科研之友
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摘要
Purpose: To propose a simple multicompartment model of the liver and use Bloch-McConnell simulations to demonstrate the effects of iron and fibrosis on shortened-MOLLI (shMOLLI) T-1 measurements. Liver T-1 values have shown sensitivity to inflammation and fibrosis, but are also affected by hepatic iron content. Modified Look-Locker inversion recovery (MOLLI) T-1 measurements are biased by the lower T-2 associated with high iron. Materials and Methods: A tissue model was generated consisting of liver cells and extracellular fluid (ECF), with iron-dependent relaxation rates. Fibrosis was imitated by increasing the ECF proportion. Simulations of the shMOLLI sequence produced a look-up table (LUT) of shMOLLI-T-1 for a given ECF fraction and iron content. The LUT was used to calculate ECF(shMOLLI-T-1), assuming normal hepatic iron content (HIC), and ECF(shMOLLI-T-1; T-2*), accounting for HIC determined by T-2*, for 77 patients and compared to fibrosis assessed by liver biopsy. Results: Simulations showed that increasing HIC decreases shMOLLI-T-1, with an increase in HIC from 1.0 to 2.5mg/g at normal ECF fraction decreasing shMOLLI-T-1 by 160 msec, while increasing ECF increased ShMOLLI-T-1, with an increase of 20% ECF at normal iron increasing shMOLLI-T-1 by 200 msec. Calculated patient ECF(shMOLLI-T-1) showed a strong dependence on Ishak score (3.3 +/- 0.8 %ECF/Ishak stage) and 1/T-2* (-0.23 +/- 0.04 %ECF/Hz). However, when iron was accounted for to produce ECF(shMOLLI-T-1; T-2*), it was independent of HIC but retained sensitivity to Ishak score. Conclusion: Use of this multicompartment model of the liver with Bloch-McConnell simulation should enable compensation of iron effects when using shMOLLI-T-1 to assess fibrosis.
- 出版日期2017-1
