TRADITIONAL POSTER - ismrm

Poster Sessions
1213. Further Test and Validation of Saturation-Recovery T1 MRI Measurement for Imaging Absolute CBF
Change
Xiao Wang 1 , Xiao-hong Zhu 1 , Yi Zhang 1 , Wei Chen 1
1 Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, United States
The feasibility of saturation-recovery T1 MRI for imaging and quantifying absolute CBF change was further tested at 9.4T using a rat hypercapnia model on
two aspects: using diffusion gradients to investigate macrovascular inflow contribution; and slab saturation with varied thickness to test the effects of blood
transit distance on measuring CBF. The results indicate that the outcomes of CBF changes induced by hypercapnia were coincident with the literature
reports, and not significantly affected by large-vessel inflow effect and blood transit time. The overall results demonstrate that the saturation-recovery T1
MRI is sensitive to microvascular perfusion; it provides a noninvasive and reliable imaging approach for studying cerebral perfusion changes induced by
physiology or pathology perturbation.
1214. In Vivo MR Measurement of Arterial Pulse Pressure in the Murine Aorta
Volker Herold 1 , Marco Parczyk 1 , Wolfgang Rudolf Bauer 2 , Eberhard Rommel 1 , Peter Michael Jakob 1
1 Department of Physics EP5, University of Wuerzburg, Wuerzburg, Bayern, Germany; 2 Medizinische Universitätsklinik, University of
Wuerzburg, Wuerzburg, Bayern, Germany
Mouse models are increasingly used to investigate functional and cardiovascular parameters. In this work we present an approach to noninvasively estimate
the arterial pulse pressure by measuring the time dependant blood flow pulse and the local pulse wave velocity. By determining the complex impedance
with solutions from the Navier-Stokes equations for incompressible fluids, the pressure pulse could be calculated from the accordant flow pulse. The present
results are in good agreement with results from the literature obtained by invasive methods.
1215. Problems for Motion Correction: Paradigm Correlated Motion Remains a Confounding Source for
FMRI Artefacts.
Lubos Budinsky 1 , Benito de Celis Alonso 2 , Marina Sergejeva 1 , Andreas Hess 2
1 Institute of Pharmacology, FAU, Erlangen, Germany; 2 Institute of Pharmacology, FAU, Erlangen, Germany
The undesired motion, which is correlated with the fMRI paradigm (often present in experiments which are using mechanical stimulation or painful
stimulus) can create false areas of an activity, which could remain real BOLD activity areas and a signal time course. Here we present series of fMRI
experiment with phantoms and dead animals to which the motion was induced by using an air driven device integrated into the animal cradle. Using results
from these experiments we suggest strategy, how to deal with this problem even if conventional motion correction algorithm are not able to remove these
false areas completely.
1216. Functional MRI in the Rat at 9.4 T and 16.4 T
David Zsolt Balla 1 , Hannes M. Wiesner 1 , Gunamony Shajan 1 , Rolf Pohmann 1
1 High Field Magnetic Resonance Center, Max Planck Insitute for Biological Cybernetics, Tübingen, Baden-Württemberg, Germany
Functional MRI (fMRI) in animals at high magnetic fields keeps expanding our knowledge about the basics of neural processing but the specificity of the
fMRI-signal is still under ongoing investigation. Yet, as the signal to noise ratio in MRI depends linearly on the magnetic field strength and calls for even
stronger magnets for the detection of even smaller anatomical details, the relation between the functional MR-response and field strength can only be
approximated with complex models. In this study the blood oxygenation dependent (BOLD) effect was measured and compared at 9.4 T and 16.4 T in the
same animal with segmented gradient-echo (GE) and spin-echo (SE) echo planar imaging (EPI) sequence using optimal echo times for the respective field.
Furthermore, high resolution fMRI acquisition at 16.4 T was performed up to a 50 µm in-plane accuracy and for an 8 s temporal resolution without the use
of cryo-coils or coil-arrays.
1217. BOLD, CBV, and CBF FMRI of Caudate Putamen in Rat Brain During Noxious Electrical
Stimulation: Its Negative Hemodynamic Response to Neural Activities
Fuqiang Zhao 1 , Denise Welsh 1 , Mangay Williams 1 , Alexandre Coimbra 1 , Mark O. Urban 2 , Richard
Hargreaves 2 , Jeffrey Evelhoch 1 , Donald S. Williams 1
1 Imaging Department, Merck Research Laboratories, West Point, PA, United States; 2 Neuroscience Department, Merck Research
Laboratories, West Point, PA, United States
In central nervous system, neuronal activity generally leads to increases in local venous blood oxygenation level (BOLD), cerebral blood flow (CBF), and
cerebral blood volume (CBV). However, previous studies have reported that the neural activity in rat caudate putamen (CPu) during noxious electrical
stimulation (NES) of paws causes BOLD and CBV decreases. To further understand the specific hemodynamic response in this anatomical structure and its
temporal characteristics, BOLD, CBV, and CBF fMRI studies were performed in a rat brain slice containing the CPu. Our results suggest that the neural
activity in the CPu during NES causes decreases in CBV and CBF, and an increase in CMRO2 which lasts >2 minutes after stopping the NES.
1218. fMRI at 17.6 T and Optical Fiber-Based Ca2+-Imaging in Rodents
Albrecht Stroh 1 , Florian Schmid 2 , Afra Wohlschlaeger 3 , Valentin Riedl 4 , Jenny Kressel 3 , Cornelius Faber 2
1 Department of Neuroradiology, Technical University Munich, Munich, Germany; 2 Institute for Clinical Radiology, University
Hospital Münster, Münster, Germany; 3 Department of Neuroradiology, Technical University Munich, Germany; 4 Department of
Neurology, Technical University Munich, Germany
n this study we tested the feasibility of rat fMRI at highest field strength in combination with an implanted optical fiber. We aim for the combination of fiber
based optical Ca2+ imaging with functional magnetic resonance imaging (fMRI) at 17.6 T in vivo. We increased the temporal resolution of fMRI to 20 ms
by applying k-space segmentation. Additionally, we conducted fiber-based Ca2+ imaging in mice upon electric forepaw stimulation, detecting neuronal
population activity. Our study indicates that a multimodal approach combining a global method like fMRI with a spatially confined, highly specific method
as optical Ca2+ imaging becomes amenable.