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ORIGINAL ARTICLE
Year : 2017  |  Volume : 24  |  Issue : 1  |  Page : 30-33

The comparison of x-ray attenuations of contrast media in different dilutions: An experimental study


1 Department of Radiology, Faculty of Medicine, Bozok University, Yozgat, Turkey
2 Department of Radiology, Atatürk Research and Education Hospital, Ankara, Turkey
3 Department of Pharmacology, Faculty of Medicine, Y?ld?r?m Beyaz?t University, Ankara, Turkey
4 Department of Radiology, Onkoloji Research and Education Hospital, Ankara, Turkey

Date of Web Publication11-Jan-2017

Correspondence Address:
Halil Ibrahim Serin
Department of Radiology, Faculty of Medicine, Bozok University, Yozgat
Turkey
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DOI: 10.4103/1115-3474.198087

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  Abstract 

Aims: Iodinated contrast materials are used as contrast material in radiologic examinations. There is an intense competition between the contrast media companies in the contrast market in areas such as price, effectivities, and lack of side effects. This experimental study was carried out for comparing the effectiveness of contrast agents. We measured X-ray attenuations of contrast agents because image quality depends on these attenuation amounts. Materials and Methods: Contrast agents are divided into two main groups in iodinated contrast materials; ionic-iodinated contrast agents and nonionic-iodinated contrast agents. Nonionic contrast materials are iopamidol, iohexol, iopromide, iobitridol, and iomeprol. In this study, by using contrast agents in different dilutions, X-ray attenuations were examined in Hounsfield units by using computed tomography. Results: There was no statistically significant difference between the slopes of five commercial forms according to dilutions. Conclusion: From our study, we concluded that iopamidol, iohexol, iopromide, iobitridol, or iomeprol are same in clinical usage.

Keywords: Computed tomography; contrast agents; X-ray attenuations


How to cite this article:
Serin HI, Arda K, Kara H, Aydin H. The comparison of x-ray attenuations of contrast media in different dilutions: An experimental study. West Afr J Radiol 2017;24:30-3

How to cite this URL:
Serin HI, Arda K, Kara H, Aydin H. The comparison of x-ray attenuations of contrast media in different dilutions: An experimental study. West Afr J Radiol [serial online] 2017 [cited 2020 Feb 25];24:30-3. Available from: http://www.wajradiology.org/text.asp?2017/24/1/30/198087


  Introduction Top


Radiographic contrast agents are the compounds which are used to improve the visibility of tissue and organs in a radiologic image. Radiographic contrast media are divided into positive and negative contrast agents. The positive contrast agents attenuate X-rays more than body's tissue and space. [1],[2]

Iodinated contrast materials are most commonly used as contrast agents in radiologic examinations. Water-soluble iodinated contrast agents are used for angiography, computed tomography (CT), and radiography. There are two main groups in iodinated contrast materials; ionic-iodinated contrast agents and nonionic-iodinated contrast agents. In clinical usage, nonionic contrast agents are preferred for intravenous applications due to effectivities and fewer side effects. [1],[2],[3],[4] Commercially available nonionic contrast media are iopamidol, iohexol, iopromide, iobitridol, and iomeprol. There are competitions between the pharmacological companies in the contrast market, in areas such as price, effectivities, and lack of side effects.

In clinical use, the success of contrast agents is known to be dependent on many factors. These factors are hemodynamic, renal functions, hydration, etc., Some basic parameters affect the success of contrast agents, remaining are unchanged, and the effectivity of contrast media has been observed to be more different. [2],[4] X-ray attenuation values directly affect contrast agents' efficiency. In this experimental study, by using contrast medium in different dilutions, phantoms were created, and then X-ray attenuations were examined in Hounsfield units (HU) by using CT.


  Materials and Methods Top


Primarily, commercial forms of iopamidol, iohexol, iopromide, iobitridol, and iomeprol containing 300 mg iodine were provided. The total volume was 10,500 μL for each item. The dilutions were done by a 10-year experienced biochemistry specialist by using bi-distilled water.

Each dilution set contained nine tubes, the dilution proportions are as follows [Table 1]:

X-ray attenuation values were calculated. Results were compared statistically for each compound. Each set was placed on Styrofoam tube pads so that phantoms were created. To avoid beam hardening and to obtain real density values as much as possible, we placed phantoms center of field of view. Each phantom was scanned in 80-120 Kvp, in 5 mm and 10 mm slice thickness, by using 64 MDCT TK LIGHT SPEED GE Medical System. After scanning, we obtained digital imaging and communications in medicine images, and we measured density as HUs by using GE work station and MVIS work station. In 0.5 cm 2 circular area, HUs were measured. All values were transferred into graphic images, and statistical evaluation was carried out by SPSS for Windows version 17.0 statistics software program (Microsoft, Seattle, USA).
Table 1: Contrast material diluton ratios

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  Results Top


At the determined rates in the dilution of contrast media, results of the measurements were shown in [Table 1],[Table 2],[Table 3],[Table 4] and [Table 5],[Table 6].

