In Vivo 3T Magnetic Resonance Imaging (MRI) of Rat Brain Glioma-Bearing Tumor: A Comparison with Digital Caliper Measurement and Histology

Abstract

Purpose: A major obstacle in brain tumor surgery is to precisely identify the boundaries of the tumor for maximal elimination without any residual tumoral tissues. Gliomas have the same color and texture as the normal brain tissues, which impose a major burden for neurosurgery. Recently, 3 Tesla Magnetic Resonance Imaging (MRI) scanners have demonstrated the potential for sub-millimeter anatomical imaging. Considering the growing importance of small animal imaging in pre-clinical research, the purpose of the present study was to evaluate the ability of contrast-enhanced MRI to determine glioma tumor volume in comparison with Caliper and Histology.
Materials and Methods: Thirteen rats were anesthetized, and fixed in stereotactic frame. C6 cells were injected into the right cortex of rats. Fourteen days later, rats were evaluated with 3 Tesla MRI equipped with a head receiver coil. Two hours before imaging, the Magnetic Nano-Particles (MNPs) were injected  through the tail of the rats, before they were placed in a magnetic field (1.3 Tesla). Axial and coronal sections of the brain were obtained with a T2-weighted turbo-spin-echo protocol. Finally, rats were sacrificed and their brains were fixed in formalin for measuring the tumor volume with Caliper, and Hematoxylin and Eosin (H&E) staining.
Results: The results of calculating tumor volume by MRI, caliper and H&E were 72.6±7.3mm³, 61±11.1mm³ and 76.4±7.8mm³, respectively. There was no significant difference in tumor volume between MRI and H&E (P= 0.24), while, there was a significant difference between MRI and caliper data (P< 0.05).
Conclusion: According to the results, it is not easy to discriminate the delicate border between normal tissue and Glioma tumor by the naked eye. However, H&E staining may help separate the boundary between normal tissue and tumor with a high precision at the cellular level. Comparing the results of 3 Tesla MRI with both the results from H&E and caliper indicated that there was not a significant difference between the findings of MRI an H&E staining, thus, MRI could be recognized as an acceptable method for non-invasive tumor volume measurement.