Rationale and objectives: The diagnostic potential of tumor microvasculatures with the monochromatic synchrotron radiation microangiography (MSRA) system was examined in an experimental model using athymic nude rats.
Materials and methods: In the lower abdominal wall in athymic nude rats (male, 120-150 g, 6 weeks old), 1 x 10(7) cells of N-nitrosomethylurea-induced rat mammary adenocarcinoma was transplanted to prepare a lower abdominal wall tumor transplanted model. A microcatheter was inserted in the abdominal aorta in a rat under anesthesia, and microangiographic images of the normal inferior epigastric artery and vein were obtained using an MSRA system. Changes in the tumor microvasculatures were observed using an MSRA system on the day 7 (n = 3), day 14 (n = 3), day 21 (n = 3), and day 28 (n = 3) after transplant. In addition, we measured the microvessel density (MVD) with a computer using the binarization method. These results were compared among the histologic MVDs.
Results: The microvasculatures of tumors measuring 20-30 microm were observable by the MSRA system in the transplanted tumor model using the inferior epigastric artery and vein as the feeding vessels. The tumor microvasculatures were observed for 7-28 days after transplantation. The tumor MVD obtained by the binarization method increased as the tumor volume increased. When histologic MVD was compared with the fixed quantitative results of angiographic MVD, a significant correlation (r = 0.933, P <.01) was observed.
Conclusion: These preliminary investigations indicate that MSRA proved to be suitable for quantification and appears to be a simple method for clearly imaging tumor microvasculatures.