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Table 1 Heterogeneity factor (HF) for the uptake of AnxA5 and [18F]FDG in FaDu xenografts in four mice, the ratios between their calculated HFs and the effects of altering post-scan processing parameters on these HFs and their ratios

From: A method for comparing intra-tumoural radioactivity uptake heterogeneity in preclinical positron emission tomography studies

Tracer HFa Alternate permutationb Reconstructionc Image sized VOI volume changee Cut-off limitf
   Coronal Sagittal FBP 256 × 256 ≈ +20 % ≈ −20 % →2 mm
AnxA5 0.1342 0.0545 0.0930 0.1004 0.0827 0.1620 0.1363 0.0287
[18F]FDG 0.1006 0.0377 0.0677 0.0869 0.0376 0.1334 0.0723 0.0157
Ratiog 1.334 1.446 1.374 1.155 2.199 1.214 1.885 1.828
AnxA5 0.3570 0.0892 0.1328 0.2881 0.1036 0.3354 0.1976 0.2351
[18F]FDG 0.3101 0.0751 0.1061 0.1911 0.0805 0.2710 0.1115 0.1480
Ratiog 1.151 1.188 1.252 1.508 1.287 1.238 1.772 1.589
AnxA5 0.2558 0.0724 0.0919 0.1694 0.0825 0.2856 0.2708 0.0944
[18F]FDG 0.1147 0.0310 0.0442 0.0982 0.0389 0.1879 0.0783 0.0209
Ratiog 2.230 2.335 2.079 1.725 2.121 1.520 3.458 4.518
AnxA5 0.3036 0.0701 0.0940 0.2870 0.0825 0.3701 0.2169 0.0966
[18F]FDG 0.1199 0.0255 0.0330 0.0955 0.0321 0.0991 0.0818 0.0292
Ratiog 2.532 2.749 2.848 3.005 2.578 3.735 2.652 3.308
  1. aHF for VOIs drawn as in “Methods” (“VOI definition” section), axial (Z-axis) planes, OSEM2D reconstruction, 512 × 512 pixels and the lower cut-off for resolution at centre of field-of-view (FOV) at 1.2 mm
  2. bPermutation for the planes in the VOI to be along the X- (coronal) or Y- (sagittal) axis instead of the Z-axis
  3. cFiltered back projection reconstruction was used instead of OSEM2D
  4. dThe pixel size was dubbled
  5. eThe size of the VOI used in the HF calculations was increased or decreased by 20 %
  6. fLower cut-off limit changed from resolution at CFOV (1.2 mm) to that toward the outer edge of FOV (2.0 mm)
  7. gRatio = HFAnxA5/HFFDG