Assessment of brain tumor angiogenesis using perfusion magnetic resonance imaging and magnetic resonance spectroscopy

Magnetic resonance (MR) imaging and spectroscopy have been used to investigate characteristics of brain cancer in vivo, specifically, those arising from angiogenesis, which is thought to be central to tumor growth and invasion. It was established that radiological assessment of angiogenesis is possible with dynamic susceptibility contrast-enhanced MRI (DSC-MRI) in patients with malignant brain tumors.; Thresholds of quality for the T2*-weighted perfusion MRI studies were determined and the effects of an angiogenesis inhibitor on relative cerebral blood flow (CBF) and cerebral blood volume (CBV) changes in patients were evaluated. Quality tests were performed on perfusion data by defining statistical thresholds of acceptance. Region of interest analyses were performed on tumors, and kinetic parameters were normalized with respect to healthy tissue. Decreases in CBF and CBV measurements were observed in patients with clinical response. It was shown that malignant brain tumors have altered perfusion parameters which may be used in the assessment of neovascularization.; The development and testing of a technique to quantify angiogenesis in brain tumor patients using perfusion MR data is presented and used to examine the spatial variance of angiogenesis. The angiogenesis potential, A, was computed for each pixel. A concentric annular model is proposed to evaluate the spatial variance of A. Inter-patient data was used to assess the spatio-temporal patterns of hemodynamics in malignant tumors. It is possible to quantify angiogenesis on a pixel-by-pixel basis using hemodynamic measures such as CBF, CBV, and T2* recovery. Malignant brain tumors have remarkable similarity in the spatial distribution of their angio-architecture. Longitudinal changes in angio-architecture can also be monitored using this method.; In the final phase, tumor hemodynamics are correlated with metabolite distributions, acquired using chemical shift imaging. The levels of N-acetyl aspartate (NAA) and choline (Cho) are found to be significantly lower in the tumor core, where CBF is very low. In the tumor fringes, where angiogenic activity is presumably high, increased CBF corresponded to increased Cho and decreased NAA. The angiogenesis potential was also compared with Cho/NAA ratio images. Hemodynamic and spectral data concur in brain tumors with respect to their spatial variation.