Low grade gliomas were studied with ultra low field magnetic resonance imaging (ULF MRI). The tumors exhibited high tissue contrast in both T1 and T2-weighted images as compared to normal brain tissue. Moreover they were sharply delineated towards the surrounding brain tissue. When compared with X-ray computed tomography the tumors were more readily detected and delineated by using ultra-low field magnetic imaging. A computer-assisted classification procedure was used to define new regions of interest for relaxation time estimations. By using this procedure more accurate estimations of the T1 and T2 values were obtained.