Objectives

Posterior Cortical Atrophy (PCA) is an atypical presentation of Alzheimer disease (AD) characterized by atrophy of posterior brain regions. This pattern of atrophy is usually evaluated with Koedam visual rating scale, a score developed to enable visual assessment of parietal atrophy on magnetic resonance imaging (MRI). However, Koedam scale is complex to assess and its utility in the differential diagnosis between PCA and typical AD has not been demonstrated yet. The aim of this study is therefore to spot a simple and reliable MRI element able to differentiate between PCA and typical AD using visual rating scales.

Methods

15 patients who presented with progressive complex visual disorders and predominant occipitoparietal hypometabolism on PET-FDG were selected from our centre and compared with 30 typical AD patients and 15 healthy subjects. We used previously validated visual rating scales including Koedam scale, which we divided into three major components: posterior cingulate, precuneus and parieto-occipital. Subsequently we validated the results using the automated software Brainvisa Morphologist and Voxel Based Morphometry (VBM).

Results

Patients with PCA, compared to typical AD, showed higher widening of the parieto-occipital sulcus, assessed both with visual rating scales and Brainvisa. In the corresponding areas, the VBM analysis showed an inverse correlation between the results obtained from the visual evaluation scales with the volume of the grey matter and a direct correlation between the same results with the cerebrospinal fluid volume.

Conclusions

A visually based rating scale for parieto-occipital sulcus can distinguish Posterior Cortical Atrophy from typical Alzheimer disease.

中文翻译：

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顶枕沟增宽可区分后皮质萎缩和典型阿尔茨海默病

 目标

后皮质萎缩（PCA）是阿尔茨海默病（AD）的一种非典型表现，其特征是后脑区域萎缩。这种萎缩模式通常用 Koedam 视觉评分量表进行评估，该评分是为了在磁共振成像 (MRI) 上对顶叶萎缩进行视觉评估而开发的。然而，Koedam 量表评估起来很复杂，其在 PCA 和典型 AD 鉴别诊断中的效用尚未得到证实。因此，本研究的目的是找到一种简单可靠的 MRI 元件，能够使用视觉评分量表区分 PCA 和典型 AD。

 方法

从我们中心选取了 15 名在 PET-FDG 上表现为进行性复杂视觉障碍和主要枕顶代谢低下的患者，并与 30 名典型 AD 患者和 15 名健康受试者进行比较。我们使用了之前经过验证的视觉评分量表，包括 Koedam 量表，我们将其分为三个主要组成部分：后扣带回、楔前叶和顶枕叶。随后，我们使用自动化软件 Brainvisa 形态学家和基于体素的形态测量 (VBM) 验证了结果。

 结果

通过视觉评定量表和 Brainvisa 进行评估，与典型 AD 患者相比，PCA 患者的顶枕沟增宽程度更高。在相应区域，VBM分析显示，视觉评估量表获得的结果与灰质体积之间呈负相关，而与脑脊液体积之间呈正相关。

 结论

基于视觉的顶枕沟评分量表可以区分后皮质萎缩和典型的阿尔茨海默病。