Departments of1Pediatric Radiology and.
2UMR 1163, Imagine Institute, Paris.
J Neurosurg Pediatr. 2023 Apr 28;32(2):173-183. doi: 10.3171/2023.3.PEDS22386. Print 2023 Aug 1.
Distinguishing tumor recurrence from therapy-induced imaging changes (TIIC) on brain MRI in children treated for primary malignant brain tumors may be challenging. The authors aimed to assess the diagnostic ability of multimodal MRI in differentiating TIIC from tumor recurrence.
The authors retrospectively included children with abnormal supratentorial brain MRI findings after treatment for primary malignant brain tumors (regardless of their localization) with complete resection and radiotherapy. A total of 18 patients with TIIC and 25 patients with tumor recurrence were compared, according to structural, apparent diffusion coefficient (ADC), and arterial spin labeling (ASL) imaging data accrued over time. TIIC were defined by a new MRI scan that was stable for at least 1 year or had regressed, or by histopathology findings in specimens obtained when the anomaly was surgically treated.
The time interval between completion of radiotherapy and the appearance of abnormal brain MRI findings was significantly shorter in the TIIC group compared with the tumor recurrence group (median 6 vs 35 months; p < 0.001). TIIC appeared as foci of increased T2-weighted signal intensity, without nodule, associated with variable contrast enhancement. Tumor recurrence appeared as a well-defined nodule with intermediate signal intensity on T2-weighted images with nodular contrast enhancement. Relative ADC values were significantly higher in the TIIC group (median 1.43 vs 0.88; p < 0.001). Relative ASL-cerebral blood flow (CBF) values were significantly lower in the TIIC group (median 0.27 vs 0.43; p = 0.04). On follow-up MRI, TIIC could progress, regress, or remain stable. In most instances (72%), they decreased in size or remained stable at 4 years of follow-up.
MRI features of TIIC include foci of increased signal intensity without a demonstrable nodule on T2-weighted images, high ADC values, and lower ASL-CBF values, whereas tumor recurrence appears as a well-defined nodule with low ADC values and higher ASL-CBF values.
在儿童脑部恶性肿瘤治疗后，区分脑 MRI 上的肿瘤复发与治疗后影像学改变（TIIC）可能具有挑战性。本研究旨在评估多模态 MRI 在区分 TIIC 与肿瘤复发方面的诊断能力。
作者回顾性纳入了原发性恶性脑肿瘤治疗后出现异常幕上脑 MRI 表现的儿童（无论肿瘤定位如何），这些患儿均接受了完全切除术和放疗。根据随时间推移获得的结构、表观扩散系数（ADC）和动脉自旋标记（ASL）成像数据，将 18 例 TIIC 患者和 25 例肿瘤复发患者进行比较。TIIC 定义为新的 MRI 扫描至少稳定 1 年或已消退，或在异常部位经手术治疗获得的标本中发现组织学结果。
TIIC 组与肿瘤复发组相比，完成放疗后出现异常脑 MRI 表现的时间间隔明显更短（中位数 6 个月比 35 个月；p < 0.001）。TIIC 表现为 T2 加权信号强度增加的病灶，无结节，伴可变对比增强。肿瘤复发表现为 T2 加权图像上具有中等信号强度的界限清楚的结节，伴结节状增强。TIIC 组的相对 ADC 值明显更高（中位数 1.43 比 0.88；p < 0.001）。TIIC 组的相对 ASL-脑血流（CBF）值明显更低（中位数 0.27 比 0.43；p = 0.04）。在随访 MRI 上，TIIC 可进展、消退或保持稳定。在大多数情况下（72%），它们在 4 年的随访中缩小或保持稳定。
TIIC 的 MRI 特征包括 T2 加权图像上无可见结节的信号强度增加病灶、高 ADC 值和低 ASL-CBF 值，而肿瘤复发表现为界限清楚的结节、低 ADC 值和高 ASL-CBF 值。
