Specific Aims: Indicate the purpose of the research, specifying the problems and/or hypotheses to be addressed.
Aim 1: Determine safety of the SONAS device Aim 1a: Obtain perfusion MRI (PWI) / quantitative MRI Aim 1b: Obtain MRI with gadolinium (gdMRI) Aim 2: Determine feasibility to detect microbubble specific frequencies
Research Design and Methods: Describe in detail the design and methodology of the study.
Since this is a 'first in human' study, testing primarily for the overall safety of the diagnostic approach, the aim is to enroll only healthy volunteers (e.g. no cerebro-/cardio-vascular history, no vascular risk factors etc.) into the study. We anticipate a total number of N=10 volunteers to be sufficient for this study.
Step 1 After written informed consent and prior to the SONAS ultrasound study each volunteer will undergo a baseline assessment in form of a physical exam, including vital signs, National Institute of Health Stroke Scale (NIHSS) assessment and Modified Ranking Scale as well as the assessment of the Medical History.
Step 2 Next, the volunteer will undergo a cranial MRI study. The MRI study will include a perfusion-weighted sequence to assess a baseline value for brain perfusion as well as gadolinium-enhanced T1-weighted images to assess the integrity of the blood-brain barrier.
Step 3
After the MRI study, the volunteer will undergo the SONAS ultrasound study. The study will be performed in supine position:
Two ultrasound transducers/probes will be positioned on both sides of the volunteer's head at the temporal bone (above and in front of the ear on each side). To hold the transducers/probes in place a customized headset has been designed which is easy to use and comforting for the proband.
Step 4 An IV line will be placed in a cubital or forearm vein. To assess a baseline value, ultrasound will be transmitted following an automated protocol to increase subsequently the output voltage from 5 volts to 50 volts. At each voltage step the received signals will be acquired and stored. Once the maximum output voltage of 50 Volts has been reached an additional 10 ultrasound pulses will be transmitted and the received data acquired. The total duration of this first data acquisition is 20 seconds.
Step 5 A bolus of 1.0ml of the ultrasound contrast agent (so called 'Microbubbles') Lumason™, internationally known as SonoVue (Bracco Pharmaceuticals, Italy), will be injected into the IV line, followed by a 5.0ml IV bolus injection of saline. Lumason™ has been FDA approved for cardiac applications to opacify the left ventricular chamber and to improve the delineation of the left ventricular endocardial border. In the context of the present study Lumason™ would be used off-label.
Step 6 Following the IV bolus injection of Lumason™, ultrasound will be transmitted and received signals acquired following the same protocol as detailed under Step 4.
Step 7 3 -5 hours after the SONAS ultrasound study has been performed Step 1 and Step 2 will be repeated.
