Objective:To explore the effect of volume of the interest(VOI)on signal to noise ratio of magnetic resonance by selecting different VOI when performing proton magnetic resonance spectroscopy(1H-MRS)on healthy women of childbearing age. Methods:Fifty healthy women of childbearing age received pelvis MRS scanning with the Siemens 1.5 T MRI. MRS scanning chose the single voxel that set on the myometrium of the mid-sagittal of the uterus fundus and the TE chose 144 ms;each volunteer was scanned two times with the VOI respectively using 5 mm×5 mm×10 mm(group A)and 10 mm×10 mm×10 mm(group B). Two radiologists who had rich MRS diagnostic experience evaluated the spectroscopy of the Choline

Creatine

Lactate and the substance in 2 ppm in a double-blind way. Any one of the spectroscopy peak of these four substances higher than the average baseline height was regarded as positive

while less than or equal to the average baseline height was regarded as negative. Results:There were good consistency(κA=0.789

κB=0.852) and statistical significance(PA=0.000

PB=0.000) between two doctor’s evaluation. The positive rate was 20% in group A and 86% in group B evaluated by doctor A. The positive rate was 14% in group A and 82% in group B evaluated by doctor B. There were significantly statistical differences in two doctor’s evaluation between two groups(P1=0.000

P2=0.000);the positive rate in group B was higher than that of group A

and the average of the positive rate was 17% in group A and 84% in group B.Conclusion:The signal to noise ratio of the group A with VOI of 10 mm×10 mm×10 mm is better than that of the group B with VOI of 5 mm ×5 mm ×10 mm

so when we performed the MRS scanning in the uterus myometrium the VOI should not less than 1 cm~3.