Biodistribution of Radiopharmaceuticals in Nuclear Medicine

Flashcards about Biodistribution of Radiopharmaceuticals in Nuclear Medicine

What is the definition of Biodistribution?

The distribution of a radiopharmaceutical within the body over time

What is the radiopharmaceutical form of Sodium Pertechnetate?

⁹⁹ᵐTcO₄⁻

How is ⁹⁹ᵐTc Sodium Pertechnetate produced?

From a ⁹⁹Mo/⁹⁹ᵐTc generator

What ions does ⁹⁹ᵐTcO₄⁻ mimic in the body?

Halide ions like iodide

What type of emission does ⁹⁹ᵐTc produce that makes it ideal for imaging?

Gamma rays at 140 keV

What factors influence biodistribution?

Molecular structure, route of administration, organ perfusion, transport mechanisms, metabolism and excretion

How is ⁹⁹ᵐTc Pertechnetate administered?

Intravenous injection

What describes the absorption of ⁹⁹ᵐTc Pertechnetate?

Immediate into bloodstream

How is ⁹⁹ᵐTc Pertechnetate distributed after administration?

Rapidly to several organs via blood

What is true about the metabolism of ⁹⁹ᵐTc Pertechnetate?

Minimal — it remains largely unchanged

What are the primary and minor routes of excretion for ⁹⁹ᵐTc Pertechnetate?

Renal (major), GI tract (minor)

What type of uptake does the thyroid show for ⁹⁹ᵐTcO₄⁻?

High uptake via active transport

How do the salivary glands interact with ⁹⁹ᵐTcO₄⁻?

Moderate uptake via active transport

What kind of uptake occurs in the gastric mucosa for ⁹⁹ᵐTcO₄⁻?

Moderate uptake via active transport

Which describes the biodistribution of ⁹⁹ᵐTcO₄⁻ in the choroid plexus?

Low uptake via passive diffusion

What is the uptake characteristic of ⁹⁹ᵐTcO₄⁻ in the kidneys and bladder?

High uptake due to excretion

How is ⁹⁹ᵐTcO₄⁻ handled in the colon?

Low uptake due to delayed excretion

What is ⁹⁹ᵐTcO₄⁻ used to detect in thyroid imaging?

Nodules, hyper/hypothyroidism

What is the purpose of using ⁹⁹ᵐTcO₄⁻ in Meckel’s Diverticulum imaging?

Detect ectopic gastric mucosa

What can ⁹⁹ᵐTcO₄⁻ imaging reveal in the salivary glands?

Obstruction or inflammation

Historically, ⁹⁹ᵐTcO₄⁻ was used in brain imaging for what now-obsolete purpose?

Tumor detection

What is the role of a target organ in nuclear medicine imaging with ⁹⁹ᵐTcO₄⁻?

It’s the organ intended for imaging

What defines a critical organ in radiopharmaceutical biodistribution?

It’s the organ that receives the highest radiation dose

In a thyroid scan using ⁹⁹ᵐTcO₄⁻, what is the critical organ?

What is Pharmacokinetics (PK)?

What the body does to the drug, includes absorption, distribution, metabolism, excretion (ADME)

What is Pharmacodynamics (PD)?

What the drug does to the body, includes receptor interactions, localization, biological effects

What is the radiopharmaceutical for Technetium Sodium Pertechnetate?

⁹⁹ᵐTcO₄⁻

What is the chemical behavior of Technetium Pertechnetate?

Mimics halide ions (especially iodide)

What is the physical half-life of Technetium Pertechnetate?

~6 hours

What is the excretion route of Technetium Pertechnetate?

Renal (major), GI tract (minor)

Where does Technetium Pertechnetate accumulate?

Thyroid, salivary glands, gastric mucosa, choroid plexus

What are the organs with normal biodistribution of Technetium Pertechnetate?

Thyroid, Salivary glands, Gastric mucosa, Choroid plexus, Kidneys/bladder, Colon

What are the thyroid imaging applications of Technetium Pertechnetate?

Nodules, hyper/hypothyroidism

What is Meckel’s Diverticulum imaging application of Technetium Pertechnetate?

Detect ectopic gastric mucosa

What is Salivary Gland imaging application of Technetium Pertechnetate?

Obstruction or inflammation

What is Brain imaging application of Technetium Pertechnetate?

Tumor detection (obsolete)

What factors affect the biodistribution of Technetium Pertechnetate?

Patient hydration status, Renal function, Medications, Pathological changes

What is the major critical organ for Technetium Pertechnetate?

Stomach

What is ⁹⁹ᵐTc Macroaggregated Albumin (MAA)?

⁹⁹ᵐTc-labeled human serum albumin particles

What is ⁹⁹ᵐTc-MAA used for?

Lung perfusion imaging

What is the particle size of ⁹⁹ᵐTc-MAA?

10–90 µm (capillary-level embolization)

What is the distribution of ⁹⁹ᵐTc-MAA?

Entrapped in pulmonary capillaries

What is the primary localization of ⁹⁹ᵐTc-MAA?

Lungs

What are the imaging applications of ⁹⁹ᵐTc-MAA?

Evaluate pulmonary embolism (PE), Preoperative lung function evaluation, Assess right-to-left shunts

What is the target organ of ⁹⁹ᵐTc-MAA?

Lungs

What is the critical organ of ⁹⁹ᵐTc-MAA?

Lungs

What factors affect the biodistribution of ⁹⁹ᵐTc-MAA?

Particle size and number, Cardiac output and pulmonary perfusion, Right-to-left shunt, Injection technique

What are the precautions of ⁹⁹ᵐTc-MAA?

Contraindicated in severe pulmonary hypertension

What are the common agents for ⁹⁹ᵐTc Phosphonate/Phosphate Radiopharmaceuticals?

⁹⁹ᵐTc-MDP, ⁹⁹ᵐTc-HDP, ⁹⁹ᵐTc -PYP

What is the chemical structure of ⁹⁹ᵐTc Phosphonate/Phosphate Radiopharmaceuticals?

phosphate or phosphonate backbone

What is the pharmacodynamics of ⁹⁹ᵐTc Phosphonates?

Localizes in areas of osteoblastic activity

What is the high uptake of ⁹⁹ᵐTc Phosphonates?

Skeletal system

What are the imaging applications of ⁹⁹ᵐTc Phosphonates?

Metastatic disease, Fracture detection, Osteomyelitis, Arthritis and degenerative bone disease, Bone viability in orthopedic procedures

What is the target organ of ⁹⁹ᵐTc Phosphonates?

Bone (skeleton)

What is the critical organ of ⁹⁹ᵐTc Phosphonates?

Bladder wall

What factors influence the biodistribution of ⁹⁹ᵐTc Phosphonates?

Bone turnover rate, Renal function and hydration, Injection technique and timing, Medications