| 1. |
- Andersson-Engels, Stefan, et al.
(author)
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In vivo luminescence imaging and tomography using upconverting nanoparticles as contrast agents
- 2012
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In: 2012 Asia Communications and Photonics Conference. - 2162-108X. ; , s. 2-3
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Conference paper (peer-reviewed)abstract
- Upconverting nanoparticles have recently drawn increasingly attention as contrast agents for optical bioimaging. They enable autofluorescence-free imaging within the tissue optical window, and improved spatial resolution as compared to conventional fluorescence-based contrast agents. (C) 2012 Optical Society of America
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| 2. |
- Andersson, Roger, et al.
(author)
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B-field energy dependent phase lag dispersion in magnetomotive ultrasound imaging
- 2015
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In: 2015 IEEE International Ultrasonics Symposium (IUS). - 1948-5719.
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Conference paper (peer-reviewed)abstract
- Magnetomotive ultrasound imaging is an emerging technique where superparamagnetic iron oxide nanoparticles can be used as an ultrasound contrast agent. A time-varying external magnetic field acts to move tissue embedded particles, and ultrasound is used to detect the resulting tissue movement. In experimental phantom studies we have observed a phase lag dispersion in the magnetomotive response in respect to applied time-varying magnetic field (B-field). We hypothesize that this dispersion is triggered by the strength of the applied B-field in combination with concentration of embedded nanoparticles in the region. The cohort response of the nanoparticles aligns as the magnetic field gets more energetic. Moreover, the tightening of the phase response indicate an asymptotic tapering towards a phase limit.
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| 3. |
- Andersson, Roger, et al.
(author)
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Effect of nanoparticle size and magnetic field strength on the displacement signal in magnetomotive ultrasound imaging
- 2016
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In: 2016 IEEE International Ultrasonics Symposium, IUS 2016. - 9781467398978 ; 2016-November
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Conference paper (peer-reviewed)abstract
- Magnetomotive ultrasound imaging is an emerging technique where superparamagnetic iron oxide nanoparticles can be used as an ultrasound contrast agent. A time-varying external magnetic field acts to move tissue embedded particles, and ultrasound is used to detect the resulting tissue movement. In this experimental phantom study we observed a variation in the magnetomotive response in respect to physical size of the embedded superparamagnetic iron oxide nanoparticles. Given the same Fe concentration a weaker response, by a factor of 2, was detected with the larger nanoparticles. However, approximately seven times larger response remains, given the volume ratio between particles, implying a seven times larger response per binding event. We hypothesize that this can have bearing in molecular imaging.
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| 4. |
- Evertsson, Maria, et al.
(author)
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Combined Magnetomotive ultrasound, PET/CT, and MR imaging of (68)Ga-labelled superparamagnetic iron oxide nanoparticles in rat sentinel lymph nodes in vivo
- 2017
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7:1
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Journal article (peer-reviewed)abstract
- Current methods for intra-surgical guidance to localize metastases at cancer surgery are based on radioactive tracers that cause logistical challenges. We propose the use of a novel ultrasound-based method, magnetomotive ultrasound (MMUS) imaging that employ a nanoparticle-based contrast agent that also may be used for pre-operative PET/MRI imaging. Since MMUS is radiation free, this eliminates the dependence between pre- and intra-operative imaging and the radiation exposure for the surgical staff. This study investigates a hypothetical clinical scenario of pre-operative PET imaging, combined with intra-operative MMUS imaging, implemented in a sentinel lymph node (SLN) rat model. At one-hour post injection of (68)Ga-labelled magnetic nanoparticles, six animals were imaged with combined PET/CT. After two or four days, the same animals were imaged with MMUS. In addition, ex-vivo MRI was used to evaluate the amount of nanoparticles in each single SLN. All SLNs were detectable by PET. Four out of six SLNs could be detected with MMUS, and for these MMUS and MRI measurements were in close agreement. The MRI measurements revealed that the two SLNs undetectable with MMUS contained the lowest nanoparticle concentrations. This study shows that MMUS can complement standard pre-operative imaging by providing bedside real-time images with high spatial resolution.
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| 5. |
- Evertsson, Maria, et al.
