Small W C, Nelson R C, Bernardino M E, Brummer L T
Department of Radiology, Emory University School of Medicine, Atlanta, GA 30322.
AJR Am J Roentgenol. 1994 Jul;163(1):87-92. doi: 10.2214/ajr.163.1.8010255.
Spiral CT allows rapid hepatic imaging during a single breath-hold. The increase in imaging speed potentially allows contrast material to be used more efficaciously than with conventional dynamic CT, perhaps allowing a decrease in the volume of required contrast agent. To determine how this can be accomplished, we studied the effect of different bolus IV injection rates and amounts of contrast material on early hepatic enhancement during dynamic bolus spiral CT.
A group of 20 healthy male volunteers were divided into four groups of five each. The groups received 75, 100, 125, or 150 ml of contrast material (Omnipaque 300, 300 mg l/ml). Each person within each group was scanned as contrast material was injected at rates of 3, 4, and 5 ml/sec. Hepatic enhancement was evaluated by comparing quantitative regions of interest before and after bolus injection of contrast material. Variations in enhancement produced by changes in volume and injection rate of contrast material were evaluated on early, middle, and late sections of the spiral, corresponding to 32-34, 41-43, and 51-53 sec, respectively, after the injection of contrast material was begun.
Hepatic enhancement increased more rapidly when the bolus of contrast material was given at a rate of 5 ml/sec than at the slower rates of 3 or 4 ml/sec. Enhancement of the liver was greatest at the late portion of the spiral (51-53 sec after start of the bolus injection), averaging 73 and 79 H for volumes of 125 and 150 ml, respectively, at 5 ml/sec, and the enhancement was still increasing at that time. Enhancement curves predict 50- and 70-H mean increases in hepatic attenuation on initial slices with scan delays of approximately 40 and 50 sec, respectively, for these two protocols.
Our results demonstrate that there is a marked dependence on early hepatic enhancement produced by variations in volume and injection rate of contrast material. We found no difference in the results produced by 125- and 150-ml volumes. These results are important for maximizing the effectiveness of IV contrast material during rapid hepatic spiral CT scanning.
螺旋CT能够在一次屏气过程中快速完成肝脏成像。成像速度的提高可能使对比剂的使用比传统动态CT更有效，或许还能减少所需对比剂的用量。为了确定如何实现这一点，我们研究了不同团注静脉注射速率和对比剂用量对动态团注螺旋CT期间肝脏早期强化的影响。
20名健康男性志愿者被分为四组，每组5人。这些组分别接受75、100、125或150毫升对比剂（欧乃派克300，300毫克碘/毫升）。每组中的每个人在以3、4和5毫升/秒的速率注射对比剂时进行扫描。通过比较团注对比剂前后的定量感兴趣区来评估肝脏强化情况。在对比剂注射开始后分别对应32 - 34秒、41 - 43秒和51 - 53秒的螺旋早期、中期和晚期层面，评估对比剂体积和注射速率变化所产生的强化差异。
以5毫升/秒的速率给予对比剂团注时，肝脏强化比以3或4毫升/秒的较慢速率时增加得更快。在螺旋晚期（团注注射开始后51 - 53秒）肝脏强化最大，对于125毫升和150毫升的体积，在5毫升/秒时平均分别为73和79亨氏单位，并且此时强化仍在增加。强化曲线预测，对于这两种方案，在初始层面上扫描延迟约40秒和50秒时，肝脏衰减平均分别增加50和70亨氏单位。
我们的结果表明，肝脏早期强化明显依赖于对比剂体积和注射速率的变化。我们发现125毫升和150毫升体积所产生的结果没有差异。这些结果对于在快速肝脏螺旋CT扫描期间使静脉对比剂的有效性最大化很重要。
