Type 2 uterine fibroids are challenging to resect surgically as≥ 50% volume of myoma lies within the myometrium. A hysteroscopic approach for ablating fibroids is minimally-invasive, but places a considerable burden on the operator to accurately place the ablation applicator within the target. We investigated the sensitivity of transcervical microwave ablation outcome with respect to position of the ablation applicator within 1 – 3 cm type 2 fibroids. Methods: A finite element computer model was developed to simulate 5.8 GHz microwave ablation of fibroids and validated with experiments in ex vivo tissue. The ablation outcome was evaluated with respect to applicator insertion angles (30, 45, 60) , depth and offset from the fibroid center (2 mm for 3 cm fibroid and 1 mm for 1 cm fibroid) with 35 W and 15 W applied power for 3 cm and 1 cm fibroids, respectively. Power deposition was stopped when thermal dose of 40 cumulative equivalent minutes at 43 C (CEM43) was accrued in adjacent myometrium. Results: Within the range of all evaluated insertion angles, depths and offsets, the ablation coverage was less sensitive to variation in angle as compared to depth and offset, and ranged from 34.9 – 83.6% for 3 cm fibroid in 140 – 400 s and 34.1 – 67.9% for 1 cm fibroid in 30 – 50 s of heating duration. Maximum achievable ablation coverage in both fibroid cases reach∼90% if thermal dose is allowed to exceed 40 CEM43 in myometrium. Conclusion: The study demonstrates the technical feasibility of transcervical microwave ablation for fibroid treatment and the relationship between applicator position within the fibroid and fraction of fibroid that can be ablated while limiting thermal dose in adjacent myometrium.

2 型子宫肌瘤很难通过手术切除，因为≥50% 的肌瘤位于子宫肌层内。用于消融肌瘤的宫腔镜方法是微创的，但会给操作者带来相当大的负担，无法准确地将消融施放器放置在目标内。我们研究了经宫颈微波消融结果相对于消融施放器在 1-3 厘米 2 型肌瘤内的位置的敏感性。方法：开发了一个有限元计算机模型来模拟肌瘤的 5.8 GHz 微波消融，并通过体外实验进行验证组织。在施加 35 W 和 15 W 功率的情况下评估消融结果，包括敷贴器插入角度（30、45、60）、深度和距肌瘤中心的偏移（3 cm 肌瘤为 2 mm，1 cm 肌瘤为 1 mm）分别为 3 厘米和 1 厘米的肌瘤。当相邻子宫肌层在 43 C (CEM43) 下累积 40 分钟累积等效分钟的热剂量时停止功率沉积。结果：在所有评估的插入角度、深度和偏移量范围内，与深度和偏移量相比，消融覆盖对角度变化的敏感性较低，140 – 400 秒内 3 cm 肌瘤的范围为 34.9 – 83.6% 和 34.1 – 67.9在 30 – 50 秒的加热持续时间内，1 cm 肌瘤的百分比。如果子宫肌层中的热剂量超过 40 CEM43，则两种肌瘤病例的最大可实现消融覆盖率均达到 90%。结论：该研究证明了经宫颈微波消融治疗肌瘤的技术可行性，以及肌瘤内涂药器位置与可消融的肌瘤部分之间的关​​系，同时限制相邻肌层的热剂量。