An interventional study of Functional MRI and FDG-PET in Glioblastoma, Glioma and Astrocytoma, sponsored by Erasme University Hospital. Recruiting at 1 site in Belgium. Open to participants aged 18 Years to 90 Years. Per ClinicalTrials.gov, last updated 2026-09-14.
Sponsored by Erasme University Hospital · Not applicable, Interventional, and Basic science
Neurovascular uncoupling (NVU) represents a major source of potential bias for the identification of eloquent brain regions through activation procedures in blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI).
Same region shows proper pattern in glucose metabolism in victiny of brain lesions, investigated with positron emitted tomography with radiolabeled glucose (PET-FDG) This research project aims at investigating the mechanisms of NVU by using a multimodal noninvasive imaging approach in neurosurgical patients.
Brain metabolism and blood flow are tightly coupled with neuronal activity. Changes in neuronal activity result in the modulation of glucose consumption by neurons. Both glucose and lactate levels return to their baseline instantly as neuronal activity ceases, a phenomenon known as neurometabolic coupling. Given the limited energetic reserves in the central nervous system, neuronal activity heavily relies on the finely regulated supply of glucose from the bloodstream. However, the dynamic increase in cerebral blood flow (CBF) during neuronal activation far exceeds the increase in oxidative metabolism. This relative hyperemic response ensures an increased oxygen gradient between blood vessels and tissue, providing ample oxygen supply. The close temporal and regional link between changes in neuronal activity and CBF increase is referred to as neurovascular coupling (NVC) and involves a complex cascade of events. Neurotransmitters, such as glutamate, released at synapses bind to receptors on neurons and astrocytes, leading to the release of various chemical mediators, like nitric oxide and prostaglandins, which directly act on arterial smooth muscle tone. More complex and incompletely understood signaling pathways, including Na+ and Ca2+-mediated astrocyte signaling mechanisms, are also presumed to contribute to NVC.
The tight relationship between neuronal activity and both regional blood flow and metabolism has provided the basis for non-invasive functional brain imaging methods, including positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). PET using [18Fluor ]-fluorodeoxyglucose (FDG) is a technique based on the accumulation of metabolized FDG (i.e., FDG-6-phosphate) in the astrocyte-neuron complex, reflecting the level of glucose consumption. Since the seminal works of Sokoloff et al., glucose utilization is considered a valid, accurate, and quantitative indicator of the level of local neuronal activity within the brain. In contrast, fMRI, which relies on the blood oxygen level-dependent (BOLD) signal, provides indirect information about neuronal activity by investigating perfusion-related changes coupled with neuronal activity. In areas of increased CBF due to modulations in neuronal activity, oxygen delivery exceeds the rate of oxygen utilization, inducing a local increase in the oxy-/deoxy-hemoglobin ratio. This leads to a detectable increase in the magnetic-susceptibility weighted MRI signal.
One of the earliest and still recognized clinical applications of fMRI has been preoperative functional mapping of the primary sensorimotor cortex in patients with brain tumors. This technique has significantly impacted surgical planning, often enabling more aggressive approaches than those considered without functional localization. fMRI has also been increasingly used in the presurgical evaluation of patients with vascular or epileptogenic lesions. However, despite the growing use of BOLD fMRI in patients with brain lesions, this technique has major limitations that must be considered when interpreting fMRI results in such populations. The main limitation is the impairment of BOLD signal changes due to lesion-related loss of normal vascular coupling with neuronal activity, a phenomenon referred to as neurovascular uncoupling (NVU). This can result in false-negative or false-positive results in critical eloquent cortex. If neuronal activity is preserved in diseased but viable cortex, NVU is presumed to occur due to astrocytic, neurotransmitter, or vascular dysfunction.
