GD is one of the most common lysosomal storage disorders. The deficiency of acid β-glucosidase causes the accumulation of the glucocerebroside in macrophages throughout the body. Spleen, liver and bone marrow are common organs involved. Dynamic observation is needed to monitor the disease progress and therapy efficacy during the longer-term treatment of this genetic disorder. Few reports have been published on the measurement of the volume and lipid content of liver and spleen using MR among children and adolescents with GD, at where MR is particularly useful for its non-radiation. Dixon technique has been widely used in measuring the fat fraction of body because of the ability of separating water and fat signal within one breath hold scan^1,2. This work is to validate the feasibility of measuring the volume and lipid content of children and adolescent GD patients’ liver and spleen using MR.25 male and 17 female bone marrow biopsy confirmed GD patients (7 to 31 years old, mean age 17.3), including 39 cases of typeⅠand 3 cases of type Ⅲ, were involved. Twelve patients had undergone total splenectomy. All patients have undergone the enzyme replacement therapy for an average of 8.4 years (5-16 years). MRI was performed on a Philips Ingenia 1.5T MR with coronal 3D FFE mDIXON and T2WI-STIR sequences. The fat fraction was derived from the water and fat images of mDXION sequence (FF = fat/(fat + water)). The volume of liver and spleen was measured on T2WI-STIR sequence images by home-made semi-automatic software (Figure A and B) and was normalized by the body weight (mL/kg). The lipid content of spleens was compared with that of their own livers by paired T test among 30 patients who didn’t have splenectomy. Statistical significance level with P＜0.05 was considered as significant.The mean volume of total 42 liver was 1679.96±513.34 mL, ranged from 870.38 to 3243.46 mL and the corresponding volume index was 33.66±6.03 (25.15-48.99) mL/Kg (Figure C). The mean volume of total 30 spleen was 745.52±398.51 mL, ranged from 227.46 to 1681.15 mL with corresponding volume index was 16.36±10.65(4.48-56.04)mL/Kg(Figure D). Liver lipid content value range of 4.63-10.09%, the average was 5.90 ±1.10%. Spleen lipid content range of 4.78-19.39%, the average was 6.63±2.62%. There was statistical difference between the lipid content of patients’ livers and spleens (P=0.039) (Figure E).The volume index smaller than 25 mL/kg in liver and 2mL/kg in spleen is considered as normal respectively³. The enlargement of spleen (8 times normal) was more severe than liver (1.3 times normal) in those patients. Normal liver lipid deposition is 1.8 (0.5-3.5) %⁴. Non-alcoholic fatty liver disease is defined as the FF higher than 5%⁵. In this work, both liver and spleen exhibited a higher FF than normal. And the fat deposition in spleen was higher than that in liver. The fat fraction derived from the mDXION technique may be affected by the short T2* of tissue, such as in liver with iron deposition. However, none of patients involved in this work have obvious iron deposition according to the comparison between in-phase images and out-phase images. The result that both the enlargement and fat deposition of spleen were larger than those of liver was consistent with pathological findings.The enlargement and fat deposition of liver and spleen in children and adolescent patients with GD could be measured using Dual-echo mDixon sequence and T2WI-STIR sequences. So MRI can be employed to monitor the progression and effect of the treatment for children and adolescent patients with GD.