Deverdun Jeremy, Molino François, Menjot de Champfleur Nicolas, Le Bars Emmanuelle
Department of neuroradiology, institut d'imagerie fonctionnelle humaine, I2FH, university hospital center, Gui-de-Chauliac hospital, 80, avenue Augustin-Fliche, 34295 Montpellier cedex 5, France.
Department of neuroradiology, institut d'imagerie fonctionnelle humaine, I2FH, university hospital center, Gui-de-Chauliac hospital, 80, avenue Augustin-Fliche, 34295 Montpellier cedex 5, France; Laboratoire Charles-Coulomb, CNRS UMR 5221, université Montpellier II, 34095 Montpellier, France; Institut de génomique fonctionnelle, UMR 5203, Inserm U661, université Montpellier II-Université Montpellier I, 34090 Montpellier, France.
J Neuroradiol. 2017 Jul;44(4):269-272. doi: 10.1016/j.neurad.2016.12.012. Epub 2017 Feb 16.
Quantitative susceptibility mapping is a new technique and its processing pipeline has to be validated before clinical practice. We described an easy to build magnetic resonance (MR) susceptibility phantom based on iron sucrose.
In a plastic container, Eppendorf tubes containing increasing iron sucrose concentration ranging from 0 to 60μg Fe/mL were inserted in an agarose gel. To estimate susceptibility, multiple coronal gradient echo acquisitions were performed with varying angle of the phantom relative to the B field, ranging from 30 to 90°. Quantitative susceptibility maps were reconstructed using the l and l norm of total variation using Split Bregman approach. Iron concentration was finally estimated from the susceptibility in the tubes.
In lnorm susceptibility and estimated iron concentration were not different from the real values while lnorm underestimated the susceptibility. A correlation was found between the angle of the phantom and the difference between real and estimated iron concentrations. The results highlight the importance of this validation by emphasizing the effects of various reconstruction parameters as well as acquisition conditions. Using optimal parameters, the quantitative susceptibility mapping provides a very good estimation of the iron concentrations in the phantom.
定量磁化率成像（QSM）是一项新技术，其处理流程在临床应用前必须经过验证。我们描述了一种基于蔗糖铁的易于构建的磁共振（MR）磁化率模型。
在一个塑料容器中，将含有浓度范围从0至60μg Fe/mL递增的蔗糖铁的微量离心管插入琼脂糖凝胶中。为了估计磁化率，以模型相对于B场30至90°的不同角度进行了多次冠状梯度回波采集。使用分裂Bregman方法，利用总变分的l1和l2范数重建定量磁化率图。最终从管内的磁化率估计铁浓度。
在l1范数磁化率中，估计的铁浓度与真实值无差异，而l2范数低估了磁化率。发现模型角度与真实和估计的铁浓度之间的差异存在相关性。结果通过强调各种重建参数以及采集条件的影响，突出了这种验证的重要性。使用最佳参数时，定量磁化率成像能够很好地估计模型中的铁浓度。
