This study is a multi-center, prospective, single-arm, non-significant risk (NSR) device study in which up to 150 evaluable subjects with suspicion of embolic stroke of undetermined source (ESUS) will be evaluated with NB-IS TCD and standard of care TTE to screen for right to left shunt (RLS) or patent foramen ovale (PFO). Additionally, up to 150 evaluable subjects will be evaluated with NB-IS TCD and standard of care TEE.

The objectives of the study is to evaluate the shunt detection rate of the NeuralBot Investigational System (NB-IS) TCD relative to standard of care diagnostic techniques (transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), and standard transcranial Doppler ultrasound (TCD) and to assess the safety, accuracy and usability of the NB-IS device.

Inclusion Criteria TTE Main Study:

1. Subject 18 years of age and older.
2. Subject presents with a clinical condition characterized by neurological signs and symptoms that, in the opinion of the investigator, include embolic stroke or transient ischemic attack (TIA) in the differential diagnosis.
3. Scheduled for a transthoracic echocardiograph (TTE) study with agitated saline contrast (bubble study) per standard of care within ±30 days of informed consent.
4. Subject is able to successfully perform a Valsalva Maneuver (VM).
5. Subject or Legally Authorized Representative has the ability to provide informed consent and comply with the protocol.

Exclusion Criteria TTE Main Study:

1. Subject has undergone a right to left shunt (RLS) or patent foramen ovale (PFO) closure.
2. Female who is pregnant or lactating at time of admission
3. Subjects who underwent partial or full craniotomy/craniectomy within the past 6 months.
4. Subjects who have a physical limitation preventing TCD headset placement

Inclusion Criteria TEE Sub-Study (after first 150 subjects in Main TTE study enrolled):

1. Subject 18 years of age and older.
2. Subject presents with a clinical condition characterized by neurological signs and symptoms that, in the opinion of the investigator, include embolic stroke or TIA in the differential diagnosis.
3. Scheduled for a transesophageal echocardiograph (TEE) study with agitated saline contrast (bubble study) per standard of care within ±30 days of informed consent.
4. Subject is able to successfully perform a Valsalva Maneuver (VM).
5. Subject or Legally Authorized Representative has the ability to provide informed consent and comply with the protocol.

Exclusion Criteria TEE Sub-Study (after first 150 subjects in Main TTE study enrolled):

1. Subject has undergone a right to left shunt (RLS) or patent foramen ovale (PFO) closure.
2. Female who is pregnant or lactating at time of admission
3. Subjects who underwent partial or full craniotomy/craniectomy within the past 6 months.
4. Subjects who have a physical limitation preventing TCD headset placement.

All de-identified imaging data will be sent to a core laboratory which will provide independent quantitative and qualitative assessment of all NB-IS TCD and Standard of care (SOC) TCD, TTE, and TEE bubble study data. They will be blinded to the study and local diagnostic report data and provide independent review. The Core Lab interpretations will supersede all local interpretations and will be applied to all study endpoint analyses as applicable.