ABSTRACT
Background: To assess whether the fat signal intensity and fat fraction (FF) of the lumbar vertebrae as measured on the Dixon chemical shift magnetic resonance imaging (MRI) technique can be correlated with the lumbar vertebra bone mineral density (BMD) measured using dual-energy X-ray absorptiometry (DXA). Methods: Forty-five patients were retrospectively collected, and 180 lumbar vertebral bodies (L1-L4) were included. All patients underwent DXA and MRI examinations of the lumbar spine. Taking the T value of DXA as the gold standard and using the diagnostic criteria of the World Health Organization: T score ≥ -1.0SD as normal, -1.0 ~ -2.5SD as osteopenia, and ≤ -2.5SD as osteoporosis. Meanwhile, the signal intensity on T2WI was measured, and FF of L1-L4 vertebral bodies was calculated on MRI images. Bone marrow fat FF calculation formula: FF = [Mfat/(Mfat + Mwater)] × 100% (Mwater and Mfat refer to the total pixel signal intensity value of the region of interest in water image and lipid image, respectively). Finally, the association of signal intensity and FF with DXA was evaluated. Results: Totally 180 vertebral bodies in 45 patients were enrolled. According to the T value, they were divided into the normal group (n = 70), osteopenia group (n = 40), and osteoporosis group (n = 70). The fat signal intensity of the normal group, osteopenia group, and osteoporosis group were 96.6 ± 21.8, 154.5 ± 48.7, 216.3 ± 92.6, and the FF were 30.1 ± 6.2%, 52.6 ± 7.6%, 77.5 ± 7.9%, respectively. Among the three groups, the lumbar T2 fat signal intensity and FF had statistical differences (P < 0.01). Besides, the lumbar fat signal intensity and FF were negatively related to DXA (r =-0.65 and -0.93, P < 0.01). Conclusion: The fat content calculated using the Dixon chemical shift MRI had an inverse relation with BMD. Moreover, the Dixon chemical shift MRI might provide complementary information to osteoporosis-related research fields.
ABSTRACT
Reduction-sensitive chondroitin sulfate A (CSA)-based micelles were developed. CSA was conjugated with deoxycholic acid (DOCA) via a disulfide linkage. The bioreducible conjugate (CSA-ss-DOCA) can form self-assembled micelles in aqueous medium. The critical micelle concentration (CMC) of CSA-ss-DOCA conjugate is 0.047mg/mL, and its mean diameter is 387nm. The anticancer drug doxorubicin (DOX) was chosen as a model drug, and was effectively encapsulated into the micelles with high loading efficiency. Reduction-sensitive micelles and reduction-insensitive control micelles displayed similar DOX release behavior in phosphate buffered saline (PBS, pH7.4). Notably, DOX release from the reduction-sensitive micelles in vitro was accelerated in the presence of 20mM glutathione-containing PBS environment. Moreover, DOX-loaded CSA-ss-DOCA (CSA-ss-DOCA/DOX) micelles exhibited intracellular reduction-responsive characteristics in human gastric cancer HGC-27 cells determined by confocal laser scanning microscopy (CLSM). Furthermore, CSA-ss-DOCA/DOX micelles demonstrated higher antitumor efficacy than reduction-insensitive control micelles in HGC-27 cells. These results suggested that reduction-sensitive CSA-ss-DOCA micelles had the potential as intracellular targeted carriers of anticancer drugs.
