非线性人类乳腺扩散线圈设计
Design of a non-linear human breast diffusion coil
AI总结：
本文提出一种非线性乳腺扩散线圈设计，通过优化梯度场强度和方向，实现高均匀性扩散加权，提升乳腺DWI的特异性与成像质量。
摘要：
扩散加权成像（DWI）在女性乳腺中的应用是一种磁共振成像（MRI）技术，可能替代或补充乳腺X线摄影和对比增强MR乳腺摄影。为提高DWI在乳腺中的特异性，更强更快的扩散加权是有利的。考虑到目标应用，梯度线圈被设计在不规则形状的半开放电流导体表面上。由于线圈框架紧密贴合非球形目标区域，非线性编码场在实现局部极高水平的梯度强度方面尤为有利。由于乳腺组织具有主要各向同性的细胞微结构，扩散加权梯度的方向可能在目标体积内变化。然而，由于b因子与梯度强度的二次依赖关系，梯度幅度的变化需要谨慎控制。为了实现上述设计目标，相应的多目标优化问题被重新表述为约束优化问题，允许灵活精确地控制线圈属性。提出了一种新的约束，限制每个切片内梯度幅度的变化，同时允许在切片内梯度方向的变化和切片间梯度幅度的变化。上述创新使设计出用于女性乳腺扩散加权的单侧线圈成为可能，该线圈在局部梯度强度超过1~T/m的情况下，实现了高度均匀的扩散加权，适用于冠状面切片方向的成像。
英文摘要：
Diffusion-weighted imaging (DWI) in the female breast is a magnetic resonance imaging (MRI) technique, which may potentially replace or effectively complement both x-ray mammography and contrast-enhanced MR mammography. To further improve specificity of DWI in the breast, stronger and faster diffusion weighting is advantageous. With the target application in mind, the gradient coil is designed on an irregularly shaped semi-open current-carrying surface. Due to the coil former closely fitting the non-spherical target region, non-linear encoding fields become particularly advantageous for achieving locally exceptionally high gradient strengths. As the breast tissue has a predominantly isotropic cellular microstructure, the direction of the diffusion-weighting gradient may be allowed to vary within the target volume. However, due to the quadratic dependency of the b-factor on the gradient strength, variation of the gradient magnitude needs to be carefully controlled. To achieve the above design goals the corresponding multi-objective optimization problem is reformulated as a constrained optimization, allowing for flexible and precise control of the coil properties. A novel constraint is proposed limiting the gradient magnitude variation within every slice while allowing for variations both the direction of the gradient within the slice and the magnitude across the slices. The above innovations enable the design of a unilateral coil for diffusion weighting in the female breast with the local gradient strengths exceeding 1~T/m with highly homogeneous diffusion weighting for imaging in the coronal slice orientation.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
