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Table 1 Grey-level size-zone matrix features

From: PEGylated recombinant human hyaluronidase (PEGPH20) pre-treatment improves intra-tumour distribution and efficacy of paclitaxel in preclinical models

Abbreviation Name Description Mathematical formula
ZP Zone percentage lower values indicate that the image is made of a few large zones with the same grey-level. Higher values indicate greater fragmentation of the image into small zones nzones/npix
LZE Large zone emphasis associated with the presence of wide areas with similar drug concentrations, regardless of whether they are low or high ij Zijj2 /nzones
HGZE High Grey-level Zone Emphasis indicative of the presence of areas with high drug concentrations, regardless of their size ij Ziji2 /nzones
LZHGE Large-zone High Grey-level Emphasis focuses on the presence of wide areas with high drug concentrations ij Zijj2 i2 /nzone
IV Intensity variability highest when there are few large zones with low drug concentrations. It decreases when the concentration increases and smaller zones are formed with higher drug concentrations i (∑j Zij)2/i4/nzones
GLNn Grey-Level Non-uniformity normalised highest when zones concentrate to a single grey level, lower when all grey levels are equally represented (poorly sensitive to redistribution among grey levels) (∑i (∑j Zij)2 /nzones)/nzones
ZSμ Zone Size mean average size of the zones, independently of the grey level. Strongly affected by the presence of a large number of small zones ij Zijj /nzones
DHI Drug-homogeneity index a recently proposed feature measuring the average area of the larger zones (over a given arbitrary threshold ν) as a fraction of the ROI area i,j ≥ ν j Zij /∑i,j ≥ ν Zij /npix
  1. i: grey levels; j: zone sizes; nzones: total number of zones; npix: total number of pixels in the ROI