Comparison of Ultrasonographic Images of Glioblastoma Tumor with Magnetic Resonance Images: Rat Animal Model

Magnetic Resonance Imaging (MRI) can guide the surgical strategy to identify brain tumors and monitor treatment response. It is possible to use transcranial Ultrasound (US) for periodical follow-ups. Ultrasound waves pass through the delicate areas of the skull called acoustic windows. In this study, the efficiency of ultrasound imaging was performed to diagnose glioblastoma brain tumors and the results were compared with MR images.

Male Wistar rats were anesthetized by intraperitoneal injection of Ketamine and Xylazine. A stereotaxic device was used to determine the injection coordinates. C6 GBM cell lines were injected into the brains of rats. After two weeks, the formation of a glioblastoma tumor was confirmed histopathologically. The brain of animals was imaged by B-mode ultrasound and MRI. The section with the largest tumor dimensions was selected and the dimensions of the skull and tumor were measured based on the pixel size of each of the imaging methods. Pearson coefficient of correlation and Limits Of Agreement (LOA) were calculated for comparisons of the skull and tumor dimensions.

The skull and the tumor dimensions showed a significant correlation between the B-mode ultrasound and the MRI measurements (R=0.99 and p<0.05). According to the Bland-Altman analysis, the mean difference was 0.31 mm (SD=0.20) for skull and tumor dimensions. The exact shape of the tumor is not completely clear in the ultrasound images, but it can be useful to detect the presence of the tumor and its approximate dimensions.

In conclusion, a glioblastoma tumor was produced in the male Wistar rat. The tumor dimensions were properly assessed by B-mode ultrasound image processing and compared with MR imaging.