A New Biometric Tool for Three-Dimensional Subcutaneous Tumor Scanning in Mice

To propose an innovative methodology for the monitoring of the evolution of induced subcutaneous tumors in mice. Materials and Methods: A new 3D scannerable to measure the tumor mass volume is presented. The scanner is based on the projection of a fringe pattern onto the sample surface (structured light). The lines are diffused by the sample and then collected by a digital camera. The obtained 2D-image is treated by the scanner’s software thatextracts the 3D information and evaluates the samplevolume. Results: The 3D scanner has been successfully used in the measurement of subcutaneous HT-29 colorectal cancer xenografts treated with 5-fluorouracil, bevacizumab and their combination. Comparison with simple caliper measurements revealed important and significant differences between the two measurement techniques. Conclusion: The proposedmethodology is more effective than the usual approach basedon caliper measurements.The efficacy of a new anticancer drug should be alwaysverified by means of the so-called experimental model of the disease, where the characteristics of the disease are recreated in cell cultures, grown in the laboratory (in vitromodels) orin laboratory animals (in vivo models) (1). Considering the latter case, tumors may be induced in mice by subcutaneous injection of human tumor cells. Subcutaneous human tumor xenograft models are widely used because they recapitulate many aspects of the biology of human tumors, including sensitivity to anticancer agents (2). Once cancer cells areinoculated, the researchers carry out treatment with the anticancer drug and follow the daily evolutions in the shape and in volume of the tumor. The tumor mass volume of treated and non-treated mice must be statistically compared in order to assess the reliability of the treatment. The testin gof human tumors in subcutaneous sites have provided relevant and predictive information to the clinic. In fact,every clinically-approved anticancer drug was tested usingthis model, and showed significant antitumor effects beforeentering early-phase clinical trials (2).Although some experimental devices are available for the measurement of tumor volume from 3-dimensional images(computed axial tomography, positron-emission tomography,and magnetic resonance imaging), these systems are primarily designed for biological, chemical, and functionalstudies of animal models (3). As well-stated by Girit and colleagues, these devices usually require many preparative efforts and expensive materials (radioactive sources, contrastagents, and fluorescent chemicals), thus their use is notpractical for animal testing facilities (4).On the basis of these considerations, in partnership withPOEMA (Progettazioni Opto-Elettroniche MetrologiaAvanzata; Cagliari, Italy; www.poemaonline.eu), we developed an innovative small non-contact device (3Dscanner) capable of rapid, highly reproducible measurements of subcutaneous tumor volumes in mice. We outline the prototype characteristics, describing hardware and software features, and give some practical examples of its use.