Quantitative Evaluation of Vertebral Microvascular Permeability and Fat Fraction in Alloxan-induced Diabetic Rabbits

Purpose To determine longitudinal relationships between lumbar vertebral bone marrow permeability and marrow adipose tissue in a rabbit diabetes model by using quantitative dynamic contrast agent-enhanced (DCE) magnetic resonance (MR) imaging and iterative decomposition of water and fat with the echo asymmetry and least-squares estimation quantitation (IDEAL IQ) sequence. Materials and Methods Twenty rabbits were randomly assigned to the diabetic (n = 10) or control (n = 10) group. All rabbits underwent sagittal MR imaging of the lumbar region at fixed time points (0, 4, 8, 12, and 16 weeks after alloxan injection). A linear mixed-effects model was used to analyze fat fraction (FF) and permeability parameter changes for 16 months after baseline. These parameters were compared between the two groups by using an independent-samples t test. Correlation of DCE MR imaging parameters with FF and with microvessel density (MVD) was analyzed by using the Spearman correlation coefficient. All statistical analyses were performed with software. Results Twelve weeks after injection, transfer constant (K rans ) and rate constant (K ep ) were markedly and significantly increased, while fractional plasma volume (V p ) significantly decreased. The volume of extravascular extracellular space (V e ) decreased significantly after 16 weeks in the diabetic group. MVD was negatively correlated with K rans and K ep and positively correlated with V e and V p , while FF was positively correlated with K rans and K ep and negatively correlated with V e and V p (P < .05 for all). Conclusion DCE MR imaging and the IDEAL IQ sequence can be used for quantitative evaluation of changes in vertebral microvascular permeability and vertebral fat deposition in alloxan-induced diabetic rabbits. This variation is highly associated with increased vertebral fat deposition. © RSNA, 2017 Online supplemental material is available for this article.