Abstract
Dopamine transporter (DAT) imaging is commonly used for monitoring Parkinson's disease (PD), where striatal DAT uptake amount is computed to assess PD severity. However, DAT imaging has a high cost and the risk of radiance exposure and is not available in general clinics. Recently, MRI patch of the nigral region has been proposed as a safer and easier alternative. This paper proposes a symmetric regressor for predicting the DAT uptake amount from the nigral MRI patch. Acknowledging the symmetry between the right and left nigrae, the proposed regressor incorporates a paired input-output model that simultaneously predicts the DAT uptake amounts for both the right and left striata. Moreover, it employs a symmetric loss that imposes a constraint on the difference between right-to-left predictions, resembling the high correlation in DAT uptake amounts in the two lateral sides. Additionally, we propose a symmetric Monte-Carlo (MC) dropout method for providing a fruitful uncertainty estimate of the DAT uptake prediction, which utilizes the above symmetry. We evaluated the proposed approach on 734 nigral patches, which demonstrated significantly improved performance of the symmetric regressor compared with the standard regressors while giving better explainability and feature representation. The symmetric MC dropout also gave precise uncertainty ranges with a high probability of including the true DAT uptake amounts within the range.
Abstract (translated)
多巴胺转运体（DAT）成像通常用于监测帕金森病（PD），其中纹状体DAT的摄取量被计算以评估PD的严重程度。然而，DAT成像具有较高的成本，且放射性暴露风险较高，一般诊所无法提供。最近，MRI纹状体区域补丁被提出作为更安全且易於替代的方案。本文提出了一种对称回归器，用于预测纹状体MRI补丁中的DAT摄取量。承认右纹状体和左纹状体之间的对称性，所提出的回归器包含了一对输入-输出模型，同时预测右和左纹状体的DAT摄取量。此外，它采用了一种对称损失，该损失对右到左预测之间的差异施加约束，类似于DAT摄取量在两个侧面之间的较高相关性。此外，我们提出了一种对称蒙特卡洛（MC）丢弃方法，用于提供DAT摄取预测的有价值的不确定性估计，该方法利用了上述对称性。我们对734个纹状体补丁进行了评估，结果显示，与标准回归器相比，对称回归器的性能显著提高，同时具有更好的解释性和特征表示。对称MC丢弃也提供了高概率包括真实DAT摄取量在范围内的精确不确定性范围。
URL
https://arxiv.org/abs/2404.11929
