The slices used here are taken from the axial plane, a plane roughly perpendicular to the long axis of the human body [4] and lie approximately 7 to 8 cm from the top of the head [5]. This ``center slice,'' was chosen in [1,2,3] because it has the best uniformity of signal within the General Electric MR coil used in this work and also contains the most reliable anatomical information. Since this work is an extension of those works, all slices used here were first processed (and found to be abnormal) by those systems with knowledge concerning extra-cranial tissues and white matter also gathered. The relevance of this is further described in Section 4.1.
Figure 1: Slices of Interest: (a) a Normal Slice (b) an Abnormal Slice.
Each brain slice consists of three feature images: T1-weighted (pulse repetition time 600ms, echo time 20ms), proton density (PD), and T2-weighted (pulse repetition 3000ms, echo time 80ms) [6]. Figure 1(a) shows a typical normal slice, while Figure 1(b) shows an abnormal slice. The labeled tissues of interest are: white matter (white), gray matter (black), and cerebro-spinal fluid (CSF) (inner gray). In the abnormal slice, pathology (light gray) occupies an area that belongs to normal tissues. In this system, only gray matter, CSF and pathology are fully processed, with pathology, and the gadolinium-enhanced tumor within it, the primary region of interest.