2013 International Workshop on Magnetic Particle Imaging (IWMPI)最新文献

{"title":"Quantification of magnetic nanoparticles in living cells","authors":"N. Loewa, F. Wiekhorst, S. Metzkow, A. Ludwig, L. Trahms","doi":"10.1109/IWMPI.2013.6528359","DOIUrl":"https://doi.org/10.1109/IWMPI.2013.6528359","url":null,"abstract":"We demonstrated the feasibility to quantify MNP uptake by nonadherent living THP-1 cells. The iron quantification by MPS is specific to MNP iron and is not distorted by biological iron in contrast to phenantrolin staining.","PeriodicalId":267566,"journal":{"name":"2013 International Workshop on Magnetic Particle Imaging (IWMPI)","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115267191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Twenty-fold acquisition time improvement in 3D projection reconstruction MPI","authors":"J. Konkle, P. Goodwill, E. Saritas, S. Conolly","doi":"10.1109/IWMPI.2013.6528322","DOIUrl":"https://doi.org/10.1109/IWMPI.2013.6528322","url":null,"abstract":"Summary form only given. Magnetic Particle Imaging (MPI) commonly utilizes a Field Free Point (FFP) magnetic field gradient to localize magnetic nanoparticles [12]. With the benefits of two orders of magnitude reduced acquisition time or one order of magnitude signal-to-noise ratio (SNR) improvement, a gradient called a Field Free Line (FFL), which localizes particles to a line instead of a point, has been theoretically developed [3-6], and experimentally demonstrated [4,6]. In this work, we use a FFL with sample rotation and projection reconstruction to demonstrate experimental images with a 20 fold improvement in acquisition time compared to the first projection reconstruction (PR) MPI results [6]. To gain this 20 fold speed up, we implement a z direction focus field coil configuration instead of the previously utilized translation stage. Our imaging system included a 2.3 T/m permanent magnet FFL, a solenoidal drive coil, two focus field x and z direction electromagnet pairs with Helmholtz configurations, a solenoidal receive coil with a gradiometer configuration, and a motor driven rotary table (see Figure 1). The system drive coil was excited to create a 22.9 kHz drive field with a 1.3 cm z partial field of view (FOV). The x slow shift (focus) field operated with a 3.3 Hz triangle wave, which produced a 5 cm x FOV. A linear ramp z focus field traversed 6 cm in 3 s, once per projection image. The drive and z shift fields summed, producing a 7.3 cm z FOV. There were 20 x axis traversals (10 cycles) per projection image. With this sequence, we acquired 40 images at linearly spaced angles over 180 degrees. The image acquisition time was 2.1 min. We collected all the necessary projection data to produce a MPI tomographic 3D volume using the above parameters. Images were reconstructed using x-space reconstruction with filtered backprojection (FBP) [5-6]. The final imaging volume was limited by bore size and the z slow shift magnets to a 4.8 cm by 4.8 cm by 7.3 cm 3D volume. The 3D volume was exported in DICOM file format and subsequently imported to Osirix (Pixmeo, Switzerland) where maximum intensity projection (MIP) images were rendered. To test our imaging sytem, we have designed a phantom with a 3D distribution of magnetic nanoparticles (see Figure 1). Polyurethane tubing with inner diameter 1.6 mm (outer diameter 3.2) filled with 43 mM Fe Micromod Nanomag-D-spio was wrapped around a cylindrical piece of acrylic with a 3.4 cm outer diameter. Resulting MIP images illustrate the ability of the FFL imager to accurately resolve nanoparticle distributions in 3D. The MIP image can be rotated to any orientation, and two such views are shown in Figure 1. In previous work, an image with a similar FOV would have taken 39 min using a translation stage [6]. The two minute acquisiton time using electromagnetic z shift demonstrates an approximately 20 fold improvement in acquisition time.","PeriodicalId":267566,"journal":{"name":"2013 International Workshop on Magnetic Particle Imaging (IWMPI)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129981474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analyzing magnetic nanoparticle content in biological samples: Acsusceptometry using offset fields","authors":"M. Visscher, S. Waanders, B. Ten Haken","doi":"10.1109/IWMPI.2013.6528357","DOIUrl":"https://doi.org/10.1109/IWMPI.2013.6528357","url":null,"abstract":"The clinical application of magnetic nanoparticles is a developing field with promising perspectives in treatment