کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10712415 | 1025184 | 2016 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Multi-contrast T2â-relaxometry upon visual stimulation at 3Â T and 7Â T
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موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
فیزیک ماده چگال
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Multi-contrast T2â-relaxometry upon visual stimulation at 3Â T and 7Â T Multi-contrast T2â-relaxometry upon visual stimulation at 3Â T and 7Â T](/preview/png/10712415.png)
چکیده انگلیسی
This study aims to quantify the mean change of the effective transverse relaxation time T2â in active brain regions of human volunteers at field strengths of B0 = 3 T and 7 T. Besides the mono-exponential signal decay model an extended model is tested that considers mesoscopic field gradients across imaging voxels. Both models are checked for cross-talk and correlations between the parameters. A visual checkerboard-stimulation experiment with pause and stimulation periods of 50 s and six repetitions was performed on healthy volunteers. Eleven contrasts were acquired in about 1.47 s/1.43 s at 3 T/7 T using a segmented multi-contrast echo-planar imaging (EPI) sequence. Average BOLD-signal time courses were calculated in a multi-step (non-)linear least-squares process. Baseline T2â values of 37.72 ms/24.99 ms (47.34 ms/33.71 ms) with stimulus-correlated changes â T2â of 1.32 ms/0.74 ms (1.99 ms/1.43 ms) resulted from the mono-exponential (extended) model for 3 T/7 T. A dependence of those values on the initial intensity S0 was observed. Stimulus-correlated changes of S0 in the order of 1% were measured at both field strengths. The mono-exponential model was found to be less prone to instabilities in the regression of both parameters. Signal alterations due to inflow were observed. Measured relaxation times agree with values from literature using repetitive stimulation. A strong dependence of the measured relaxation times on the inflow-related model parameter was found for both models. The extended model is applicable to dynamic neurofunctional measurements, but is currently limited due to the low number of contrasts acquired.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Magnetic Resonance Imaging - Volume 34, Issue 7, September 2016, Pages 864-874
Journal: Magnetic Resonance Imaging - Volume 34, Issue 7, September 2016, Pages 864-874
نویسندگان
Moritz C. Berger, Peter Bachert, Jens Gröbner, Armin M. Nagel,