TISSUE CHARACTERIZATION BY MAGNETIC-RESONANCE SPECTROSCOPY AND IMAGING - RESULTS OF A CONCERTED RESEARCH-PROJECT OF THE EUROPEAN-ECONOMIC-COMMUNITY .1. INTRODUCTION, OBJECTIVES, AND ACTIVITIES

The multi-parameter dependence of magnetic resonance (MR) images allow s a unique flexibility of soft tissue contrast and gives access to pec uliar sources of in vivo tissue characterization, mainly associated wi th magnetic relaxation properties. However, MR methodologies have not yet expressed their full potential in terms of tissue characterization for several reasons: a) problems of quality control and quantitation have generally not been addressed by centers using MRI equipment, nor in most of the published literature; and b) data scattering of quantit ative measurements obtained from tissues in vitro and in vivo appear t o be a major factor in inhibiting or limiting the clinical utility of MRI, for a possible in vivo characterization of pathological tissues. An international project, aimed at evaluating the clinical significanc e of tissue characterization by MR, was activated in 1984 by the Biome dical Engineering Advisory Committee of the European Communities (EC C OMAC-BME) within the 3rd EC Medical and Health Research Programme (MHR P). The scientific achievements of this first project (Magn. Reson. Im aging, 6:171-222; 1988) represented the basis for launching and perfor ming a second Concerted Action, in the frame of the 4th MHRP (1988- 19 92). Main areas of research of this second project were: a) developmen t of standard methodologies for quantitative measurements of MR parame ters and correlation with histo- and physiopathology; b) performance a ssessment and calibration of MR clinical equipment; c) harmonization o f test procedures with other centers and industry; and d) pilot multi- center collections of data. A series of papers is presented here which illustrates a) objectives and scientific programme of this project; b ) protocols and test objects adopted for performance assessment and qu ality control in MRI; c) the conclusions of validating experimental tr ials; d) development and results of in vivo multi-center studies on pr oton relaxation in human brain, liver, and skeletal muscle; e) the ana lysis of the first international data bank on in vitro NMR relaxation times; and f) problems and value of adoption of common approaches to t issue characterization by MR image texture analysis.