Benefits and Pitfalls

The main benefit of mono-exponential T₂ mapping is its simplicity and straightforward implementation, making it a convenient and efficient method for T₂ fitting. Additionally, as mentioned previously, the use of multi-echo spin echo (MESE) sequences significantly reduces the acquisition time, further enhancing its practicality Fatemi et al., 2020Milford et al., 2015.

Despite these advantages, mono-exponential methods have certain drawbacks. First, by assuming a single T₂ relaxation constant per voxel, the mono-exponential method tends to over-simplify the tissue microstructure, potentially leading to inaccurate T₂ estimations. This limitation can be particularly problematic when studying tissues that have a complex microstructure, where a single voxel may contain components with different T₂ relaxation times. Furthermore, it has been shown that MESE sequences are sensitive to imperfections in the radiofrequency pulses. For instance, factors such as B₁ inhomogeneities and reduced flip angles have been shown to overestimate T₂ times when using mono-exponential methods Fatemi et al., 2020.