(author)
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Frequency- and Phase-Sensitive Magnetomotive Ultrasound Imaging of Superparamagnetic Iron Oxide Nanoparticles
- 2013
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In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - 0885-3010. ; 60:3, s. 481-491
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Journal article (peer-reviewed)abstract
- It has recently been demonstrated that superparamagnetic iron oxide nanoparticles can be used as magnetomotive ultrasound contrast agents. A time-varying external magnetic field acts to move the particles and, thus, the nanoparticle-laden tissue. However, the difficulty of distinguishing this magnetomotive motion from undesired movement induced in regions without nanoparticles or other motion artifacts has not been well reported. Using a high-frequency linear-array system, we found that displacements outside nanoparticle-laden regions can be similar in magnitude to those in regions containing nanoparticles. We also found that the displacement outside the nanoparticle regions had a phase shift of approximately p radians relative to that in the nanoparticle regions. To suppress signals arising from undesirable movements, we developed an algorithm based on quadrature detection and phase gating at the precise frequency of nanoparticle displacement. Thus, clutter at other frequencies can be filtered out, and the processed signal can be color-coded and superimposed on the B-mode image. The median signal-to-clutter ratio improvement using the proposed algorithm was 36 dB compared with simply summing the movement energy at all frequencies. This clutter rejection is a crucial step to move magnetomotive ultrasound imaging of nanoparticles toward in vivo investigations.
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| 6. |
- Evertsson, Maria, et al.
(author)
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In vivo magnetomotive ultrasound imaging of rat lymph nodes - a pilot study
- 2015
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In: 2015 IEEE International Ultrasonics Symposium (IUS). - 1948-5719.
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Conference paper (peer-reviewed)abstract
- The drive to gain a better understanding of how diseases arise and how to provide ever-earlier detection are some of the key factors for the development of molecular imaging. Compared to other imaging modalities ultrasound has not received the same attention for molecular imaging mainly due to its limited contrast resolution, together with contrast agents confined to the intravascular space. To overcome these issues, new nano-sized contrast agents and new ultrasound imaging techniques e.g. photo acoustic imaging, have been developed. Another such imaging technique under development is magnetomotive ultrasound imaging (MMUS). We have previously developed a frequency and phase tracking algorithm which is able to detect superparamagnetic iron oxide nanoparticles (SPIO NPs) using MMUS, where our suggested first clinical application is to detect sentinel lymph nodes (SLNs) in breast cancer surgery. Recently we have shown detection of SPIO laden rat SLNs in situ. Here we present the feasibility of in vivo detection of SLNs in rats. The algorithm clearly pinpoints the NP laden SLN, even in presence of significant artefactual tissue movement. The magnetomotive displacement increased when a higher voltage was applied on the coil creating the magnetic field (e.g. 56.6% increasing the voltage from 20V to 50V). An uneven concentration distribution of NPs in the SLN was found. The maximum magnetomotive displacement difference between two different cross sections in one SLN was 9.76 times. The study also showed that for a higher concentration of NPs a lower magnetic coil excitation voltage could be used in order to create a magnetomotive displacement of a certain magnitude. The result from this in vivo study shows that the method has potential for future clinical use.
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| 7. |
- Evertsson, Maria, et al.
(author)
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Magnetomotive Ultrasound Imaging Of Rat Lymph Nodes In Situ: Assessment Of Imaging Parameters
- 2013
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In: 2013 IEEE International Ultrasonics Symposium (IUS). - 9781467356855 ; , s. 600-603
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Conference paper (peer-reviewed)abstract
- Detection and removal sentinel lymph nodes (SLN) is important in the diagnosis and treatment of breast cancer and malignant melanoma. The SLN is the first regional lymph node draining the cancer tumor and if the cancer has spread it is most likely to find cancer cells in the SLN. In this study we have been able to detect multimodal superparamagnetic iron oxide nanoparticles (SPIO-NP) in rat SLNs in situ using magnetomotive ultrasound imaging (MMUS). In MMUS a time-varying external magnetic field acts to move the NPs and, thus, the NP-laden tissue. This movement can be detected by proper processing of ultrasound data. We have recently developed an MMUS algorithm, based on quadrature detection and phase gating at the frequency of NP displacement, and this is the first study where the algorithm is evaluated in animals. For both higher NP-concentration, as well as smaller NPs, we found that the MMUS data showed a larger displacement (1.56 +/- 0.43 and 1.94 +/- 0.54 times larger, respectively). The MMUS displacement also increased with a lower excitation frequency (1.95 +/- 0.64 times larger for 5 Hz compared to 15 Hz) and higher excitation voltage (2.95 +/- 1.44 times larger for 30V compared to 10V). The results from this study show that the MMUS technique has potential to be used as bedside guidance during SLN surgery, well as being used as standalone technique in a number of other applications such as stem cell tracking and cardiovascular research.
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| 8. |
- Evertsson, Maria, et al.
