Comparison of Ultrasound Cerebral Perfusion Imaging With Routine Perfusion CT

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.

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.

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.

Concordance of areas reported hypoperfused or healthy, with the volume analyzed by SYLVER superimposed on the equivalent volume sample given by CTP

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

Concordance of Doppler velocities in the Middle Cerebral Artery (MCA) provided by TCD acquisitions and the ones calculated from SYLVER parameters

Total diagnostic care cost per patient with and without use of SYLVER as a diagnostic tool. The measure aggregates: (1) physician time, (2) nursing-assistant time, (3) radiology technician ("radio manipulator") time, and (4) radiological inteprentation time, each recorded in minutes and multiplied by the corresponding unit cost (cost per minute) to obtain a total personnel cost. Additional diagnostic resource costs directly related to the diagnostic strategy (e.g., imaging procedures) may be included according to a predefined cost schedule. The primary reported value will be the mean total diagnostic cost per patient (in local currency) in the SYLVER vs non-SYLVER pathways, and the difference between groups.

Number and proportion of participants with at least one adverse event (AE), serious adverse event (SAE), or device deficiency occurring during use of the SYLVER device. AEs and SAEs will be collected from inclusion to the end of follow-up and classified by seriousness, severity, and relationship to the device or procedures, according to applicable regulatory definitions. Device deficiencies (e.g., malfunction, use error, or failure of the device to perform as intended) will be collected and summarized. Results will be reported as counts and percentages of participants with AEs, SAEs, and device deficiencies.