Imaging of Orthotopic Glioblastoma Xenografts in Mice Using a Clinical CT Scanner: Comparison with Micro CT and Histology
Purpose There is an increasing need for small animal in vivo imaging in murine orthotopic glioma models. Because dedicated small animal scanners are not available ubiquitously, the applicability of a clinical CT scanner for visualization and measurement of intracerebrally growing glioma xenografts in living mice was validated. Materials and Methods 2.5x106 U87MG cells were orthotopically implanted in NOD/SCID/gc mice (n 9) Mice underwent contrast enhanced (300 ml Iomeprol i.v. imaging using a micro CT (80 kV, 75 mAs, 360deg rotation, 1,000 projections, scan time 33 s, resolution 40 x 40 x 53 mm) and a clinical CT scanner (4 row multislice detector; 120 kV, 150 mAs, slice thickness 0.5 mm, feed rotation 0.5 mm, resolution 98 x 98 x 500 mm) Mice were sacrificed and the brain was worked up histologically. In all modalities tumor volume was measured by two independent readers. Contrast to noise ratio (CNR) and Signal to noise ratio (SNR) were measured from reconstructed CT scans (0.5 mm slice thickness; n 18) Results Tumor volumes (mean+ SD mm3) were similar between both CT modalities (micro CT: 19.8+ 19.0, clinical CT: 19.8+ 18.8; Wilcoxon signed rank test p 0.813) Moreover, between reader analyses for each modality showed excellent agreement as demonstrated by correlation analysis (Spearman Rho >0.9; p<0.01 for all correlations) Histologically measured tumor volumes (11.0+ 11.2) were significantly smaller due to shrinkage artifacts (p<0.05) CNR and SNR were 2.1+ 1.0 and 1.1+ 0.04 for micro CT and 23.1+ 24.0 and 1.9+ 0.7 for the clinical CTscanner, respectively. Conclusion Clinical CT scanners may reliably be used for in vivo imaging and volumetric analysis of brain tumor growth in mice.
PloS one