Background

We evaluated a magnetic resonance (MR)-conditional high-power microwave ablation system.

Methods

An ex vivo 1.5-T evaluation was conducted by varying the sequence (T1-weighted volume interpolated breath-hold examination, T1w-VIBE; T1-weighted fast low-angle shot, T1w-FLASH; T2-weighted turbo spin-echo, T2w-TSE), applicator angulation to B₀ (A-to-B₀), slice orientation, and encoding direction. Tip location error (TLE) and artefact diameters were measured, and influence of imaging parameters was assessed with analysis of variance and post hoc testing. Twenty-four ex vivo ablations were conducted in three bovine livers at 80 W and 120 W. Ablation durations were 5, 10, and 15 min. Ablation zones were compared for short-axis diameter (SAD), volume, and sphericity index (SI) with unpaired t test.

Results

The artefact pattern was similar for all sequences. The shaft artefact (4.4 ± 2.9 mm, mean ± standard deviation) was dependent on the sequence (p = 0.012) and the A-to-B₀ (p < 0.001); the largest shaft diameter was measured with T1w-FLASH (6.3 ± 3.4 mm) and with perpendicular A-to-B₀ (6.7 ± 2.4 mm). The tip artefact (1.6 ± 0.7 mm) was dependent on A-to-B₀ (p = 0.001); TLE was -2.6 ± 1.0 mm. Ablation results at the maximum setting (15 min, 120 W) were SAD = 42.0 ± 1.41 mm; volume = 56.78 ± 3.08 cm³, SI = 0.68 ± 0.05. In all ablations, SI ranged 0.68–0.75 with the smallest SI at 15 min and 120 W (p = 0.048).

Conclusion

The system produced sufficiently large ablation zones and the artefact was appropriate for MR-guided interventions.

中文翻译：

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MR条件高功率微波系统在牛肝中的假象和消融性能：一项离体研究。

背景

我们评估了磁共振（MR）条件大功率微波消融系统。

方法

一个离 体1.5-T评价通过改变序列（T1加权的体积内插屏气检查，T1W-VIBE进行; T1加权快速低角度拍摄，T1W-FLASH; T2加权快速自旋回波，T2加权-TSE），涂抹器角度对乙₀（甲-到-乙₀），切片取向和编码方向。测量尖端位置误差（TLE）和假象直径，并通过方差分析和事后检验评估成像参数的影响。二十四个离 体在80 W和120 W的三个牛肝中进行消融。消融时间为5、10和15分钟。使用不成对的t检验比较消融区的短轴直径（SAD），体积和球形度（SI）。

结果

对于所有序列，伪像模式都是相似的。轴的假象（4.4±2.9 mm，平均值±标准偏差）取决于序列（p = 0.012）和A to B ₀（p <0.001）；最大的轴直径是用T1w-FLASH（6.3±3.4 mm）和垂直的A to B ₀（6.7±2.4 mm）测量的。尖端伪影（1.6±0.7 mm）取决于A to B ₀（p = 0.001）；TLE为-2.6±1.0毫米。在最大设置（15分钟，120 W）下的烧蚀结果为SAD = 42.0±1.41 mm；体积= 56.78±3.08 cm ³，SI ＝ 0.68±0.05。在所有消融中，SI的范围为0.68-0.75，最小的SI在15分钟和120 W时（p = 0.048）。

结论

该系统产生了足够大的消融区，并且该伪像适合于MR引导的干预措施。