BACKGROUND Few noninvasive methods are available for equine hoof wall evaluation. The highly organised wall structures and composition of proteoglycans and collagens may make this region amenable to quantitative MRI (qMRI) techniques of T1ρ and T2 mapping to identify pathology related to proteoglycan content and collagen organisation respectively. OBJECTIVE To establish normative T1ρ and T2 values of the equine hoof wall of 3-year-old Quarter Horses with histological comparison. STUDY DESIGN Cadaveric anatomical study. METHODS Six cadaveric left thoracic feet from 3-year-old racing Quarter Horses with no reported lameness were evaluated using T1ρ and T2 mapping. Mapping was performed at six regions of interest at the toe of each hoof including proximal and distal regions of the inner epidermis, stratum lamellatum and corium. Histology was evaluated for standard hoof morphology and proteoglycan staining. RESULTS T2 values of the stratum lamellatum and corium were similar (42.9 [95% CI: 41.6-44.2] ms and 44 [95% CI: 42.7-45.3] ms respectively), but both were significantly different to the inner epidermis (35.8 [95% CI: 34.5-37.1] ms, P<0.001). T1ρ values for the inner epidermis, stratum lamellatum and corium were significantly different (25.1 [95% CI: 23.1-27.1] ms, 44.4 [95% CI: 42.4-46.4] ms and 50.1 [95% CI: 48.1-52.1] ms, respectively, P<0.001). Histology demonstrated normal organised morphology. Proteoglycan staining was only visible in the stratum lamellatum and corium. MAIN LIMITATIONS Cadaveric study with frozen samples used. CONCLUSIONS Variation of qMRI metrics through the depth of the equine hoof wall was found. Although the highly ordered environment of collagen may contribute to T2 values, there was lack of evidence to support proteoglycan content as a major contributor of T1ρ values. It is possible T1ρ values had a greater dependence on total water content as the lowest values were seen in the epidermis. Additional research using qMRI is needed to determine mapping values in different disease states.

中文翻译：

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3 岁夸特马的定量磁共振成像和组织学蹄壁评估。

背景技术很少有无创方法可用于马蹄壁评估。高度有组织的壁结构和蛋白多糖和胶原蛋白的组成可能使该区域适合于 T1ρ 和 T2 映射的定量 MRI (qMRI) 技术，以分别识别与蛋白多糖含量和胶原组织相关的病理学。目的通过组织学比较建立3岁季马蹄壁T1ρ和T2规范值。研究设计 尸体解剖学研究。方法 使用 T1ρ 和 T2 映射评估 3 岁赛马夸特马的六个尸体左胸足，没有报告跛行。在每个蹄趾的六个感兴趣区域进行映射，包括内表皮、板层和真皮的近端和远端区域。评估组织学的标准蹄形态和蛋白多糖染色。结果 板层和真皮的 T2 值相似（分别为 42.9 [95% CI: 41.6-44.2] ms 和 44 [95% CI: 42.7-45.3] ms），但两者与内表皮有显着差异（35.8 [ 95% CI：34.5-37.1] ms，P<0.001)。内表皮、板层和真皮的 T1ρ 值显着不同（25.1 [95% CI: 23.1-27.1] ms、44.4 [95% CI: 42.4-46.4] ms 和 50.1 [95% CI: 48.1-52.1] ms ，分别， P <0.001）。组织学显示正常的有组织的形态。蛋白多糖染色仅在板层和真皮中可见。主要限制 使用冷冻样品的尸体研究。结论 通过马蹄壁的深度发现了 qMRI 指标的变化。尽管胶原蛋白的高度有序环境可能有助于 T2 值，但缺乏证据支持蛋白聚糖含量是 T1ρ 值的主要贡献者。T1ρ 值可能对总含水量有更大的依赖性，因为在表皮中可以看到最低值。需要使用 qMRI 进行额外的研究来确定不同疾病状态的映射值。