T1 Mapping for Differentiating of Haemorrhagic Transformation from Extravasation of Iodine Contrast Agents: A Phantom...

To evaluate T1 mapping values in different concentrations of iodine and mixed blood and to simulate the application of T1 mapping in differentiating iodine contrast extravasation and haemorrhage transformation after revascularisation in acute ischemic stroke.

A phantom-based experimental study. Place and Duration of the Study: Department of Radiology, the Second Affiliated Hospital of Soochow University, China, from October 2020 to December 2021.

Fresh blood, pure iodine, blood-iodine mixtures (75/25, 50/50, and 25/75 ratios), and diluted iodine (at a concentration of 2.1 mmol I/L) were scanned in a phantom on 3-T MR T1 mapping imaging. A total of 10 layers in the middle section of tubes were scanned. The mean value of T1 mapping and 95% confidence interval for the investigated sample compositions were calculated and compared by ANOVA.

The mean values (95% CI) for fresh blood, [2/3] blood +[1/3] iodine, [1/2] blood +[1/2] iodine, [1/3] blood +[2/3] iodine, and pure iodine were 2108.69 ± 1966.68-2250.71(ms), 1991.72 ± 1763.22-2220.21(ms), 1811.62 ± 1614.79-2008.45(ms), 1624.39 ± 1442.41-1806.37(ms), 1294.68 ± 1172.92-1416.44(ms), respectively. The differences between the T1 mapping values of all compositions were significant (p <0.01), except for fresh blood and the sample consisting of 67% blood. The mean value on T1 mapping (95% CI) was 1294.68 ± 1172.92-1416.44 (ms) in the samples only with diluted iodine, which was significantly different from other investigated samples (p <0.01). The intra-class correlation coefficient between the two times drawing of radiologist A was excellent (ICC=0.913, p<0.01), and between radiologists A and B was 0.99.

Iodine contrast extravasation in a phantom setting might be distinguished from haemorrhagic transformation using T1 mapping.

Acute ischemic stroke, Haemorrhage transformation, Contrast extravasation, Magnetic resonance imaging, T1 mapping, 3T MRI.