Final answer:
MRI contrast is influenced by the use of contrast agents, typically stable complexes of gadolinium, which enhance the differentiation between different soft tissues. Scanning techniques like T1, T2, and proton density scans also play a role in contrast by using different relaxation mechanisms of hydrogen nuclei.
Step-by-step explanation:
The factors that influence MRI contrast origin primarily include the interaction of hydrogen nuclei with magnetic fields, and the use of MRI contrast agents. These agents are usually paramagnetic metal complexes, like complexes of gadolinium (Gd3+), which are particularly effective due to their strong paramagnetic properties stemming from their seven unpaired electrons. However, since free gadolinium ions can be toxic, they are administered as stable compounds like DTPA3- (diethylene triamine pentaacetic acid) to ensure they do not dissociate and are safely excreted. The presence of an MRI contrast agent alters the magnetic properties of water within different cellular environments leading to detailed images with enhanced contrast between tissues such as tumors, organ tissue, and blood vessels.
Aside from these agents, contrast in MRI images can also be enhanced through different scanning techniques like T1, T2, or proton density scans. These rely on varying relaxation times of hydrogen nuclei that depend on the magnetic field's strength in different parts of the body and tissue characteristics.