Multixeponential T2 Relaxation Analysis of Multislice MR Images in a Stroke Model
Tomanek A, Foniok T, Tuor U, Burda K, Barber P, McCreary C, Dunn J, Qiao M, Tomanek B, Nguyen A
University of Calgary
A multiexponential analysis of T2 relaxation times within brain injured by hypoxia-ischemia was investigated. T2 maps were acquired using a 128-echo multi-slice spin echo sequence using either Gauss or sinc selective 90 and 180 pulses 48 hours after a transient episode of cerebral hypoxia-ischemia. A least squares multiexponential method was used to fit the T2 decay curve. As expected following stroke, there was an increase in T2 in the ischemic region irrespective of MR sequence used. Control parietal cortex was best described by a monoexponential and ischemic cortex by a biexponential T2 when Gauss selective pulses were used. In contrast, with sinc pulses both control and parietal cortex had mono-exponential T2 characteristics. For both Gauss and sinc pulses, in regions that included CSF bi-exponential T2 fits with a long and regular component were optimal. It appears that imperfections of the Gauss selective pulse can contribute to the bi-exponential character of T2 in regions such as stroke.