Kavli Affiliate: Lihong V. Wang
| Authors: Alejandro Garcia-Uribe, Todd N. Erpelding, Haixin Ke, Kavya Narayana Reddy, Anshuman Sharma, Lihong V. Wang
| Summary:
In many clinical conditions, such as head trauma, stroke, and low cardiac
output states, the brain is at risk for hypoxic-ischemic injury. The metabolic
rate and oxygen consumption of the brain are reflected in internal jugular
venous oxygen saturation (sijvO2). The current gold standard for monitoring
brain oxygenation is invasive; it requires jugular vein catheterization under
fluoroscopic guidance and therefore is rarely used. Photoacoustic (PA)
measurement, on the other hand, can estimate the oxygen consumption of the
brain non-invasively in real time. Such a convenient method can potentially aid
earlier detection and prevention of impending hypoxic brain injury. A
dual-wavelength photoacoustic tomography (PAT) and ultrasound imaging (US)
system was used to image the internal jugular vein (IJV) and estimate the
sijvO2 in seven healthy volunteers. The system captured simultaneous
co-registered PAT and US images at a rate of five frames per second. For each
volunteer, the internal jugular vein was identified under ultrasound guidance,
then, additional PA images from two optical wavelengths were collected and used
to estimate the oxygen saturation of the internal jugular vein. For each
volunteer, the oxygen saturation was calculated from transverse and
longitudinal views of the internal jugular vein. The average sijvO2 was 72 +/-
7 %. The preliminary results are encouraging and agree with those reported in
the literature. Photoacoustic images were successfully used to calculate the
blood hemoglobin oxygen saturation in the internal jugular vein. These results
raise confidence that this emerging technology can be used clinically for
accurate, noninvasive estimation of sijvO2. In addition, the fast
co-registration with US images makes the technique suitable for studying the
temporal variations of oxygen saturation in response to physiologic challenges
in clinical settings.