Korean J Radiol.  2011 Jun;12(3):358-364. 10.3348/kjr.2011.12.3.358.

The T2-Shortening Effect of Gadolinium and the Optimal Conditions for Maximizing the CNR for Evaluating the Biliary System: a Phantom Study

• Lee MJ
• Kim MJ
• Yoon CS
• Song SY
• Park K
• Kim WS

• KMID: 1122333
• DOI: http://doi.org/10.3348/kjr.2011.12.3.358

Abstract

OBJECTIVE
Clear depiction of the common bile duct is important when evaluating neonatal cholestasis in order to differentiate biliary atresia from other diseases. During MR cholangiopancreatography, the T2-shortening effect of gadolinium can increase the contrast-to-noise ratio (CNR) of the bile duct and enhance its depiction. The purpose of this study was to confirm, by performing a phantom study, the T2-shortening effect of gadolinium, to evaluate the effect of different gadolinium chelates with different gadolinium concentrations and different magnetic field strengths for investigating the optimal combination of these conditions, and for identifying the maximum CNR for the evaluation of the biliary system.
MATERIALS AND METHODS
MR imaging using a T2-weighted single-shot fast spin echo sequence and T2 relaxometry was performed with a sponge phantom in a syringe tube. Two kinds of contrast agents (Gd-DTPA and Gd-EOB-DTPA) with different gadolinium concentrations were evaluated with 1.5T and 3T scanners. The signal intensities, the CNRs and the T2 relaxation time were analyzed.
RESULTS
The signal intensities significantly decreased as the gadolinium concentrations increased (p < 0.001) with both contrast agents. These signal intensities were higher on a 3T (p < 0.001) scanner. The CNRs were higher on a 1.5T (p < 0.001) scanner and they showed no significant change with different gadolinium concentrations. The T2 relaxation time also showed a negative correlation with the gadolinium concentrations (p < 0.001) and the CNRs showed decrease more with Gd-EOB-DTPA (versus Gd-DTPA; p < 0.001) on a 3T scanner (versus 1.5T; p < 0.001).
CONCLUSION
A T2-shortening effect of gadolinium exhibits a negative correlation with the gadolinium concentration for both the signal intensities and the T2 relaxation time. A higher CNR can be obtained with Gd-DTPA on a 1.5T MRI scanner.

Keyword

Magnetic resonance imaging (MRI); Gadolinium; Biliary system; Phantom

MeSH Terms

Analysis of Variance
Biliary Atresia/diagnosis
Cholangiopancreatography, Magnetic Resonance/*methods
Cholestasis/diagnosis
Contrast Media/*administration & dosage/diagnostic use
Diagnosis, Differential
Gadolinium DTPA/*administration & dosage/diagnostic use
Humans
Image Processing, Computer-Assisted
Linear Models
*Phantoms, Imaging

Figure

• 

  Fig. 1 Size comparison between normal neonate liver, common bile duct and sponge phantom. T2-weighted coronal (A) and axial (B) images of normal neonate liver and axial image of sponge phantom (C) (all magnified by same factor) seem to be similar in size. Also, diameter of common bile duct (2 mm, arrow in A) in normal neonate is similar with inner diameter of 1 cc syringe tube (3 mm, arrow in C) in sponge phantom.

• 

  Fig. 2 Line chart depicting relationship between signal intensities and gadolinium concentrations with different gadolinium chelates and different magnetic field strengths. Signal intensities of sponge phantom decreased as concentration of gadolinium chelate increased under all conditions; these were higher on 3T. ANOVA = analysis of variance, DTPA = Gd-DTPA, EOB = Gd-EOB-DTPA

• 

  Fig. 3 Line chart depicting relationship between contrastto-noise ratios and gadolinium concentrations with different gadolinium chelates on different magnetic field strengths. Contrast-to-noise radios of tube in sponge phantom were not correlated with gadolinium concentration. However, contrast-to-noise ratios were higher on 1.5T with both contrast agents. ANOVA = analysis of variance, DTPA = Gd-DTPA, EOB = Gd-EOB-DTPA

• 

  Fig. 4 Line chart depicting relationship between contrast-to-noise ratios and gadolinium concentrations with Gd-EOB-DTPA on 1.5T (A) and 3T (B). Different tube gadolinium concentrations (on both magnetic field strengths) and sponge gadolinium concentration changes (on 3T) had significantly influence on the contrast-to-noise ratios. ANOVA = analysis of variance

• 

  Fig. 5 Line chart depicting relationship between T2 relaxation time and gadolinium concentration with different gadolinium chelates on different magnetic field strengths. T2 relaxation time decreased as gadolinium concentration increased in all conditions. T2 relaxation times were longer with Gd-DTPA on 1.5T. ANOVA = analysis of variance, DTPA = Gd-DTPA, EOB = Gd-EOB-DTPA

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