Storey Pippa, Thompson Alexis A, Carqueville Christine L, Wood John C, de Freitas R Andrew, Rigsby Cynthia K
Radiology Department, Evanston Northwestern Healthcare, Evanston, Illinois 60201, USA.
J Magn Reson Imaging. 2007 Mar;25(3):540-7. doi: 10.1002/jmri.20816.
To determine normative R2* values in the liver and heart at 3T, and establish the relationship between R2* at 3T and 1.5T over a range of tissue iron concentrations.
A total of 20 healthy control subjects and 14 transfusion-dependent patients were scanned at 1.5T and 3T. At each field strength R2* imaging was performed in the liver and heart.
Normative R2* values in the liver were estimated from the control group to be 39.2 +/- 9.0 second(-1) at 1.5T and 69.1 +/- 21.9 second(-1) at 3T. Normative cardiac values were estimated as 23.4 +/- 2.2 second(-1) at 1.5T and 30.0 +/- 3.7 second(-1) at 3T. The combined R2* data from patients and control subjects exhibited a linear relationship between 3T and 1.5T. In the liver, the line of best fit to the 3T vs. 1.5T data had a slope of 2.00 +/- 0.06 and an intercept of -11 +/- 4 second(-1). In the heart, it had a slope of 1.88 +/- 0.14 and an intercept of -15 +/- 4 second(-1).
These preliminary data suggest that the iron-dependent component of R2* scales linearly with field strength over a wide range of tissue iron concentrations. The incidence of susceptibility artifacts may, however, also increase with field strength.
确定3T场强下肝脏和心脏的正常R2值，并建立一系列组织铁浓度范围内3T场强与1.5T场强下R2值之间的关系。
对20名健康对照者和14名依赖输血的患者分别在1.5T和3T场强下进行扫描。在每个场强下，均对肝脏和心脏进行R2*成像。
根据对照组估算，肝脏的正常R2值在1.5T场强下为39.2±9.0秒⁻¹，在3T场强下为69.1±21.9秒⁻¹。心脏的正常R2值在1.5T场强下为23.4±2.2秒⁻¹，在3T场强下为30.0±3.7秒⁻¹。患者和对照者的综合R2*数据显示3T场强与1.5T场强之间呈线性关系。在肝脏中，3T与1.5T数据的最佳拟合线斜率为2.00±0.06，截距为-11±4秒⁻¹。在心脏中，斜率为1.88±0.14，截距为-15±4秒⁻¹。
这些初步数据表明，在广泛的组织铁浓度范围内，R2*的铁依赖性成分与场强呈线性关系。然而，磁化率伪影的发生率可能也会随场强增加。
