Featured Research

from universities, journals, and other organizations

Light assists in monitoring brain injuries

Date:
August 29, 2013
Source:
Nałęcz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences
Summary:
The information about alterations in cerebral perfusion is of crucial importance in treatment of patients with severe neurological injuries. The medical equipment used in clinics does not allow, however, for continuous measuring of brain activity in critically ill patients. This may change – due to an instrument allowing for assessment of brain perfusion with light.

A new diagnostic instrument allows for assessment of brain perfusion with light.
Credit: Image courtesy of Nałęcz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences

The information about alterations in cerebral perfusion is of crucial importance in treatment of patients with severe neurological injuries. The medical equipment used in clinics does not allow, however, for continuous measuring of brain activity in critically ill patients. This may change -- due to an instrument allowing for assessment of brain perfusion with light that is being developed at the Institute of Biocybernetics and Biomedical Engineering of the Polish Academy of Sciences.

Light will enable physicians to gain information about alterations in brain perfusion in critically ill patients, as follows from the research conducted at the Institute of Biocybernetics and Biomedical Engineering of the Polish Academy of Sciences (IBBE PAS) in Warsaw. Earlier work on optical methods for brain perfusion analysis, carried out in clinics worldwide, yielded ambiguous outcome. „The results of our research have been obtained with advanced optoelectronic equipment are more convincing," says Dr Adam Liebert, professor at the IBBE PAS.

The work on the instrument for brain perfusion assessment has been initiated at the IBBE PAS by Prof. Roman Maniewski as early as in the 1990s. At present, the research is continued by the team headed by Prof. Liebert.

Optical methods for brain monitoring make use of the fact that skull bones are to some extent transparent for light, in particular from the near infrared range, with wavelengths between 650 and 850 nanometer. The properties of hemoglobin are of essential importance here, and especially the fact that oxygenated form of hemoglobin interacts with light differently than the reduced form. The phenomenon allows for estimating the degree of oxygenation in the observed region of the body by analysing the intensity of light penetrating the tissue.

The essential elements of optical diagnostic devices are small light sources (laser diodes) and highly-sensitive detectors. The sources and detectors, usually placed at a distance of 2-5 cm from each other, are paired. Simultaneously, from a few to over a dozen of such pairs can be put at the patient's head, which potentially allows for examining a substantial part of human brain. Signals recorded by the detectors are transmitted via optical fibres to photomultipliers. After amplification, they are transmitted to a PC equipped with cards allowing for counting single photons.

„The volume penetrated by light inside the skull resembles a banana in shape, with one end at the light source, and the other at the detector. At the place where the depth of photon penetration in the skull is at its maximum, we reach the cerebral cortex. This means that a fraction of recorded photons has interacted with hemoglobin from the blood circulating in blood vessels of the external layers of the brain," explains Prof. Liebert.

The researchers have recently carried out measurements for a record-breaking distance between the light source and the detector, equal to 9 cm. The brain perfusion was assessed using indocyanine green -- a low-toxic optical contrast agent, well known in the clinical environment. The contrast agent was administered in patients by intravenous injection during the measurement.

Optical signals recorded during the monitoring of brain activity not only provide information on what's going on in the cerebral cortex, but are also contaminated by data originating from perfusion of extracerebral tissues, including skin. There are a few methods for separating the information originating from intracerebral tissues from undesired interference signals. The instrument from the IBBE PAS is among the most technologically advanced devices, recording the time of flight of single photons in the tissue. In this technique, the light source emits many short (picosecond) light pulses. The longer time between photon emission and detection means the higher chance that the photon has interacted with deeper intracranial tissue structures -- and so with the cerebral cortex.

„In the highest resolution, the images of both brain hemispheres obtained with our instrument consist of 32 pixels corresponding to source-detector pairs on the surface of the head," says Daniel Milej, a PhD student at the IBBE PAS, and explains: „A not high spatial resolution is due to physical constraints. In optical observations of the brain, the phenomena related to light scattering dominate those resulting from light absorption. That's why the resolution of these images is significantly lower than that of tomography-based medical imaging methods."

