Researchers have identified MRI features at 24 hours post-cryoablation that were predictive of local liver tumor progression, according to a study published by the American Journal of Roentgenology. These include a minimum ablation margin less than or equal to three millimeters and a blood vessel bridging the margin. 

Percutaneous liver cryoablation has been shown to provide lower complication rates than other open cryosurgical series. Though the procedure has many advantages in comparison to other ablation techniques, postablation imaging features that are utilized to predict local tumor progression are problematic. Lead author Paul B. Shyn, MD, of Brigham and Women’s Hospital in Boston, and colleagues, aimed to identify which MRI features seen 24 hours after technically successful percutaneous cryoablation of liver tumors predict subsequent local tumor progression and describe the evolution of imaging findings after the procedure.

The study included 39 adult patients who underwent successful imaging-guided percutaneous cryoablation for 54 liver tumors. Two readers independently assessed MRI features related to the tumor, ablation margin, and surrounding liver 24 hours after treatment.

Of 14 tumors with progression, 11 had a minimum ablation margin of 3 millimeters. Fifteen of 40 tumors without progression were observed with the same margin. The researchers discovered a blood vessel bridging the ablation margin in 11 of 14 tumors with and nine of 40 without progression. Tumor enhancement incidence 24 hours after cryoablation was akin to tumors with or without local progression. Lastly, MRI allowed for assessment of the entire cyroablation margin in 90.7 percent, or 49 of the 54, treated tumors.

“Liver tumor enhancement on MRI after percutaneous cryoablation is common and alone does not indicate inadequate treatment; however, a small (≤ 3 mm) minimum ablation margin or the presence of a blood vessel (≥ 3 mm) bridging the ablation margin are each predictive of local progression,” concluded Shyn and colleagues.