Evaluation of the SONAS® Ultrasound Device for the Assessment of Bilateral Cerebral Perfusion in Subjects With Acute Stroke

Inclusion Criteria: 1. Written informed consent obtained 2. Male or female subject ≥18 years 3. Clinical diagnosis of acute stroke (NIHSS score: ≥10) 4. Time of stroke symptoms onset: ≤24 hours 5. Confirmed occlusion of either the proximal middle cerebral artery (occlusion of the proximal, middle or distal M1-segment) or the distal internal carotid artery (including carotid-T occlusion) by cMRI or cCT (including perfusion weighted imaging sequences) 6. Women of childbearing potential must have a negative urine or serum beta human chorionic gonadotropin result, obtained within 24 hours before administration of SonoVue® 7. Women of non-childbearing potential can be included in the clinical investigation, if confirmed by fulfilling at least 1 of the following criteria: * Postmenopausal (age-related amenorrhea for ≥12 consecutive months) * Documentation (based on medical records, medical examination, or medical history interview) of irreversible surgical sterilization by bilateral oophorectomy, bilateral salpingectomy, or hysterectomy Exclusion Criteria: 1. Subjects with known contraindications to the use of SonoVue®: * Subjects known to have right-to-left shunts, severe pulmonary hypertension (pulmonary artery pressure \>90 mmHg), uncontrolled systemic hypertension, and subjects with acute respiratory distress syndrome * SonoVue® must not be used in combination with dobutamine in subjects with conditions suggesting cardiovascular instability where dobutamine is contraindicated * Known hypersensitivity to any of the following substances: * Sulphur hexafluoride * Macrogol 4000 * Distearoylphosphatidylcholine * Dipalmitoylphosphatidylglycerol sodium * Palmitic acid 2. Pregnant women 3. Subjects with severe cardiac or pulmonary disease as defined by the treating physician 4. Subjects with acute endocarditis and/or artificial heart valve 5. Subjects with acute systemic inflammation and/or sepsis 6. Subjects with hyperactive coagulation states and/or a recent thromboembolism 7. Subjects with end stage renal or hepatic disease 8. Subjects with known metal skull implants in the anatomical area of the temporal/parietal bones, or with anatomical formation of the head or ear that may interfere with proper headset placement, or with significant observable asymmetry in head formation 9. Subjects with known implanted deep brain stimulation devices 10. Subjects with known or suspected fracture(s) of the temporal/parietal skull bones, or with open skin injuries in the anatomical area of the temporal/parietal lobes 11. Subjects with known significant blood loss prior to or during the test procedure, SONAS® should not be used unless the blood pressure of the subject is verified to be stabilized 12. Subjects with axial (coronal) skull diameters of \<12 cm or \>18 cm 13. Subjects participating in another clinical investigation with an investigational drug or device within 3 months of enrollment or planned participation at any time during this clinical investigation 14. Previous participation in this clinical investigation 15. Employees of the clinical investigation site or the sponsor directly involved with the conduct of the clinical investigation, or immediate family members of any such individuals 16. Subjects committed to an institution by an order issued either by the courts or by an authority