טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentGolan Lior
SubjectImaging of Flowing Cells Using Spectrally Encoded Confocal
Microscopy
DepartmentDepartment of Biomedical Engineering
Supervisor Professor Dvir Yelin
Full Thesis textFull thesis text - English Version


Abstract

Blood tests characterize the composition of a patient’s blood, providing useful parameters for medical diagnosis. Although blood tests are considered simple and accurate, they require painful extraction of blood, associated with anxiety and infections, and a laboratory procedure which takes time and limits availability. Undoubtedly, a noninvasive blood test providing immediate results to the doctor at the point-of-care could improve the quality of the diagnostic procedure and open up new clinical applications. Optical microscopy techniques could be utilized for this goal, but suffer from the scattering of light by tissue which severely limits imaging depth.

In this work, we have developed an optical microscopy technique termed spectrally encoded flow cytometry (SEFC), which provides subcellular resolution confocal images of blood cells flowing deep under the surface of the human body without any need for fluorescent labeling or mechanical scanning. By utilizing a spectral encoding scheme and the natural movement of the cells during flow, the optical system  was made simple and scan-free, with a hand-held probe containing no moving parts, and a remote console containing the near infra-red light source and detector, connected to the probe by flexible optical fibers. SEFC images of flowing red and white blood cells were obtained in 10-50 um diameter capillary vessels 70-100 um under the surface of the lower lip of human volunteers, recording flow phenomena such as cellular deformation and aggregation that were previously visualized only in laboratory animals. Different subtypes of white blood cells could be resolved in the images and subcellular features were identified in flowing cells. A preliminary study in vitro and in vivo showed that hematological parameters such as a patient’s hematocrit and white blood cell count could potentially be calculated from SEFC images.

Additional improvement of the acquisition rate in the SEFC system was introduced by utilizing a swept-source-based interferometric detection concept that enabled imaging of cells flowing at velocities up to 10 mm/s. A portable SEFC system with a compact hand-held probe was also designed, constructed and tested, which would enable clinical experiments outside of the optical laboratory. Future SEFC-based devices could enable noninvasive blood counts with immediate results available to the doctor at the point-of-care.