Determination of experimental Tumor Volume of a mouse using optical imaging system in different processing stages

Fluorescence molecular imaging (FMI) in reflectance mode is a powerful method for providing valuable information about pathologic processes.Tumor growth is a common pathologic process which can be traditionally obtained by caliper measurement. The caliper measurement has several major disadvantages. However FMI method can be used as a non-invasibly method. The goal of this project is validating FMI of tumor growth by comparing it to traditional tumor volume measurement method such as caliper measurement. Here we used an animal tumor model to evaluate the extent on correlation between noninvasively measured fluorescence and traditional methods. BALB/c mice received subcutaneous injection of WEHI-164 cells. The tumor size was measured. Fluorescein was directly injected in center of the tumor. Serial measurements of fluorescence intensities were performed with FMI. After imaging, the mice were sacrificed and tumor was removed for weighting. The results showed that Spearman correlation coefficient between tumor volume and the maximum height of fluorescent intensity in the first, the second and the third group are 0.019, 0.5 and 0.09 respectively. The ROC analysis showed that the cutoff point of tumor volume and the weight are 93 mm3 and 0.12g respectively. The measurement of tumor growth in the BALB/c mice by imaging fluorescence correlates well with the traditional method of determining the tumor volume and with the increase in tumor weight that results from tumor growth. Given the great advantages of measuring fluorescence intensity, we conclude that FMI imaging is a the reliable and superior method for measuring experimental tumor growth in the small animals.