Volumetric measurement of brain tumors from MR imaging.

Residual tumor volume has been considered important in predicting survival following brain surgery. The purpose of this study was to develop a procedure for quantifying pre- and postsurgical brain tumor volumes that is less subjective than the traditional qualitative grading scale still used by surgeons and radiologists to assess extent of resection (such as gross total, subtotal, and partial resection). Pre- and postsurgical magnetic resonance (MR) imaging brain scans on GE Medical System optical disks were transferred to a Macintosh personal computer using a Pioneer optical disk drive subsystem, and the MedVision 1.41 computer software program was used to analyze regions of interest (ROIs) within them for computation of the volume of tumor tissue therein. Because this procedure puts the original MRI (or CT scan) data file for a patient directly into the personal computer, it bypasses the need for scanning and digitizing MR (or CT scan) film images. Between June 1993 and May 1996, pre- and postsurgical volumetric measurements were made in more than 1,000 brain tumor resection cases and 49 radiosurgery cases. The average intra-observer error was estimated to be 1.8%. This method should facilitate the examination of the effects of various therapies on extent of brain tumor resection. The method is fast, is more precise than intraoperative visual assessment of tumor removal or qualitative comparison of pre- and postoperative scans, and it allows the computation of pre- and postsurgical (three-dimensional) volumes of even irregularly shaped tumors.