Quantification of BOLD fMRI parameters to infer cerebrovascular reactivity of the middle cerebral artery

Mazzetto-Betti, Kelley C.; Leoni, Renata Ferranti; Pontes-Neto, Octávio M.; Sturzbecher, Marcio J.; Santos, Antônio Carlos dos; Leite, João P.; Silva, Afonso C.; Araújo, Dráulio Barros de

doi:10.1002/jmri.23943

Cited by 2 publications

(2 citation statements)

References 20 publications

(30 reference statements)

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“…BOLD-fMRI signals provide real-time cerebral oxygen distribution under normal physiological conditions, based on local magnetic field properties resulting from a mismatch between local oxygen consumption caused by neuronal activity and increased CBF reactivity (85). BOLD signal has four parameters: onset time, time to peak, full width at half maximum (FWHM), and amplitude (86). The increase of local CBF causes a reduction in the local amount of deoxygenated hemoglobin generated by metabolism in response to neuronal activity, presenting signal enhancement (T2 and T2*) in related brain regions (100).…”

Section: Blood Oxygenation Level-dependent Functional Mrimentioning

confidence: 99%

Role of MRI-Based Functional Imaging in Improving the Therapeutic Index of Radiotherapy in Cancer Treatment

Zhang

Yang

2021

Front. Oncol.

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Advances in radiation technology, such as intensity-modulated radiation therapy (IMRT), have largely enabled a biological dose escalation of the target volume (TV) and reduce the dose to adjacent tissues or organs at risk (OARs). However, the risk of radiation-induced injury increases as more radiation dose utilized during radiation therapy (RT), which predominantly limits further increases in TV dose distribution and reduces the local control rate. Thus, the accurate target delineation is crucial. Recently, technological improvements for precise target delineation have obtained more attention in the field of RT. The addition of functional imaging to RT can provide a more accurate anatomy of the tumor and normal tissues (such as location and size), along with biological information that aids to optimize the therapeutic index (TI) of RT. In this review, we discuss the application of some common MRI-based functional imaging techniques in clinical practice. In addition, we summarize the main challenges and prospects of these imaging technologies, expecting more inspiring developments and more productive research paths in the near future.

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Section: Blood Oxygenation Level-dependent Functional Mrimentioning

confidence: 99%

Role of MRI-Based Functional Imaging in Improving the Therapeutic Index of Radiotherapy in Cancer Treatment

Zhang

Yang

2021

Front. Oncol.

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“…• Pode-se obter outros fatores de importância vascular, como por exemplo o tempo do início de resposta, duração e amplitude (MAZZETTO-BETTI et al, 2013).…”

Section: Ressonância Magnética De Marcação Do Sangue Arterialunclassified

Mapeamento da vasorreatividade cerebral sem estímulo vasoativo: um estudo de imagens em estado de repouso

Secchinato¹

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Cerebrovascular reactivity (CVR) represents the ability of the vascular smooth muscle to dilate or contract in response to changes in metabolic demand changes or vasoactive stimuli to regulate cerebral blood flow when necessary. This response can be affected in several neurological diseases, mainly cerebrovascular diseases, both in magnitude and in time delay. The latter is observed as a temporal shift (TS) of the response. Such measures are valuable to report the hemodynamic state of the brain and are of interest in several studies trying to predict the risk of stroke, such as in patients with carotid artery stenosis. However, standard methods require specific conditions, such as administering acetazolamide or inhalation of CO 2 while magnetic resonance images (MRI) are acquired. In the present study, we evaluated CVR and TS from fluctuations in the MRI signal based on the blood oxygenation-dependent contrast (BOLD) at rest, without performing hypercapnia challenges. In the first part of the study, we identified an adequate frequency range for temporal filtering of the resting-state signal to obtain CVR maps, based on the spatial correlation with standard CVR maps obtained with CO 2 inhalation and breath-holding. Five patients with unilateral severe asymptomatic carotid stenosis (70 ± 3 years) and five controls (65 ± 3 years) performed the experiment with CO 2 inhalation, and 23 healthy elderly (67 ± 6 years) performed the experiment with breath-holding. CVR maps obtained through the general linear regression model showed a more significant spatial correlation when using the regressor of the global signal filtered at 0.02 to 0.04 Hz when compared with reference maps. Thus, this frequency band was used for the second part of the study, in which we evaluated CVR and TS in 20 patients with unilateral severe asymptomatic carotid stenosis (12 women; 8 men; mean age = 67 ± 10 years) comparing with a group of healthy control (8 women; 12 men; mean age = 68 ± seven years). In patients, reduced CVR values were observed bilaterally in regions irrigated by the intermediary portion of the anterior cerebral artery (ACA) when compared to the proximal portion and for the proximal, middle cerebral artery (MCA) when compared to the distal (p < 0.05). TS values were higher in patients in the three portions of the MCA territory and the distal portion of the posterior cerebral artery (PCA) territory, in the hemisphere ipsilateral to the stenosis, when compared to the corresponding regions of the control group (p < 0.04 ). In addition, in patients, TS was higher in the distal MCA ipsilateral to the stenosis compared to the same region in the contralateral hemisphere (p = 0.0025). Similar regional changes in CVR and TS were observed when visually analyzing individual maps suggesting that the methodologies are complementary. These parameters may reflect subclinical hemodynamic changes and help investigate areas with a higher risk of neuronal damage or ischemic stroke at an individual level. Therefore, the study of cerebral hemodynamic...

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Quantification of BOLD fMRI parameters to infer cerebrovascular reactivity of the middle cerebral artery

Cited by 2 publications

References 20 publications

Role of MRI-Based Functional Imaging in Improving the Therapeutic Index of Radiotherapy in Cancer Treatment

Role of MRI-Based Functional Imaging in Improving the Therapeutic Index of Radiotherapy in Cancer Treatment

Mapeamento da vasorreatividade cerebral sem estímulo vasoativo: um estudo de imagens em estado de repouso

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