Abstract

Purpose

During stereotactic radiosurgery (SRS) planning for brain metastases (BM), brain MRIs are reviewed to select appropriate targets based on radiographic characteristics. Some BM are difficult to detect and/or definitively identify and may go untreated initially, only to become apparent on future imaging. We hypothesized that in patients receiving multiple courses of SRS, reviewing the initial planning MRI would reveal early evidence of lesions that developed into metastases requiring SRS.

Methods

Patients undergoing two or more courses of SRS to BM within 6 months between 2016 and 2018 were included in this single-institution, retrospective study. Brain MRIs from the initial course were reviewed for lesions at the same location as subsequently treated metastases; if present, this lesion was classified as a “retrospectively identified metastasis” or RIM. RIMs were subcategorized as meeting or not meeting diagnostic imaging criteria for BM (+ DC or -DC, respectively).

Results

Among 683 patients undergoing 923 SRS courses, 98 patients met inclusion criteria. There were 115 repeat courses of SRS, with 345 treated metastases in the subsequent course, 128 of which were associated with RIMs found in a prior MRI. 58% of RIMs were + DC. 17 (15%) of subsequent courses consisted solely of metastases associated with + DC RIMs.

Conclusion

Radiographic evidence of brain metastases requiring future treatment was occasionally present on brain MRIs from prior SRS treatments. Most RIMs were + DC, and some subsequent SRS courses treated only + DC RIMs. These findings suggest enhanced BM detection might enable earlier treatment and reduce the need for additional SRS.

中文翻译：

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接受立体定向放射外科重复疗程的患者中难以检测的回顾性脑转移瘤的发生率和影像学特征

摘要

目的

在针对脑转移 (BM) 进行立体定向放射外科 (SRS) 计划期间，会审查脑部 MRI，以根据放射学特征选择适当的目标。有些 BM 很难检测和/或明确识别，并且最初可能未经治疗，只是在未来的成像中变得明显。我们假设，在接受多个疗程 SRS 的患者中，回顾最初计划的 MRI 将揭示病变发展为需要 SRS 转移的早期证据。

方法

这项单机构回顾性研究纳入了 2016 年至 2018 年期间 6 个月内接受两个或多个 SRS 至 BM 疗程的患者。对初始病程中的脑部 MRI 检查与随后治疗的转移灶相同位置的病变；如果存在，该病变被归类为“回顾性发现的转移”或 RIM。 RIM 被细分为满足或不满足 BM 诊断成像标准（分别为 + DC 或 -DC）。

结果

在接受 923 个 SRS 疗程的 683 名患者中，98 名患者符合纳入标准。 SRS 重复进行了 115 个疗程，在后续疗程中治疗了 345 个转移瘤，其中 128 个与先前 MRI 中发现的 RIM 相关。 58% 的 RIM 为 + DC。 17 (15%) 的后续课程仅包含与 + DC RIM 相关的转移。

结论

先前 SRS 治疗的脑 MRI 中偶尔会出现需要未来治疗的脑转移的放射影像证据。大多数 RIM 是 + DC，而一些后续的 SRS 课程仅处理 + DC RIM。这些发现表明，增强 BM 检测可能有助于早期治疗并减少额外 SRS 的需求。