MR-pathological comparison in F98-Fischer glioma model using a human gantry

This study reports our findings in assessing in vivo tumour growth with magnetic resonance imaging using a commercial magnet and antenna in F98 implanted Fischer rats. A comparison of T1 gadolinium-enhanced coronal MR scans and pathology specimens in corresponding animals was accomplished.

One rat was used in serial experiments to establish adequate imaging parameters. Afterward, 12 animals implanted with F98 cells underwent a MR study following intervals spanning five, ten, 15 and 20 days on a 1.5T human Siemens. Using a small loop antenna, a coronal T1 weighted MRI scan with Gadolinium was performed. Images were analyzed and volumes of enhancing tumour were calculated. The animals were sacrificed after the imaging procedure and brain were harvested and processed in pathology. Pathology specimens and MR images were analyzed using image processing software. One hematoxylin + eosin (H&E) slide per specimen was compared to the corresponding MR slice depicting the largest area of enhancement.

The MR enhancement areas obtained were 2.18 mm2, 8.25 mm2, 21.6 mm2 and 23.17 mm2 at five, ten, 15 and 20 days. Tumour margin measurements on pathologic samples produced areas of 0.29 mm2, 4.43 mm2, 8.3 mm2, and 12.9 mm2 at five, ten, 15 and 20 days respectively.

The T1-enhancing images constantly overestimated the tumour bulk on H&E. This phenomenon is explained by enhancement of the brain around tumour, the extra-axial tumour growth, and a shrinking factor of 17% related to the fixation process. Nonetheless, the radiological tumour growth paralleled the histological samples. This technology is thus suitable to follow tumour growth in F98 implanted rats.