CT image summation boosts accuracy of RF ablation targeting

Merging multiple CT images (summation of CT scans) increases the accuracy of probe repositioning during radiofrequency ablation treatments of various lesions, according to a recent study performed at Dartmouth-Hitchcock Medical Center.

"During radiofrequency ablation, the probe often needs to be repositioned in order to effectively treat an entire lesion," said author Dr. John M. Gemery, an assistant professor of vascular and interventional radiology at Dartmouth. "During RF ablation, it is hard to determine the areas that have already been treated when moving the probe around. Looking at summated images of several CT scans allows one to quickly check where the ablation probe has been."

Forty patients have been successfully treated using the summation method.

Probe repositioning has most commonly been used on patients who have lesions within the liver and kidneys. It also has been used on lesions found in the lungs and bones, according to Gemery.

The summation method allows for three or more probe placements to be seen at one time, Gemery said. It takes about 30 seconds on a single-slice CT scanner to summate CT scans of different placements into a single set of images. The process is much faster on newer multislice systems because of their high-speed computers.

"I think that our discovery is an incremental step forward to improving image-guided treatments," he said.

The study appears in the September issue of the American Journal of Roentgenology (AJR 2008: 191: 790-792).

-- By Heather Curry, American Roentgen Ray Society

For more information from the Diagnostic Imaging archives:

TACE plus RFA extends survival in liver cancer patients

Image-guided ablation eases bone tumor pain

RF ablation proves its worth in Barrett's esophagus

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