Chemical exchange saturation transfer imaging and diffusion weighted imaging for colon 26 tumor bearing mice.

We aimed to assess tumor growth and cell density in colon cancer-bearing mouse models using CEST and diffusion-weighted imaging (DWI). Mouse carcinoma models were created by transplanting the mouse colon cancer cell line colon-26. They were divided into three groups at 6, 8, and 10 days after transplantation and underwent T2WI, CEST, and DWI using 7T-MRI. The Magnetization Transfer Ratio asymmetry (MTR) of 1.2 ppm reflecting hydroxyl metabolite in CEST imaging and the apparent diffusion coefficient (ADC) of the same region were statistically analyzed for each group. The MTR and ADC values were 6.51 ± 3.47% and 1.14 ± 0.34 × 10− 3 mm2/s, 3.65 ± 1.65% and 0.77 ± 0.20 × 10− 3 mm2/s, and 2.84 ± 0.82%, and 0.54 ± 0.02 × 10− 3 × mm2/s on days 6, 8, and 10, respectively. The MTR and ADC values were high at 6 days after cell transplantation, and both values tended to decrease with tumor growth. These results indicate that hydroxyl metabolism was high on the sixth day, and both values decreased after the eighth day. CEST imaging and DWI may be useful markers of cell proliferation and metabolism in tumors.