To improve and develop the MR-methods, we utilize a 7.05 Tesla BRUKER Biospec in combination with preclinical models as phantoms and xenografts. One of the advantages of preclinical models is the opportunity to make use of higher magnetic field, that improves the temporal and spatial resolution. We are using Dynamic Contrast Enhanced MRI (DCE MRI), Apparent Diffusion Coefficient (ADC) mapping and MR Spectroscopy (MRS). In combination with the MR methods we also use ex vivo methods as histology, proteomics, genomics and HR MAS MRS.

DCE MRI and kinetic modelling

Angiogenesis is a complex process critical to growth, metastasis and treatment respons of malignant tumors. Tumor vasculature consist of chaotic, irregular and leaky blood vessels that differ from normal tissue vasculature. An injection of contrast agent will therefore cause a higher and different enhancement in tumors than normal tissue. By taking a serie MR images with high resolution in short timelag after contrast agent administration, concentration curves as a function of time for each voxel can be obtained. Kinetic modelling of these curves yields parameters (e.g. Ktrans) which describes the tumor biology. The changes in these parameters after treatment, are related to histopathological outcome and patient survival.

ADC mapping

Tumor cells often have a high proliferation rate, witch cause a high cell density. High cell density, in combination with poor blood supply often induce hypoxia. In areas with low cell density, the water molecules may diffuse long distances in EES compared to areas with high cell density. After successful treatment the cell dies and the cell density decreases. By calculating maps of the diffusion coefficient before and after treatment, it is possible to evaluate early treatment response.

Figure: Tumors often have a high proliferationrate causing a high cell density, which result in a low diffusion coefficient. When the supply of nutrient and oxygen is too low the cell dies and necrosis can be observed as areas with very high diffusion coefficient. Treatment seek to kill tumor cells. If this is acheived the cell density will decrease and the diffusion of water molecules will increase. ADC map can therefore be tool for evaluating treatment response.

In vivo MRS

In vivo MRS gives the opportunity to monitor changes in metabolic profile after treatment. The advantage of the high field makes it easier to classify tumor or identify changes in caused by treatment. MRS are further explained under tissue characterization.