School of Biomedical Engineering and Imaging Sciences, Kings College London, St Thomas' Hospital, London, United Kingdom.
MR Research Collaborations, Siemens Healthcare Limited, Camberley, United Kingdom.
J Cardiovasc Magn Reson. 2024 Summer;26(1):101000. doi: 10.1016/j.jocmr.2024.101000. Epub 2024 Jan 17.
Myocardial quantitative susceptibility mapping (QSM) may offer better specificity to iron than conventional T* imaging in the assessment of cardiac diseases, including intra-myocardial hemorrhage. However, the precision and repeatability of cardiac QSM have not yet been characterized. The aim of this study is to characterize these key metrics in a healthy volunteer cohort and show the feasibility of the method in patients.
Free breathing respiratory-navigated multi-echo 3D gradient echo images were acquired, from which QSM maps were reconstructed using the Morphology Enhanced Dipole Inversion toolbox. This technique was first evaluated in a susceptibility phantom containing tubes with known concentrations of gadolinium. In vivo characterization of myocardial QSM was then performed in a cohort of 10 healthy volunteers where each subject was scanned twice. Mean segment susceptibility, precision (standard deviation of voxel magnetic susceptibilities within one segment), and repeatability (absolute difference in segment mean susceptibility between repeats) of QSM were calculated for each American Heart Association (AHA) myocardial segment. Finally, the feasibility of the method was shown in 10 patients, including four with hemorrhagic infarcts.
The phantom experiment showed a strong linear relationship between measured and predicted susceptibility shifts (R > 0.99). For the healthy volunteer cohort, AHA segment analysis showed the mean segment susceptibility was 0.00 ± 0.02 ppm, the mean precision was 0.05 ± 0.04 ppm, and the mean repeatability was 0.02 ± 0.02 ppm. Cardiac QSM was successfully performed in all patients. Focal iron deposits were successfully visualized in the patients with hemorrhagic myocardial infarctions.
The precision and repeatability of cardiac QSM were successfully characterized in phantom and in vivo experiments. The feasibility of the technique was also successfully demonstrated in patients. While challenges still remain, further clinical evaluation of the technique is now warranted.
This work does not report on a health care intervention.
心肌定量磁化率映射（QSM）在评估心脏疾病（包括心肌内出血）方面可能比传统的 T*成像提供更好的铁特异性。然而，心脏 QSM 的精度和可重复性尚未得到描述。本研究的目的是在健康志愿者队列中描述这些关键指标，并展示该方法在患者中的可行性。
采集自由呼吸呼吸导航多回波 3D 梯度回波图像，使用 Morphology enhanced Dipole Inversion 工具箱从这些图像中重建 QSM 图。该技术首先在包含已知浓度钆管的磁敏感体模中进行评估。然后，在 10 名健康志愿者的队列中进行心肌 QSM 的体内特征描述，每位受试者均进行两次扫描。计算每个美国心脏协会（AHA）心肌节段的 QSM 平均节段磁化率、精度（一个节段内体素磁化率的标准差）和可重复性（两次重复之间节段平均磁化率的绝对差异）。最后，在 10 名患者中展示了该方法的可行性，包括 4 名患有出血性梗死的患者。
体模实验表明，测量和预测的磁化率偏移之间存在很强的线性关系（R > 0.99）。对于健康志愿者队列，AHA 节段分析显示平均节段磁化率为 0.00 ± 0.02 ppm，平均精度为 0.05 ± 0.04 ppm，平均可重复性为 0.02 ± 0.02 ppm。所有患者均成功进行了心脏 QSM。在患有出血性心肌梗死的患者中，成功地显示了局灶性铁沉积物。
在体模和体内实验中成功地描述了心脏 QSM 的精度和可重复性。该技术的可行性也在患者中成功得到证明。尽管仍然存在挑战，但现在有必要对该技术进行进一步的临床评估。
本工作未报告医疗干预措施。
