Magnetic Particle Imaging for Quantification of Vascular Stenoses: A Phantom Study

Abstract

Magnetic particle imaging (MPI) is a promising new tomographic imaging method to detect the spatial distribution of superparamagnetic iron-oxide nanoparticles (SPIOs). The aim of this paper was to investigate the potential of MPI to quantify artificial stenoses in vessel phantoms. Custom-made stenosis phantoms (length 40 mm; inner diameter 8 mm) with different degrees of stenosis (0%, 25%, 50%, 75%, and 100%) were scanned in a custom-built MPI scanner (in-plane resolution: ~1-1.5 mm and field of view: 65 29 29 mm). Phantoms were filled with diluted Feru-carbotran [SPIO agent, 5 mmol (Fe)/l]. Each measurement (overall acquisition time: 20 ms per image, 400 averages) was repeated ten times to assess reproducibility. The MPI signal was used for semi-automatic stenosis quantification. Two stenosis evaluation approaches were compared based on the signal intensity profile alongside the stenosis phantoms. Using a novel multi-step image evaluation approach, MPI allowed for accurate quantification of different stenosis grades. While low grade stenoses were slightly over-estimated, high grade stenoses were slightly underestimated. In particular, the 0%, 25%, and 50% stenosis phantoms revealed a 6.2% ± 0.8, 25.7% ± 1.0, and 48.0% ± 1.5 stenosis, respectively. The higher grade 75% stenosis phantom revealed a 73.3% ± 2.8 and the 100% stenosis phantom a 95.8%± 1.9 stenosis. MPI accurately visualized and quantified different stenosis grades in vessel phantoms with high reproducibility demonstrating its great potential for fast and radiation-free preclinical cardiovascular imaging.

Application prospect of nanomaterials mediated magnetic technology in the diagnosis and treatment of surgical diseases

“…MPI的高对比度和灵敏度, 通过采用低剂量的超顺磁 氧化铁纳米材料, Herz等人 [47] 准确定量了不同狭窄程 度的体外血管模型. Weizenecker研究组 [48] 则利用铁羧 葡胺作为示踪剂显示了搏动的小鼠心脏, 这个三维的 MPI在体研究结果表明, MPI在临床应用上又进了一 步, 在心脏外科有非常广阔的应用前景, 可用于先天性 心脏病的诊断、心脏结构缺失的判断等.…”

Magnetic particle imaging in vascular medicine

“…As MPI features a high spatial resolution, it is interesting to be used for investigating the degree of stenosis [51]. By use of a stenosis phantom, which has a normal lumen of 10 mm diameter and allows a narrowing from 9 to 1 mm, referring to a stenosis degree of 19%–99%, the visualization of the stenosis degree with MPI was possible.…”

Magnetic Particle Imaging: In vitro Signal Analysis and Lumen Quantification of 21 Endovascular Stents

“…3 In the last decade, several studies demonstrated the potential of MPI for cardiovascular imaging and vascular interventions. [3][4][5][6][7][8] Most recently the proof of principle of MPI guided stent implantations and first safety measurements of stents became available. 9,10 Stent implantation is becoming increasingly common in clinical routine and interventional radiology and cardiology are steadily replacing surgical procedures.…”