ABSTRACT
Objective: To establish a curve of dosage gradient-liver signal intensity of superparamagnetic iron oxide (SPIO) in normal rats and to find an appropriate dose for enhancement. Methods: Seventy-two SD rats, 4 rats a group at random, underwent MR enhancement with 0, 2, 5, 8, 10, 12, 15, 20, 30, 40, 50, 60, 70, 80, 100, 140, 210, 280 μmol/kg SPIO respectively after plane examination. The signal-to-noise ratio of liver was measured and a curve of dosage gradient-liver signal intensity was made. Results: (1)With the increase of SPIO dose, the signal intensity of both T1 and T2 weighted images of liver declined. (2)T2 weighted images was more sensitive than T1 weighted images in small dose, the ED50 of T1 weighted was 8 μmol/kg, and the ED50 of T2 weighted was 5 μmol/kg. (3)When the dose was greater than 15 μmol/kg, the signal intensity of T1 weighted images declined more rapidly than T2 weighted, the effect of enhanced T1 weighted images resembled T2 weighted ones, and its images was with more fine resolution. (4)At the dose of 40 μmol/kg, the signal intensity of T1 weighted images approached the background noise, and at the dose of 15 μmol/kg, the signal intensity of T2 weighted images approached the background noise. Conclusion: Good effect of T1 and T2 enhanced MR imaging can be acquired at the dose of 20-10 μmol/kg SPIO respectively, the best contrast-to-noise ratio is found on T2 weighted enhanced MR image.
ABSTRACT
Objective: To establish a curve of dosage gradient-liver signal intensity of superparamagnetic iron oxide (SPIO) in normal rats and to find an appropriate dose for enhancement. Methods: Seventy-two SD rats, 4 rats a group at random, underwent MR enhancement with 0, 2, 5, 8, 10, 12, 15, 20, 30, 40, 50, 60, 70, 80, 100, 140, 210, 280 μmol/kg SPIO respectively after plane examination. The signal-to-noise ratio of liver was measured and a curve of dosage gradient-liver signal intensity was made. Results: (1)With the increase of SPIO dose, the signal intensity of both T1 and T2 weighted images of liver declined. (2)T2 weighted images was more sensitive than T1 weighted images in small dose, the ED50 of T1 weighted was 8 μmol/kg, and the ED50 of T2 weighted was 5 μmol/kg. (3)When the dose was greater than 15 μmol/kg, the signal intensity of T1 weighted images declined more rapidly than T2 weighted, the effect of enhanced T1 weighted images resembled T2 weighted ones, and its images was with more fine resolution. (4)At the dose of 40 μmol/kg, the signal intensity of T1 weighted images approached the background noise, and at the dose of 15 μmol/kg, the signal intensity of T2 weighted images approached the background noise. Conclusion: Good effect of T1 and T2 enhanced MR imaging can be acquired at the dose of 20-10 μmol/kg SPIO respectively, the best contrast-to-noise ratio is found on T2 weighted enhanced MR image.