Contrast agents are increasingly being applied as interactive tools during intervention. With diagnostic applications, a contrast agent is administered typically once at the beginning of imaging; with intervention procedures, repeated smaller contrast agent doses administered intermittently during a procedure may sometimes be helpful. Contrast agents can be used to highlight a target that is not visualized well on unenhanced scans. However, the benefi t of most contrast agents in interventional procedures is limited, as they are rapidly cleared and
their effects are often transient. Since the use of these agents is dose limited due to renal toxicity, the volume administered during a procedure must be carefully monitored.
造影剂被越来越多地被应用在肿瘤介入治疗中的互动方法。与诊断的应用程序，一个对比剂是典型的一次在成像的开始，与干预程序，重复较小的对比剂剂量给药间歇过程中，有时可能会有所帮助。造影剂可以用来突出一个不显示在增强扫描的目标。然而，在介入手术中的大部分造影剂的优点是有限的，因为他们是迅速清除的影响常常是短暂的。由于这些药物的使用剂量有限，由于肾毒性，在一个过程中的管理过程中，必须仔细监测。
New contrast agents are becoming available for all imaging modalities. US contrast agents can provide similar tissue enhancement characteristics as CT contrast agents, without subjecting patients to the risk of nephrotoxicity posed by iodinated contrast agents ( 62 ). Contrast agents have been used in US examinations to plan, target, and monitor radiofrequency ablations ( 63 – 65 ). New, blood-pool, iodinated contrast agents that stay in the vascular space for an extended time can be used during CT-guided interventions to delineate blood vessels throughout the procedure and can leak out, preferentially where vascular permeability changes exist due to ablation ( 66 , 67 ). Similar agents are being developed for use in MR imaging ( 68 ). Also, MR imaging contrast agents that are aimed at Kupffer-cell uptake and agents used to depict the hepatobiliary tree are all tools that can be applied to specific cases ( 69 ). Additionally, new thermosensitive MR contrast agents can offer a monitoring tool during thermal ablation by, for example, releasing a contrast agent from a liposome under certain thermal conditions (eg, 43°–45°C or 55°C) ( 70 – 72 ). Last, advances in molecular imaging are likely to provide improved targeting opportunities that are specifi c and personalized. For example, new radiotracer-labeled antibodies can specifi cally target colon cancers or clear cell renal cancers and guide interventional procedures ( 73 – 75 ).
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