FLAIR超分辨率是清除还是幻觉了小白质病变？
Does FLAIR super-resolution erase or hallucinate small white-matter lesions?
- University of Pennsylvania（宾夕法尼亚大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
该研究针对FLAIR超分辨率是否影响白质病变的问题，采用ADNI数据对比多种上采样方法，发现超分辨率主要清除小病灶，ECLARE的小病灶信号恢复效果最优。
AI中文摘要：
Flair序列扫描中的白质高信号（WMH）亮区与脑血管病理及神经退行性病变相关，临床中FLAIR通常采用厚层采集，导致层间分辨率较差。超分辨率（SR）是从各向异性扫描中恢复各向同性体积的常用方法，但在WMH分割前应用SR是否能保留病变内容仍未知：模型可能清除真实小病变或幻觉出不存在的病变。本研究使用ADNI队列29名受试者的1毫米各向同性高分辨率（HR）FLAIR扫描数据，每例均由专家手动分割WMH，随后将其降质为模拟的3毫米和5毫米层间采集数据，采用多对比度隐式神经表示（INR）、单对比度自监督模型（ECLARE）及三次插值将其上采样至HR网格。以模拟厚层切片的WMH分割结果为下限，原始HR FLAIR的分割结果为上限，开展病灶水平分析。在4种WMH分割方法（WMH-SynthSeg、segcsvd、MARS-WMH、TrUE-Net）中，选择对HR图像中小病灶最敏感的MARS-WMH，采用检测灵敏度、清除率（重建后丢失的HR检测病灶比例）、幻觉率（手动及HR分割均不存在的预测成分比例）作为评估指标。结果显示，SR的主要影响是清除真实小病灶而非幻觉，且清除率随层厚增加而升高，不过所有重建方法的病灶检测性能均优于原始厚层切片；ECLARE在两种层厚下均能最佳恢复小病灶信号，而INR的表现与三次插值无差异。
英文摘要：
White matter hyperintensities (WMH), bright regions on Fluid-attenuated Inversion Recovery (FLAIR) scans are associated with cerebrovascular pathology and neurodegeneration. FLAIR is usually acquired with thick slices in clinical settings, giving it poor through-plane resolution. Super-resolution (SR) is a widely used method for recovering an isotropic volume from an anisotropic scan. Yet whether applying it prior to WMH segmentation preserves lesion content remains unknown: a model may erase small real lesions or hallucinate absent ones. We used 1-mm isotropic high-resolution (HR) FLAIR scans from 29 individuals in the ADNI cohort, each manually segmented for WMH by an expert. Then, we degraded each to simulated 3 and 5 mm through-plane acquisitions. Multi-contrast implicit neural representation (INR), a single-contrast self-supervised model (ECLARE), and cubic interpolation were used to upsample them onto the HR grid. WMH segmentation from a simulated thick slice and the original HR FLAIR set the floor and ceiling, respectively, for the per-lesion analysis. Of four WMH segmentation methods (WMH-SynthSeg, segcsvd, MARS-WMH, TrUE-Net), we ran the analysis under the most sensitive one to small lesions on HR (MARS-WMH) with the evaluation metrics of detection sensitivity, erasure rate (HR-detected lesions lost after reconstruction), and hallucination rate (predicted components absent from both the manual and HR segmentation). The dominant effect of SR was erasure of small real lesions, not hallucination, and it increased with slice thickness, though every reconstruction still improved lesion detection over the raw thick slice. ECLARE recovered small lesion signal best at both thicknesses, while the INR was no better than cubic interpolation.
