Optimization of Gadodiamide Concentration for MR Arthrography at 3 T

Optimization of Gadodiamide Concentration for MR Arthrography at 3 T

Jeffrey N. Masi, David Newitt, Christian A. Sell, Heike Daldrup-Link, Lynne Steinbach, Sharmila Majumdar and Thomas M. Link

Department of Radiology, University of California, San Francisco, 400 Parnassus Ave., A 367, Box 0628, San Francisco, CA 94143-0628.

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Fig. 1. —Diagram shows phantom, including individual dilutions of gadolinium (Gd) in saline, albumin, and iodinated contrast agent (iohexol) as well as fat and water controls. ROI = region of interest, SNR = signal-to-noise ratio.

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Fig. 2A. —MR images of phantom. T1-weighted spin-echo image (TR/TE, 700/14) of entire phantom obtained at 1.5 T.

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Fig. 2B. —MR images of phantom. T1-weighted spin-echo image (700/14) at 1.5 T of part of phantom outlined by box in A. Note that highest signal intensity at 1.5 T was determined in 1.25 mmol/L solution (long arrow indicates saline, short arrow indicates albumin).

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Fig. 2C. —MR images of phantom. T1-weighted spin-echo image (700/14) at 3 T as outlined by box in A. Note that at 3 T highest signal intensity was measured in 0.625 mmol/L solution (long arrow indicates saline, short arrow indicates albumin), but with little change in signal intensity compared with 1.25 mmol/L solution.

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Fig. 3. —Graph shows T1 decay time versus gadolinium concentration for all examined solutions (gadolinium in normal saline, saline with albumin, and saline with iodinated contrast agent iohexol) at 1.5 and 3 T. Note that curves for normal saline and albumin gadolinium solutions are similar at 3 and 1.5 T, with albumin giving slightly lower T1 for concentrations less than 1 mmol/L. Iohexol has substantial effect on curves, reducing T1 by approximately factor of 4, with somewhat greater reduction at 1.5 T than 3 T.

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Fig. 4. —Graph shows T2 decay time versus gadolinium concentration for all examined solutions at 1.5 and 3 T. Again shown are similarities of saline and albumin curves, whereas T2 values of iohexol curves are substantially lower.

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Fig. 5A. —Graphs show calculated normalized signal intensity variation due to measured T1 and T2 versus gadolinium concentration for T1-weighted spin-echo sequence. Calculated graph for T1-weighted spin-echo sequence with TR/TE of 500/15. Note that at 3 T, curve is shifted slightly to lower concentrations for albumin solutions. Curves for normal saline solutions were similar and are not shown. Substantially lower signal intensities are found for solutions with gadodiamide and iohexol, with significantly greater decrease at 3 T than at 1.5 T.

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Fig. 5B. —Graphs show calculated normalized signal intensity variation due to measured T1 and T2 versus gadolinium concentration for T1-weighted spin-echo sequence. Calculated graph for more heavily T1-weighted spin-echo sequence with TR/TE of 500/8. Note that for gadodiamide concentrations below about 1 mmol/L, the addition of iodinated contrast material should increase signal-to-noise ratio (SNR) for this sequence, although peak SNR achievable with iodinated contrast material is still less than that achievable with gadodiamide alone.

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Fig. 6A. —Measured signal-to-noise ratio (SNR) versus concentration of gadodiamide in normal saline, and saline with iohexol (iodinated contrast material), for four sample sequences. SNR curves for other T1- and T2-weighted sequences were similar in form to those shown here. T1-weighted spin-echo sequence, TR/TE, 500/15 (1.5 and 3 T) (A); proton density-weighted spin-echo sequence, 2,550/30 (1.5 and 3 T) (B); T2-weighted spin-echo sequence, 4,000/45 (1.5 and 3 T) (C); and gradient-echo sequences, 33.3/13 (3 T) and 34/13 (1.5 T) (D). In A and B, observe some shift to lower concentrations for saline solutions at 3 T relative to 1.5 T. Note increase in SNR at 3 T for all sequences except for T2-weighted sequence with iodinated contrast material. Also note decrease in SNR with iodinated contrast material except for T1-weighted sequence at low gadolinium concentrations.

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Fig. 6B. —Measured signal-to-noise ratio (SNR) versus concentration of gadodiamide in normal saline, and saline with iohexol (iodinated contrast material), for four sample sequences. SNR curves for other T1- and T2-weighted sequences were similar in form to those shown here. T1-weighted spin-echo sequence, TR/TE, 500/15 (1.5 and 3 T) (A); proton density-weighted spin-echo sequence, 2,550/30 (1.5 and 3 T) (B); T2-weighted spin-echo sequence, 4,000/45 (1.5 and 3 T) (C); and gradient-echo sequences, 33.3/13 (3 T) and 34/13 (1.5 T) (D). In A and B, observe some shift to lower concentrations for saline solutions at 3 T relative to 1.5 T. Note increase in SNR at 3 T for all sequences except for T2-weighted sequence with iodinated contrast material. Also note decrease in SNR with iodinated contrast material except for T1-weighted sequence at low gadolinium concentrations.

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Fig. 6C. —Measured signal-to-noise ratio (SNR) versus concentration of gadodiamide in normal saline, and saline with iohexol (iodinated contrast material), for four sample sequences. SNR curves for other T1- and T2-weighted sequences were similar in form to those shown here. T2-weighted spin-echo sequences, TR/TE, 4,000/45 (1.5 and 3 T).

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Fig. 6D. —Measured signal-to-noise ratio (SNR) versus concentration of gadodiamide in normal saline, and saline with iohexol (iodinated contrast material), for four sample sequences. SNR curves for other T1- and T2-weighted sequences were similar in form to those shown here. Gradient-echo sequences, 34/13 (1.5 T) and 33.3/13 (3 T).

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Fig. 7A. —Measured signal-to-noise ratio (SNR) versus concentration of gadodiamide in normal saline, with curves scaled to equal peak heights for 1.5 and 3 T. T1-weighted spin-echo sequence, TR/TE of 700/14 (A) and T2-weighted spin-echo sequence, 4,000/45 (B). Note shift of peak to lower concentrations at 3 T for T1-weighted sequence.

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Fig. 7B. —Measured signal-to-noise ratio (SNR) versus concentration of gadodiamide in normal saline, with curves scaled to equal peak heights for 1.5 and 3 T. T1-weighted spin-echo sequence, TR/TE of 700/14 (A) and T2-weighted spin-echo sequence, 4,000/45 (B). Note shift of peak to lower concentrations at 3 T for T1-weighted sequence.

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