Contributing factors and mitigation strategies of the cryoprobe-induced artifacts during MRI-guided cryoablation procedures

Motivation: Metallic needles such as cryoprobes used in MRI-guided ablations can result in significant undesirable artifacts that significantly compromise the capability to use MRI for needle placement guidance and treatment monitoring. Goal(s): To investigate contributing factors of the needle-induced artifacts and identify practical mitigation strategies. Approach: Ex-vivo cryoablation experiments were conducted on a 1.5T MRI scanner with various cryoprobe and RF coil configurations and imaging sequences. Results: Cryoprobe-induced B1 inhomogeneity was shown to be the primary artifact source. The artifacts were dependent on the imaging sequences and configurations of the cryoprobes and RF coils, and correlated to RF-induced heating on the cryoprobes. Impact: Applicators used in MRI-guided ablations can introduce artifacts that compromise the accuracy of the needle placement and treatment monitoring. Understanding the artifact sources and identify mitigation strategies is critical to improve the treatment efficacy.