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Table 2 Description of semiquantitative histology scores

From: In vivo canine study of three different coatings applied to p64 flow-diverter stents: initial biocompatibility study

  0 (none) 1 (minimal) 2 (mild) 3 (moderate) 4 (severe)
Endothelium
 Endothelial loss None < 25% of the circumference 25–50% of the circumference 51–75% of the circumference > 75% of the circumference
Tissue matrix
 Surface (fibrin/platelet deposition) None Minimal, focal Mild, multifocal Moderate, regionally diffuse Severe, marked diffuse, or total luminal occlusion
Inflammation
 Intima/media None < 20 inflammatory cells/HPF in < 25% of area 21–100 inflammatory cells/HPF in 25–50% of area 101–150 inflammatory cells/HPF > 51–75% of area > 150 inflammatory cells/HPF > 75% of area
 Adventitia None < 25% of area 25–50% of area > 51–75% of area > 75% of area
Haemorrhage
 Media None Focal, occasional Multifocal and regional Regionally diffuse 100% red blood cells
 Adventitia None Focal, occasional Multifocal and regional Regionally diffuse 100% red blood cells
Medial cell loss
 Medial smooth muscle loss (depth) None < 25% of medial thickness 25–50% of medial thickness 51–75% of medial thickness > 75% of medial thickness
 Medial smooth muscle loss (circumference) None < 25% of circumference 25–50% of circumference 51–75% of circumference >  75% of circumference
Adventitial fibrosis
 Adventitial fibrosis None < 25% of the area 25–50% of the area 51–75% of the area > 75% of the area
Medial injury/rupture
 Medial injury None Partial disruption involving the medial wall (focal disruption of the internal elastic lamina) Complete medial disruption with containment (intact external elastic lamina) Complete disruption of the arterial wall involving the media Complete disruption of the arterial wall involving the media
  1. HPF high-power field