Cryoneedle Artifacts During MRI-Guided Cryoablation: Sources and Potential Mitigation Strategies

Area of Science:

• Medical Imaging
• Interventional Radiology
• Biomedical Engineering

Background:

• Cryoneedle artifacts are common in MRI-guided cryoablations, potentially hindering visualization of critical anatomy.
• These artifacts can compromise the accuracy of needle placement during procedures.
• Understanding the factors contributing to these artifacts is crucial for improving treatment efficacy.

Purpose of the Study:

• To experimentally investigate the factors contributing to cryoneedle artifacts in MRI-guided cryoablations.
• To identify effective strategies for mitigating these artifacts.
• To assess the relationship between artifact characteristics and potential tissue radiofrequency heating.

Main Methods:

• Ex vivo porcine tissue with cryoneedles was imaged using a 1.5T MRI scanner.
• Fast spin echo (FSE) and spoiled gradient echo (GRE) sequences were employed with varying echo times and specific absorption rates (SARs).
• Cryoneedle temperatures were monitored, and configurations with multiple needles and different coil setups were analyzed.

Main Results:

• Artifact width was smaller in GRE sequences compared to FSE sequences and correlated with cryoneedle temperature elevations.
• Artifact width was independent of echo time and specific absorption rates (SARs).
• Artifact intensity increased with more cryoneedles and the use of a surface loop coil.

Conclusions:

• Cryoneedle artifacts can indicate tissue radiofrequency heating risk during cryoablation.
• Gradient echo (GRE) sequences are effective in reducing artifact width.
• Adjusting coil and cryoneedle configurations can mitigate artifact intensity and improve treatment safety.