Appl. Opt. 50, 3589–3597 (2011)

Credit: © 2011 OSA

In the field of pathology, chromatographic agents are used in the analysis of blood samples to obtain useful information about cell morphology for diagnosing a wide range of diseases. Unfortunately, the sample preparation and analysis stages of this process may take several hours if the red blood cells being imaged are particularly young. Mona Mihailescu and co-workers in Romania have now combined holography with image processing to simultaneously image, identify and count more than 1,000 red blood cells from several three-dimensional images of the same sample. Based on the interference patterns obtained by digital holographic microscopy, they noted that mature and immature cells exhibit very different diffractive patterns when illuminated with a central intensity distribution in a given plane along the propagation axis. They then developed a computer programme capable of automatically and simultaneously identifying, separating and counting individual cells, even when they partially overlap, using at least six images obtained in the reconstruction phase of digital holographic microscopy. The technique accurately measures the morphological features of cells and can separate mature from immature red blood cells through a decision based on their gradient and radius values.