and diagnosis [1]. After the first applications as a contrast agent in MRI, other magnetic methods have been developed for excitation and detection of magnetic nanoparticles. For magnetic detection, the nonlinear behavior of superparamagnetic iron oxides provide excellent contrast in the linear magnetic human body. To exploit these properties, the design of magnetic nanoparticles as well as detection systems has to be optimized for clinical practice. The particles have to provide optimal sensitivity in contrast to tissue, whereas the signal-to-noise ratio and applicability of a measurement system are important for successful clinical implementation. In this contribution a setup is presented that is able to assess these both elements for sentinel lymph node mapping. Small intact biological samples, such as lymph nodes, can be measured at room temperature to characterize the magnetic nanoparticle content by differential magnetometry. Furthermore, the system can be used as a tool to analyze the magnetic properties of nanoparticles, providing insight in the quality for nonlinear particle detection.","PeriodicalId":267566,"journal":{"name":"2013 International Workshop on Magnetic Particle Imaging (IWMPI)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123473878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Truncation artifacts in Magnetic Particle Imaging","authors":"M. Gruttner, T. Sattel, G. Bringout, M. Graeser, W. Tenner, H. Wojtczyk, T. Buzug","doi":"10.1109/IWMPI.2013.6528335","DOIUrl":"https://doi.org/10.1109/IWMPI.2013.6528335","url":null,"abstract":"Figure 1 clearly shows the effect of truncation artifacts when particles are not covered by the trajectory. With the removal of edge pixels these artifacts disappear. However, some information of the image is lost depending on the size of the necessary cut-off. With the multi-resolution approach the full information is used. Instead of removing pixels they are combined to large pixels. This method results in a better quality with small cut-offs compared to the non-compensated images.","PeriodicalId":267566,"journal":{"name":"2013 International Workshop on Magnetic Particle Imaging (IWMPI)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116237337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cancellation techniques for MPI","authors":"M. Graeser, Tobias Knopp, M. Gruttner, T. Sattel, G. Bringout, W. Tenner, H. Wojtczyk, T. Buzug","doi":"10.1109/IWMPI.2013.6528331","DOIUrl":"https://doi.org/10.1109/IWMPI.2013.6528331","url":null,"abstract":"Due to the superposition of the high magnitude drive field signal and the low magnitude particle signal in magnetic particle imaging (MPI), the received signal has to be separated at its fundamental frequency [1]. This is often done by filtering causing DC offset drifts in the particle answer using x-space reconstruction. These errors are currently corrected by dividing the FOV in partial FOVs [2]. However, small FOV sizes reduce the temporal resolution if the region of interest stays the same. This work proposes a combination of filtering and cancellation to prevent the fundamental frequency of the particle signal as well as provide the possibility of larger FOVs and presents three different cancellation coil techniques.","PeriodicalId":267566,"journal":{"name":"2013 International Workshop on Magnetic Particle Imaging (IWMPI)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128260329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Human PNS and SAR study in the frequency range from 24 to 162 kHz","authors":"I. Schmale, B. Gleich, Joachim D Schmidt, J. Rahmer, C. Bontus, R. Eckart, B. David, M. Heinrich, O. Mende, O. Woywode, Jonas Jokram, J. Borgert","doi":"10.1109/IWMPI.2013.6528346","DOIUrl":"https://doi.org/10.1109/IWMPI.2013.6528346","url":null,"abstract":"In order to identify suitable operating conditions for future clinical Magnetic Particle Imaging, peripheral nerve stimulation (PNS) and specific absorption rate (SAR) experiments have been performed by exposing volunteers to sinusoidally time-varying magnetic fields along and transverse to the body axis at frequencies from 24 kHz to 162 kHz. The findings show that future clinical MPI can advantageously be performed at elevated drive-field frequencies, with PNS restriction actually relaxed at higher frequencies, and with still acceptable SAR exposure.","PeriodicalId":267566,"journal":{"name":"2013 International Workshop on Magnetic Particle Imaging (IWMPI)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134194928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of biofunctionalization and tracer cross-linking in magnetic particle spectrometry","authors":"H. Arami, R. M. Ferguson, A. Khandhar, A. Tomitaka, K. Krishnan","doi":"10.1109/IWMPI.2013.6528378","DOIUrl":"https://doi.org/10.1109/IWMPI.2013.6528378","url":null,"abstract":"In this paper, we present a ligand exchange and PEGylation approach for developing monodisperse MPI tracers (core size ~ 20nm) with the required reactive -NH2 and/or -SH functional groups on their surface. First, free carboxyl groups were introduced on the surface of the NPs through a silanization reaction. Then, a carbodiimide reagent (DCC) was used to bond the amine groups of the NH2-PEG-NH2 or NH2-PEG-SH molecules to these carboxyl groups.","PeriodicalId":267566,"journal":{"name":"2013 International Workshop on Magnetic Particle Imaging (IWMPI)","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124131746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heating of interventional instruments in magnetic particle imaging - First experiences of safety measurements","authors":"R. Duschka, H. Wojtczyk, N. Panagiotopoulos, J. Haegele, G. Bringout, J. Rahmer, C. Bontus, T. Buzug, J. Borgert, J. Barkhausen, F. Vogt","doi":"10.1109/IWMPI.2013.6528370","DOIUrl":"https://doi.org/10.1109/IWMPI.2013.6528370","url":null,"abstract":"It seems that signal generating devices, especially those which were made of stainless steel, are not optimal for cardiovascular interventions, if these devices show ferromagnetic characteristics. CVI seem to be safe in MPI using non-signal generating devices. Labeling and visualization of devices with SPIOSs is possible and has been described in recent studies. Based on the complexity of stents themselves and different components of the stent delivery systems, it is necessary to address heating behavior of those instruments in further studies. Stents which heat up to temperatures only a few degrees above body temperature seem to be suitable for cardiovascular interventions in MPI. Further in-vivo studies are necessary to investigate heating of interventional instruments in MPI in contrast to cooling due to blood flow.","PeriodicalId":267566,"journal":{"name":"2013 International Workshop on Magnetic Particle Imaging (IWMPI)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130155460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of scanning rate on relaxation-induced blurring in magnetic particle image","authors":"L. Croft, P. Goodwill, D. A. Price, E. Saritas, Ada X. Li, S. Conolly","doi":"10.1109/IWMPI.2013.6528382","DOIUrl":"https://doi.org/10.1109/IWMPI.2013.6528382","url":null,"abstract":"We measured the relaxation times of PSFs acquired at a range of scanning rate, which was varied by changing the excitation field strength. As excitation scanning rate increased, measured relaxation times decreased (Figure 1b). This effect is likely due to the stronger magnetic torque acting on the particles. Relaxation field delays were calculated for the same data to observe how relaxation time delays translated to delays in field after taking into account the scanning rate. As the excitation field was scanned faster, relaxation field delays increased (Figure 1c). FWHM measurements followed a similar trend as the relaxation field delays and increased as scanning rate increased (Figure 1d). Although faster scanning decreases relaxation times, increasing scanning rate exacerbates image blur due to relaxation.","PeriodicalId":267566,"journal":{"name":"2013 International Workshop on Magnetic Particle Imaging (IWMPI)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130087640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of frequency and pulse duration on magnetostimulation limits for MPI","authors":"E. Saritas, P. Goodwill, D. Chang, S. Conolly","doi":"10.1109/IWMPI.2013.6528334","DOIUrl":"https://doi.org/10.1109/IWMPI.2013.6528334","url":null,"abstract":"The time-varying drive field in MPI is subject to magnetostimulation and specific absorption rate (SAR) limits. For frequencies up to 50 kHz, magnetostimulation is the dominant safety concern [1-2]. In this work, we investigate both the frequency and duration dependence of magnetostimulation limits for the drive field in MPI.","PeriodicalId":267566,"journal":{"name":"2013 International Workshop on Magnetic Particle Imaging (IWMPI)","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121758894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}