MRI是诊断广泛的急性和慢性踝关节疾病的有价值的工具。包括韧带撕裂,肌腱病,骨软骨损伤.传统的二维(2D)MRI提供了高的图像信号和解剖结构的对比度,用于准确表征关节软骨。骨髓,滑膜,韧带,肌腱,和神经。然而,2DMRI限制是厚切片和固定切片方向。在临床实践中,2DMRI限制为2至3毫米的切片厚度,由于图像切片内的体积平均效应,这可能会导致倾斜结构的轮廓模糊。此外,图像平面方向是固定的,扫描后不能改变,导致2DMRI缺乏沿倾斜和弯曲解剖结构的个性化图像平面取向的多平面和多轴重建能力,如脚踝韧带和肌腱。相比之下,三维(3D)MRI是一种较新的,临床可用的MRI技术,能够获取具有各向同性体素大小的高分辨率踝关节MRI数据集。3DMRI固有的高空间分辨率允许高达5倍的更薄(0.5mm)的图像切片。此外,3DMRI可以在所有三个空间维度(各向同性)中获得具有相同边缘长度的图像体素,允许在MRI扫描后不受限制的多平面和多轴图像重建和后处理。具有0.5至0.7mm各向同性体素大小的踝关节的临床3DMRI可解决最小的解剖踝关节结构以及韧带和肌腱纤维的异常,骨软骨损伤,和神经。获取图像后,操作员可以沿着任何感兴趣的解剖结构单独对齐图像平面,如韧带和肌腱段。此外,弯曲的多平面图像重组可以展开多轴弯曲结构的整个过程,如踝关节周围肌腱,成一个图像平面。我们建议在传统的2DMRI协议中添加3DMRI脉冲序列,以可视化小且弯曲的脚踝结构,从而获得更好的优势。本文就踝关节三维MRI的临床应用作一综述,比较2D和3DMRI诊断踝关节异常的诊断性能,并说明了临床3D踝关节MRI的应用。
MRI is a valuable tool for diagnosing a broad spectrum of acute and chronic ankle disorders, including ligament tears, tendinopathy, and osteochondral lesions. Traditional two-dimensional (2D) MRI provides a high image signal and contrast of anatomic structures for accurately characterizing articular cartilage, bone marrow, synovium, ligaments, tendons, and nerves. However, 2D MRI limitations are thick slices and fixed slice orientations. In clinical practice, 2D MRI is limited to 2 to 3 mm slice thickness, which can cause blurred contours of oblique structures due to volume averaging effects within the image slice. In addition, image plane orientations are fixated and cannot be changed after the scan, resulting in 2D MRI lacking multiplanar and multiaxial reformation abilities for individualized image plane orientations along oblique and curved anatomic structures, such as ankle ligaments and tendons. In contrast, three-dimensional (3D) MRI is a newer, clinically available MRI technique capable of acquiring high-resolution ankle MRI data sets with isotropic voxel size. The inherently high spatial resolution of 3D MRI permits up to five times thinner (0.5 mm) image slices. In addition, 3D MRI can be acquired image voxel with the same edge length in all three space dimensions (isotropism), permitting unrestricted multiplanar and multiaxial image reformation and postprocessing after the MRI scan. Clinical 3D MRI of the ankle with 0.5 to 0.7 mm isotropic voxel size resolves the smallest anatomic ankle structures and abnormalities of ligament and tendon fibers, osteochondral lesions, and nerves. After acquiring the images, operators can align image planes individually along any anatomic structure of interest, such as ligaments and tendons segments. In addition, curved multiplanar image reformations can unfold the entire course of multiaxially curved structures, such as perimalleolar tendons, into one image plane. We recommend adding 3D MRI pulse sequences to traditional 2D MRI protocols to visualize small and curved ankle structures to better advantage. This article provides an overview of the clinical application of 3D MRI of the ankle, compares diagnostic performances of 2D and 3D MRI for diagnosing ankle abnormalities, and illustrates clinical 3D ankle MRI applications.