Elsevier

Clinical Radiology

Volume 63, Issue 3, March 2008, Pages 263-271
Clinical Radiology

Effect of duration of contrast material injection on peak enhancement times and values of the aorta, main portal vein, and liver at dynamic MDCT with the dose of contrast medium tailored to patient weight

https://doi.org/10.1016/j.crad.2007.02.024Get rights and content

Aim

To investigate the effects of contrast material injection duration on peak enhancement times and attenuation values of the aorta, main portal vein, and liver at MDCT when the dose of contrast material is adjusted to patient weight.

Material and methods

Seventy-five patients were randomly assigned to one of five groups, with durations of injection of 25, 30, 35, 40, or 45 s. All patients were injected with 2 ml/kg iodine (300 mg/ml). Attenuation values and peak enhancement times for the aorta, main portal vein, and liver were determined. The relationship between patient weight and enhancement times and values, the differences regarding peak enhancement times, and the relationship between injection duration and enhancement values were investigated using Pearson correlation, analysis of variance (ANOVA), and Spearman rank correlation, respectively.

Results

No significant correlations were seen between patient weight and peak enhancement times or values. Mean peak enhancement times for the aorta, main portal vein, and liver were 9–11 s, 18–22 s, and 30–34 s, respectively (p > 0.05). The correlations between injection duration and peak enhancement values were significant and negative.

Conclusions

Regardless of patient weight and injection duration, peak enhancement times of aorta, main portal vein and liver were approximately 10, 20, and 30 s, respectively. The enhancement values tended to be higher for shorter injection durations.

Introduction

Optimization of contrast enhancement has become crucial with the introduction of multidetector-row helical computed tomography (MDCT), given the shorter image acquisition time compared with that of single-row detector helical CT. Many abdominal CT applications require intravenous administration of contrast medium to enhance lesion conspicuity, and proper selection of acquisition timing is critical to optimize contrast medium enhancement. Technical factors for the administration of contrast material generally include dose (volume of injected contrast material for a given concentration), injection rate, and scan delay time.1 Recent studies have shown that the dose should be tailored according to the patient's weight to achieve adequate enhancement, particularly for the liver.1, 2, 3, 4, 5, 6, 7 There are two methods for administering an optimal dose of contrast material tailored for individual patients: injecting the contrast material at a fixed rate in all patients, which is the method commonly used at present; and injecting the contrast material for a fixed duration. For both methods, it is important to predict the enhancement pattern of the aorta, liver, and main portal vein to permit an optimal imaging protocol with proper scan delays to be determined.7

Recently, Awai et al.7 showed that the temporal scan window for peak aortic enhancement was more uniform with an injection protocol with fixed injection durations of 25 and 35 s than with a fixed injection rate of 4 ml/s. They also stated that the fixed injection duration method could reduce variations in aortic peak enhancement values.7 In earlier studies, Bae et al.8 reported that the time to the peak in aortic enhancement corresponded to the sum of the injection duration and the bolus transfer time from the injection site to the aorta, and that for hepatic enhancement corresponded to the sum of injection duration and the time to reach the distribution equilibrium.8, 9

Although Awai et al. showed that an injection protocol with a fixed injection duration might be effective in providing more uniform scan timing and enhancement,1, 7 to our knowledge, no comprehensive data are available on the correlation of peak enhancement times and values with different duration times; information that would be crucial for establishing the optimal parameters for contrast-enhanced hepatic CT. Therefore, the aim of the present study was to investigate the effect of different injection duration times on the peak enhancement times and values of the aorta, main portal vein, and liver.

Section snippets

Subjects

Between January 2002 and May 2002, 75 patients (39 men, 36 women; mean age 48.7 years, range 25–71 years) with a previous history of resected pelvic malignancies who underwent contrast-enhanced abdominal CT for the evaluation of local recurrence or distant metastases were prospectively enrolled. Surgical resections for the primary pelvic malignancies in all patients had been performed at least 24 months (range 25–75 months; mean 41 months) before the present study. No patients showed any

Results

Mean ages and weights of the patients in each group and gender distributions are summarized in Table 1. One-way ANOVA revealed no significant intergroup differences in patient age (p = 0.98), patient weight (p = 0.33), or gender distribution (p = 0.86).

Scatter diagrams demonstrating the relationship between patient weight and peak enhancement values and times of aorta, main portal vein, and liver showed no statistically significant correlations between patient weight and delay to peak enhancement or

Discussion

Awai et al.1, 7 recently showed that variations in aortic peak times and aortic peak enhancement values can be reduced by using an injection protocol in which a volume of contrast material tailored to the patient dose is administered intravenously with a fixed injection duration. In earlier studies, Bae et al.8, 9 showed that the time from the initiation of the injection to the peak aortic enhancement is closely associated with injection duration. It appears from these studies that fixed

References (13)

  • K. Awai et al.

    Effect of contrast injection protocol with dose tailored to patient weight and fixed injection duration on aortic and hepatic enhancement at multidetector-row helical CT

    Eur Radiol

    (2003)
  • P.A. Garcia et al.

    Effect of rate of contrast medium injection on hepatic enhancement at CT

    Radiology

    (1996)
  • T. Kim et al.

    Pancreatic CT imaging: effects of different injection rates and doses of contrast material

    Radiology

    (1999)
  • Y. Yamashita et al.

    Abdominal helical CT: evaluation of optimal doses of intravenous contrast material—a prospective randomized study

    Radiology

    (2000)
  • T. Murakami et al.

    Hypervascular hepatocellular carcinoma: detection with double arterial phase multi-detector row helical CT

    Radiology

    (2001)
  • H. Onishi et al.

    CT angiography using multi-detector row helical CT with low dose contrast medium

    Eur Radiol

    (2000)
There are more references available in the full text version of this article.

Cited by (40)

  • Optimal iodine dose for 3-dimensional multidetector-row CT angiography of the liver

    2012, European Journal of Radiology
    Citation Excerpt :

    A recent trend in multiphasic contrast-enhanced hepatic MDCT protocols involves tailoring the dose of contrast material according to patients’ body weights to achieve adequate contrast enhancement because a certain fixed dose of contrast material affects diagnostic performance or image quality in patients with various body weights [16–19]. By introducing a body-weight-tailored dose of contrast material, variation between patients with different body weights in the degree of contrast enhancement in the aorta and liver can be eliminated [16–19]. Some investigators attempted to determine an optimal patients’ body-weight-tailored dose of contrast material for multiphasic contrast-enhanced CT of the liver.

  • Improving image quality in portal venography with spectral CT imaging

    2012, European Journal of Radiology
    Citation Excerpt :

    The quality of the venography is depended on the contrast between portal vein and liver parenchyma and soft tissue outside liver. Although increasing the contrast injection rate or dosage can increase the attenuation in the artery [9–12], its effect on the portal veins is rather limited [10,11]. Increasing contrast could also increase the beam hardening artifacts with the conventional imaging using polychromatic X-ray beam [13,14].

View all citing articles on Scopus
View full text