1、PATHOPHYSIOLOGY AND MECHANISMS OF RADIOPHARMACEUTICAL LOCALIZATION_CONT.20140721 morning meeting 胡蓮欣The Pathophysiological basis of Nuclear Medicine 2nd ed. Springer. The mechanisms of radioisotope localization1. Isotope dilution2. Capillary blockade3. Physicochemical adsorption4. Cellular migration
2、 and sequestration5. Membrane transport Simple diffusion Diffusion and intracellular metabolism/binding Diffusion and mitochondrial binding Diffusion and increased capillary and plasma membrane permeability Facilitated diffusion Active transport Phagocytosis Receptor-mediated endocytosis6. Metabolic
3、 Substrates and Precursors Precursors: Radiolabeled Amino Acids 7. Tissue Hypoxia8. Cell Proliferation9. Specific Receptor Binding Radiolabeled Peptides Steroid Hormone Receptors Adrenergic Presynaptic Receptors and Storage LDL Receptors Radiolabeled Antibodies10. Imaging Gene ExpressionIn vivo, MUG
4、A, RBC scanMAA lung perfusionMDP bone scanWBC scan, denatured RBC spleen scanXe-133 ventilationHMPAO/ECD brain perfusion scanTc-99m MIBIDiffusion and increased capillary others diffuse out of the gland Affected by iodine containing medications, TSH levels, thyroid & nonthyroid drugs, total body iodi
5、ne pool Salivary glands, stomach, bowel & GU tract Also significant uptake (secretion) of radioiodide and pertechnetateThallous chloride (Tl-201) & Rubidium-82 Tl(OH)2+ & Rb + act as K + ion Uptake of myocardium involves (Tl & Rb): Passive diffusion ATP-dependent pathways Uptake by tumor cells (Tl-2
6、01) Increased blood flow and increased permeability Na+/K+ ATPase Cellular uptake (Tl-201) Na+/K+ ATPase oubain, digitalis and furosemide Chloride cotransport system furosemid Calcium-dependent ion channel: minimal amountblockblockAddictive blockade effectRenal agents Agents for GFR I-125 iothalamate, Tc-99m DTPA, Cr-51 EDTA Mostly filtered by glomerulus No specific transport mechanism involved Dependents on hydrostatic & colloid osmotic pressure Agents for ERPF OIH and MAG3 Partly filtered and mostly secreted by tubules Actively transported by renal hippurate anionic transport system