It is, however, not only the image resolution that decides about the usefulness of the equipment. The primary advantage of the instrument from the IBBE PAS is that the measurements are non-invasive. Light emitted by laser diodes is absolutely safe and does not induce changes in tissues. Equally important is the simplicity of examinations. The measurement requires only that a cap with fixed optical fibres is placed on the patient's head and the patient is injected with a small dose of a contrast agent. The very examination lasts for a few minutes only and can be repeatedly carried out during the day. Moreover, the size of the measurement equipment in a lab, and so in a still non-miniaturised version, resembles a refrigerator. It is mobile and applicable at the bedside, even in critically ill patients treated in intensive care unit environment. It can also be used in an operating room.

The advantages of optical methods of brain observation are obvious when compared with other imaging techniques used in hospitals. Computer tomography and magnetic resonance require large, stationary equipment. The patient must be transported to special diagnostic rooms, which often results in necessary disconnection from other medical equipment. In addition, the patient must be immobilised and the examination is expensive. In practice, the hospitals do not have any equipment that would allow for a continuous bedside monitoring of alterations in cerebral microperfusion.

In collaboration with the Medical University of Warsaw and the Praski Hospital Department of Intensive Care in Warsaw, the researchers from the IBBE PAS have recently carried out optical measurements of brain perfusion in patients with post-traumatic brain injuries. Patients with cerebral edema and subcortical hematoma were included in the study. In both cases, differences with respect to signals collected in healthy volunteers have been observed. The results of the research have been recently published in the journal NeuroImage.

„The possibility of continuous monitoring of the brain perfusion parameters may be of key importance in treatment of patients with severe neurological injuries. The results of our work suggest that the optical method can be useful in clinical practice," says Dr Wojciech Weigl, an anaesthesiologist who coordinated clinical studies on the new measurement method. Further studies are, however, needed before the instrument from the IBBE PAS could be delivered to hospitals and clinics.

The research on the non-invasive methods for optical brain monitoring at the IBBE PAN has been and still is supported by grants from the Polish Ministry of Science and Higher Education, the National Science Centre, and by the EU-funded nEUROPt project.


Story Source:

The above story is based on materials provided by Nałęcz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences. Note: Materials may be edited for content and length.


Journal Reference:

  1. W. Weigl, D. Milej, A. Gerega, B. Toczylowska, M. Kacprzak, P. Sawosz, M. Botwicz, R. Maniewski, E. Mayzner-Zawadzka, A. Liebert. Assessment of cerebral perfusion in post-traumatic brain injury patients with the use of ICG-bolus tracking method. NeuroImage, 2013; DOI: 10.1016/j.neuroimage.2013.06.065

Cite This Page:

Nałęcz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences. "Light assists in monitoring brain injuries." ScienceDaily. ScienceDaily, 29 August 2013. <www.sciencedaily.com/releases/2013/08/130829093137.htm>.
Nałęcz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences. (2013, August 29). Light assists in monitoring brain injuries. ScienceDaily. Retrieved August 30, 2014 from www.sciencedaily.com/releases/2013/08/130829093137.htm
Nałęcz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences. "Light assists in monitoring brain injuries." ScienceDaily. www.sciencedaily.com/releases/2013/08/130829093137.htm (accessed August 30, 2014).

Share This




More Matter & Energy News

Saturday, August 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Australian Airlines Relax Phone Ban Too

Australian Airlines Relax Phone Ban Too

Reuters - Business Video Online (Aug. 26, 2014) Qantas and Virgin say passengers can use their smartphones and tablets throughout flights after a regulator relaxed a ban on electronic devices during take-off and landing. As Hayley Platt reports the move comes as the two domestic rivals are expected to post annual net losses later this week. Video provided by Reuters
Powered by NewsLook.com
Hurricane Marie Brings Big Waves to California Coast

Hurricane Marie Brings Big Waves to California Coast

Reuters - US Online Video (Aug. 26, 2014) Huge waves generated by Hurricane Marie hit the Southern California coast. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Chinese Researchers Might Be Creating Supersonic Submarine

Chinese Researchers Might Be Creating Supersonic Submarine

Newsy (Aug. 26, 2014) Chinese researchers have expanded on Cold War-era tech and are closer to building a submarine that could reach the speed of sound. Video provided by Newsy
Powered by NewsLook.com
Breakingviews: India Coal Strained by Supreme Court Ruling

Breakingviews: India Coal Strained by Supreme Court Ruling

Reuters - Business Video Online (Aug. 26, 2014) An acute coal shortage is likely to be aggravated as India's supreme court declared government coal allocations illegal, says Breakingviews' Peter Thal Larsen. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins