Department of Radiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China.
Department of Medical Imaging Product, Neusoft, Group Ltd., Shenyang, 110179, China.
Neuroradiology. 2023 Dec;65(12):1707-1714. doi: 10.1007/s00234-023-03231-9. Epub 2023 Oct 14.
To investigate the predictive value of the "soap bubble" sign on molecular subtypes (Group A [PFA] and Group B [PFB]) of posterior fossa ependymomas (PF-EPNs).
MRI scans of 227 PF-EPNs (internal retrospective discovery set) were evaluated by two independent neuroradiologists to assess the "soap bubble" sign, which was defined as clusters of cysts of various sizes that look like "soap bubbles" on T2-weighted images. Two independent cohorts (external validation set [n = 31] and prospective validation set [n = 27]) were collected to validate the "soap bubble" sign.
Across three datasets, the "soap bubble" sign was observed in 21 PFB cases (7.4% [21/285] of PF-EPNs and 12.9% [21/163] of PFB); none in PFA. Analysis of the internal retrospective discovery set demonstrated substantial interrater agreement (1st Rating: κ = 0.71 [0.53-0.90], 2nd Rating: κ = 0.83 [0.68-0.98]) and intrarater agreement (Rater 1: κ = 0.73 [0.55-0.91], Rater 2: κ = 0.74 [0.55-0.92]) for the "soap bubble" sign; all 13 cases positive for the "soap bubble" sign were PFB (p = 0.002; positive predictive value [PPV] = 100%, negative predictive value [NPV] = 44%, sensitivity = 10%, specificity = 100%). The findings from the external validation set and the prospective validation set were similar, all cases positive for the "soap bubble" sign were PFB (p < 0.001; PPV = 100%).
The "soap bubble" sign represents a highly specific imaging marker for the PFB molecular subtype of PF-EPNs.
研究“肥皂泡”征在后颅窝室管膜瘤（PF-EPNs）分子亚型（A 组[PFA]和 B 组[PFB]）中的预测价值。
对 227 例 PF-EPNs（内部回顾性发现集）的 MRI 扫描由两名独立的神经放射科医生进行评估，以评估“肥皂泡”征，其定义为在 T2 加权图像上呈现各种大小的囊肿簇，看起来像“肥皂泡”。两个独立的队列（外部验证集[n=31]和前瞻性验证集[n=27]）被收集以验证“肥皂泡”征。
在三个数据集的 21 例 PFB 病例中观察到“肥皂泡”征（7.4%[21/285]PF-EPNs 和 12.9%[21/163]PFB）；在 PFA 中未见。内部回顾性发现集的分析显示出很大的组内评分者间一致性（第 1 次评分：κ=0.71[0.53-0.90]，第 2 次评分：κ=0.83[0.68-0.98]）和组内评分者间一致性（评分者 1：κ=0.73[0.55-0.91]，评分者 2：κ=0.74[0.55-0.92]）“肥皂泡”征；所有 13 例“肥皂泡”征阳性的病例均为 PFB（p=0.002；阳性预测值[PPV]为 100%，阴性预测值[NPV]为 44%，敏感性为 10%，特异性为 100%）。外部验证集和前瞻性验证集的结果相似，所有“肥皂泡”征阳性的病例均为 PFB（p<0.001；PPV 为 100%）。
“肥皂泡”征代表 PF-EPNs 的 PFB 分子亚型的高度特异性影像学标志物。
