Balint Richard, Lowe Tristan, Shearer Tom
School of Materials, University of Manchester, Manchester, United Kingdom.
Henry Moseley X-ray Imaging Facility, School of Materials, University of Manchester, Manchester, United Kingdom.
PLoS One. 2016 Apr 14;11(4):e0153552. doi: 10.1371/journal.pone.0153552. eCollection 2016.
X-ray computed tomography has become an important tool for studying the microstructures of biological soft tissues, such as ligaments and tendons. Due to the low X-ray attenuation of such tissues, chemical contrast agents are often necessary to enhance contrast during scanning. In this article, the effects of using three different contrast agents--iodine potassium iodide solution, phosphotungstic acid and phosphomolybdic acid--are evaluated and compared. Porcine anterior cruciate ligaments, patellar tendons, medial collateral ligaments and lateral collateral ligaments were used as the basis of the study. Three samples of each of the four ligament/tendon types were each assigned a different contrast agent (giving a total of twelve samples), and the progression of that agent through the tissue was monitored by performing a scan every day for a total period of five days (giving a total of sixty scans). Since the samples were unstained on day one, they had been stained for a total of four days by the time of the final scans. The relative contrast enhancement and tissue deformation were measured. It was observed that the iodine potassium iodide solution penetrated the samples fastest and caused the least sample shrinkage on average (although significant deformation was observed by the time of the final scans), whereas the phosphomolybdic acid caused the greatest sample shrinkage. Equations describing the observed behaviour of the contrast agents, which can be used to predict optimal staining times for ligament and tendon X-ray computed tomography, are presented.
X射线计算机断层扫描已成为研究生物软组织（如韧带和肌腱）微观结构的重要工具。由于此类组织的X射线衰减较低，在扫描过程中通常需要使用化学造影剂来增强对比度。在本文中，对使用三种不同造影剂——碘化钾碘溶液、磷钨酸和磷钼酸——的效果进行了评估和比较。研究以猪的前交叉韧带、髌腱、内侧副韧带和外侧副韧带为基础。四种韧带/肌腱类型中的每种各取三个样本，分别使用不同的造影剂（共十二个样本），并通过在总共五天的时间里每天进行一次扫描（共六十次扫描）来监测造影剂在组织中的渗透过程。由于样本在第一天未染色，到最后一次扫描时它们总共被染色了四天。测量了相对对比度增强和组织变形情况。观察到碘化钾碘溶液渗透样本的速度最快，平均导致的样本收缩最小（尽管在最后一次扫描时观察到了明显的变形），而磷钼酸导致的样本收缩最大。本文给出了描述造影剂观察行为的方程，这些方程可用于预测韧带和肌腱X射线计算机断层扫描的最佳染色时间。
