The primary goal of neurocritical care is to prevent secondary brain injury, which worsens neurological outcomes. Because clinical monitoring is often insufficient due to the patient's condition and medical treatments, multimodal monitoring using biophysical, electrophysiological, and imaging data is essential. In patients with subarachnoid hemorrhage (SAH), the most frequent and severe complication is delayed cerebral ischemia, often linked to arterial vasospasm and potentially leading to infarction. Early diagnosis combines transcranial Doppler (TCD), sensitive to vasospasm, with perfusion CT (CTP), which measures cerebral perfusion; this approach guides therapy and improves prognosis. Ultrasound, especially when enhanced with contrast agents (CEUS), allows non-invasive, bedside, repeated visualization of cerebral blood flow and perfusion-even through the skull. Agents like SonoVue® help quantify perfusion using time-intensity curves. The study aims to assess whether cerebral perfusion measurements from the SYLVER device are equivalent to those from CTP in ICU or CCU patients.
Patient ≥ 18 years old
Patient Informed Consent, or from his/her relative if the patient is not conscious and able to consent
Admission to ICU or CCU with indication to perform at least one CTP
Affiliated with or benefiting from a social security scheme
Guardianship, curatorship or any deprivation of liberty by judicial or administrative decision
Pregnant or breast-feeding women
Known contra-indication or hypersensitivity to SonoVue® (to sulfur hexafluoride microbubbles or to one of its excipients such as polyethylene glycol (PEG))
Right-to-left shunts
Single group
Ultrasound contrast agent (Contrast-enhanced ultrasound)
DeviceThe V0 (screening) visit occurs during ICU/CCU hospitalization, with routine clinical exam, eligibility check, and informed consent from the patient or a relative. Assessments include demographics, medical history, clinical exam, treatments, cerebral perfusion by CTP, anatomy by CTA, SYLVER perfusion/anatomy, TCD velocities, and AE/device deficiency recording. V0 lasts \~30 min. V1 (Day 1 or possibly Day 0 in urgent cases) includes clinical exam, TCD, CTP/CTA, and SYLVER use (\~30 min extra; total \~1h30). Imaging order is flexible but times are logged. V2-V5 occur if, by Day 21, ICU/CCU stay continues and care requires further CTP for suspected hypoperfusion (max once/day).
Performance of SYLVER system by determining the concordance with CT for principal vascular network localization and perfusion parameters.
On all the patients recruited during the study, assess the performance of the SYLVER system by determining the concordance between the cerebral perfusion parameters from the evaluated medical device and those provided by CTP.
Calibration Function Between SYLVER Perfusion Metrics and CTP Measurements
Mathematical calibration function describing the relationship between perfusion parameters measured by the SYLVER device and corresponding perfusion parameters measured by CT perfusion (CTP). For each paired assessment (SYLVER + CTP), the following will be derived and reported at the subject level and/or aggregated level (as applicable): i) Estimated functional form of the calibration model (e.g., linear or non-linear relationship between SYLVER and CTP perfusion parameters). ii) Estimated calibration parameters of the model (e.g., slope, intercept, and other model coefficients linking SYLVER values to CTP values). iii) Goodness-of-fit metrics for the calibration model (e.g., correlation coefficients, error metrics) if pre-specified in the analysis plan. iv) Calibration parameters and model characteristics will be obtained from all available paired SYLVER and CTP measurements collected between V0 and V5.
Correlation Between SYLVER-Reference Parameters Mismatch and Clinical and Technical Variables
Mismatch between parameters measured by SYLVER and reference modalities, and its correlation with routine clinical variables. Parameters mismatch includes: (1) Time to Peak (TTP, seconds) SYLVER vs CT perfusion; (2) systolic and diastolic cerebral blood flow (cm/s) SYLVER vs transcranial Doppler; (3) anatomical visualization of brain vessels (vessel visualization score / agreement) SYLVER vs CT angiography; (4) hypoperfusion zone identification (presence, number, and/or volume of hypoperfused areas) SYLVER vs CT perfusion. Correlated variables include heart rate (bpm), blood pressure (mmHg), medication use, Glasgow Coma Scale score, neurological deficits. Correlation coefficients (dimensionless) will be reported.
Sensitivity and Specificity of SYLVER for Detecting Hypoperfusion Compared With CT Perfusion
Concordance of areas reported hypoperfused or healthy, with the volume analyzed by SYLVER superimposed on the equivalent volume sample given by CTP
Agreement of Brain Vessel Morphological Reconstruction Between SYLVER and CT Angiography
Concordance of major cerebral morphological structures visualization assessed by an investigator, or by a qualitative assessment according to the morphological atlas for optimized parameter analysis
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