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Optimization of the contrast mixture ratio for simultaneous direct MR and CT arthrography: an in vitro study.

Choi JY, Kang HS, Hong SH, Lee JW, Kim NR, Jun WS, Moon SG, Choi JA - Korean J Radiol (2008 Nov-Dec)

Bottom Line: Scatter diagrams were plotted for all gadolinium/iodinated contrast agent combinations and two radiologists in consensus identified the mixtures that yielded the optimal CT numbers and MR signal intensities.The CT numbers showed significant correlation with iodinated contrast concentrations (r = 0.976, p < 0.001), whereas the signal intensities as measured on MR images showed a significant correlation with both gadolinium and iodinated contrast agent concentrations (r = -484 to -0.719, p < 0.001).A review of the CT and MR images, graphs, and scatter diagram of 42 combinations of the contrast agent showed that a concentration of 1.25 mmol/L gadolinium and 25% iodinated contrast agent was the best combination for simultaneous CT and MR imaging.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul, Korea.

ABSTRACT

Objective: This study was designed to determine the optimal mixture ratio of gadolinium and iodinated contrast agent for simultaneous direct MR arthrography and CT arthrography.

Materials and methods: An in vitro study was performed utilizing mixtures of gadolinium at six different concentrations (0.625, 1.25, 2.5, 5.0, 10 and 20 mmol/L) and iodinated contrast agent at seven different concentrations (0, 12.5, 25, 37.5, 50, 75 and 92-99.9%). These mixtures were placed in tissue culture plates, and were then imaged with CT and MR (with T1-weighted sequences, proton-density sequences and T2-weighted sequences). CT numbers and signal intensities were measured. Pearson's correlation coefficients were used to assess the correlations between the gadolinium/iodinated contrast agent mixtures and the CT numbers/MR signal intensities. Scatter diagrams were plotted for all gadolinium/iodinated contrast agent combinations and two radiologists in consensus identified the mixtures that yielded the optimal CT numbers and MR signal intensities.

Results: The CT numbers showed significant correlation with iodinated contrast concentrations (r = 0.976, p < 0.001), whereas the signal intensities as measured on MR images showed a significant correlation with both gadolinium and iodinated contrast agent concentrations (r = -484 to -0.719, p < 0.001). A review of the CT and MR images, graphs, and scatter diagram of 42 combinations of the contrast agent showed that a concentration of 1.25 mmol/L gadolinium and 25% iodinated contrast agent was the best combination for simultaneous CT and MR imaging.

Conclusion: A mixture of 1.25 mmol/L gadolinium and 25% iodinated contrast agent was found to be optimal for simultaneous direct MR arthrography and CT arthrography.

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Changes in signal intensities (region of interest values) at various gadolinium concentrations with different volume percentages of iodinated contrast agent as seen on proton density MR images (TR/TE = 3000/14, ETL = 5). ETL = echo train length
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Figure 3: Changes in signal intensities (region of interest values) at various gadolinium concentrations with different volume percentages of iodinated contrast agent as seen on proton density MR images (TR/TE = 3000/14, ETL = 5). ETL = echo train length

Mentions: Iodinated contrast agent mixtures containing iodine at concentrations of 37.5% or less showed peak signal intensity as seen on T1-weighted images at a gadolinium concentration of 1.25 mmol/L. With a greater concentration of gadolinium, the signal intensity showed a gradual decrease with increasing gadolinium concentration. In the remaining iodinated contrast agent mixtures, the signal intensities gradually decreased with increasing gadolinium concentrations (Fig. 3). The increase in the concentration of iodinated contrast agent at a constant gadolinium concentration led to a decrease in MR signal intensity. As seen on proton-density-weighted sequences (Fig. 4) and T2-weighted sequences (Fig. 5), the signal intensities decreased as the gadolinium and iodinated contrast concentrations increased; this effect was more apparent as seen on T2-weighted images. As seen on T1-weighted, proton-density-weighted and T2-weighted images, negative linear correlations were found between signal intensity and the gadolinium concentration (r = -0.719, p < 0.001; r = -0.719, p < 0.001; r = -0.489, p = 0.001, respectively, for T1-weighted, proton-density-weighted and T2-weighted sequences). Negative linear correlations were also found between signal intensity and the iodinated contrast agent concentration (r = -0.608, p < 0.001; r = -0.619, p < 0.001; r = -0.484, p = 0.001, respectively, for T1-weighted, proton-density-weighted and T2-weighted sequences) (Table 1).


