Diagnostics
Figure 1: LabUMat-2 & UriSed-2 Complete Urine Laboratory System
Figure 2: UriSed Measurement Process
Empty cuvette is placed to filling position
Sample in test tube is homogenised
Sample is aspirated from test tube
Centrifugation of cuvettes is performed at 2,000 rpm for 10 seconds (equivalent to 260 g due to the compact size of the centrifuge; therefore, cuvettes are exposed to much less force than in the case of manual microscopy, during which the urine sample is exposed to 400 g). This moderate process does not destroy the cells and casts of the urine sediment. UriSed analyses native urine; the purpose of centrifugation is to create a monolayer of particles at the bottom of the cuvette, thus forcing all the particles into the same layer, enabling all particles to be contrasted on the image. Therefore, all the particles are found by UriSed.
The cuvette containing the settled urine sample is placed onto the microscope table. Since the correct focus level depends on the urine particles of the sample (urine samples may contain bacteria, which are 1–2 µm in size; white blood cells (WBC), which are 10–14 µm in size; as well as 50–100 µm casts and epithelial cells), an automatic focusing algorithm chooses the sharpest image at every single field of view position. In the first field of view position the focusing algorithm scans a large range in order to find the correct focus level. Once the correct focus level is found, a narrower range is scanned in every further position.
In the course of the measurement process, UriSed produces high-resolution bright-field microscopic images of each sample. The high power field (HPF)-like UriSed images correspond to standard 400x magnification manual microscopic images. The default setting is 15 images/sample, in which case 2.2 µl of native urine is examined. In the case of manual microscopy the amount of native urine examined is highly dependent on the sample preparation process, the concentration level of the urine sediment and the objective and ocular of the microscope. Fifteen UriSed Images correspond to 10 manual microscopy fields of view performed as suggested by the European Urinalysis guideline,4 provided that a 400x magnification microscope is used and the concentration level of the sample is 20x.
UriSed images are evaluated by the AIEM, an automatic, realtime image processing application that scans the image and identifies each urine sediment particle in it, as shown in Figure 3. The basis of the AIEM is a complex artificial neural network structure similar to that of the human brain. The development of the AIEM includes a sophisticated training process. As a result, the AIEM gains the knowledge of highly qualified professionals via a huge number of manually labelled images of all kinds of urine sediment particles. In this way, the AIEM can evaluate the trained particles with high accuracy. The algorithm upon which the AIEM classifies the particles in the image is similarly complicated as the way the human brain functions and it is beyond the scope of this article; for example, it
140
Sample is injected into cuvette
Centrifuge process is performed
Sample aspiration probe is cleaned
Cuvette is placed to first microscope position
Focusing process is performed
Image is taken by built-in camera
Cuvette is moved to next microscope position
Recorded images are evaluated
Results and HPF-like images are displayed
Results are forwarded to LIS system
Used cuvette is placed into the waste bin
HPF = high power field; LIS = laboratory information system.
EUROPEAN INFECTIOUS DISEASE
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92