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Neuroimaging in the Evaluation of Neurogenic Bladder Dysfunction
Published in Jacques Corcos, Gilles Karsenty, Thomas Kessler, David Ginsberg, Essentials of the Adult Neurogenic Bladder, 2020
However, despite these achievements, the use of neuroimaging in the evaluation of neurogenic bladder dysfunction is still in its infancy, and there are still many lessons to be learned. Results often originate from rather small group sizes (n < 20) and are presented on low significance levels (e.g., p ≤ 0.05 uncorrected). There is a large heterogeneity of applied methodology/protocols, analysis, and outcome reporting that hamper a reasonable comparison of studies. Study conclusions often remain vague and do not progress to the level of explaining the meaning of the findings in the pathophysiologic context of the investigated LUTD. Currently, functional neuroimaging is a pure research tool without clear or significant clinical implications, which is also due to the fact that results are not conclusive on a single subject level. Due to the rather limited reliability of BOLD-MRI and the large number of confounding factors, evaluation of treatment effects should be interpreted with great caution.
Biomedical Imaging Magnetic Resonance Imaging
Published in Lawrence S. Chan, William C. Tang, Engineering-Medicine, 2019
MRI is useful for imaging not only anatomy, but also functions. In neurofunctional imaging, BOLD contrast is a primary contrast mechanism based on which the vast majority of functional MRI (fMRI) studies have been performed. When neurons are activated, the increased need for oxygen is overcompensated by a larger increase in delivery of oxygenated blood supply. As a result, the venous oxyhemoglobin concentration increases and the deoxyhemoglobin concentration decreases. Because oxyhemoglobin is diamagnetic while deoxyhemoglobin paramagnetic, the T2* value in the activated areas increases, resulting in an elevated MRI signal intensity in a -weighted image (Ogawa et al. 1990). Conversely, when there is no neuronal activation, a lower signal intensity is expected. This alternating signal pattern can be correlated to the task-on and task-off states according to a pre-designed paradigm for investigating a specific neurocognitive function (Kwong et al. 1992).
Physical Principles of BOLD fMRI—What Is Important for the Clinician
Published in Andrei I. Holodny, Functional Neuroimaging, 2019
The main idea behind BOLD fMRI is that when there is an increase in neuronal activity in a part of the brain, that part will show a change in signal intensity that can be detected by MRI. Neuronal activity is associated with many complex physiological processes in which metabolic byproducts, cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral metabolic rate of oxygen (CMRO2), and blood oxygenation all combine to create the BOLD effect in fMRI.
Altered resting-state cerebellar-cerebral functional connectivity in patients with end-stage renal disease
Published in Renal Failure, 2023
Jie Fang, Yingying Miao, Fan Zou, Yarui Liu, Jiangle Zuo, Xiangming Qi, Haibao Wang
Resting-state fMRI is a method that indirectly infers information about brain activity by measuring Blood-Oxygen-Level Dependent (BOLD) signal. The temporal correlations of BOLD signals in different brain regions can be used to reflect brain FC [30]. The abnormalities in resting-state fMRI connectivity reflect alterations in the interactions among different brain regions [31]. Considering that DMN, ECN, ALN, and SMN are abnormal in ESRD, and that cerebellar sub-regions can identify the cerebellar-cerebral DMN, ECN, ALN, and SMN, we hypothesized that the cerebellum-cerebral FC is abnormal and related to cognitive impairment in ESRD patients. Therefore, the present study aimed to explore whether the cerebellar-cerebral FC is altered in ESRD patients with cerebellar sub-regions as seeds using resting-state fMRI, and further investigate the relationship between the altered FC, neuropsychological function, and clinical parameters in patients with ESRD.
Focal cortical dysplasia: an update on diagnosis and treatment
Published in Expert Review of Neurotherapeutics, 2021
With the introduction of higher field strengths, high-sensitivity, and high-resolution techniques such as T2*- and BOLD-based imaging have become routine [98] (Figure 4). The application of 3 T imaging has increased the detection rate of structural abnormalities in about 5% of previously MRI-negative cases at lower field strength [14,96]. Ultra-high-field imaging (UHF) at 7 T has an added value compared to 1.5 and/or 3 T in patients with epilepsy [99]. In an initial study [100], FCD could be demonstrated in up to one-third of patients with refractory focal epilepsy and unrevealing conventional MRI, with the best diagnostic gain deriving from GRE and FLAIR images. The added diagnostic yield of 7 T MRI in detecting subtle FCD has been confirmed in further studies [15,101–103].
Transcranial magnetic stimulation and neuroimaging for cocaine use disorder: Review and future directions
Published in The American Journal of Drug and Alcohol Abuse, 2021
Yong Shen, Heather Burrell Ward
Probing the brain circuitry involved in cocaine addiction further, Hanlon et al. (54) used an interleaved TMS/fMRI methodology to subject cocaine users and matched controls to external neurostimulation and then subsequently quantify frontal-striatal functional connectivity. Twenty non-treatment seeking cocaine users and 20 non-drug using controls were recruited. All of the cocaine users met DSM-IV criteria for cocaine dependence, had a positive urine drug screen for cocaine (indicating use within ~72 h), and did not meet criteria for dependence on any other class of drugs. Participants received two interleaved TMS-BOLD imaging runs to the (1) DLPFC and (2) medial prefrontal cortex (MPFC). The order was randomized. During each run, a series of 12 single pulses of TMS were applied to either the MPFC or the DLPFC, with a 12 s interpulse interval. Two interleaved TMS-BOLD imaging runs were given to each subject. The group discovered that cocaine users exhibited a lower ventral striatal BOLD response to MPFC/frontal pole stimulation after stimulation with TMS. The dorsal striatal BOLD response profiles in cocaine users and controls are similar. In addition, the reciprocal relationship between DLPFC stimulation and MPFC attenuation observed in controls is disrupted in cocaine users.