Hu Cheng1, John Kirsch2, Rebecca Ward1, Thea Atwood1, Arian Ashourvan1, Yang Wang3
1Indiana University, Bloomington, IN, United States; 2Siemens Medical Solutions, United States; 3Indiana University, Indianapolis, IN, United States
Temporal characteristics of the noise in multi-run fMRI scans using GRAPPA are examined with a gel phantom for acceleration factors 2-4 and various number of ACS lines. It is demonstrated that the noise distribution can change significantly from run to run. However, little change is observed from the offline reconstruction if the same reference scans are used. The results indicate that the variation is mainly caused by the noise fluctuation in the reference scans.