Table 2 Quantification of the U-NET efficiency of the two-step segmentation process for 220 images, mean ± s.d

From: Dermal features derived from optoacoustic tomograms via machine learning correlate microangiopathy phenotypes with diabetes stage

Step 1. Segmentation of the whole skin layer regions (epidermal/SVP layer, dermal layer)

Segmented region

U-NET vs Operator A

U-NET vs Operator B

Operator A vs Operator B

Dice score

Cohen’s Kappa coefficient

Hausdorff distance

Dice score

Cohen’s Kappa coefficient

Hausdorff distance

Dice score

Cohen’s Kappa coefficient

Hausdorff distance

Epidermal/SVP layer

0.91 ± 0.01

0.89 ± 0.01

29.61 ± 2.18

0.87 ± 0.02

0.85 ± 0.02

34.54 ± 3.27

0.90 ± 0.02

0.89 ± 0.02

21.00 ± 2.99

Dermal layer

0.89 ± 0.01

0.83 ± 0.01

65.80 ± 3.29

0.86 ± 0.01

0.79 ± 0.01

73.11 ± 4.04

0.91 ± 0.01

0.87 ± 0.01

40.52 ± 3.06

Step 2. Segmentation of the microvasculature within the skin layers (epidermal/SVP layer, dermal layer)

Segmented microvasculature

U-NET vs Adaptive thresholding/tubeness filter

Dice score

Cohen’s Kappa coefficient

Hausdorff distance

Epidermal/SVP layer

0.90 ± 0.01

0.89 ± 0.01

23.35 ± 0.91

Dermal layer

0.87 ± 0.01

0.85 ± 0.01

39.00 ± 1.86