scholarly journals Hemodynamic evaluation of patients with Moyamoya Angiopathy: comparison of resting-state fMRI to breath-hold fMRI and [15O]water PET

2021 ◽  
Author(s):  
Leonie Zerweck ◽  
Constantin Roder ◽  
Till-Karsten Hauser ◽  
Johannes Thurow ◽  
Annerose Mengel ◽  
...  
Keyword(s):  
Resting State ◽  
Resting State Fmri ◽  
Cerebrovascular Reactivity ◽  
Breath Hold ◽  
Data Sets ◽  
Moyamoya Angiopathy ◽  
Perfusion Reserve ◽  
Hemodynamic Evaluation ◽  
Patient Cooperation ◽  
High Level

Abstract Purpose Patients with Moyamoya Angiopathy (MMA) require hemodynamic evaluation to assess the risk of stroke. Assessment of cerebral blood flow with [15O]water PET and acetazolamide challenge is the diagnostic standard for the evaluation of the cerebral perfusion reserve (CPR). Estimation of the cerebrovascular reactivity (CVR) by use of breath-hold-triggered fMRI (bh-fMRI) as an index of CPR has been proposed as a reliable and more readily available approach. Recent findings suggest the use of resting-state fMRI (rs-fMRI) which requires minimum patient compliance. The aim of this study was to compare rs-fMRI to bh-fMRI and [15O]water PET in patients with MMA. Methods Patients with MMA underwent rs-fMRI and bh-fMRI in the same MRI session. Maps of the CVR gained by both modalities were compared retrospectively by calculating the correlation between the mean CVR of 12 volumes of interest. Additionally, the rs-maps of a subgroup of patients were compared to CPR-maps gained by [15O]water PET. Results The comparison of the rs-maps and the bh-maps of 24 patients revealed a good correlation (Pearson’s r = 0.71 ± 0.13; preoperative patients: Pearson’s r = 0.71 ± 0.17; postoperative patients: Pearson’s r = 0.71 ± 0.11). The comparison of 7 rs-fMRI data sets to the corresponding [15O]water PET data sets also revealed a high level of agreement (Pearson’s r = 0.80 ± 0.19). Conclusion The present analysis indicates that rs-fMRI might be a promising non-invasive method with almost no patient cooperation needed to evaluate the CVR. Further prospective studies are required.

scholarly journals A practical modification to a resting state fMRI protocol for improved characterization of cerebrovascular function

2021 ◽  
Author(s):  
Rachael C. Stickland ◽  
Kristina M. Zvolanek ◽  
Stefano Moia ◽  
Apoorva Ayyagari ◽  
César Caballero-Gaudes ◽  
...  
Keyword(s):  
Resting State ◽  
Incidental Finding ◽  
Pressure Change ◽  
Resting State Fmri ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Breath Hold ◽  
Bold Fmri ◽  
Cerebrovascular Function

ABSTRACTCerebrovascular reactivity (CVR), defined here as the Blood Oxygenation Level Dependent (BOLD) response to a CO2 pressure change, is a useful metric of cerebrovascular function. Both the amplitude and the timing (hemodynamic lag) of the CVR response can bring insight into the nature of a cerebrovascular pathology and aid in understanding noise confounds when using functional Magnetic Resonance Imaging (fMRI) to study neural activity. This research assessed a practical modification to a typical resting-state fMRI protocol, to improve the characterization of cerebrovascular function. In 9 healthy subjects, we modelled CVR and lag in three resting-state data segments, and in data segments which added a 2–3 minute breathing task to the start of a resting-state segment. Two different breathing tasks were used to induce fluctuations in arterial CO2 pressure: a breath-hold task to induce hypercapnia (CO2 increase) and a cued deep breathing task to induce hypocapnia (CO2 decrease). Our analysis produced voxel-wise estimates of the amplitude (CVR) and timing (lag) of the BOLD-fMRI response to CO2 by systematically shifting the CO2 regressor in time to optimize the model fit. This optimization inherently increases grey matter CVR values and fit statistics. The inclusion of a simple breathing task, compared to a resting-state scan only, increases the number of voxels in the brain that have a significant relationship between CO2 and BOLD-fMRI signals, and improves our confidence in the plausibility of voxel-wise CVR and hemodynamic lag estimates. We demonstrate the clinical utility and feasibility of this protocol in an incidental finding of Moyamoya disease, and explore the possibilities and challenges of using this protocol in younger populations. This hybrid protocol has direct applications for CVR mapping in both research and clinical settings and wider applications for fMRI denoising and interpretation.

