TISSUE CHARACTERIZATION BY MAGNETIC-RESONANCE SPECTROSCOPY AND IMAGING - RESULTS OF A CONCERTED RESEARCH-PROJECT OF THE EUROPEAN-ECONOMIC-COMMUNITY .4. IN-VIVO MEASUREMENTS OF PROTON RELAXATION-TIMES IN HUMAN BRAIN, LIVER, AND SKELETAL-MUSCLE - A MULTICENTER MRI STUDY

Quantitative magnetic resonance imaging may offer unique potential for tissue characterization in vivo. In this connection texture analysis of quantitative MR images may be of special importance. Because evalua tion of texture analysis needs large data material, multicenter approa ches become mandatory. Within the frame of BME Concerted Action on Tis sue Characterization by MRI and MRS, a pilot multicenter study was lau nched in order to evaluate the technical problems including comparabil ity of relaxation time measurements carried out in the individual site s. Human brain, skeletal muscle, and liver were used as models. A tota l of 218 healthy volunteers were studied. Fifteen MRI scanners with fi eld strength ranging from 0.08 T to 1.5 T were induced. Measurement ac curacy was tested on the Eurospin relaxation time test object (TO5) an d the obtained calibration curve was used for correction of the in viv o data. The results established that, by following a standardized proc edure, comparable quantitative measurements can be obtained in vivo fr om a number of MR sites. The overall variation coefficient in vivo was in the same order of magnitude as ex vivo relaxometry. Thus, it is po ssible to carry out international multicenter studies on quantitative imaging, provided that quality control with respect to measurement acc uracy and calibration of the MR equipments are performed.