Litt H I, Brody A S
Department of Biophysical Sciences, State University of New York at Buffalo, USA.
Acad Radiol. 2001 May;8(5):377-83. doi: 10.1016/S1076-6332(03)80544-5.
Phantom studies are an important part of the evaluation of imaging techniques; however, presently available phantom construction materials are not adequate for studies involving both magnetic resonance (MR) imaging and computed tomography (CT). The purpose of this study was to design a phantom construction material useful for multimodality imaging experiments.
Iodinated contrast agent or BaSO4 was added during the formation of agarose gels. Both CT and MR imaging were performed, and T1 and T2 values and CT numbers (in Hounsfield units) were obtained for multiple combinations of contrast material and agarose. Results. The T2 values of agarose gels span the range of those values found in biologic tissues. Phantoms containing iodinated contrast agent were not stable; contrast agent diffused across concentration gradients. BaSO4-loaded agarose phantoms were stable, however, and varying barium concentrations produced phantoms that spanned the range of CT numbers found in biologic tissues. Addition of BaSO4 did not substantially alter T1 or T2 values of agarose gels. Agarose concentration had only a small effect on the CT numbers of BaSO4 suspensions.
BaSO4-loaded agarose is an effective material for construction of multimodality imaging phantoms. It provides adequate signal intensity for MR imaging and attenuation for CT, with independently variable contrast in both modalities.
体模研究是成像技术评估的重要组成部分；然而，目前可用的体模构建材料并不适用于同时涉及磁共振（MR）成像和计算机断层扫描（CT）的研究。本研究的目的是设计一种适用于多模态成像实验的体模构建材料。
在琼脂糖凝胶形成过程中加入碘化造影剂或硫酸钡。同时进行CT和MR成像，并获取造影剂与琼脂糖多种组合的T1和T2值以及CT值（以亨氏单位表示）。结果：琼脂糖凝胶的T2值涵盖了生物组织中的T2值范围。含碘化造影剂的体模不稳定；造影剂会沿浓度梯度扩散。然而，含硫酸钡的琼脂糖体模是稳定的，不同钡浓度产生的体模其CT值涵盖了生物组织中的CT值范围。加入硫酸钡对琼脂糖凝胶的T1或T2值没有实质性影响。琼脂糖浓度对硫酸钡悬浮液的CT值影响较小。
含硫酸钡的琼脂糖是构建多模态成像体模的有效材料。它为MR成像提供了足够的信号强度，为CT提供了衰减，且在两种模态中对比度均可独立变化。