High-level Integrative Networks: A Resting-state fMRI Investigation of Reading and Spelling

2019 ◽  
Vol 31 (7) ◽  
pp. 961-977 ◽  
Author(s):  
Gali Ellenblum ◽  
Jeremy J. Purcell ◽  
Xiaowei Song ◽  
Brenda Rapp
Keyword(s):  
Resting State ◽  
Resting State Fmri ◽  
Visual Word ◽  
Orthographic Processing ◽  
Word Form ◽  
Visual Word Form Area ◽  
Reference Networks ◽  
High Level ◽  
Reading And Spelling ◽  
Processing Networks

Orthographic processing skills (reading and spelling) are evolutionarily recent and mastered late in development, providing an opportunity to investigate how the properties of the neural networks supporting skills of this type compare to those supporting evolutionarily older, well-established “reference” networks. Although there has been extensive research using task-based fMRI to study the neural substrates of reading, there has been very little using resting-state fMRI to examine the properties of orthographic networks. In this investigation using resting-state fMRI, we compare the within-network and across-network coherence properties of reading and spelling networks directly to these properties of reference networks, and we also compare the network properties of the key node of the orthographic networks—the visual word form area—to those of the other nodes of the orthographic and reference networks. Consistent with previous results, we find that orthographic processing networks do not exhibit certain basic network coherence properties displayed by other networks. However, we identify novel distinctive properties of the orthographic processing networks and establish that the visual word form area has unusually high levels of connectivity with a broad range of brain areas. These characteristics form the basis of our proposal that orthographic networks represent a class of “high-level integrative networks” with distinctive properties that allow them to recruit and integrate multiple, lower level processes.

scholarly journals The Role of Cerebrovascular-Reactivity Mapping in Functional MRI: Calibrated fMRI and Resting-State fMRI

2021 ◽  
Vol 12 ◽  
Author(s):  
J. Jean Chen ◽  
Claudine J. Gauthier
Keyword(s):  
Functional Mri ◽  
Resting State ◽  
Resting State Fmri ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Resting State Functional Connectivity ◽  
Non Invasive ◽  
Oxygenation Level ◽  
Calibrated Fmri

Task and resting-state functional MRI (fMRI) is primarily based on the same blood-oxygenation level-dependent (BOLD) phenomenon that MRI-based cerebrovascular reactivity (CVR) mapping has most commonly relied upon. This technique is finding an ever-increasing role in neuroscience and clinical research as well as treatment planning. The estimation of CVR has unique applications in and associations with fMRI. In particular, CVR estimation is part of a family of techniques called calibrated BOLD fMRI, the purpose of which is to allow the mapping of cerebral oxidative metabolism (CMRO2) using a combination of BOLD and cerebral-blood flow (CBF) measurements. Moreover, CVR has recently been shown to be a major source of vascular bias in computing resting-state functional connectivity, in much the same way that it is used to neutralize the vascular contribution in calibrated fMRI. Furthermore, due to the obvious challenges in estimating CVR using gas challenges, a rapidly growing field of study is the estimation of CVR without any form of challenge, including the use of resting-state fMRI for that purpose. This review addresses all of these aspects in which CVR interacts with fMRI and the role of CVR in calibrated fMRI, provides an overview of the physiological biases and assumptions underlying hypercapnia-based CVR and calibrated fMRI, and provides a view into the future of non-invasive CVR measurement.

