Smith Matthew, Zhai Xu, Harter Ray, Sisney Gale, Elezabye Mai, Fain Sean
Medical Physics, University of Wisconsin, Clinical Science Center-J5, Madison, Wisconsin 53792-3252, USA.
Med Phys. 2008 Aug;35(8):3779-86. doi: 10.1118/1.2952442.
MRI is rapidly growing as a tool for image-guided procedures in the breast such as needle localizations, biopsy, and cryotherapy. The ability of MRI to resolve small (<1 cm) lesions allows earlier detection and diagnosis than with ultrasound. Most MR-guidance methods perform a two-dimensional compression of the breast that distorts tissue anatomy and limits medial access. This work presents a system for localizing breast lesions with 360 degrees access to breast tissue. A novel system has been developed to perform breast lesion localization using MR guidance that uses a 3D radial coordinate system with four degrees of freedom. The device is combined with a novel breast RF coil for improved signal to noise and rotates 360 degrees around the breast to allow medial, lateral, superior, and inferior access minimizing insertion depth to the target. Coil performance was evaluated using a human volunteer by comparing signal to noise from both the developed breast RF coil and a commercial seven-channel breast coil. The system was tested with a breast-shaped gel phantom containing randomly distributed MR-visible targets. MR-compatible localization needles were used to demonstrate the accuracy and feasibility of the concept for breast biopsy. Localization results were classified based on the relationship between the final needle tip position and the lesion. A 3D bladder concept was also tested using animal tissue to evaluate the device's ability to immobilize deformable breast tissue during a needle insertion. The RF breast coil provided signal to noise values comparable to a seven-channel breast coil. The needle tip was in contact with the targeted lesion in 89% (25/28) of all the trials and 100% (6/6) of the trials with targeted lesions >6 mm. Target lesions were 3-4 mm in diameter for 47% (13/28), 5-6 mm in diameter for 32% (9/28), and over 6 mm in diameter for 21% (6/28) of the trials, respectively. The 3D bladder concept was shown to immobilize a deformable animal tissue phantom during needle insertion. It is concluded that the MR-guidance system accurately localizes small targets on the order of 3-4 mm in a breast phantom with 360 degrees rotational access.
磁共振成像（MRI）作为一种用于乳腺图像引导手术（如针定位、活检和冷冻治疗）的工具正在迅速发展。与超声相比，MRI分辨小（<1cm）病变的能力使得能够更早地进行检测和诊断。大多数MR引导方法对乳腺进行二维压缩，这会扭曲组织结构并限制对内侧的 access。这项工作提出了一种用于乳腺病变定位的系统，该系统能够360度 access 乳腺组织。已经开发出一种新颖的系统，该系统使用具有四个自由度的3D径向坐标系，通过MR引导来进行乳腺病变定位。该设备与一种新颖的乳腺射频线圈相结合，以提高信噪比，并围绕乳腺旋转360度，从而实现从内侧、外侧、上方和下方 access，将到达目标的插入深度降至最低。通过比较所开发的乳腺射频线圈和商用七通道乳腺线圈的信噪比，使用一名人类志愿者对线圈性能进行了评估。该系统使用含有随机分布的MR可见目标的乳腺形状的凝胶体模进行了测试。使用与MR兼容的定位针来证明该概念用于乳腺活检的准确性和可行性。根据最终针尖位置与病变之间的关系对定位结果进行分类。还使用动物组织对一种3D膀胱概念进行了测试，以评估该设备在针插入过程中固定可变形乳腺组织的能力。该射频乳腺线圈提供的信噪比与七通道乳腺线圈相当。在所有试验中，针尖与目标病变接触的比例为89%（25/28），在目标病变>6mm的试验中这一比例为100%（6/6）。在试验中，目标病变的直径分别为3 - 4mm的占47%（13/28），5 - 6mm的占32%（9/28），超过6mm的占21%（6/28）。结果表明，3D膀胱概念在针插入过程中能够固定可变形的动物组织体模。得出的结论是，该MR引导系统能够在具有360度旋转 access 的乳腺体模中准确地定位3 - 4mm左右的小目标。
