Effects of iodinated contrast on various magnetic resonance imaging sequences and field strength: Implications for characterization of hemorrhagic transformation in acute stroke therapy

Table 1 Relaxation times of iodinated contrast material, blood and physiologic saline at 1.5T¹

	T1 relaxation time (ms)	T2 relaxation time (ms)
Iodinated contrast (Iopamidol 300 mg/L)2	Approximately 1100	Approximately 80-100
Blood3	1200-1400	290-320
Physiologic saline4	Approximately 3000	Approximately 1800

¹There is notable difference between the relaxation times (RT) for physiologic saline and iodinated contrast (ICM) or blood. While ICM and blood have closer and similar RT;

²Modified from Hergan et al[2], T1 values represent time after correction for known 25%-40% increase with every doubling of the magnetic field strength;

³Expected RT at 95% oxygen level[3,4];

⁴References[2,5].

Table 2 Contrast to noise ratios of Iopamidol and Iodixanol at 1.5T and 3T

Iodinated contrast/sequences	Iopamidol magnetic field and concentration				Iodixanol magnetic field and concentration
	1.5T		3T		1.5T		3T
	100%	50%	100%	50%	100%	50%	100%	50%
T1-SE	4.2 ± 2	1.6 ± 0.7	15.2 ± 3.5	10.4 ± 3.5	20.8 ± 4	16 ± 4	21.2 ± 3.4	16 ± 3
T2-SE	49.3 ± 1	27 ± 3	92.6 ± 0.3	72 ± 1	23 ± 1.7	6.5 ± 3.8	77.5 ± 0.9	47 ± 3
Gradient-echo	13.6 ± 0.8	3.7 ± 0.6	34 ± 0.4	23.7 ± 1.4	6.3 ± 1.5	2.4 ± 1.6	37.7 ± 1	18.3 ± 0.9
Fluid-attenuation-inversion-recovery	14.5 ± 0.3	1.8 ± 0.2	40.8 ± 0.3	29.6 ± 1	4.2 ± 0.2	4.9 ± 0.5	32.3 ± 0.4	14.8 ± 1.5
Statistics: Kruskall-Wallis test	P < 0.001	P < 0.001	P < 0.00	P < 0.00	P < 0.001	P < 0.004	P < 0.00	P < 0.002

SE: Spin-echo