MRI of the denture foundation -Development of a new contrast enhancement for MRI-

为了诊断功能下的义齿基托，磁共振成像（MRI）是一种非侵入性的，高灵敏度的诊断成像程序。用0.5T电阻性MR机对2例无牙颌患者进行了MR成像。然而，由于义齿基托和丙烯酸树脂义齿的敏感性较低，两者之间的区别并不明显，本研究旨在开发一种新的MR增强技术，用于口腔类印模材料的MR成像，并取得了以下结果.增强造影剂由92%水、5%琼脂、2%聚乙烯醇（PVA）、1%硅油（Silicone）和钆-二乙烯三胺五乙酸（Gd-DTPA）混合而成. GD-DTPA在水胶体中均匀分散，其复合物在热循环试验中稳定.在初步的磁共振成像实验中，石膏模型和丙烯酸树脂义齿之间的对比增强剂可以清楚地区分.结果表明，当GD-DTPA浓度大于1.6mmol/kg时，采用T1（自旋-晶格-弛豫时间）加权技术可获得适当的增强效果，但对活体进行MRI时，还需进一步检查MRI的密度和仪器参数。

To diagnose the denture foundation under function, magnetic resonance imaging(MRI)was employed as a noninvasive, highly sensitive diagnostic imaging procedure. MR images of two edentulous patients were obtained with the 0.5T resistive MR unit. However, the denture foundation was not distinguished clearly from acrylic resin dentures because of their low sensitivity.The purpose of this study was to develop a new contrast enhancement for MR imaging which can be used in oral cavity like impression materials, and the following results were obtained.1. The contrast agent for enhancement consists of hydrocolloid 92% water, 5% agar, 2%, -PVA(polyvinyl-alcohol)1% silicone), and Gd-DTPA(gadolinium-diethylenetriaminepentaacetic-acid)was mixed.2. GD-DTPA was dispersed in the hydrocolloid equally, and it's complex was stable in the thermal cycling test.3. In a preliminary MR imaging experiment, plaster models and acrylic resin dentures were distinguished clearly using the contrast enhancer between them.4. It was suggested that the proper contrast enhancement was achieved using Tl(spin-lattice-relaxation time)-weighted techniques with more than 1.6mmol/kg GD-DTPA in hydrocolloid, and the density and the proper parameters of MRI instruments must be examined still more to use MRI for living bodies.