Analysis of volume MRI and MR spectroscopic imaging data for the evaluation of patients with brain tumors

The combination of volumetric MRI and multivoxel localized MR spectroscopic imaging (MRSI) data provides the potential for quantifying variations in t issue morphology and function. These techniques have numerous applications for the evaluation of neurological diseases. While state-of-the-art whole-b ody MR scanners are able to acquire both types of data, there have been rel atively few reports which have presented clinical applications of the techn ology. One of the reasons for this has been the need to develop software fo r reconstruction and reliable interpretation of 3D imaging and spectral dat a. In this article, we describe the strategy developed for quantitative ana lysis of combined MRI and MRSI examinations from patients with brain tumors and evaluate the key components of this procedure using both simulations a nd empirical data from phantoms, normal volunteers, and patients. Important factors are the use of volume or interleaved multislice anatomic images as a reference, the reconstruction and correction of the spectral data for fr equency, phase, and baseline distortions and consideration of the character istics of the coil, RIF pulses used for spatial selection, and phase encodi ng procedures. These studies show that the metabolic parameters most critic al for distinguishing tumor from normal and necrotic tissue were relative l evels of choline and NAA. Levels of creatine and lactate were found to be v ariable, both in terms of their spatial distribution within individual lesi ons and between different patients. (C) 2001 Wiley-Liss, Inc.