Rationale and Objectives
We sought to intraindividually compare intravascular contrast enhancement in multidector computed tomography (MDCT) of the chest using contrast media (CM) containing 300 and 400 mg iodine/ml.
Materials and Methods
Seventy-one patients underwent repeated MDCT scanning of the chest at baseline and follow-up. CM with standard iodine (protocol A: 300 mg iodine/ml; Iopromide 300) and high iodine concentration (protocol B: 400 mg iodine/ml; Iomeprol 400) were used. The iodine delivery rate (1.29 g iodine/s) and total iodine load (37 g iodine) were identical for the two protocols. Contrast enhancement was measured in the right and left ventricles, pulmonary trunk, right and left pulmonary arteries, and ascending and descending aortas. Results were compared using paired t -tests; P values were adjusted using Bonferroni correction ( P ≤ .005).
Results
Contrast enhancement values showed no statistically significant differences between the two protocols at all anatomic sites (all P > .005). In the right ventricle, pulmonary trunk, and right and left pulmonary arteries, higher attenuation values for protocol A were detected compared to protocol B (379.0 ± 110.5 vs. 349.8 ± 117.6, 354.5 ± 112.2 vs 330.9 ± 118.3, 348.6 ± 106.0 vs. 321.8 ± 109.9, and 347.9 ± 102.4 vs. 321.0 ± 104.9 HU, respectively). After the lung circulation (left ventricle, ascending aorta, and descending aorta), attenuation values were marginally higher for protocol B. Using both protocols resulted in suitable contrast enhancement with a mean pulmonary attenuation higher than 300 HU.
Conclusions
Using an adapted injection protocol, the administration of 300 and 400 mg iodine CM resulted in a suitable intravascular contrast enhancement in the chest. The use of 400 mg iodine CM does not lead to a statistically significant improvement in contrast enhancement compared to the 300 mg iodine CM.
Computed tomography (CT) angiography (CTA) is performed in daily routine and is an important diagnostic procedure for the evaluation of the vessels, such as in patients with suspected pulmonary embolism. The quality of CTA is mainly influenced by the intravascular contrast enhancement obtained. A high vessel attenuation is crucial for an excellent identification of small vessels. The arterial contrast enhancement is determined by the iodine delivery rate (IDR) (i.e., the amount of iodine per time [gram of iodine per second]). The IDR can be increased either by using an increased flow rate or by injection of a contrast medium (CM) containing a higher concentration of iodine ( ). The development of multidetector row computed tomography (MDCT) has led to new injection protocols for contrast medium due to faster scanning times and larger scanning volumes. Furthermore, a thinner collimation is used; therefore, the structure of peripheral pulmonary arteries can be examined in more detail and subsegmental pulmonary emboli can be detected ( ).
Previous studies reported that the use of highly concentrated iodinated contrast media led to a higher intravascular and parenchymal attenuation compared to the administration of standard contrast media ( ). However, the results of these studies are often controversial and not comparable as different injection protocols with inconsistent IDRs or different total amounts of iodine were used. Furthermore, the comparison of the contrast enhancement was performed interindividually with the great disadvantage of interpatient variables such as age, body weight, cardiac output, and/or circulation times. These factors influence contrast enhancement significantly and can result in a wide range of enhancement values among these patients, although the same injection protocol is used ( ).
