Self-gated non–contrast-enhanced functional lung MR imaging allows for site-resolved assessment of quantitative pulmonary ventilation in patients with cystic fibrosis without contrast material application or breath holds. PurposeTo assess the clinical feasibility of self-gated non–contrast-enhanced functional lung (SENCEFUL) magnetic resonance (MR) imaging for quantitative ventilation (QV) imaging in patients with cystic fibrosis (CF).Materials and MethodsTwenty patients with CF and 20 matched healthy volunteers underwent functional 1.5-T lung MR imaging with the SENCEFUL imaging approach, in which a two-dimensional fast low-angle shot sequence is used with quasi-random sampling. The lungs were manually segmented on the ventilation-weighted images to obtain QV measurements, which were compared between groups. QV values of the patients were correlated with results of pulmonary function testing. Three radiologists rated the images for presence of ventilation deficits by means of visual inspection. Mann-Whitney U tests, receiver operating characteristic analyses, Spearman correlations, and Gwet agreement coefficient analyses were used for statistical analysis.ResultsQV of the entire lungs was lower for patients with CF than f...

Purpose:To assess the feasibility of magnetic particle imaging (MPI) to guide stenting in a phantom model. Materials and Methods: MPI is a new tomographic imaging method based on the background-free magnetic field detection of a tracer agent composed of superparamagnetic iron oxide nanoparticles (SPIOs). All experiments were conducted on a custom-built MPI scanner (field of view: 29-mm diameter, 65-mm length; isotropic spatial resolution 1–1.5-mm). Stenosis phantoms (n=3) consisted of polyvinyl chloride (PVC) tubes (8-mm inner diameter) prepared with centrally aligned cable binders to form a ~50% stenosis. A dedicated image reconstruction algorithm allowed precise tracking of endovascular instruments at 8 frames/s with a latency time of ~115 ms. A custom-made MPI-visible lacquer was used to manually label conventional guidewires, balloon catheters, and stainless steel balloon-expandable stents. Vascular stenoses were visualized by injecting a diluted SPIO tracer (ferucarbotran, 10 mmol iron/L) into the vessel phantoms. Balloon angioplasty and stent placement were performed by inflating balloon catheters and stent delivery balloons with diluted ferucarbotran. Results: After deployment of the stent, the markers on its ends were clearly visible. The applied lacquer markers were thin enough to not relevantly alter gliding properties of the devices while withstanding friction during the experiments. Placing an optimized flexible lacquer formulation on the preexisting radiopaque stent markers provided enough stability to withstand stent expansion. Final MPA confirmed successful stenosis treatment, facilitated by the disappearance of the lacquer markers on the stent due to differences in SPIO concentration. Thus, the in-stent lumen could be visualized without interference by the signal from the markers. Conclusion: Near real-time visualization of MPI-guided stenting of stenoses in a phantom model is feasible. Optimized MPI-visible markers can withstand the expansion process of stents.

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 ³ ). 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.