NVU has been mainly reported in patients with high-grade glial tumors and meningiomas. In such patients, the volume of task-based fMRI signal increases has been shown to be reduced adjacent to the tumor compared to homologous fMRI signal changes in the contralesional hemisphere, despite the absence of neurological deficit. In line with experimental data in healthy subjects showing that BOLD signal may decrease as cerebral blood volume (CBV) increases, impaired cerebrovascular reactivity (CVR) in brain tumor patients may be explained by changes in local perfusion. In hypervascularized tumors such as high-grade gliomas and meningiomas, local hyperperfusion has been suggested to explain the decreased BOLD signal on task-based fMRI. However, recent studies have demonstrated that NVU may also occur in low-grade gliomas. Given the absence of hyperperfusion in this tumor type, different mechanisms need to be considered. In low-grade gliomas, the observed NVU is currently thought to be, at least in part, due to disruption of astrocyte-vascular coupling (gliovascular uncoupling). Patients with arteriovenous malformations may exhibit impaired peri-nidal cerebrovascular reserve due to high-flow shunting, making perfusion-dependent mapping signals unreliable. Epilepsy patients may also exhibit regional impairment of CVR due to dramatic increases in brain metabolism and CBF during the ictal period, disruption of the brain-blood barrier, and an acute loss of cerebral pressure autoregulation.
According to previous research, CVR can be studied through the "hypercapnia challenge" during fMRI recordings, including breath-hold fMRI (BH fMRI) and carbogen inhalation fMRI. Hypercapnia is a potent vasodilator that increases the BOLD baseline signal by detecting an increase in tissue oxygenation resulting from increases in CBF while oxidative metabolism demands are considered to remain constant. However, the influence of hypercapnia on neural activity and neurometabolic/neurovascular couplings is not well understood and remains debated. In practice, areas of reduced or absent hypercapnia-induced increase in fMRI signal on CVR maps compared to homologous contralateral activation are assumed to indicate NVU. Recent studies suggest potential advantages in using resting-state (rs) fMRI as a preoperative technique. rs-fMRI is a functional neuroimaging technique that allows the measurement of spontaneous brain activity in patients at rest. Spontaneous BOLD signal fluctuations are highly correlated in distinct and long-ranged brain regions, indicating functional connectivity within specific and highly organized neuroanatomical networks. Functional connectivity studies have also demonstrated a high degree of spatial correlation between rs-fMRI functional brain connectivity and those studied during a hypercapnia challenge. Interestingly, recent research suggests that rs-BOLD signal may be impaired in patients in whom task-based increases in fMRI signals are reduced or absent due to NVU. Therefore, alterations in functional brain connectivity studied with rs-fMRI might provide insights into the presence of NVU as studied with CVR during hypercapnia. Such findings would be of interest in clinical practice as they could avoid the need for CVR-mapping with a hypercapnia challenge.
2,132 studies on the registry are indexed under Glioblastoma; 464 are open to participants now.
This study's planned enrollment of 40 is above the median of 36 across 1,753 interventional studies indexed under Glioblastoma.
Browse Glioblastoma studies →Erasme University Hospital is the lead sponsor of 181 studies on the registry; 35 are open to participants now.
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Exclusion Criteria:
As compared to the pre-surgical evaluation that brain tumor patients routinely undergo in our institution, patients are asked to undergo some additional examinations.
Diagnostic Test: Functional MRI · Diagnostic Test: FDG-PET · Diagnostic Test: Structural MRI
11 minutes of Functional MRI alternating breathing Air-Room and gaz mix (5%CO2 21%O2 74%N2). All procedure are acquired simultaneously on a single acquisition on the PET/MRI camera in the institution.
Some patients who did not benefit from a FDG-PET in their clinical evaluation or more than 1 month before the inclusion in the present study will be ask to also undergo a brain FDG-PET , the dose is set at 2 Mega becquerel per Kg. All procedure are acquired simultaneously on a single acquisition on the PET/MRI camera in the institution.
Patient will benefit Different anatomical sequence of acquisition listed here : T1 , T1 with contrast agent (gadovist) , T2 flair , T2 and DSC (Dynamic susceptibility contrast) , and Time Of Flight . All procedure are acquired simultaneously on a single acquisition on the PET/MRI camera in the institution.
Effects of Hypercapnia administration on fMRI data
For brain fRMI data: BOLD signal variation (Arbitrary Unit from a percent change from baseline).
Time frame: end of acquisition ( group of 40 subject estimated at 10 months after first subjet acquisition)
Effects of Hypercapnia administration on PET-FDG regional standardized data.
