The investigators prospectively want to use the Infrascanner in patients with ischemic stroke, patients with brain surgery, patients with brain tumors, patients with intracranial hemorrhage and patients with a normal CT scan of the brain as part of a diagnostic work-up after head trauma or headache to determine to positive and negative predictive value of the Infrascanner in these different settings.

Infrascanner is a portable device initially designed to detect intracranial hemorrhage in battlefield traumas. Infrascanner uses near infrared spectroscopy to measure cerebral blood flow non-invasively. This is achieved by putting the device against the scalp in 4 different areas (frontal, temporal, parietal, occipital) on the left and right side and by comparing both sides.This allows for the detection of intracranial hemorrhages with a volume upwards of 3.5ml and to a depth of 2.5cm. However, little is known about the influence of other intracranial conditions that could confound the measurements of the Infrascanner (e.g. ischemic stroke, brain surgery, brain tumors,...).

Therefore, the investigators prospectively want to use the Infrascanner in patients with ischemic stroke, patients with brain surgery, patients with brain tumors, patients with intracranial hemorrhage and patients with a normal CT scan of the brain as part of a diagnostic work-up after head trauma or headache to determine the positive and negative predictive value of the Infrascanner in these different settings.

Inclusion Criteria:

• Patients with ischemic stroke diagnosed by clinical examination and CT-scan
• Patients with a brain tumor diagnosed by clinical examination and CT-scan or MRI
• Patients with an intracranial hemorrhage diagnosed by clinical examination and CT-scan
• Patients that have undergone brain surgery
• Patients with a normal CT-scan of the brain after head trauma
• Patients with headache complaints and a normal CT-scan of the brain as part of their diagnostic work-up

Exclusion Criteria:

• none