International Journal of Cell Cloning, Vol 2, 142-160, Copyright © 1984 by AlphaMed Press
Evaluation of an automated image analysis system for counting human tumor colonies
SE Salmon, L Young, J Lebowitz, S Thomson, J Einsphar, T Tong and TE Moon
The Omnicon FAS II image analysis system was applied to counting tumor
colonies grown in a soft agar human tumor clonogenic assay with a detailed
protocol designed to assess the instrument's sensitivity, specificity,
precision, and accuracy. Comparisons of technician and instrument counts
were done on a blinded basis. Sensitivity studies (which used metal
microspheres) yielded a correlation coefficient (r) of 0.999 between
technicians and the counter. A field-by-field analysis of the instrument's
specificity for identifying individual objects correctly as tumor colonies
rather than artifacts (as identified by the technician) was excellent (r =
0.95). In the precision studies (determined with repeated automated
counting of the same samples for five days), the median coefficient of
variation was less than 7%. Accuracy was evaluated on cultures of fresh
biopsies from 30 human cancers obtained for drug sensitivity testing as
well as on a series of tumor cell lines. The correlation between the mean
number of colonies counted by the technicians and by the colony counter was
greater than 0.91. Similar comparisons of mean percent survival of tumor
colony- forming cells after drug exposure between technician and machine
were also quite acceptable (r = 0.85). We conclude that the colony counter
provided sufficient reliability to be applied to counting human tumor
colonies grown in vitro. In addition, the colony counter performed the
Petri dish counts ten times faster than experienced technicians and without
associated operator fatigue.
