P077] T1, T2 Relaxation times measurements methods: A comparison between standard sequences performed by an NMR spectrometer and MRI devices from different vendors at 1.5T

Abstract

Purpose The aim of this study is to evaluate the accuracy and the standardization of measurements of relaxation times values obtained from post-processing phantom images acquired with different vendors MRI scanners used in clinical and an NMR spectrometer, giving the basis for the evaluation of accuracy of T 1 , T 2 mapping for cardiac applications. Methods Six vials filled with agarose doped with gadolinium of an Eurospin phantom (Diagnostic Sonar, Livingston, UK) were scanned with an NMR spectrometer at Pavia University’s laboratory in order to restate the golden standard T 1 , T 2 relaxation times values at 1.5 T. SR (Saturation Recovery), IR (Inversion Recovery), SE (Spin Echo) and CPMG (Carr-Purcell-Meiboom-Gill) sequences were used. The vials were also scanned with a Magnetom Aera (Siemens, 1.5 T) and a Signa (General Electric, 1.5 T) MRI devices using clinical SE and IR sequences. Images were then processed with vendor independent software: cvi42 (Circle Cardiovascular Imaging Inc.), and an open source software developed with Matlab, Segment (http://www.medviso.com). Results Experimental values obtained by MRI devices with IR and SE sequences are in good agreement (10% for both relaxation times) with those measured by SR, IR and CPMG sequences with the NMR spectrometer even though they were measured at different room-temperature (20 °C for Siemens Aera, 21 °C for GE Signa and 23 °C for the NMR spectrometer): a linear dependence from temperature is observed, the same prospected by the Eurospin’s manual. SE sequences performed with the NMR spectrometer give much lower values of T 2 (70%) compared to the other measured ones due to diffusion: this suggests that those sequences named SE in MRI devices are CPMG sequences. Conclusions This is a preliminary study showing a good standardization level of different MRI and NMR devices for relaxation times estimation: next studies may investigate the agreement of values obtained with cardiac mapping sequences (MOLLI, Sh-MOLLI, T 2 -prep TrueFISP) with the standard sequences used in this study.