The Significance of Echo Time in fMRI BOLD Contrast: A Clinical Study during Motor and Visual Activation Tasks at 1.5 T
Themistoklis Boursianis,
Georgios Kalaitzakis,
Katerina Nikiforaki,
Emmanouela Kosteletou,
Despina Antypa,
George A. Gourzoulidis,
Apostolos Karantanas,
Efrosini Papadaki,
Panagiotis Simos,
Thomas G. Maris,
Kostas Marias
Affiliations
Themistoklis Boursianis
Department of Medical Physics, School of Medicine, University of Crete, 71003 Heraklion, Greece
Georgios Kalaitzakis
Department of Medical Physics, School of Medicine, University of Crete, 71003 Heraklion, Greece
Katerina Nikiforaki
Computational Biomedicine Laboratory (CBML), Institute of Computer Science, Foundation for Research and Technology—Hellas (FORTH), 70013 Heraklion, Greece
Emmanouela Kosteletou
Institute of Applied Mathematics, FORTH, 70013 Heraklion, Greece
Despina Antypa
Department of Psychiatry, School of Medicine, University of Crete, 71003 Heraklion, Greece
George A. Gourzoulidis
Research & Measurements Center of OHS Hazardous Agents, OHS Directorate, Hellenic Ministry of Labor, 10110 Athens, Greece
Apostolos Karantanas
Computational Biomedicine Laboratory (CBML), Institute of Computer Science, Foundation for Research and Technology—Hellas (FORTH), 70013 Heraklion, Greece
Efrosini Papadaki
Computational Biomedicine Laboratory (CBML), Institute of Computer Science, Foundation for Research and Technology—Hellas (FORTH), 70013 Heraklion, Greece
Panagiotis Simos
Computational Biomedicine Laboratory (CBML), Institute of Computer Science, Foundation for Research and Technology—Hellas (FORTH), 70013 Heraklion, Greece
Thomas G. Maris
Department of Medical Physics, School of Medicine, University of Crete, 71003 Heraklion, Greece
Kostas Marias
Computational Biomedicine Laboratory (CBML), Institute of Computer Science, Foundation for Research and Technology—Hellas (FORTH), 70013 Heraklion, Greece
Blood Oxygen Level Dependent (BOLD) is a commonly-used MR imaging technique in studying brain function. The BOLD signal can be strongly affected by specific sequence parameters, especially in small field strengths. Previous small-scale studies have investigated the effect of TE on BOLD contrast. This study evaluates the dependence of fMRI results on echo time (TE) during concurrent activation of the visual and motor cortex at 1.5 T in a larger sample of 21 healthy volunteers. The experiment was repeated using two different TE values (50 and 70 ms) in counterbalanced order. Furthermore, T2* measurements of the gray matter were performed. Results indicated that both peak beta value and number of voxels were significantly higher using TE = 70 than TE = 50 ms in primary motor, primary somatosensory and supplementary motor cortices (p p < 0.001). Gray matter T2* of the corresponding areas did not vary significantly. In conclusion, the optimal TE value (among the two studied) for visual and motor activity is 70 ms affecting both the amplitude and extent of regional hemodynamic activation.
