Parent Ephraim E, Patel Dhruv, Nye Jonathon A, Li Zhuo, Olson Jeffrey J, Schuster David M, Goodman Mark M
Department of Radiology, Mayo Clinic, Jacksonville, USA.
Department of Radiology and Imaging Sciences, Emory University School of Medicine, 1841 Clifton Rd. NE, 2nd Floor, Atlanta, GA, 30329, USA.
EJNMMI Res. 2020 Dec 7;10(1):148. doi: 10.1186/s13550-020-00739-6.
Stereotactic radiosurgery (SRS) is often the primary treatment modality for patients with intracranial metastatic disease. Despite advances in magnetic resonance imaging, including use of perfusion and diffusion sequences and molecular imaging, distinguishing radiation necrosis from progressive tumor remains a diagnostic and clinical challenge. We investigated the sensitivity and specificity of F-fluciclovine PET to accurately distinguish radiation necrosis from recurrent intracranial metastatic disease in patients who had previously undergone SRS.
Fluciclovine PET imaging was performed in 8 patients with a total of 15 lesions that had previously undergone SRS and had subsequent MRI and clinical features suspicious for recurrent disease. The SUVmax of each lesion and the contralateral normal brain parenchyma were summated and evaluated at four different time points (5 min, 10 min, 30 min, and 55 min). Lesions were characterized as either recurrent disease (11 of 15 lesions) or radiation necrosis (4 of 15 lesions) and confirmed with histopathological correlation (7 lesions) or through serial MRI studies (8 lesions).
Time activity curve analysis found statistically greater radiotracer accumulation for all lesions, including radiation necrosis, when compared to contralateral normal brain. While the mean and median SUV for recurrent disease were statistically greater than those of radiation necrosis at all time points, the difference was more significant at the earlier time points (p = 0.004 at 5 min-0.025 at 55 min). Using a SUV threshold of ≥ 1.3, fluciclovine PET demonstrated a 100% accuracy in distinguishing recurrent disease from radiation necrosis up to 30 min after injection and an accuracy of 87% (sensitivity = 0.91, specificity = 0.75) at the last time point of 55 min. However, tumor-to-background ratios (TBR) were not significantly different between recurrent disease and radiation necrosis at any time point due to variable levels of fluciclovine uptake in the background brain parenchyma.
Fluciclovine PET may play an important role in distinguishing active intracranial metastatic lesions from radiation necrosis in patients previously treated with SRS but needs to be validated in larger studies.
立体定向放射外科（SRS）通常是颅内转移性疾病患者的主要治疗方式。尽管磁共振成像取得了进展，包括使用灌注和扩散序列以及分子成像，但区分放射性坏死与肿瘤进展仍然是一项诊断和临床挑战。我们研究了F-氟代脱氧胸苷正电子发射断层显像（F-fluciclovine PET）在准确区分先前接受过SRS治疗的患者放射性坏死与复发性颅内转移性疾病方面的敏感性和特异性。
对8例患者共15个病灶进行了氟代脱氧胸苷正电子发射断层显像（fluciclovine PET）检查，这些病灶先前接受过SRS治疗，随后的MRI及临床特征提示可能为复发性疾病。在四个不同时间点（5分钟、10分钟、30分钟和55分钟）对每个病灶及对侧正常脑实质的最大标准摄取值（SUVmax）进行汇总和评估。病灶被分为复发性疾病（15个病灶中的11个）或放射性坏死（15个病灶中的4个），并通过组织病理学相关性（7个病灶）或连续MRI研究（8个病灶）进行确认。
时间-活性曲线分析发现，与对侧正常脑相比，所有病灶（包括放射性坏死）的放射性示踪剂摄取在统计学上均更高。虽然复发性疾病的平均和中位数SUV在所有时间点均在统计学上高于放射性坏死，但在较早时间点差异更为显著（5分钟时p = 0.004，55分钟时p = 0.025）。使用SUV阈值≥1.3，氟代脱氧胸苷正电子发射断层显像在注射后30分钟内区分复发性疾病与放射性坏死的准确率为100%，在最后一个时间点55分钟时准确率为87%（敏感性 = 0.91，特异性 = 0.75）。然而，由于背景脑实质中氟代脱氧胸苷摄取水平的变化，复发性疾病与放射性坏死在任何时间点的肿瘤与背景比值（TBR）均无显著差异。
氟代脱氧胸苷正电子发射断层显像在区分先前接受SRS治疗患者的活动性颅内转移性病灶与放射性坏死方面可能发挥重要作用，但需要在更大规模的研究中进行验证。
