A pilot trial for assessing early microvascular alterations after aneurysmal subarachnoid hemorrhage using dynamic 18F-FDG PET/CT. The primary endpoint will be the measure of early changes in cerebral glucose uptake reflecting microperfusion.

We hypothesize that an early irreversible microvascular deterioration following initial bleeding could contribute to DCI occurrence. More precisely, we suspect that DCI areas are somehow overlaps of regions in which microperfusion is precociously altered, shortening circulatory reserves, and territories of secondarily spasmed arteries further lowering blood flow, resulting in ischemia. We aim to explore the potential microvasculature alteration through cerebral glucose perfusion and metabolism assessment using early dynamic 18F-fluorodesoxyglucose Positron Emission Tomography/Computer Tomography (dynamic 18F-FDG PET/CT). If our hypothesis turned out to be valid, we would at the same time be able to determine risk factors for this unpredictable complication and gain remarkable insight into DCI pathophysiology. Thus, the purpose of this trial is to demonstrate, in patients affected by SAH, the correlation between early cerebral glucose uptake defects in 18F-FDG PET/CT and delayed cerebral infarction in magnetic resonance imaging (MRI).

Inclusion Criteria:

• written informed consent to participate in the study must be obtained from the subject or proxy/legal representative prior to enrollment.
• males and females aged 18 years and older.
• SAH proven by computed tomography (CT) and that has occurred within the last 72 hours.
• ruptured saccular aneurysm angiographically confirmed by digital subtraction angiogram or CT angiogram, which has been successfully secured by surgical clipping or endovascular coiling.
• high-risk subjects for DCI: "thick clot" on the hospital admission CT (grade 3 or grade 4 on the modified Fisher Scale).
• a woman of childbearing potential is eligible only if the serum pregnancy test performed during the screening period is negative.

Exclusion Criteria:

• PET/CT contradications
• MRI contradications
• gadolinium or meglumine hypersensitivity
• glomerular filtration rate <30mL/min
• SAH due to other causes than ruptured saccular aneurysm.
• post-HSA cardiac arrest.
• high sustained ICP ( >20mmHg lasting >20min) despite optimal treatment.
• significant and concomitant organ failure amongst the following: hypotension with systolic blood pressure <90mmHg refractory to treatment; unresolved pulmonary edema or pneumonia with severe hypoxia defined as PaO2/FiO2 <150; severe cardiac failure requiring inotropic support.
• patients with "do-not-resuscitate" orders, withdrawal of care situation, dying patient.
• vulnerable patient populations (minor, legal vulnerability, prisoner)
• pregnant and nursing mothers.

12 months after the main publication

Data are provided to qualified investigators free of charge. Required documents to request data include a summary of the research plan, request form, and IRB review. Dataset will be shared after careful examination by the study board of investigators.