ABSTRACT
@#The study aims to establish a human gastric cancer orthotopic transplantation model in nude mice and to use 7T MRI for detection. After poorly differentiated human gastric adenocarcinoma SGC-7901 cells were injected subcutaneosly into the right flanks of nude mice, the model of in nude mice was established with orthotopic transplanted cancer of gastric tumor by the Compont® gel pasted method. 7T MRI scan was conducted on the mice after operating model about 20 days later. Histopathological examinations were carried out on the stomach. Two of three mice on which 7T MRI scan were performed showed visible suspected stomach tumor and their presence was verified again by histopathological examinations; tumor formation rate in the nude mice gastric orthotopic transplantation model was 66. 7%. This study suggested that 7T MRI could be used in the live detection of in situ tumor and that MRI could be used for pre-clinical gastric cancer drug development and clinical gastric carcinoma diagnosis.
ABSTRACT
PURPOSE: To compare the depiction of brain metastases on contrast-enhanced images with 7.0 tesla (T) and at 1.5T MRI. MATERIALS AND METHODS: Four consecutive patients with brain metastases were scanned on 7.0T whole-body scanner and 1.5T MRI. A 3D T1-weighted gradient echo sequence (3D T1-GRE) at 1.5T (voxel size = 0.9 x 0.9 x 1.5 mm3 after double-dose, gadoterate meglumine, Gd-DOTA) was compared to a 7.0T 3D T1-GRE sequence (voxel size = 0.4 x 0.4 x 0.8 mm3, single-dose Gd-DOTA) in four patients after a 5 minute delay. The number of contrast-enhancing metastases in MPRAGE images was compared in each patient by two radiologists in consensus. We measured contrast ratio of enhancing brain metastases and white matter in 1.5T and 7.0T. RESULTS: In all four patients 7.0T 3D T1-GRE images after single-dose Gd-DOTA and 1.5T after double-dose Gd-DOTA depicted 11 brain metastases equally. In the quantitative analysis of contrast ratios of enhancing brain metastases and white matter, the 1.5T 3D T1-GRE after double-dose showed an increased contrast ratio compared to 7.0T 3D T1-GRE after single-dose (0.961 +/- 0.571 versus 0.885 +/- 0.494; n = 11 metastases). But this difference was not statistically significant (P = 0.711). CONCLUSION: Our preliminary results indicate that 7.0T single-dose Gd-enhanced images were not different to 1.5T double-dose Gd-enhanced images for the detection of brain metastases.