Noninvasive imaging should facilitate the analysis of changes in experimental
tumors and
metastases-expressing
photoproteins and result in improved data consistency and experimental animal welfare. We analyzed quantitative aspects of noninvasive imaging of
luciferase-labeled
tumors by comparing the efficiency of noninvasive light detection with in vitro quantification of
luciferase activity. An intensified charge coupled device video camera was used to noninvasively image
luciferase-expressing human prostate
tumors and
metastases in nude mice, after ip inoculation of
luciferin. Repeated imaging of anesthetized animals after intervening growth periods allowed monitoring of
tumor and
metastases development. Comparison of photon events recorded in
tumor images with the number of relative light units from luminometric quantification of homogenates from the same
tumors, revealed that the efficiency with which light escapes
tumors is inversely related to
tumor size and that intensified charge coupled device images alone are not sufficient for quantitative evaluation of
tumor growth. However, a combined videometric and luminometric approach did allow quantification and was used to show the
cytostatic effects of
paclitaxel in three different human prostate
tumors growing in nude mice.