Background

COVID-19 vaccination-related axillary lymphadenopathy has become an important problem in cancer imaging. Data are needed to update or support imaging guidelines for conducting appropriate follow-up.

Purpose

To investigate the prevalence, predisposing factors, and MRI characteristics of COVID-19 vaccination-related axillary lymphadenopathy.

Materials and Methods

Prospectively collected prevaccination and postvaccination chest MRI scans were secondarily analyzed. Participants who underwent two doses of either the Pfizer-BioNTech or Moderna COVID-19 vaccine and chest MRI from June to October 2021 were included. Enlarged axillary lymph nodes were identified on postvaccination MRI scans compared with prevaccination scans. The lymph node diameter, signal intensity with T2-weighted imaging, and apparent diffusion coefficient (ADC) of the largest enlarged lymph nodes were measured. These values were compared between prevaccination and postvaccination MRI by using the Wilcoxon signed-rank test.

Results

Overall, 433 participants (mean age, 65 years ± 11 [SD]; 300 men and 133 women) were included. The prevalence of axillary lymphadenopathy in participants 1–14 days after vaccination was 65% (30 of 46). Participants with lymphadenopathy were younger than those without lymphadenopathy (P < .001). Female sex and the Moderna vaccine were predisposing factors (P = .005 and P = .003, respectively). Five or more enlarged lymph nodes were noted in 2% (eight of 433) of participants. Enlarged lymph nodes greater than or equal to 10 mm in the short axis were noted in 1% (four of 433) of participants. The median signal intensity relative to the muscle on T2-weighted images was 4.0; enlarged lymph nodes demonstrated a higher signal intensity (P = .002). The median ADC of enlarged lymph nodes after vaccination in 90 participants was 1.1 × 10⁻³ mm²/sec (range, 0.6–2.0 × 10⁻³ mm²/sec), thus ADC values remained normal.

Conclusion

Axillary lymphadenopathy after the second dose of the Pfizer-BioNTech or Moderna COVID-19 vaccines was frequent within 2 weeks after vaccination, was typically less than 10 mm in size, and had a normal apparent diffusion coefficient.

© RSNA, 2022

中文翻译：

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Pfizer-BioNTech 和 Moderna COVID-19 疫苗接种后的腋窝淋巴结肿大：MRI 评估

背景

COVID-19疫苗接种相关的腋窝淋巴结肿大已成为癌症影像学中的一个重要问题。需要数据来更新或支持成像指南以进行适当的随访。

目的

调查 COVID-19 疫苗接种相关腋窝淋巴结肿大的患病率、诱发因素和 MRI 特征。

材料和方法

对前瞻性收集的疫苗接种前和疫苗接种后胸部 MRI 扫描进行了二次分析。从 2021 年 6 月到 2021 年 10 月接受了两剂 Pfizer-BioNTech 或 Moderna COVID-19 疫苗和胸部 MRI 的参与者被包括在内。与接种前扫描相比，接种后 MRI 扫描发现腋窝淋巴结肿大。测量淋巴结直径、T2 加权成像信号强度和最大肿大淋巴结的表观扩散系数 (ADC)。通过使用 Wilcoxon 符号秩检验比较接种前和接种后 MRI 的这些值。

结果

总体而言，包括 433 名参与者（平均年龄 65 岁 ± 11 [SD]；300 名男性和 133 名女性）。接种疫苗后 1-14 天参与者腋窝淋巴结肿大的患病率为 65%（46 人中的 30 人）。有淋巴结肿大的参与者比没有淋巴结肿大的参与者更年轻 ( P < .001)。女性和 Moderna 疫苗是诱发因素（分别为P = .005 和P = .003）。2%（433 人中有 8 人）的参与者发现有 5 个或更多淋巴结肿大。1%（433 人中有 4 人）的参与者发现短轴淋巴结肿大大于或等于 10 毫米。T2 加权图像上相对于肌肉的中位信号强度为 4.0；肿大的淋巴结表现出更高的信号强度（P=.002）。90 名参与者接种疫苗后淋巴结肿大的中位 ADC 为 1.1 × 10 ^-3 mm ² /sec（范围，0.6–2.0 × 10 ^-3 mm ² /sec），因此 ADC 值保持正常。

结论

接种第二剂 Pfizer-BioNTech 或 Moderna COVID-19 疫苗后的腋窝淋巴结肿大在接种后 2 周内很常见，通常小于 10 毫米，表观扩散系数正常。

©北美放射学会，2022