Barbara Dymerska1, Pedro Cardoso1, Nina Mahr2, Eva Matt2, Florian Fischmeister2, Roland Beisteiner2, Siegfried Trattnig1, and Simon Daniel Robinson1
1High Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria, 2High Field MR Centre, Department of Neurology, Medical University of Vienna, Vienna, Austria
Temporal signal fluctuations (tSNR) and local effective echo time (TElocal) are explored and their influence on BOLD sensitivity is investigated at 7T for healthy subjects and tumor patients, where prominent spatial variations in those two measures are expected. We show that tSNR may indicate sufficient sensitivity to detect activation but that BOLD sensitivity may be dramatically reduced by changes in TElocal close to pathologies and vital brain functions (motor, speech, auditory). Neglecting local TE variations can thus lead to false negative results in clinical fMRI. We thus suggest a new BOLD sensitivity metric based on TElocal∙tSNR.