FDG uptake offers clearer picture of high-risk carotid plaque

Swiss researchers assessing carotid plaque stenoses using FDG-PET found the procedure accurate in detecting high-risk plaques. They also noted a strong correlation between uptake values of FDG and the presence of microembolic signals detected via transcranial Doppler.

Lead researcher Hubertus Fritz Georg Müller, MD, of the neurology department at the University Hospital of Geneva, and colleagues enrolled 110 patients with 50-to-99 percent symptomatic or asymptomatic carotid disease without carotid occlusion. Patients had either a recent stroke or transit ischemic attack (TIA) or were identified as having an asymptomatic carotid stenosis.

Patients underwent contrast angiography using PET/CT with FDG to measure uptake of the glucose dye at the stenosis. Müller et al used transcranial Doppler to detect degree of stenosis, peak systolic velocities and microembolic signals.

They found higher uptake of FDG in softer areas as opposed to calcified ones with a median value of 2.25 vs. 1.99, respectively. Uptake was higher in symptomatic rather than asymptomatic patients with a median value of 2.07 vs. 1.78, respectively. However, in patients with increased plaque FDG uptake, values correlated with higher identification of microembolic signals in both symptomatic and asymptomatic patients (79 percent vs. 80 percent, respectively).

Microembolic signals were detected in 16 percent of lesions. More than three times more symptomatic patients had stenoses that were positive for microembolic signals (25 percent vs 9 percent).

While Müller et al did not find significant differences between the number of microembolic signals seen and patients’ regimen of dual antiplatelet therapy, they did note that risk for recurrent TIA and stroke reduced when microembolic signals stopped after aggressive antithrombotic therapy.

Although assessment of microembolic signals is highly accurate, Müller et al suggested that may not be as effective in clinical practice due to time and skill.

The study was published in the December issue of Stroke.