FACTORS AFFECTING PERCEIVED TUMOR VOLUMES IN MAGNETIC-RESONANCE-IMAGING

Irregularly structured brain tumors, such as glioblastomas, challenge attempts to visualize and quantify their three-dimensional structure. Magnetic resonance imaging (MRI) represents one tool for attempting to noninvasively track tumor size. MR images demonstrate widely varying perceived tumor margins. In addition, adjunct therapies, such as the a dministration of steroids, greatly affect the volumes perceived in ima ges formed by certain pulse sequences. In this study tumors were grown in 15 dogs and the tumor size tracked for a period of time. The dogs were placed on dexamethasone for a week and another series of scans wa s obtained. No other therapies were provided. The data for visualized tumor size are provided for T1, T2, and proton density. Weighted image s are provided and the relationships between the scans are discussed.