Evaluation of measurement accuracy of a T1 and T2 mapping tool

Recently, software tools have been introduced to magnetic resonance (MR) imaging for easy measurement of T1, T2, and T2* relaxation times. The software permits measurement in a shorter time than with either inversion recovery (IR) or spin echo (SE) methods, but accuracy depends on the scan parameters used for measurement. Therefore, use of a T1 or T2 map as a quantitative image requires selection of optimum scan parameters. We investigated the relationship between mapping tool scan parameters and the resulting accuracy of T1 and T2 quantitative maps. We performed measurements with syngo MapIt (Siemens Medical Systems, Erlangen, Germany), a tool for creating relaxation time maps. We compared measurements between the conventional method and the mapping tool using phantom experiments and investigated measurement accuracy of the mapping tool when scan parameters of the tool were changed. Compared with the conventional method, both the T1 (R=0.999) and T2 (R=0.999) maps showed very high correlations. A change according to change of T1 estimate with T1 map was large. Similarly, a change according to change of the maximum echo time with T2 map was large. These results suggest that careful choice of relevant scan parameters can improve measurement accuracy. Our study results demonstrate the reliability of measurements made with the mapping tool. However, caution is advised because measurement results may change with T1 value, T2 value, and measurement scan parameters. (author)