Simple and Easy-to-use Graphical User Interface (GUI) for Accurate and Stable Mapping of T₂ Relaxation Values

Background: T₂ contrast is used for a wide range of non-invasive diagnosis and characterization of pathologies. Traditionally, MRI produces qualitative image-contrast, which varies between scanners, scan-settings, and subjected to reader bias. Quantitative evaluation of T₂, on the other hand, offers a more accurate characterization of the tissue. Reliable assessment of T₂, however, is challenging due to the inherent deviation of multi spin-echo (MSE) protocols from the theoretical exponential model S(t)=S₀exp[–t/T₂] as a result of stimulated and indirect echoes, non-rectangular slice profiles, and inhomogeneous transmit (B₁⁺) field profiles. We recently presented a new method- the Echo Modulation Curve (EMC) algorithm, which has been shown to deliver the true T₂ value of the tissue – closely matching values obtained using reference single spin-echo acquisitions. We present also a software for producing quantitative T₂ maps based on rapid MSE data using intuitive and easy-to-use GUI.

Methods: Data were collected for single subject using six different MSE parameter sets, and for a group of 37 healthy volunteers using a single parameter set. T₂ maps were reconstructed using the EMC algorithm and using conventional mono-exponential model. Mean, standard deviation (SD), and coefficient of variation (CV) were calculated for 5 brain ROIs.

Results and conclusions: (1) Statistically acceptable repeatability (CV <5%) in all brain regions. (2) Improved results due to the use of accurate spin dynamics model. (3) High stability across different scanners and scan settings. (4) The GUI provides easy platform for generating T2 and PD maps as well as EMC tailored databases. (5) Basic post-processing is available via integrated statistical analysis of manually defined ROIs.