Radiation Biology for Physical Scientists/Imaging Tumour Physiology

Magnetic Resonance Imaging Based
Oxygenated haemoglobin has different magnetic properties than its de-oxygenated form. These magnetic differences can be detected and imaged using a technique called Blood Oxygen Level Dependent (BOLD) Magnetic Resonance Imaging.BOLD characterization of haemoglobin oxygen saturation can be used to reflect vascular hypoxia but not tissue hypoxia1.

Dynamic Contrast Enhanced (DCE-MRI) with gadolinium diethylene-triamine penta-acetic acid as the contrast agent can be used to image hypoxic fraction. MRI T1-weighted images are taken before and after an intravenous injection of gadolinium2.

Positron Emission Tomography Based
Positron Emission Tomography combined with the hypoxia PET reagent 18F misonidazole3 or 60Cu-ATSM4 (copper-60 labeled diacetyl-bis( N(4)-methylthiosemicarbazone))4.

Optical Based
Optical spectroscopy measures haemoglobin saturation 5 which is correlated to vascular hypoxia. This technique is limited to imaging sites that offer optical access.

Interstitial fluid pressure
Dynamic Contrast Enhanced (DCE) Magnetic Resonance Imaging can be used to image the interstitial fluid pressure in tumors using gadolinium diethylene-triamine penta-acetic acid (Gd-DTPA) as the contrast agent.

Metabolism

 * Fludeoxyglucose (18F) abbreviated to FDG can be used with Positron Emission Tomography to image tumour metabolism.


 * Lactic acid is the product of anaerobic metabolism. Lactic acid metabolism can be measured using hyperpolarized 13C-pyruvate.