This is a randomized, placebo-controlled, phase 3 clinical trial to evaluate the efficacy and safety of transcranial ultrasound (US) as an adjunctive therapy to tissue plasminogen activator (tPA) treatment in subjects with acute ischemic stroke.

The primary objective of this trial is to provide information regarding the efficacy of a combined treatment with transcranial US and systemic tPA (Target group) compared to systemic tPA alone (Control group) in subjects with acute ischemic stroke. The primary efficacy endpoint is functional outcome at 3 months from stroke onset (modified Rankin Score ordinal shift analysis). The primary safety endpoint is the proportion of subjects in the Target vs Control group experiencing symptomatic intracranial hemorrhage (sICH) within 24 hours of treatment.

Inclusion Criteria:

1. Males or females 18 - 80 years of age

2. Subjects presenting within timeframe for intravenous tPA treatment approved by local regulatory authorities but no more than 4.5 hours from onset of symptoms

3. No signs of intracranial bleeding on assessment by non-contrast CT

4. Subjects with neurological deficits of a total NIHSS score ≥ 10 points

5. Subjects that in the opinion of the treating physician require treatment with full dose IV tPA as standard of care per institutional standards

6. SBP < 185 mmHg and DBP < 105 mmHg at baseline or after treatment of hypertension with medications prior to tPA bolus

7. Pre-morbid modified Rankin score of 0-1

8. Provision of informed consent as demonstrated by the subject's signature or by the signature of the subject's authorized legal representative on the Informed Consent Form in accordance with all local and national regulations

9. Co-signature on the Informed Consent Form by a qualified member of the study staff signifying that, in his/her professional opinion, informed consent has been obtained in accordance with all local and national regulations

10. For subjects in the optional arterial recanalization substudy:

    1. Occlusion located in the intracranial carotid tee through mid M2 or proximal A2, or intracranial vertebrobasilar or P1/proximal P2 segments or tandem lesions
    2. Estimated glomerular filtration rate (eGFR) ≥ 60 mL/min for patients undergoing CTA or MRA

Exclusion Criteria:

1. Subjects with primary intra-arterial thrombolysis
2. Females who are pregnant or breast feeding
3. Subjects receiving other investigational drugs, procedures, or therapies within 30 days prior to study treatment
4. Subjects with any standard contraindication for intravenous tPA therapy
5. Significant concurrent medical/neurological conditions or test values that, in the opinion of the investigator, pose significant risk to the subject and warrant exclusion from the study