scholarly journals Effects of Thresholding on Voxel-Wise Correspondence of Breath-Hold and Resting-State Maps of Cerebrovascular Reactivity

2021 ◽  
Vol 15 ◽  
Author(s):  
Nooshin J. Fesharaki ◽  
Amy B. Mathew ◽  
Jedidiah R. Mathis ◽  
Wendy E. Huddleston ◽  
James L. Reuss ◽  
...  
Keyword(s):  
Gray Matter ◽  
Resting State ◽  
Surgical Planning ◽  
Cerebrovascular Reactivity ◽  
Breath Hold ◽  
Good Correspondence ◽  
Spatial Correspondence ◽  
Wide Range ◽  
Cortical Gray Matter ◽  
A Site

Functional magnetic resonance imaging for presurgical brain mapping enables neurosurgeons to identify viable tissue near a site of operable pathology which might be at risk of surgery-induced damage. However, focal brain pathology (e.g., tumors) may selectively disrupt neurovascular coupling while leaving the underlying neurons functionally intact. Such neurovascular uncoupling can result in false negatives on brain activation maps thereby compromising their use for surgical planning. One way to detect potential neurovascular uncoupling is to map cerebrovascular reactivity using either an active breath-hold challenge or a passive resting-state scan. The equivalence of these two methods has yet to be fully established, especially at a voxel level of resolution. To quantitatively compare breath-hold and resting-state maps of cerebrovascular reactivity, we first identified threshold settings that optimized coverage of gray matter while minimizing false responses in white matter. When so optimized, the resting-state metric had moderately better gray matter coverage and specificity. We then assessed the spatial correspondence between the two metrics within cortical gray matter, again, across a wide range of thresholds. Optimal spatial correspondence was strongly dependent on threshold settings which if improperly set tended to produce statistically biased maps. When optimized, the two CVR maps did have moderately good correspondence with each other (mean accuracy of 73.6%). Our results show that while the breath-hold and resting-state maps may appear qualitatively similar they are not quantitatively identical at a voxel level of resolution.

scholarly journals Case Series of Applications of Resting State Functional MRI in Brain Tumor Surgery: A Novel Technique

2022 ◽  
Author(s):  
Arpita Sahu ◽  
Vineeth Kurki ◽  
Antariksh Vijan ◽  
Amit Janu ◽  
Prakash Shetty ◽  
...  
Keyword(s):  
Resting State ◽  
Case Series ◽  
Critical Factor ◽  
Oncologic Outcome ◽  
Resting State Fmri ◽  
Extent Of Resection ◽  
Promising Tool ◽  
Preoperative Mapping ◽  
Clinical Scenarios ◽  
Patient Cooperation

Abstract Background The extent of resection for brain tumors is a critical factor in determining the oncologic outcome for a patient. However, a balance between preservation of neurological function and maximal resection is essential for true benefit.Functional magnetic resonance imaging (fMRI) is one of the approaches that augments the neurosurgeon's ability to attain maximal safe resection by providing preoperative mapping. It may not be possible to perform awake craniotomy with intraoperative localization by direct cortical stimulation in all patients, such as children and those with neurocognitive impairment. Task-based fMRI may have limited value in these cases due to low patient cooperability. Methods In this article we present in a case-based format, the various clinical scenarios where resting state fMRI (rs-fMRI) can be helpful in guiding neurosurgical resection. rs-fMRI of the patients has been acquired on Philips 1.5 T system. Seed voxel method has been used for processing and analysis. Conclusion rs-fMRI does not require active patient cooperation to generate useful information and thus can be a promising tool in patients unable to cooperate for task-based studies.

Resting-state fMRI used for intraoperative neuronavigation in children

2013 ◽  
Vol 44 (S 01) ◽  
Author(s):  
C Dorfer ◽  
T Czech ◽  
G Kasprian ◽  
A Azizi ◽  
J Furtner ◽  
...  
Keyword(s):  
Resting State ◽  
Resting State Fmri
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