Vaalma Sarah, Rahmer Jürgen, Panagiotopoulos Nikolaos, Duschka Robert L, Borgert Jörn, Barkhausen Jörg, Vogt Florian M, Haegele Julian
Clinic for Radiology and Nuclear Medicine, University Hospital Schleswig Holstein, Lübeck, Germany.
Research Laboratories, Philips Technologie GmbH Innovative Technologies, Hamburg, Germany.
PLoS One. 2017 Jan 5;12(1):e0168902. doi: 10.1371/journal.pone.0168902. eCollection 2017.
Magnetic Particle Imaging (MPI) is able to provide high temporal and good spatial resolution, high signal-to-noise ratio and sensitivity. Furthermore, it is a truly quantitative method as its signal strength is proportional to the concentration of its tracer, superparamagnetic iron oxide nanoparticles (SPIOs). Because of that, MPI is proposed to be a promising future method for cardiovascular imaging. Here, an interesting application may be the quantification of vascular pathologies like stenosis by utilizing the proportionality of the SPIO concentration and the MPI signal strength. In this study, the feasibility of MPI based stenosis quantification is evaluated based on this application scenario. Nine different stenosis phantoms with a normal diameter of 10 mm each and different stenoses of 1-9 mm and ten reference phantoms with a straight diameter of 1-10 mm were filled with a 1% Resovist dilution and measured in a preclinical MPI-demonstrator. The MPI signal intensities of the reference phantoms were compared to each other and the change of signal intensity within each stenosis phantom was used to calculate the degree of stenosis. These values were then compared to the known diameters of each phantom. As a second measurement, the 5 mm stenosis phantom was used for a serial dilution measurement down to a Resovist dilution of 1:3200 (0.031%), which is lower than a first pass blood concentration of a Resovist bolus in the peripheral arteries of an average adult human of at least about 1:1000. The correlation of the stenosis values based on MPI signal intensity measurements and based on the known diameters showed a very good agreement, proving the high precision of quantitative MPI in this regard.
磁粒子成像（MPI）能够提供高时间分辨率和良好的空间分辨率、高信噪比和灵敏度。此外，它是一种真正的定量方法，因为其信号强度与示踪剂超顺磁性氧化铁纳米颗粒（SPIOs）的浓度成正比。因此，MPI被认为是未来心血管成像的一种有前景的方法。在此，一个有趣的应用可能是利用SPIOs浓度与MPI信号强度的比例关系对血管病变（如狭窄）进行量化。在本研究中，基于这种应用场景评估了基于MPI的狭窄量化的可行性。九个正常直径均为10毫米、狭窄程度为1 - 9毫米的不同狭窄模型以及十个直径为1 - 10毫米的直筒模型，均填充1%的Resovist稀释液，并在临床前MPI演示器中进行测量。将参考模型的MPI信号强度相互比较，并利用每个狭窄模型内信号强度的变化来计算狭窄程度。然后将这些值与每个模型的已知直径进行比较。作为第二项测量，使用5毫米狭窄模型进行系列稀释测量，直至Resovist稀释至1:3200（0.031%），该稀释度低于平均成年人体内外周动脉中Resovist团注的首过血药浓度，至少约为1:1000。基于MPI信号强度测量的狭窄值与基于已知直径的狭窄值之间的相关性显示出非常好的一致性，证明了定量MPI在这方面的高精度。