For brain PET-FDG: regional SUV value (Standardized Uptake Ratio) .The SUV is a mathematically derived ratio of tissue radioactivity concentration at a point in time at a specific region of interest and the injected dose of radioactivity per kilogram of the patient's body weight
Time frame: end of acquisition ( group of 40 subject estimated at 10 months after first subjet acquisition)
Effects of Hypercapnia administration on PET-FDG global data
For brain PET-FDG: Statistical Parametric Mapping analysis (SPM) for voxel-wise comparison and multiple correlations (t-score)
Time frame: end of acquisition ( group of 40 subject estimated at 10 months after first subjet acquisition)
Effects of Hypercapnia administration on oxygen saturation (SpO2)
SpO2 Variation: Measured in percentage points (%), reflecting the change from baseline levels.
Time frame: end of acquisition ( group of 40 subject estimated at 10 months after first subjet acquisition)
End tidal CO2
End Tidal CO2 during the experiment allow the modelisation and quantification of MRI signal among brain tissue. End tidal CO2 pressure is measured in mmHg
Time frame: end of acquisition ( group of 40 subject estimated at 10 months after first subjet acquisition)
Breathing Rate
Breathing Rate during the experiment allow the modelisation and quantification of MRI signal among brain tissue. Breathing rate is measure in respiration per minute
Time frame: end of acquisition ( group of 40 subject estimated at 10 months after first subjet acquisition)
Regional Cerebral Blood Volume
CBV represents the volume of blood present in 100 grams of brain tissue at a given time. It is used to assess the vascular capacity of the brain. unit are in mL per 100g of brain tissue .A DSC (Dynamic susceptibility contrast) -MRI is needed, the sequence involves the intravenous injection of a contrast agent, usually gadolinium-based. The contrast agent passes through the brain, and changes in the MRI signal are recorded over time.
Time frame: end of acquisition ( group of 40 subject estimated at 10 months after first subjet acquisition)
Regional Cerebral Blood Flow
CBF measures the amount of blood flowing through 100 grams of brain tissue in one minute. This is a crucial measure for assessing cerebral perfusion and identifying areas of under- or hyperperfusion.(mL/100g/min)A DSC-MRI is needed, the sequence involves the intravenous injection of a contrast agent, usually gadolinium-based. The contrast agent passes through the brain, and changes in the MRI signal are recorded over time.
Time frame: end of acquisition ( group of 40 subject estimated at 10 months after first subjet acquisition)
Tumor Grading
Tumor Grading, respectively with the World Health Organisation (WHO) 2021 guideline about brain neoplasm
Time frame: up to 2 week after last acquisition to allow Multidisciplinary oncologic commission to fix the grading status
Tumor Histology
respectively with the WHO 2021 guideline about brain neoplasm from the surgery clinically planned
Time frame: up to 2 week after last acquisition to allow Multidisciplinary oncologic commission to fix the grading status
Cerebrovascular reactivity mapping
Integration of the variation in fMRI signal and end tidal CO2, and breathing rate into a quantification . The produced data are in % of MRI signal change per mmHg of CO2
Time frame: up to 1 month after the last acquisition to allow processing time , all the 40 patient together
Correlation map
Correlation on coregistration of fMRI and PET procedure among the brain and plotted in a linear regression. Correlation will be expressed in Spearman's "R".
Time frame: up to 1 month after the last acquisition to allow processing time , all the 40 patient together
Functional connectivity
Measured on resting state data acquired during the experiment , allowing to construct a functional "FC" measure of the hub connected together in the brain. Measured in arbitrary unit.
Time frame: up to 1 month after the last acquisition to allow processing time , all the 40 patient together
Started Feb 2025 (actual). Primary completion is estimated for Sep 2026, 18 months after the start.
Of 131 non-industry interventional studies with no phase under Glioblastoma, half reached primary completion within 54 months of starting (the median), counting those still running; a quarter within 37 and three quarters within 97. This study's planned 18 months is below that.
Counting every sponsor, half of 149 studies reached it within 54 months; a quarter within 36 and three quarters within 88.
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