Cormode found a way to reconstitute the peptides with phospholipids similar to those found on the outer shell of HDL. The result: a disc-like structure with the peptides on the outside of a phospholipids bilayer.
He then spiked the outer phospholipid layer with chelated gadolinium, a metal chemically bonded to organic molecules to render it nontoxic. The gadolinium, long used in blood contrast agents, allows the cholesterol to stand out in an MRI image.
Twenty-four hours after injecting the HDL-like molecules into mice, MRI tests showed that measuring and assessing cholesterol-filled cells in the arterial walls yielded a 79 percent increase in detection compared with the initial baseline images taken the day before. Mice without the plaques showed no enhancement of imaging.
The effects of the contrast agent provided a viewing window of up to 48 hours. In addition, the strength of the signal correlated with the presence of the macrophage cells in which cholesterol accumulated. The more cholesterol-filled cells in an area, the brighter the signal.
Development of the technique may help physicians better assess the risk of heart attack or stroke for individual patients, and follow patients to see how theyre responding to therapy.
For patients with a heavy plaque burden, we can start aggressive treatment to lower low-density lipoproteins and then do a repeat scan to see if the plaque is regressing, says Fisher, who is Leon H. Charney Professor of Cardiovascular Medicine at New York University School of Medicine.
Though the procedure requires more testing, Fayad says the technique could become part of standard clinical practice in the next few years.
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27-Mar-2007