Glioblastoma multiforme (GBM) is the most common type of brain tumor found in adults and is fatal in all cases. A very promising therapeutic approach for GBM is the use of oncolytic viruses (OVs) that selectively infect, replicate in, and destroy tumor cells while sparing the surrounding normal cells. Nevertheless, to achieve successful oncolytic virotherapy, frequent non-invasive monitoring of the process must be performed. This is crucial for gaining a better understanding of the interactions between the virus and its tumor-host and predicting therapeutic response. Thus, the development of a non-invasive method capable of accurately quantifying the location and extent of the viral spread in the tumor is highly required and is of great importance. Accordingly, the main research goal of this action is to develop a magnetic resonance imaging (MRI)- based method for accurate, quantitative, and rapid imaging of OVs delivery and spread in clinically relevant tumor models. The specific research objectives include developing a method for the detection and imaging of OV treatment response, increasing the specificity and sensitivity of the method using quantitative MRI techniques and machine learning, quantifying and validating the results using mouse tumor models, translating of the MRI protocols to clinical scanners, and examination of the method for additional applications. The envisioned technology could be expanded to various additional clinical conditions, and its dissemination could improve patient care. Following the project results and analysis, we conclude that a new method for noninvasive MRI of brain tumor treatment response was developed and validated (mostly in preclinical settings), demonstrating a rapid and quantitative assessment of tissue state.