Analysis of bone marrow fatty acid composition using high-resolution proton NMR spectroscopy.

High-resolution 1H NMR spectroscopy as a complementary method in the analysis of human bone marrow fatty acid (FA) composition was examined. Marrow FA composition in 10 bone samples measured by NMR and gas chromatography (GC) were compared. NMR T1 relaxation time of FA was determined and reproducibility tests were performed to assess the variability. Good correlations were obtained between the NMR and GC results for omega-6 polyunsaturated fatty acid (PUFA) (Spearman r, 0.878), omega-3 PUFA (0.895), monounsaturated FA (0.964) and saturated FA (0.939). The NMR method tended to overestimate saturated FA and underestimate omega-3/omega-6 ratio compared to GC results. T1 relaxation time of marrow FA was 0.56-3.65s. Coefficient of variation of the NMR method was 0.6-8.2% in intra-experimental and 0.2-8.4% in inter-experimental measurements. This study demonstrates a complementary role for 1H NMR spectroscopy as an additional analytical tool in human lipid research.

CT compared with arthroscopy in quantifying glenoid bone loss.

OBJECTIVE: This study investigated the accuracy of CT in determining the presence and severity of glenoid bone loss in patients with unilateral anterior shoulder dislocation. SUBJECTS AND METHODS: Fifty patients (45 males, five females; mean age, 28.7 years; age range, 14-56 years) with anterior shoulder dislocation underwent shoulder CT examination before arthroscopy (mean time interval between CT and arthroscopy, 28.5 days; range, 9-73 days). Thirteen (26%) of the 50 patients had a single dislocation, whereas the remaining 37 patients (74%) had recurrent dislocation (mean, 8.2 dislocations; range, 2-50 dislocations). RESULTS: Glenoid bone loss was evident in 41 (82%) of the 50 patients at arthroscopy. Compared with arthroscopy, CT had a sensitivity in detecting glenoid bone loss of 92.7%; specificity, 77.8%; positive predictive value, 95.0%; and negative predictive value, 70.0%. Three false-negative CT assessments had 5%, 10%, and 10% glenoid bone loss, respectively, at arthroscopy. Two false-positive CT assessments had 8.7% and 5.7% glenoid bone loss on CT, although no bone loss was apparent at arthroscopy. There was a strong correlation between CT and arthroscopy with respect to the severity of glenoid bone loss (r = 0.79, 95% CI = 0.659-0.877, p < 0.0001). CONCLUSION: CT has both a high sensitivity and a high specificity for detecting glenoid bone loss, and agreement with arthroscopy regarding the severity of glenoid bone loss is good. CT can be used to assess glenoid bone loss and the need for bone augmentation surgery.

Compromised bone marrow perfusion in osteoporosis.

A link between bone blood flow and osteoporosis may exist. Outside of the spine, the proximal femur is the most common site of osteoporotic fracture and is also an area prone to avascular necrosis and fracture nonunion. This study of the proximal femur investigates the relationship between BMD, bone marrow fat content, bone perfusion, and muscle perfusion. One hundred twenty healthy female subjects (mean age, 74 yr; age range, 67-89 yr) underwent DXA examination of the hip, proton MR spectroscopy, and dynamic contrast-enhanced MR imaging of the right proximal femur, acetabulum, and adductor thigh muscle. In all bone areas examined (femoral head, femoral neck, femoral shaft, acetabulum), perfusion indices (maximum enhancement, enhancement slope) were significantly reduced in subjects with osteoporosis compared with subjects with osteopenia or normal BMD. Adductor muscle perfusion was not affected by change in BMD. As marrow perfusion decreased in the proximal femur, marrow fat increased (r = 0.827). This increase in fat content seemed to account for the decrease in marrow perfusion more than a reduction in BMD. For normal BMD subjects, perfusion parameters in the femoral head were one third of those in the femoral neck or shaft and one fifth of those in the acetabulum. Perfusion throughout the proximal femur is reduced in osteoporotic subjects compared with osteopenic and normal subjects. This reduction in perfusion only affects bone and not those tissues outside of bone with the same blood supply. As bone perfusion decreased, there was a corresponding increase in marrow fat.