To compare the dilution values in the five commercial forms (iopamidol, iohexol, iopromide, iobitridol, and iomeprol), we used a one-phase exponential decay model. More explicitly, the exponential decay model was established using the following equation:

Measure = Initial level × exp(−t × k),

where, t and k signify dilution and exponential rate constant, respectively.
Table 2: Iohexol

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Table 3: Iomeprol

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Table 4: Iobitridol

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Table 5: Iopromide

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Table 6: Ioversol

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We estimated the relevant rate constants by nonlinear regression of the one-phase exponential model on the average measure in each commercial form. For the statistical comparison of the rate estimates, we used one-way ANOVA, in which the asymptotic standard errors of the estimates with their associated degree of freedom were used to calculate the F-statistics and the corresponding probabilities. Brown-Forsythe test was used for pair-wise comparison between the five commercial forms.

There is no statistically significant difference between the slopes of five commercial forms according to dilutions (F {4, 40} =0.7061, P = 0.5925) [Figure 1].
Figure 1: Slopes of dilution and X-ray attenuation values in the five commercial forms of contrast mediums

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  Discussion Top


Mainly, commercially available contrast agents contain iopamidol, iohexol, iopromide, iobitridol, or iomeprol. Manufacturers try to show the superior properties of their drugs as much as possible because this condition creates doubts among clinical users. Inevitably, they begin to compare their drugs.

Iomeprol, iopamidol, iohexol, iopromide, and iobitridol are monomeric nonionic, iodinated contrast agents. In the literature, it was reported that there was no difference between the diagnostic efficiencies of contrast agents significantly from that of others. [1],[2] Our study results are the similar of the literatures. Despite the above-mentioned contrast agents show differences, enhancement effects are generally regarded as the same. Hemodynamic, cardiac, renal, and thyroid functions are tested in vivo. [3],[4] Molecular structure of the iodinated contrast agents is based on single tri-iodinated benzene ring. The most recent class of agents is dimers that consist of a molecule with two benzene rings (again, each with three iodine atoms) that do not dissociate in water (nonionic) which are designated as iso-osmolar contrast agents. [3],[4],[5] The toxicity of contrast agents decreases as osmolality approaches that of serum. This has been accomplished by developing nonionizing compounds and then combining two monomers to form a dimer, the currently used iodinated agents are cleared almost completely by glomerular filtration. With reduced renal function, there is vicarious excretion primarily in bile and through the bowel. Circulatory half-life is 1-2 h, assuming normal renal function. [4],[5]

Side chains of the contrast agents are slightly different. Although side chains have two hydroxyl and one amide group, the differences are on the conformation. The study demonstrated that the differences might not effect statistically on the absorption of X-ray. [1],[3],[4],[5]

The results of these studies are subjective. Dimeric nonionic iodinated contrast has a lower osmolality than monomeric nonionic iodinated contrast, but it is available at lower iodine concentrations, less dilution of intravascular fluid by influx from the extravascular space is proposed to occur with decreasing osmolality, and there is less intravascular dilution of iso-osmolar contrast. [6] Injection of iodinated radiographic contrast media is generally safe; however, with increased use, adverse events are more likely to occur; the most important adverse effects include hypersensitivity reactions, contrast-induced nephropathy, and thyrotoxicosis. [7] In patients with moderate renal dysfunction, adequate hydration and use of as little contrast media as practical are recommended. Contrast-induced nephropathy is often transient. [7],[8]

We aimed to compare the characteristics of attenuation of contrast agents objectively; this study reviews absorption data about X-ray contrast media in vitro. In some references, animal-human data are used in areas where no absorption data are available. These references report that the pharmacokinetic properties of all contrast media (iopamidol, iohexol, iopromide, iobitridol and iomeprol) are similar.


  Conclusion Top


According to our study, there is no difference in the clinical usage of iopamidol, iohexol, iopromide, iobitridol, or iomeprol.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Dooley M, Jarvis B. Iomeprol: A review of its use as a contrast medium. Drugs 2000;59:1169-86.  Back to cited text no. 1
    
2.
McCormack PL. Iobitridol: A review of its use as a contrast medium in diagnostic imaging. Clin Drug Investig 2013;33:155-66.  Back to cited text no. 2
    
3.
Rosati G. Clinical pharmacology of iomeprol. Eur J Radiol 1994;18 Suppl 1:S51-60.  Back to cited text no. 3
    
4.
Bourin M, Jolliet P, Ballereau F. An overview of the clinical pharmacokinetics of X-ray contrast media. Clin Pharmacokinet 1997;32:180-93.  Back to cited text no. 4
    
5.
ACR Manual on Contrast Media. Ver. 10.2. 2010. Available from: http://www.acr.org/quality-safety/resources/contrast-manual.  Back to cited text no. 5
    
6.
Pannu HK, Thompson RE, Phelps J, Magee CA, Fishman EK. Optimal contrast agents for vascular imaging on computed tomography: Iodixanol versus iohexol. Acad Radiol 2005;12:576-84.  Back to cited text no. 6
    
7.
Thomson KR. Safe use of radiographic contrast media. Aust Prescr 2010;33:19-22.  Back to cited text no. 7
    
8.
Hughes PM, Bisset R. Non-ionic contrast media: A comparison of iodine delivery rates during manual injection angiography. Br J Radiol 1991;64:417-9.  Back to cited text no. 8
    


    Figures

  [Figure 1]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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