Home
Radiology Guides Anatomy Physio & Path Medicine Physics Contact
RADIOPHARMACEUTICALS-MECHANISMS OF LOCALIZATION, PT 1

Physics

RADIOPHARMACEUTICALS-MECHANISMS OF LOCALIZATION, PT 1

1. Compartmental localization and leakage - introduction of the radiopharmaceutical into an anatomic compartment to identify an abnormal opening (e.g. Tc-99m labeled RBCs to identify GIT bleeding).

2. Cell sequestration - to evaluate splenic morphology and function, RBCs are withdrawn from the patient, labeled with Tc-99m, and slightly damaged by in vitro. They are reinjected and the spleen’s ability to recognize and remove (i.e., sequester) the damaged RBCs is evaluated.

3. Phagocytosis - Tc-99m-labeled sulfur colloid particles are phagocytosed by the liver reticuloendothelial system in a liver scan.

4. Passive diffusion - Tc-99m DTPA crosses damaged BBB to localize pathology. Tc-99m MIBI accumulates in the myocardium, indicating perfusion abnormalities.

5. Active transport - classic example in nuclear medicine is the trapping and organification of radioactive iodide. Non-uniform distribution of Tl-201 in the myocardium indicates a myocardial perfusion deficit. FDG (glucose-analog) is used to assist in the evaluation of malignancy in patients with known or suspected malignancy.


Avatar
REFERENCES

1. Bushberg, J. T. (2012). The essential physics of medical imaging. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. Find it at Amazon
2. Heggie, J. C., Liddell, N. A., & Maher, K. P. (1997). Applied imaging technology. Melbourne: St. Vincents Hospital.

Ⓒ A. Manickam 2018

+ Home