Get Radiology Tree app to read full this article<
Materials and methods
Patient Population
Get Radiology Tree app to read full this article<
Table 1
Patient Characteristics
Characteristic Value Women (n) 30 Men (n) 41 Age (y, mean ± SD) (range) 61.2 ± 13.6 (25–83) Height (cm, mean ± SD) (range) 172 ± 10 (150–195) Time interval (days, mean ± SD) (range) 138 ± 89 (31–454)
Table 2
Body Weight and Body Mass Index (BMI) at Baseline and Follow-up Examinations
Characteristic Baseline Examination Follow-up Examination Body weight (kg, mean ± SD) (range) 78.1 ± 17.5 (49–120) 77.7 ± 18.0 (50–129) BMI (kg/m 2 , mean ± SD) (range) 26.4 ± 4.7 (17.9–40.1) 26.2 ± 4.8 (18.5–41.2)
Get Radiology Tree app to read full this article<
Injection and Scan Protocol
Get Radiology Tree app to read full this article<
Get Radiology Tree app to read full this article<
Get Radiology Tree app to read full this article<
Quantitative Analysis
Get Radiology Tree app to read full this article<
Get Radiology Tree app to read full this article<
Statistical Analysis
Get Radiology Tree app to read full this article<
Get Radiology Tree app to read full this article<
Get Radiology Tree app to read full this article<
Results
Get Radiology Tree app to read full this article<
Table 3
Contrast Enhancement in the Chest: Comparison of Contrast Enhancement (in Hounsfield units) in Right Ventricle, Pulmonary Trunk, Pulmonary Artery, Left Ventricle, and Ascending and Descending Thoracic Aortas Between Protocol A and Protocol B
Region/Vessel Protocol A Protocol B_P_ Value Right ventricle 379.0 ± 110.5 349.8 ± 117.6 .0140 Pulmonary trunk 354.5 ± 112.2 330.9 ± 118.3 .0784 Right pulmonary artery 348.6 ± 106.0 321.8 ± 109.9 .0439 Left pulmonary artery 347.9 ± 102.4 321.0 ± 104.9 .0405 Left ventricle 302.7 ± 60.1 311.3 ± 72.2 .2572 Ascending aorta 298.8 ± 54.0 308.8 ± 67.1 .1499 Descending aorta I 272.7 ± 65.3 279.8 ± 64.8 .3404 Descending aorta II 290.3 ± 63.8 301.4 ± 75.2 .1176
Values given as mean ± SD; P value of corresponding paired t -test.
![Figure 1, Intraindividual comparison of the mean contrast enhancement in the right ventricle, pulmonary trunk, pulmonary artery, left ventricle, and ascending and descending thoracic aortas between protocols A and B (300 mg and 400 mg iodine contrast media [CM], respectively). There were no statistically significant differences between the two protocols at all measured anatomic sites. However, in the anatomic sites located before the lung circulation, the mean attenuation showed higher values for the 300 mg iodine CM compared to the 400 mg iodine CM. After the lung circulation, marginally higher attenuation values for the 400 mg iodine CM were measured. Graphs represent mean CT density in Hounsfield units (HU) ±1 standard deviation (SD).](https://storage.googleapis.com/dl.dentistrykey.com/clinical/ContrastEnhancementinChestMultidetectorComputedTomography/0_1s20S1076633208002882.jpg)
Get Radiology Tree app to read full this article<
Discussion
Get Radiology Tree app to read full this article<
Get Radiology Tree app to read full this article<
Get Radiology Tree app to read full this article<
Get Radiology Tree app to read full this article<
Get Radiology Tree app to read full this article<
Get Radiology Tree app to read full this article<
Get Radiology Tree app to read full this article<
Conclusion
Get Radiology Tree app to read full this article<
References
1. Fleischmann D.: High-concentration contrast media in MDCT angiography: Principles and rationale. Eur Radiol 2003; 13: pp. N39-N43.
2. Fleischmann D.: Use of high concentration contrast media: Principles and rationale–vascular district. Eur J Radiol 2003; 45: pp. S88-S93.
3. Schoepf U.J., Holzknecht N., Helmberger T.K., et. al.: Subsegmental pulmonary emboli: Improved detection with thin-collimation multi-detector row spiral CT. Radiology 2002; 222: pp. 483-490.
4. Coche E., Pawlak S., Dechambre S., et. al.: Peripheral pulmonary arteries: Identification at multi-slice spiral CT with 3D reconstruction. Eur Radiol 2003; 13: pp. 815-822.
5. Patel S., Kazerooni E.A., Cascade P.N.: Pulmonary embolism: Optimization of small pulmonary artery visualization at multi-detector row CT. Radiology 2003; 227: pp. 455-460.
6. Cademartiri F., de Monye C., Pugliese F., et. al.: High iodine concentration contrast material for noninvasive multislice computed tomography coronary angiography: Iopromide 370 versus iomeprol 400. Invest Radiol 2006; 41: pp. 349-353.
7. Setty B.N., Sahani D.V., Ouellette-Piazzo K., et. al.: Comparison of enhancement, image quality, cost, and adverse reactions using 2 different contrast medium concentrations for routine chest CT on 16-slice MDCT. J Comput Assist Tomogr 2006; 30: pp. 818-822.
