Wunderlich A P, Cario H, Bommer M, Beer M, Schmidt S A, Juchems M S
Section for experimental Radiology, Universitätsklinikum Ulm, Germany.
Children's Hospital, Universitätsklinik Ulm, Germany.
Rofo. 2016 Sep;188(9):846-52. doi: 10.1055/s-0042-108859. Epub 2016 Jun 14.
To evaluate the feasibility of addressing liver iron content (LIC) in regularly transfused patients by MR imaging at 3 T based on the signal intensity ratio (SIR). An innovative data analysis approach was developed for this purpose.
47 consecutive examinations of regularly transfused patients were included. In all cases, we expected high LIC levels. Patients were scanned with MRI at 3 T with multi-echo gradient echo sequences (GRE) at four different flip angles between 20° and 90° with echo times (TE) ranging from 0.9 to 9.8 ms. Spin-echo protocols were acquired to determine the LIC with a reference MRI method working at 1.5 T. 3 T GRE data were analyzed using the liver-to-muscle SIR. Since the method known for 1.5 T was not expected to be applicable for analyzing 3 T data, theoretic dependence of the SIR on the LIC was derived from the equation describing R2* signal decay. Obtained SIR values were correlated to reference LIC to get a relation for calculating LIC from SIR quantities. LIC values and their uncertainties were determined from GRE data and correlated to LIC reference values. For two LIC thresholds, the diagnostic accuracy was determined.
LIC was reliably determined from SIR in our patient cohort even for large LIC values. Median of LIC uncertainties was 10 %, and the diagnostic accuracy was 0.92 and 0.91, respectively.
Determination of even high LIC, resulting in small SIR values, is feasible at 3 T using appropriate SIR analysis.
• Determination of Liver Iron Concentration (LIC) based on GRE MRI at 3T is feasible even for high LIC levels using Signal Intensiy Ratios. • Relative uncertainty of LIC determined with 3T GRE MRI was below 13 % in most cases. • The patient-management relevant threshold (LIC = 80 µmol/g (4.5 mg/g)) yielded an accuracy of .92 in our cohort. • The proposed method is quick and simple, both in terms of data acquisition and analysis. Citation Format: • Wunderlich AP, Cario H, Bommer M et al. MRI-Based Liver Iron Content Determination at 3T in Regularly Transfused Patients by Signal Intensity Ratio Using an Alternative Analysis Approach Based on R2* Theory. Fortschr Röntgenstr 2016; 188: 846 - 852.
基于信号强度比（SIR）评估3T磁共振成像（MR）测量长期输血患者肝脏铁含量（LIC）的可行性。为此开发了一种创新的数据分析方法。
纳入47例连续接受检查的长期输血患者。所有病例预计LIC水平较高。患者在3T行MRI扫描，采用多回波梯度回波序列（GRE），翻转角在20°至90°之间的四个不同角度，回波时间（TE）范围为0.9至9.8毫秒。采用自旋回波协议，通过在1.5T工作的参考MRI方法测定LIC。使用肝脏-肌肉SIR分析3T GRE数据。由于已知的1.5T方法预计不适用于分析3T数据，SIR对LIC的理论依赖性由描述R2*信号衰减的方程推导得出。将获得的SIR值与参考LIC相关联，以得到从SIR量计算LIC的关系。从GRE数据确定LIC值及其不确定性，并与LIC参考值相关联。针对两个LIC阈值，确定诊断准确性。
在我们的患者队列中，即使对于LIC值较大的情况，也能从SIR可靠地确定LIC。LIC不确定性的中位数为10%，诊断准确性分别为
0.92和0.91。
使用适当的SIR分析，在3T时即使是导致SIR值较小的高LIC的测定也是可行的。
• 基于3T GRE MRI使用信号强度比测定肝脏铁浓度（LIC）即使对于高LIC水平也是可行的。• 在大多数情况下，3T GRE MRI测定的LIC相对不确定性低于13%。• 在我们的队列中，与患者管理相关的阈值（LIC = 80 μmol/g（4.5 mg/g））的准确性为0.92。• 所提出的方法在数据采集和分析方面既快速又简单。引用格式：• Wunderlich AP, Cario H, Bommer M等。通过基于R2*理论的替代分析方法使用信号强度比在3T时对长期输血患者进行基于MRI的肝脏铁含量测定。Fortschr Röntgenstr 2016; 188: 846 - 852。
