From the Department of Radiology, Division of Neuroimaging and Neurointervention (F.K., N.N.N., M.I.).
Departments of Neurology (Neuro-Oncology) (S.N.).
AJNR Am J Neuroradiol. 2022 May;43(5):689-695. doi: 10.3174/ajnr.A7501. Epub 2022 Apr 28.
Differentiation between tumor and radiation necrosis in patients with brain metastases treated with stereotactic radiosurgery is challenging. We hypothesized that MR perfusion and metabolic metrics can differentiate radiation necrosis from progressive tumor in this setting.
We retrospectively evaluated MRIs comprising DSC, dynamic contrast-enhanced, and arterial spin-labeling perfusion imaging in subjects with brain metastases previously treated with stereotactic radiosurgery. For each lesion, we obtained the mean normalized and standardized relative CBV and fractional tumor burden, volume transfer constant, and normalized maximum CBF, as well as the maximum standardized uptake value in a subset of subjects who underwent FDG-PET. Relative CBV thresholds of 1 and 1.75 were used to define low and high fractional tumor burden.
Thirty subjects with 37 lesions (20 radiation necrosis, 17 tumor) were included. Compared with radiation necrosis, tumor had increased mean normalized and standardized relative CBV (= .002) and high fractional tumor burden (normalized, = .005; standardized, = .003) and decreased low fractional tumor burden (normalized, = .03; standardized, = .01). The area under the curve showed that relative CBV (normalized = 0.80; standardized = 0.79) and high fractional tumor burden (normalized = 0.77; standardized = 0.78) performed the best to discriminate tumor and radiation necrosis. For tumor prediction, the normalized relative CBV cutoff of ≥1.75 yielded a sensitivity of 76.5% and specificity of 70.0%, while the standardized cutoff of ≥1.75 yielded a sensitivity of 41.2% and specificity of 95.0%. No significance was found with the volume transfer constant, normalized CBF, and standardized uptake value.
Increased relative CBV and high fractional tumor burden (defined by a threshold relative CBV of ≥1.75) best differentiated tumor from radiation necrosis in subjects with brain metastases treated with stereotactic radiosurgery. Performance of normalized and standardized approaches was similar.
在接受立体定向放射外科治疗的脑转移瘤患者中，区分肿瘤和放射性坏死具有挑战性。我们假设，在这种情况下，磁共振灌注和代谢指标可以区分放射性坏死和进展性肿瘤。
我们回顾性评估了既往接受立体定向放射外科治疗的脑转移瘤患者的 DSC、动态对比增强和动脉自旋标记灌注成像 MRI。对于每个病变，我们获得了平均归一化和标准化相对 CBV 和肿瘤负荷分数、容积转移常数和归一化最大 CBF，以及一部分接受 FDG-PET 的患者的最大标准化摄取值。相对 CBV 阈值为 1 和 1.75，用于定义低和高肿瘤负荷分数。
30 例患者（37 个病灶），其中 20 个为放射性坏死，17 个为肿瘤。与放射性坏死相比，肿瘤具有更高的平均归一化和标准化相对 CBV（= 0.002）和高肿瘤负荷分数（归一化，= 0.005；标准化，= 0.003）和更低的低肿瘤负荷分数（归一化，= 0.03；标准化，= 0.01）。曲线下面积表明，相对 CBV（归一化= 0.80；标准化= 0.79）和高肿瘤负荷分数（归一化= 0.77；标准化= 0.78）对区分肿瘤和放射性坏死的效果最好。对于肿瘤预测，归一化相对 CBV 临界值≥1.75 的灵敏度为 76.5%，特异性为 70.0%，而标准化临界值≥1.75 的灵敏度为 41.2%，特异性为 95.0%。容积转移常数、归一化 CBF 和标准化摄取值均无统计学意义。
在接受立体定向放射外科治疗的脑转移瘤患者中，相对 CBV 增加和高肿瘤负荷分数（定义为相对 CBV 临界值≥1.75）最佳区分肿瘤和放射性坏死。归一化和标准化方法的性能相似。