8. Furuta A., Ito K., Fujita T., et. al.: Hepatic enhancement in multiphasic contrast-enhanced MDCT: Comparison of high- and low-iodine-concentration contrast medium in same patients with chronic liver disease. AJR Am J Roentgenol 2004; 183: pp. 157-162.
9. Sultana S., Morishita S., Awai K., et. al.: Evaluation of hypervascular hepatocellular carcinoma in cirrhotic liver by means of helical CT: Comparison of different contrast medium concentrations within the same patient. Radiat Med 2003; 21: pp. 239-245.
10. Tsurusaki M., Sugimoto K., Fujii M., et. al.: Multi-detector row helical CT of the liver: quantitative assessment of iodine concentration of intravenous contrast material on multiphasic CT: A prospective randomized study. Radiat Med 2004; 22: pp. 239-245.
11. Schoellnast H., Deutschmann H.A., Fritz G.A., et. al.: MDCT angiography of the pulmonary arteries: Influence of iodine flow concentration on vessel attenuation and visualization. AJR Am J Roentgenol 2005; 184: pp. 1935-1939.
12. Chambers T.P., Baron R.L., Lush R.M., et. al.: Hepatic CT enhancement: Comparison of ionic and nonionic contrast agents in the same patients. Radiology 1994; 190: pp. 721-725.
13. Chambers T.P., Baron R.L., Lush R.M., et. al.: Hepatic CT enhancement: A method to demonstrate reproducibility. Radiology 1993; 188: pp. 627-631.
14. Prokop M.: Multislice CT angiography. Eur J Radiol 2000; 36: pp. 86-96.
15. Bae K.T., Tran H.Q., Heiken J.P.: Multiphasic injection method for uniform prolonged vascular enhancement at CT angiography: Pharmacokinetic analysis and experimental porcine model. Radiology 2000; 216: pp. 872-880.
16. Bae K.T., Tran H.Q., Heiken J.P.: Uniform vascular contrast enhancement and reduced contrast medium volume achieved by using exponentially decelerated contrast material injection method. Radiology 2004; 231: pp. 732-736.
17. Fleischmann D., Rubin G.D., Bankier A.A., et. al.: Improved uniformity of aortic enhancement with customized contrast medium injection protocols at CT angiography. Radiology 2000; 214: pp. 363-371.
18. Yanaga Y., Awai K., Nakayama Y., et. al.: Pancreas: Patient body weight tailored contrast material injection protocol versus fixed dose protocol at dynamic CT. Radiology 2007; 245: pp. 475-482.
19. Schoellnast H., Brader P., Oberdabernig B., et. al.: High-concentration contrast media in multiphasic abdominal multidetector-row computed tomography: Effect of increased iodine flow rate on parenchymal and vascular enhancement. J Comput Assist Tomogr 2005; 29: pp. 582-587.
20. Keil S., Plumhans C., Behrendt F.F., et. al.: MDCT angiography of the pulmonary arteries: intravascular contrast enhancement does not depend on iodine concentration when injecting equal amounts of iodine at standardized iodine delivery rates.2008. (epub ahead of print)
21. Behrendt F.F., Mahnken A.H., Keil S., et. al.: Contrast enhancement in multidetector-row computed tomography (MDCT) of the abdomen: Intraindividual comparison of contrast media containing 300 mg versus 370 mg iodine per ml. Eur Radiol 2008; 18: pp. 1199-1205.
22. Han J.K., Kim A.Y., Lee K.Y., et. al.: Factors influencing vascular and hepatic enhancement at CT: Experimental study on injection protocol using a canine model. J Comput Assist Tomogr 2000; 24: pp. 400-406.
23. Awai K., Inoue M., Yagyu Y., et. al.: Moderate versus high concentration of contrast material for aortic and hepatic enhancement and tumor-to-liver contrast at multi-detector row CT. Radiology 2004; 233: pp. 682-688.
24. Tsai I.C., Lee T., Tsai W.L., et. al.: Contrast enhancement in cardiac MDCT: Comparison of iodixanol 320 versus iohexol 350. AJR Am J Roentgenol 2008; 190: pp. W47-W53.