Novel steerable needle better than the conventional kind in CT-guided biopsy

Using a lean flank steak embedded with simulated anatomic obstacles, researchers have demonstrated the superiority of a steerable needle over a straight one in percutaneous CT-guided needle biopsy, according to a study published online April 26 in the Journal of Computer Assisted Tomography.

Sandra Rutigliano, MD, of the University of Pennsylvania and colleagues embedded a fresh, raw meat sample—lean bovine flank, to be precise—with cylindrical radiopaque and radiolucent obstacles designed to simulate vessels (radiolucent objects) and bones (radiopaque objects) on CT, according to the study abstract.

A pit-containing olive served as the partially radiopaque biopsy target.

Two radiologists with different levels of experience positioned a conventional straight needle and the experimental steerable needle from each of two skin sites toward the target. Both physicians used CT guidance as efficiently as possible, avoiding the obstacles, the authors report.

The results:

• For the straight needle, mean time to reach the target was 592 seconds. For the steerable needle, mean time to target was 309 seconds—almost 50 percent faster.
• The number of CT scans needed for needle positioning averaged 6.25 for the straight needle and 3.5 for the steerable needle. That’s 44 percent fewer scans, representing significant savings in radiation dose.  
• Repositioning events (withdrawing and readvancing the needle) ranged from 3 to 10 for the straight needle (mean, 6.5) and 0 for the steerable needle.

The authors point out that percutaneous CT-guided needle biopsy has proven an efficacious method for sampling of many soft tissue lesions, especially deep-seated masses in the abdomen and pelvis.

“Using an in vitro model embedded with obstacles,” they conclude, “the steerable needle performed better than a straight needle with regard to procedure time, needle repositioning events and CT scans required for placement.”