Pelvic and lower extremity arterial imaging: diagnostic performance of three-dimensional contrast-enhanced MR angiography

OBJECTIVE

The diagnostic performance of a three-dimensional MR angiography-based strategy was assessed with regard to its ability to characterize the arterial vasculature from the aortic bifurcation to the lower extremity runoff vessels. A single-injection, two-station protocol in combination with a lower-extremity vascular coil was used.

SUBJECTS AND METHODS

Both conventional digital subtraction angiography and three-dimensional contrast-enhanced MR angiography with a dedicated peripheral vascular coil were performed in 61 patients with suspected peripheral vascular disease. In a prospective analysis, one reviewer evaluated the digital subtraction angiographic images and a second reviewer evaluated the MR angiographic images; both were unaware of the results of the other imaging technique. Each vascular segment (29 segments per patient) was evaluated for the presence of occlusive vessel disease. The following grading system was applied: 0, normal; 1, vessel irregularity with a luminal reduction of less than 10%; 2, mild stenosis (lumen reduction, 10-49%); 3, severe stenosis (lumen reduction, 50-99%); and 4, occlusion (lumen reduction, 100%). In 11 patients surgical graft patency was assessed.

RESULTS

MR angiography provided an image quality comparable with that of digital subtraction angiography. Overall sensitivity and specificity for MR angiography were 92% and 96.6%, respectively, for the detection of hemodynamically significant disease and 92.3% and 99.4%, respectively, for the detection of occlusions.

CONCLUSION

Two-station contrast-enhanced three-dimensional MR angiography with a dedicated lower-extremity vascular coil proved effective enough to consider it as a noninvasive alternative to digital subtraction angiography in the assessment of the pelvic and lower extremity arterial vasculature.

Protein and amino acid oxidation is associated with increased chemiluminescence

Incubation of 4% bovine serum albumin (BSA) with 1 mM tert-butyl hydroperoxide (t-BOOH) resulted in a peak of chemiluminescence followed by decay to a steady-state level of 18 counts per second above control. When using BSA of differing fatty acid content, the intensity of the initial peak was proportional to fatty acid content, while the steady-state chemiluminescence was independent of lipid content and depended only on BSA concentration. Light emission was inhibited by superoxide dismutase, desferrioxamine, and the antioxidant U-78518F. Oxidation of BSA by neutrophils activated with phorbol myristate acetate also increased chemiluminescence, in a process inhibitable by superoxide dismutase and U-78518F. When adding 1 mM t-BOOH in the presence of 20 microM heme to tryptophan, tyrosine, or to a lesser extent histidine, chemiluminescence correlated with increased oxygen consumption and the appearance of carbonyl derivatives, suggesting that chemiluminescence is a result of the decay to ground level of excited carbonyls. Lysine and glycine, on the other hand, were not oxidized to carbonyls after exposure to t-BOOH and did not emit light or consume significant oxygen during this challenge.