The machine as a second reader
Unit 8 of 8
See which criteria the eight inputs touch, where the model and the expert disagree, and which criterion decides it.
The model reads eight numbers, all of them from nuclei: three sizes, one texture, and three shape values off the traced outline. That is the whole of what it sees. The panel below lists them against the criteria they touch, and beside them the criteria nothing here measures.
Its weakest link is not the mathematics, it is the scale. The coefficients were fitted on 569 patients measured on a 1990s camera at an unknown pixel scale, and the bridge from our 0.25 microns per pixel to theirs was fitted on four benign slides. Treat its odds as a second opinion from a reader who has seen only nuclei.
In the drills you commit first, then the call appears, then you are asked who is right and which criterion decides it. Only your first commit is scored. Agreement is tracked separately, on the Progress page.
What the outline measures
The eight inputs are the 1993 definitions, computed on our own 64 point outlines. The panel below pairs each one with the criterion it touches, and lists what no measurement on this site captures.
C5 Malignant
An unequivocal statement that the material is malignant, and the type of malignancy identified should be stated whenever possible.
- Risk of malignancy
- 99 to 100 percent
- Management
If the triple test is concordant, proceed to definitive management; if discrepant, CNB or excision biopsy is mandatory.
The worked example
Loading the case library.
What the machine sees
The eight inputs
- worst radius
- mean of the three largest nuclei's mean radius. Touches nuclear enlargement.
- worst perimeter
- mean of the three largest nuclei's perimeter. Touches nuclear enlargement.
- worst area
- mean of the three largest nuclei's area. Touches nuclear enlargement.
- worst texture
- standard deviation of grey values inside the three largest nuclei. Touches chromatin, in part.
- worst smoothness
- local variation in radius length, three largest nuclei. Touches pleomorphism of the nuclear margin.
- worst concavity
- severity of concave portions of the outline, three largest nuclei. Touches pleomorphism of the nuclear margin.
- worst concave points
- number of concave portions of the outline, three largest nuclei. Touches pleomorphism of the nuclear margin.
- mean concave points
- number of concave portions of the outline, every nucleus. Touches pleomorphism of the nuclear margin.
Not measured here:
- cohesion and architecture (sheets, three-dimensional fragments, dispersal)
- myoepithelial cells and bare bipolar nuclei
- nucleoli
- cellularity of the whole smear
- the background (stroma, mucin, cyst fluid, pus, fat)
- necrosis
- mitoses
A reader who sees only the first column can be right about the size of the nuclei and wrong about the smear. That is why your call comes first and the model answers second.
The reliability diagram and the calibration table are on the explainer, under Model. They show how far the odds can be trusted, on the 569 patients the model was fitted on.
About 20 trials, 5 to 8 minutes. You can stop at any point.