Optimization of the contrast mixture ratio for simultaneous direct MR and CT arthrography: an in vitro study.

Choi JY, Kang HS, Hong SH, Lee JW, Kim NR, Jun WS, Moon SG, Choi JA - Korean J Radiol (2008 Nov-Dec)

Changes in signal intensities (region of interest values) at various gadolinium concentrations with different volume percentages of iodinated contrast agent as seen on proton density MR images (TR/TE = 3000/14, ETL = 5). ETL = echo train length
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2627248&req=5

Figure 3: Changes in signal intensities (region of interest values) at various gadolinium concentrations with different volume percentages of iodinated contrast agent as seen on proton density MR images (TR/TE = 3000/14, ETL = 5). ETL = echo train length
Mentions: Iodinated contrast agent mixtures containing iodine at concentrations of 37.5% or less showed peak signal intensity as seen on T1-weighted images at a gadolinium concentration of 1.25 mmol/L. With a greater concentration of gadolinium, the signal intensity showed a gradual decrease with increasing gadolinium concentration. In the remaining iodinated contrast agent mixtures, the signal intensities gradually decreased with increasing gadolinium concentrations (Fig. 3). The increase in the concentration of iodinated contrast agent at a constant gadolinium concentration led to a decrease in MR signal intensity. As seen on proton-density-weighted sequences (Fig. 4) and T2-weighted sequences (Fig. 5), the signal intensities decreased as the gadolinium and iodinated contrast concentrations increased; this effect was more apparent as seen on T2-weighted images. As seen on T1-weighted, proton-density-weighted and T2-weighted images, negative linear correlations were found between signal intensity and the gadolinium concentration (r = -0.719, p < 0.001; r = -0.719, p < 0.001; r = -0.489, p = 0.001, respectively, for T1-weighted, proton-density-weighted and T2-weighted sequences). Negative linear correlations were also found between signal intensity and the iodinated contrast agent concentration (r = -0.608, p < 0.001; r = -0.619, p < 0.001; r = -0.484, p = 0.001, respectively, for T1-weighted, proton-density-weighted and T2-weighted sequences) (Table 1).

Bottom Line: Scatter diagrams were plotted for all gadolinium/iodinated contrast agent combinations and two radiologists in consensus identified the mixtures that yielded the optimal CT numbers and MR signal intensities.The CT numbers showed significant correlation with iodinated contrast concentrations (r = 0.976, p < 0.001), whereas the signal intensities as measured on MR images showed a significant correlation with both gadolinium and iodinated contrast agent concentrations (r = -484 to -0.719, p < 0.001).A review of the CT and MR images, graphs, and scatter diagram of 42 combinations of the contrast agent showed that a concentration of 1.25 mmol/L gadolinium and 25% iodinated contrast agent was the best combination for simultaneous CT and MR imaging.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul, Korea.

ABSTRACT

Objective: This study was designed to determine the optimal mixture ratio of gadolinium and iodinated contrast agent for simultaneous direct MR arthrography and CT arthrography.

Materials and methods: An in vitro study was performed utilizing mixtures of gadolinium at six different concentrations (0.625, 1.25, 2.5, 5.0, 10 and 20 mmol/L) and iodinated contrast agent at seven different concentrations (0, 12.5, 25, 37.5, 50, 75 and 92-99.9%). These mixtures were placed in tissue culture plates, and were then imaged with CT and MR (with T1-weighted sequences, proton-density sequences and T2-weighted sequences). CT numbers and signal intensities were measured. Pearson's correlation coefficients were used to assess the correlations between the gadolinium/iodinated contrast agent mixtures and the CT numbers/MR signal intensities. Scatter diagrams were plotted for all gadolinium/iodinated contrast agent combinations and two radiologists in consensus identified the mixtures that yielded the optimal CT numbers and MR signal intensities.

Results: The CT numbers showed significant correlation with iodinated contrast concentrations (r = 0.976, p < 0.001), whereas the signal intensities as measured on MR images showed a significant correlation with both gadolinium and iodinated contrast agent concentrations (r = -484 to -0.719, p < 0.001). A review of the CT and MR images, graphs, and scatter diagram of 42 combinations of the contrast agent showed that a concentration of 1.25 mmol/L gadolinium and 25% iodinated contrast agent was the best combination for simultaneous CT and MR imaging.

Conclusion: A mixture of 1.25 mmol/L gadolinium and 25% iodinated contrast agent was found to be optimal for simultaneous direct MR arthrography and CT arthrography.

Show MeSH