?

0.007 mSv/MBq

What is the major critical organ for Sodium Pertechnetate

Stomach

How do we minimize dose?

• Short imaging time post-injection

• Hydration and frequent voiding