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Combined blood oxygenation level-dependent (BOLD) and arterial spin labeling (ASL) functional MRI (fMRI) was performed for simultaneous investigation of neurovascular coupling in the primary visual cortex (PVC), primary motor cortex (PMC), and supplementary motor area (SMA). The hypercapnia-calibrated method was employed to estimate the fractional change in(More)
The change in cerebral rate of oxidative metabolism (CMR(O(2))) during neural activation may be estimated from blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) and arterial spin-labeling (ASL) fMRI measurements. The established method relies on an epoch of iso-metabolic blood flow increase, typically induced by CO2(More)
Cerebrospinal fluid (CSF) provides hydraulic suspension for the brain. The general concept of bulk CSF production, circulation, and reabsorption is well established, but the mechanisms of momentary CSF volume variation corresponding to vasoreactive changes are far less understood. Nine individuals were studied in a 3T MR scanner with a protocol that(More)
OBJECT The goal of this study was to examine the relationship between cerebral autoregulation, intracranial pressure (ICP), arterial blood pressure (ABP), and cerebral perfusion pressure (CPP) after head injury by using transcranial Doppler (TCD) ultrasonography. METHODS Using ICP monitoring and TCD ultrasonography, the authors previously investigated(More)
OBJECTIVES Cerebral haemodynamic responses to short and longlasting episodes of decreased cerebral perfusion pressure contain information about the state of autoregulation of cerebral blood flow. Mathematical simulation may help to elucidate which of the indices, that can be derived using transcranial Doppler ultrasonography and trends of intracranial(More)
OBJECT Plateau waves of intracranial pressure (ICP) are often recorded during intensive care monitoring of severely head injured patients. They are traditionally interpreted as meaningful secondary brain insults because of the dramatic decrease in cerebral perfusion pressure (CPP). The aim of this study was to investigate both the hemodynamic profile and(More)
OBJECT The aim of the study was to assess how cerebrospinal fluid (CSF) pressure-volume compensation depends on cerebrovascular tone. METHODS In 26 New Zealand White rabbits, intracranial pressure (ICP), arterial blood pressure, and basilar artery blood flow velocity were measured continuously. Saline was infused into the cranial subarachnoid space to(More)
Changes in cerebral blood flow (f) and vascular volume (v) are of major interest in mapping cerebral activity and metabolism, but the relation between them currently lacks a sufficient theoretical basis. To address this we considered three models: a uniform reactive tube model (M1); an extension of M1 that includes passive arterial inflow and venous volume(More)
OBJECTIVE To evaluate if impaired wakefulness (IW) in normal pressure hydrocephalus (NPH) is associated with reduced blood flow in regions associated with the brain arousal system. METHOD NPH (n = 28) patients were studied before and after surgery. Wakefulness was assessed using a new developed scale. Relative regional cerebral blood flow (rrCBF) was(More)
OBJECTIVE The direct calculation of cerebral perfusion pressure (CPP) as the difference between mean arterial pressure and intracranial pressure (ICP) produces a number which does not always adequately describe conditions for brain perfusion. A non-invasive method of CPP measurement has previously been reported based on waveform analysis of blood flow(More)