Automated microscopic cell analysis
This disclosure describes single-use test cartridges, cell analyzer apparatus, and methods for automatically performing microscopic cell analysis tasks, such as counting and analyzing blood cells in biological samples. A small measured quantity of a biological sample, such as whole blood, is placed in a mixing bowl on the disposable test cartridge after being inserted into the cell analyzer. The analyzer also deposits a known amount of diluent/stain in the mixing bowl and mixes it with the blood. The analyzer takes a measured amount of the mixture and dispenses in a sample cup on the cartridge in fluid communication with an imaging chamber. The geometry of the imaging chamber is chosen to maintain the uniformity of the mixture, and to prevent cells from crowding or clumping as it is transferred into the imaging chamber by the analyzer. Images of all of the cellular components within the imaging chamber are counted and analyzed to obtain a complete blood count.
1. A method of counting and analyzing red cells, white cells, and platelets, utilizing an automated microscope with image processing software, and a single use test cartridge having a single, serpentine imaging chamber, the method comprising:
a) diluting a known volume of test sample of whole blood with a known volume of diluent and/or stain to obtain a known dilution ratio between 10:1 to 250:1,
b) mixing the test sample and diluent and/or stain to a substantially uniform mixture,
c) introducing a portion of the mixture into single the imaging chamber of the test cartridge, the chamber having a shape in planar view which is serpentine, wherein the imaging chamber is defined by walls in the test cartridge and has a bottom and a predetermined depth, wherein the serpentine chamber has dimensions that keep a distribution of cells and platelets in the chamber substantially uniform, at the known dilution ratio, as the cells and platelets in the mixture settle to the bottom of the imaging chamber to form a monolayer wherein the cells and platelets do not crowd or overlap,
d) introducing the test cartridge with the portion of the mixture into the automated microscope with image processing software,
e) capturing one or more digital images of the settled red cells, white cells and platelets in the portion of the mixture in the monolayer in the single serpentine imaging chamber that are selected to be statistically representative of a number and distribution of the red cells, white cells, and platelets in the mixture in the imaging chamber, and
f) deriving a quantitative characterization of the distribution of the red cells, white cells, and platelets in the serpentine imaging chamber based on the images captured of the settled red cells, white cells and platelets in the portion of the mixture.
2. A method of claim 1 wherein the step of deriving a quantitative characterization includes analyzing the red cells, white cells and platelets in the captured images with pattern recognition software.
3. A method of claim 1 wherein the step of deriving a quantitative characterization includes counting all of at least one type of cell in the images using the imaging processing software, and calculating the at least one type of cell per unit volume in the sample.
4. A method of claim 1 wherein the capturing of the one or more digital images includes brightfield and fluorescent images.
5. A method of claim 1 wherein a geometry of the imaging chamber has dimensions that are sufficient that the red cells, white cells and platelets do not overlap, crowd, or screen when they settle to the bottom of the imaging chamber.
6. A method of claim 1 wherein the step of capturing the one or more digital images includes capturing images that include all the red cells, white cells and platelets in the imaging chamber.
7. A method of claim 1 wherein a rate of introducing of the mixture of diluent and sample is such that the portion of the mixture remains substantially uniform.
8. A method of claim 1 wherein the serpentine imaging chamber includes a plurality of convex curves, wherein each of the convex curves has an inside turning diameter and an outside turning diameter, and wherein the outside turning diameter of each of the convex curves is about twice the inside turning diameter of the convex curves of the serpentine imaging chamber.
9. A method of claim 1 wherein the depth of the imaging chamber is uniform throughout a length of the imaging chamber and the depth is between 10 μm and 200 μm.
10. A method of claim 1 wherein a width and the depth of the imaging chamber are uniform throughout a length of the imaging chamber and a depth to width ratio of the imaging chamber is greater than 2 to 1.
11. A method of claim 1 further comprising performing a three-part differential of white cells in the sample.
12. A method of claim 1 further comprising performing a five-part differential of white cells in the sample.