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

磁共振成像(MRI)是一种非侵入性、高灵敏度的诊断方法，用于诊断功能正常的义齿基托。用0.5T阻性磁共振仪对2例无牙颌患者进行磁共振成像。然而，由于其敏感性较低，义齿基托与丙烯酸树脂义齿的区别并不明显。本研究的目的是开发一种新的用于口腔印模材料的磁共振成像对比度增强方法，并取得了以下结果。增强造影剂由92%的水、5%的琼脂、2%的聚乙烯醇、1%的硅胶和Gd-DTPA(gadolinium-diethylenetriaminepentaacetic-acid)was混合物组成。Gd-DTPA均匀分散于水胶体中，其络合物在热循环实验中稳定。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使用对比度增强器可以清楚地区分它们。提示在水胶体中使用超过1.6 mmol/kg的Gd-DTPA的TL(自旋-晶格-松弛时间)加权技术可获得适当的对比度增强，但要将MRI用于活体，还需进一步检查MRI仪器的密度和合适的参数。

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.