Blood Screening

Posted on September 29, 2011 by admin

The existing clinical technologies used to characterize patient blood such as impedance counters and flow cytometers though very effective are expensive, bulky, costly to maintain and often require careful calibration. These automated counters are designed to produce accurate measurements of normal blood and to alert the technician with flagswhen numerical abnormalities exist. These flags are a necessity since the automated counters are incapable of recognizing morphological abnormalities and thus an experienced pathologist is required to examine the sample before any significant condition can be diagnosed. We applied quantitative phase imaging techniques including Diffraction Phase Microscopy (DPM) and SLIM have proven their capabilities for accurate measurements of normal blood and of characterizing specific morphological abnormalities in diseased blood. QPI is significantly cheaper and more portable than current automated cytometers and requires little maintenance. The techniques developed adds on to the capabilities of the current RBC parameters reported in the CBC by including detailed 3D morphological parameters such as Volume, Surface Area, Sphericity and Minimum Cylindrical Diameter. This research is in collaboration with Dr. Krishna Tangella at the Provena Medical Center in Champaign.

One of the parameters measured by QPI is Sphericity which quantifies how spherical a cell is. The figure to the left here shows the capabilities of our method to quantify the sphericity of individual red blood cells in a patient, this is a feat that was previously impossible and illustrated the capabilities of blood screening using QPI.

We have also conducted a study to compare the values measured by our technology with those measured by the clinical blood analyzer. The results of this study showed excellent agreement and are summarized in Figure 2 here.

More recently we have also developed the capability to measure hemoglobin concentration at the single cell level. This is accomplished by taking an absorption measurement in addition to the QPI image. With this new development we may study diseases that include both changes in morphology and defects in hemoglobin. The third figure here  illustrates this method: (a) Quantitative phase map acquired using SLIM, color bar is in radians. (b) Absorption map acquired at 430 nm, color bar is in 16-bit gray scale values. (a-b) Insets show an example of a single RBC from the maps. (c) Overlay of l line profiles drawn through the center of a single cell, the phase values are shown in red against the left axis and the corresponding intensity from the absorption maps are shown in black against the right axis. (d) Average absorption vs. phase for each of the 7 patients analyzed in this study, a strong linear relationship (dotted line) indicates the feasibility of this method. For the cell shown here the volume and hemoglobin concentration were calculated to be 86.18 fL and 0.3 g/mL respectively.

In addition to improving the clinical utility of QPI based blood screening methods we have also made progress on translating this technology to a point of care instrument. To this end we are adopting commercial CD-ROM technology and transforming it into cheap quantitative phase microscopes. This will allow anybody with a personal computer to perform highly sensitive blood screening without relying on any other infrastructure.

Relevant Publications

  1. M. Mir, K. Tangella and G.Popescu, Blood testing at the single cell level using quantitative phase and amplitude microscopy, Biomed. Opt. Exp., 2 (12), 2011.
  2. M.Mir, H.Ding, Z.Wang, J. Reedy, K. Tangella and G. Popescu, Blood screening using diffraction phase cytometry, J. Biomed. Opt., 15 (2), (2010).
  3. M. Mir, Z. Wang, K. Tangella and G. Popescu, Diffraction Phase Cytometry: Blood on a CD-Rom, Opt. Exp. 17, 2579-2585(2009).