WASHINGTON, DC - A nuclear medicine technique that measures arterial circulation, before and after a hyperemic response, can help surgeons target the specific area of obstruction in patients with peripheral vascular disease. Dr. Ahmed Outif from the University of Bristol, UK, presented preliminary results from his study at the American Roentgen Ray Society meeting on May 8.
"Nuclear medicine has not been applied to lower limb arterial obstruction very often," Outif said. "We are now trying to find out its uses for the treatment of lower artery obstruction. This test provides both quantitative and qualitative information."
In this study population, 15 patients with arterial insufficiency in 20 treated limbs were positioned with the affected limb in the field of view of a gamma camera, and allowed to rest for 10 minutes. A radioisotope, 99mTc-HAS, was injected intravenously and allowed to mix with the patient's blood pool for about three minutes. Pressure cuffs were then placed above the knees.
"The cuff inflation is done to induce a hyperemic response once the cuff is deflated," Outif said.
The cuff remained on for a total of 4 minutes; image acquisition was started 15 seconds before the cuff was removed. A time activity curve was generated for each limb, and the maximum rate of filling, or net inflow, was then calculated. The test was performed before and after either angioplasty or surgical reconstruction.
The maximum rate of filling was lower pre-treatment, 0.222 minutes, then post treatment at 0.815 minutes. In addition, the time activity curve patterns were able to pinpoint the site where there was maximum obstruction to blood flow.
"Based on the time activity curve alone, we can determine the site of the obstruction," Outif said. "This test is giving us physiological information that other tests don't. With MR, you get an image of the obstruction, but you can't help the surgeon determine where he should go in to alleviate the problem."
Outif said future research will focus on using a similar technique to assess venous and arterial flow simultaneously.
Previous research in the area of nuclear medicine and lower limb imaging has been to assess muscular blood flow in patients with peripheral vascular disease. In a German study, positron emission tomography was used to measure muscular blood flow of the calf to determine if capillary nutritive blood flow is improved with the injection of a vasodilation agent (Clin Sci, Aug. 1997, Vol. 93:2, pp.159-165). Another German group measured regional nutritive muscular blood flow in patients with peripheral vascular disease with oxygen-15-water PET (J Nucl Med, Jan.1997, Vol. 38:1, pp.93-98).
By Shalmali Pal
AuntMinnie.com staff writer
May 9, 2000
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