Numerical simulation of the blood oxygenation level–dependent functional magnetic resonance signal using finite element method

2019 ◽  
Vol 36 (2) ◽  
Author(s):  
Fabio Mangini ◽  
Mauro DiNuzzo ◽  
Laura Maugeri ◽  
Marta Moraschi ◽  
Daniele Mascali ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Magnetic Resonance Signal ◽  
Functional Magnetic Resonance ◽  
Resonance Signal ◽  
Blood Oxygenation Level ◽  
Oxygenation Level

Attenuated Brain Response to Auditory Word Stimulation with Sevoflurane

2005 ◽  
Vol 103 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Chantal Kerssens ◽  
Stephan Hamann ◽  
Scott Peltier ◽  
Xiaoping P. Hu ◽  
Michael G. Byas-Smith ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Occipital Cortex ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Brain Response ◽  
Auditory Word ◽  
Blood Oxygenation Level ◽  
Oxygenation Level

Background Functional magnetic resonance imaging offers a compelling, new perspective on altered brain function but is sparsely used in studies of anesthetic effect. To examine effects on verbal memory encoding, the authors imaged human brain response to auditory word stimulation using functional magnetic resonance imaging at different concentrations of an agent not previously studied, and tested memory after recovery. Methods Six male volunteers were studied breathing 0.0, 2.0, and 1.0% end-tidal sevoflurane (awake, deep, and light states, respectively) via laryngeal mask. In each condition, they heard 15 two-syllable English nouns via closed headphones. Each word was repeated 15 times (1/s), followed by 15 s of rest. Blood oxygenation level-dependent brain activations during blocks of stimulation versus rest were assessed with a 3-T Siemens Trio scanner and a 20-voxel spatial extent threshold. Memory was tested approximately 1.5 h after recovery with an auditory recognition task (chance performance = 33% correct). Results Scans showed widespread activations (P < 0.005, uncorrected) in the awake state, including bilateral superior temporal, frontal, and parietal cortex, right occipital cortex, bilateral thalamus, striatum, hippocampus, and cerebellum; more limited activations in the light state (bilateral superior temporal gyrus, right thalamus, bilateral parietal cortex, left frontal cortex, and right occipital cortex); and no significant auditory-related activation in the deep state. During recognition testing, subjects correctly selected 77 +/- 12% of words presented while they were awake as "old," versus 32 +/- 15 and 42 +/- 8% (P < 0.01) correct for the light and deep stages, respectively. Conclusions Sevoflurane induces dose-dependent suppression of auditory blood oxygenation level-dependent signals, which likely limits the ability of words to be processed during anesthesia and compromises memory.

scholarly journals Measuring vascular reactivity with resting-state blood oxygenation level-dependent (BOLD) signal fluctuations: A potential alternative to the breath-holding challenge?

2016 ◽  
Vol 37 (7) ◽  
pp. 2526-2538 ◽  
Author(s):  
Hesamoddin Jahanian ◽  
Thomas Christen ◽  
Michael E Moseley ◽  
Nicholas M Pajewski ◽  
Clinton B Wright ◽  
...  
Keyword(s):  
Functional Magnetic Resonance Imaging ◽  
Resting State ◽  
Vascular Reactivity ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Breath Holding ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Blood Oxygenation Level ◽  
Oxygenation Level

Measurement of the ability of blood vessels to dilate and constrict, known as vascular reactivity, is often performed with breath-holding tasks that transiently raise arterial blood carbon dioxide (PaCO2) levels. However, following the proper commands for a breath-holding experiment may be difficult or impossible for many patients. In this study, we evaluated two approaches for obtaining vascular reactivity information using blood oxygenation level-dependent signal fluctuations obtained from resting-state functional magnetic resonance imaging data: physiological fluctuation regression and coefficient of variation of the resting-state functional magnetic resonance imaging signal. We studied a cohort of 28 older adults (69 ± 7 years) and found that six of them (21%) could not perform the breath-holding protocol, based on an objective comparison with an idealized respiratory waveform. In the subjects that could comply, we found a strong linear correlation between data extracted from spontaneous resting-state functional magnetic resonance imaging signal fluctuations and the blood oxygenation level-dependent percentage signal change during breath-holding challenge ( R2 = 0.57 and 0.61 for resting-state physiological fluctuation regression and resting-state coefficient of variation methods, respectively). This technique may eliminate the need for subject cooperation, thus allowing the evaluation of vascular reactivity in a wider range of clinical and research conditions in which it may otherwise be impractical.

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