This is a pilot, monocentric clinical investigation to evaluate the suitability of StrokeWave in distinguishing haemorragic from ischaemic strokes. The StrokeWave is a microwave device which employs a novel technique to generate images by processing very low power (<1mW) microwaves. The trial design has been developed in order not to interfere with thw standard diagnostic approach used for the hyperacute stroke patients, nor to modify the usual standard timing of the routine assessment.

The number of participants will be 60. Patients with hyperacute stroke (within 4 hours from the onset) or with awake or unknow time of onset strokes will be enrolled in the study. All patients will be registered at emergency room of Hospital, and according to the internal procedure will be clinically evaluated by the Neurologist of the stroke team. NIHSS and mRS will be administered and scores registered. The scanning with StrokeWave will be performed in 5 minutes, after NCCT and before the CTA acquisition, in the CT room. StrokeWave will be placed on the head of the patients in the CT room passing toward the gantry of the CT avoiding any loose of time. After the StrokeWave scanning, the system will be removed. The data collected will be processed through an imaging algorithm which is integrated in the device. The final output will be composed by one or more images, plus one or more parameters describing the images.

Inclusion Criteria:

• Adult > 18 years old
• Patients with hyperacute stroke, i.e. which are referred to the emergency room with a 'stroke code'

Exclusion Criteria:

• mRS >3 before the stroke onset
• Life expectancy <3 months
• GCS=3