Treb Kevin J, Woodrum David A, Thompson Scott M, Adamo Daniel A, Gorny Krzysztof R, Lu Aiming
Department of Radiology, Mayo Clinic, 200 1st Street WS, Rochester, MN, 55905, USA.
Cardiovasc Intervent Radiol. 2025 May;48(5):678-686. doi: 10.1007/s00270-025-04021-x. Epub 2025 Apr 7.
Cryoneedle artifacts are frequently observed in MRI-guided cryoablations, and may obscure visualization of critical anatomy and compromise needle placement accuracy. This work experimentally investigated the contributing factors of these artifacts to identify effective mitigation strategies.
Ex vivo porcine tissue with inserted cryoneedles was imaged on a 1.5-Tesla MRI. Fast spin echo (FSE) and spoiled gradient echo (GRE) sequences with echo times from 1.04 to 60 ms and specific absorption rates (SARs) from 0.01 to 2.1 W/kg were used. During MRI, cryoneedle temperatures were monitored using fiber-optic sensors. Configurations with one to three cryoneedles oriented at 0-degree or 45-degree angles to the patient table were investigated. The body coil was used for transmit/receive, both with and without an additional receive-only surface loop coil. Artifact width and intensity were measured for analysis.
Cryoneedle artifact widths were unrelated to echo time for both FSE (p = 0.6) and GRE (p = 0.3) and were smaller in GRE than in FSE images (p << 0.05). Artifact widths correlated with cryoneedle temperature elevations (r = 0.969, p << 0.05) but were not correlated with SAR (GRE: p = 0.3; FSE: p = 0.5). The artifact intensity with the cryoneedle oriented at 0 degrees increased with a greater number of cryoneedles in the tissue (p = 0.006), and when the surface loop coil was used (p = 0.008).
Clinically observed cryoneedle artifacts compromising treatment efficacy can be indicative of tissue radiofrequency heating risk, and effectively mitigated by either using GRE-based sequences or adjusting coil/cryoneedle configurations.
在磁共振成像（MRI）引导下的冷冻消融术中经常观察到冷冻针伪影，这些伪影可能会模糊关键解剖结构的可视化，并影响针放置的准确性。本研究通过实验调查了这些伪影的影响因素，以确定有效的缓解策略。
将插入冷冻针的离体猪组织在1.5特斯拉MRI上成像。使用回波时间从1.04到60毫秒、比吸收率（SAR）从0.01到2.1瓦/千克的快速自旋回波（FSE）和扰相梯度回波（GRE）序列。在MRI过程中，使用光纤传感器监测冷冻针的温度。研究了一至三根冷冻针与患者检查床呈0度或45度角的配置。体线圈用于发射/接收，同时使用和不使用额外的仅用于接收的表面环形线圈。测量伪影宽度和强度进行分析。
对于FSE（p = 0.6）和GRE（p = 0.3），冷冻针伪影宽度均与回波时间无关，且GRE图像中的伪影宽度小于FSE图像中的伪影宽度（p << 0.05）。伪影宽度与冷冻针温度升高相关（r = 0.969，p << 0.05），但与SAR无关（GRE：p = 0.3；FSE：p = 0.5）。冷冻针与组织呈0度角时，伪影强度随组织中冷冻针数量的增加而增加（p = 0.006），并且在使用表面环形线圈时也会增加（p = 0.008）。
临床上观察到的影响治疗效果的冷冻针伪影可能表明组织射频加热风险，通过使用基于GRE的序列或调整线圈/冷冻针配置可有效减轻。
