Digernes Ingrid, Grøvik Endre, Nilsen Line B, Saxhaug Cathrine, Geier Oliver, Reitan Edmund, Sætre Dag Ottar, Breivik Birger, Reese Timothy, Jacobsen Kari Dolven, Helland Åslaug, Emblem Kyrre Eeg
Department of Diagnostic Physics, Oslo University Hospital, Oslo, Norway.
Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway.
Adv Radiat Oncol. 2018 May 17;3(4):559-567. doi: 10.1016/j.adro.2018.05.005. eCollection 2018 Oct-Dec.
This study aimed to investigate the hemodynamic status of cerebral metastases prior to and after stereotactic radiation surgery (SRS) and to identify the vascular characteristics that are associated with the development of pseudoprogression from radiation-induced damage with and without a radionecrotic component.
Twenty-four patients with 29 metastases from non-small cell lung cancer or malignant melanoma received SRS with dose of 15 Gy to 25 Gy. Magnetic resonance imaging (MRI) scans were acquired prior to SRS, every 3 months during the first year after SRS, and every 6 months thereafter. On the basis of the follow-up MRI scans or histology after SRS, metastases were classified as having response, tumor progression, or pseudoprogression. Advanced perfusion MRI enabled the estimation of vascular status in tumor regions including fractions of abnormal vessel architecture, underperfused tissue, and vessel pruning.
Prior to SRS, metastases that later developed pseudoprogression had a distinct poor vascular function in the peritumoral zone compared with responding metastases ( < .05; number of metastases = 15). In addition, differences were found between the peritumoral zone of pseudoprogressing metastases and normal-appearing brain tissue ( < .05). In contrast, for responding metastases, no differences in vascular status between peritumoral and normal-appearing brain tissue were observed. The dysfunctional peritumoral vasculature persisted in pseudoprogressing metastases after SRS.
Our results suggest that the vascular status of peritumoral tissue prior to SRS plays a defining role in the development of pseudoprogression and that advanced perfusion MRI may provide new insights into patients' susceptibility to radiation-induced effects.
本研究旨在调查立体定向放射外科手术（SRS）前后脑转移瘤的血流动力学状态，并确定与有或无放射性坏死成分的放射性损伤所致假性进展发生相关的血管特征。
24例患有29个非小细胞肺癌或恶性黑色素瘤转移瘤的患者接受了剂量为15 Gy至25 Gy的SRS。在SRS前、SRS后第一年每3个月以及此后每6个月进行磁共振成像（MRI）扫描。根据SRS后的随访MRI扫描或组织学结果，将转移瘤分为有反应、肿瘤进展或假性进展。先进的灌注MRI能够估计肿瘤区域的血管状态，包括异常血管结构分数、灌注不足组织和血管修剪情况。
在SRS前，与有反应的转移瘤相比，后来发生假性进展的转移瘤在瘤周区域的血管功能明显较差（P<0.05；转移瘤数量=15）。此外，假性进展转移瘤的瘤周区域与外观正常的脑组织之间也存在差异（P<0.05）。相比之下，对于有反应的转移瘤，未观察到瘤周和外观正常脑组织之间的血管状态差异。SRS后，假性进展转移瘤中功能失调的瘤周血管系统持续存在。
我们的结果表明，SRS前瘤周组织的血管状态在假性进展的发生中起决定性作用，先进的灌注MRI可能为患者对放射性损伤的易感性提供新的见解。
