Many studies have shown that changes in the blood circulation is associated with the loss of bone mineral density(BMD), but there is still no related research results show the physiological mechanism of this relationship. This study utilized dynamic contrast enhanced (DCE) MRI and blood oxygen level dependent (BOLD) MRI as imaging method, using half quantitative analysis of two kinds of methods to study the relationship between the marrow blood perfusion, oxygen metabolism and bone mineral density. Fifty two elderly females (age 65±4.9 yrs) were studied. They all recruited to undergo BOLD imaging of the lower limb using a 3T whole body scanner (Achieva TX, Philips Healthcare) and DCE imaging of 1.5T (Intera NT, Philips, Best, Netherlands). Bone mineral density (BMD) was measured by dual energy X ray absorptiometry (DXA) and we classified the subjects to three classes based on BMD: normal, osteopenia, osteoporosis. Axial T1 weighted (TR/TE,450/11 ms; 4 mm thick) and DCE MRI (2.7/0/95; prepulse inversion time, 400 ms; flip angle, 15°) data were acquired through the mid L3 vertebral body region. T2* weighted sequence (TR/TE 372/40 ms; slice thickness 5 mm; NEX 1; FOV 330 mm; dynamic measurements 2400; scan time 900s) and BOLD MRI data were collected through the upper end of crus shin.This research applied pharmacokinetic Brix model to study bone marrow perfusion of spine and extract reliable parameters from DCE MRI data. A region of interest (ROI) was drawn manually on bone marrow area (Fig.1) and the time signal intensity curve generated by averaging signal intensity within the ROI and curve fitting was based on nonlinear least squares fitting. Then we can get the constant parameters:A, kep and kel, where A refers to the absorption intensity of contrast agent, kep was the rate constant that contrast agent from the clearance space to the plasma, kel was the change rate of contrast medium in plasma.We can calculate the characteristic parameters of fitting curve simultaneously (Fig.2): maximum enhancement (MaxEn), maximum rising slope (MaxSlope). As for BOLD MRI data, ROI was also drawn manually in the marrow region of BOLD images and used time signal intensity curve to analyze BOLD MRI signals and extracted four parameters: Halflife, minimum ischemic value (MIV), Slope, hyperemia peak value (HPV).All statistical analyses were performed using SPSS 19.The results of DCE MRI experiment obtained from the 52 subjects are shown in Table 1 and the results of BOLD MRI experiment are shown in Table 2. Significant differences were observed in A, MaxEn and Halflife parameters among different BMD groups (p<0.05). Firstly, this study commendably combined DCE MRI method and BOLD MRI method to investigate the relationship between oxygen metabolism and bone mineral density, which provided a more reliable and robust analysis and can versatilely expound the process of marrow blood perfusion. Secondly, the parameters A and MaxEn all diminished with the decrease of BMD in the DCE MRI experiment (p<0.05). The parameters A reflected that the total blood volume in marrow of osteoporosis subjects, which contained the vascular volume and the gap volume outside vessels, was significantly reduced compared to normal subjects. The parameters MaxEn reduced maybe indicated that the arterial permeability in the osteoporosis subjects was declined so that the maximal MRI signal intensity would be down under same conditions. Thirdly, in the different BMD groups of BOLD MRI experiment, although only the parameter Halflife had significant difference, the normal subjects and the osteoporosis subjects also had a big difference in other parameters (Table 2). The parameter Halflife reflects the blood oxygen metabolism ability of marrow in the condition of ischemia. The normal subjects had smaller vaule of Halflife compared with low BMD groups meant that normal subjects had a stronger ability of oxygen metabolism.In conclusion, different BMD groups has significant difference in perfusion ability on marrow. There is a link between the bone mineral density and marrow blood circulation and metabolism of oxygen. The changed blood circulation may be one of the reasons induced osteoporosis.