20 April 2017 SCOT improves stroke diagnosis

New viable and non-invasive 3D method for imaging the small animal brain and quantifying cerebral blood flow. Stroke is the number one cause of disability and one of the leading causes of death, killing over 400.000 people every year in Europe. Often called "brain attacks", they occur when blood flow to an area in the brain is cut off.

Cerebral blood flow (CBF) plays a crucial role in supplying oxygen to the brain tissue and removing the by-products of metabolism. When a stroke occurs, the CBF decreases drastically and brain cells are deprived of the oxygen and glucose needed to survive, and if not properly treated, they die. Most treatments aim at restoring the blood flow to the damaged area in the brain. Tissue plasminogen activator, or tPA, is the most common treatment, but such treatment becomes inefficient the longer it takes to administer the drug. That is, if a stroke is not caught early enough, permanent brain damage or death can occur.

Recently, ICFO researchers Tanja Dragojević, Dr. Hari M. Varma, Dr. Joseph L. Hollmann, Dr. Claudia P. Valdes led by ICREA Prof. at ICFO Turgut Durduran, in collaboration with scientists from the Washington University School of Medicine and IDIBAPS in Barcelona, reported on the development a new 3D technique based on speckle contrast optical tomography (SCOT) for minimally invasive in vivo measurements of cerebral blood flow in small animals. The results of the study have been published in Neuroimage.

SCOT, or High-Density Speckle Contrast Optical Tomography, is an enhanced technique of Speckle Contrast Optical Spectroscopy (SCOS), a deep tissue spectroscopic method that merges deep tissue flow measurements of diffuse correlation spectroscopy (DCS) and laser speckle imaging (LSI).

The team of researchers conducted SCOT in vivo measurements of the CBF by imaging the mouse brain transcranially in a minimally invasive way after the induction of a local ischemic stroke. Thousands of detectors were used per animal to reconstruct the volumetric change of blood flow after the ischemia was induced by photothrombosis. The transcanially reconstructed 3D volume image was then compared to anatomical MRI images after 24 hours.

The results indicate that SCOT is a viable method for imaging the small animal brain and quantifying the CBF changes in three dimensions. The results obtained in this study pave the way for developing high-density SCOT as a tool for studying CBF in small animal models in a non-invasive, longitudinal and quantitative approach.