The relationship between myocardial and hepatic T2 and T2* at 1.5T and 3T MRI in normal and iron-overloaded patients

Abstract

Background Cardiac and liver iron assessment using magnetic resonance imaging (MRI) is non-invasive and used as a preclinical "endpoint" in asymptomatic patients and for serial iron measurements in iron-overloaded patients. Purpose To compare iron measurements between hepatic and myocardial T2* and T2 at 1.5T and 3T MRI in normal and iron-overloaded patients. Material and Methods The T2 and T2* values from the regions of interest (ROIs) at mid-left ventricle and mid-hepatic slices were evaluated by 1.5T and 3T MRI scans for healthy and iron-overloaded patients. Results For iron-overloaded patients, the myocardial T2 (1.5T) and myocardial T2 (3T) values were 60.3 ms (range = 56.2-64.8 ms) and 55 ms (range = 51.6-60.1 ms) (ρ = 0.3679) while the myocardial T2* (3T) 20.5 ms (range = 18.4-25.9 ms) was shorter than the myocardial T2* (1.5T) 35.9 ms (range = 31.4-39.5 ms) (ρ = 0.6454). The hepatic T2 at 1.5T and 3T were 19.1 ms (range = 14.8-27.9 ms) and 15.5 ms (14.6-20.4 ms) (ρ = 0.9444) and the hepatic T2* at 1.5T and 3T were 2.7 ms (range = 1.8-5.6 ms) and 1.8 ms (range = 1.1-2.9 ms) (ρ = 0.9826). The line of best fit exhibiting the linearity of the hepatic T2* (1.5T) and hepatic T2* (3T) had a slope of 2 and an intercept of -0.387 ms (R = 0.984). Conclusion Our study found myocardial T2 (1.5T) nearly equal to T2 (3T) with myocardial T2* (3T) 1.75 shorter than myocardial T2* (1.5T). The relationship of hepatic T2* (1.5T) and hepatic T2* (3T) was linear with T2* (1.5T) approximately double to T2* (3T) in iron-overloaded patients. This linear relationship between hepatic T2* (1.5T) and hepatic T2 (3T) could be an alternative method for estimating liver iron concentration (LIC) from 3T.

Cardiovascular magnetic resonance native T2 and T2* quantitative values for cardiomyopathies and heart transplantations: a systematic review and meta-analysis

“…2). At 3 T, these were 21.8 ± 7.8 ms in iron overload patients and 22.4 ± 3.8 ms in controls [81,88,127,148] (Table 1, Fig. 3).…”

Effect of respiratory motion on free‐breathing 3D stack‐of‐radial liver relaxometry and improved quantification accuracy using self‐gating

“…Second, R 2 was quantified using a breath‐hold single‐voxel spectroscopy sequence with multiple echo times and was greater than 40.4 s −1 . This threshold value of R 2 was adapted from the averaged results of healthy control subjects and empirical conversion equations in previous literatures . Third, the self‐gating temporal resolution of the free‐breathing stack‐of‐radial acquisition was less than 400 ms in order to ensure good self‐gating performance.…”

“…This threshold value of R 2 was adapted from the averaged results of healthy control subjects and empirical conversion equations in previous literatures. 19,36 Third, the self-gating temporal resolution of the free-breathing stack-of-radial acquisition was less than 400 ms in order to ensure good self-gating performance. Fourth, there were no severe motion artifacts on the breathhold Cartesian images; thus, the breath-hold Cartesian PDFF and R * 2 maps could be used as a valid reference.…”

Cardiac T2* mapping: Techniques and clinical applications

“…In general, myocardial T 2 * is measured using a bright‐blood 16 or black‐blood 17 gradient echo sequence using a 1.5T MR scanner, with a typical acquisition given in Table 1. The T 2 * value is derived by fitting signal intensities of left ventricular (LV) myocardium regions of interests (ROIs) at different echo times (TEs) to a monoexponential equation 18 : …”

“…Nevertheless, with the increased availability of higher‐field MR equipment, further investigations have been conducted to investigate the performance of T 2 * measurement at 3.0T and 7.0T. To link the T 2 * value acquired at 3.0T to its corresponding 1.5T T 2 * value, some studies proposed a conversion relationship 18,32 . Moreover, at 7.0T, acquisition techniques were introduced to reduce the influence of the substantial macroscopic magnetic field inhomogeneities in T 2 * measurement 33–35 .…”