(author)
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Multimodal Detection of Iron Oxide Nanoparticles in Rat Lymph Nodes Using Magnetomotive Ultrasound Imaging and Magnetic Resonance Imaging
- 2014
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In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - 0885-3010. ; 61:8, s. 1276-1283
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Journal article (peer-reviewed)abstract
- Detection and removal of sentinel lymph nodes (SLN) is important in the diagnosis and treatment of cancer. The SLN is the first regional lymph node draining the primary tumor, and if the cancer has spread, it is most likely to find metastases in the SLN. In this study, we have for the first time been able to image the very same contrast agent, superparamagnetic iron oxide nanoparticles (SPIO-NPs), in rat SLNs by using both our frequency-and phase-gated magnetomotive ultrasound (MMUS) algorithm and conventional magnetic resonance imaging (MRI); MMUS post mortem, MRI in vivo. For both higher NP-concentration and smaller NPs, we found that the MMUS data showed a larger magnetomotive displacement (1.56 +/- 0.43 and 1.94 +/- 0.54 times larger, respectively) and that the MR-images were affected to a higher degree. The MMUS displacement also increased with lower excitation frequency (1.95 +/- 0.64 times larger for 5 Hz compared with 15 Hz) and higher excitation voltage (2.95 +/- 1.44 times larger for 30 V compared with 10 V). The results show that MMUS has potential to be used as bedside guidance during SLN surgery, imaging the same particles that were used in prior staging with other imaging techniques.
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| 9. |
- Evertsson, Maria, et al.
(author)
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Normalization of Magnetic Field Effects: Towards Quantitative Magnetomotive Ultrasound Imaging
- 2012
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In: 2011 IEEE International Ultrasonics Symposium (IUS). - 9781457712531 ; , s. 775-778
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Conference paper (peer-reviewed)abstract
- In magnetomotive ultrasound (MMUS) imaging superparamagnetic iron oxide nanoparticles (NP) are used as contrast agents and a time-varying external magnetic field acts to move the particles and thereby the nanoparticle-laden tissue. Recently we proposed a frequency and phase sensitive algorithm to reduce motion artifacts. However, the method is not quantitative as the particle movement induced is dependent not only on the field strength, but also on the field gradient, plus material parameters. Here we assess the measured nanoparticle movement across the image plane in comparison with simulations of the magnetic force, to evaluate the potential for image normalization of magnetic field effects. We found that the movement decreased with distance to the iron core tip, from which the magnetic field was extending, and approaches zero at the transducer face. This finding did not coincide with the simulation and may make it difficult to enable quantification. The coefficient of variation between measurements on the homogeneous phantom was typically in the order of 15% for all frequencies, indicating the expected accuracy for quantitative measurements.
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| 10. |
- Fredriksson, Ida, et al.
(author)
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Effect of the dopamine stabilizer (-)-OSU6162 on potentiated incubation of opioid craving after electric barrier-induced voluntary abstinence.
- 2020
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In: Neuropsychopharmacology. - : Nature Publishing Group. - 0893-133X .- 1740-634X. ; 45:5, s. 770-779
-
Journal article (peer-reviewed)abstract
- In the classical incubation of drug craving rat model, drug seeking is assessed after homecage forced abstinence. However, human abstinence is often voluntary because negative consequences of drug seeking outweigh the desire for the drug. Here, we developed a rat model of incubation of opioid craving after electric barrier-induced voluntary abstinence and determined whether the dopamine stabilizer (-)-OSU6162 would decrease this new form of incubation. We trained male and female rats to self-administer oxycodone (0.1 mg/kg/infusion, 6 h/day) for 14 days. We then exposed them to either homecage forced abstinence or voluntary abstinence induced by an electric barrier of increasing intensity near the drug-paired lever. On abstinence days 1, 15, or 30, we tested the rats for oxycodone seeking without shock and drug. We also examined the effect of (-)-OSU6162 (7.5 and 15 mg/kg) on oxycodone seeking on abstinence day 1 or after 15 days of either voluntary or forced abstinence. Independent of sex, the time-dependent increase in oxycodone seeking after cessation of opioid self-administration (incubation of opioid craving) was stronger after voluntary abstinence than after forced abstinence. In males, (-)-OSU6162 decreased incubated (day 15) but not non-incubated (day 1) oxycodone seeking after either voluntary or forced abstinence. In females, (-)-OSU6162 modestly decreased incubated oxycodone seeking after voluntary but not forced abstinence. Results suggest that voluntary abstinence induced by negative consequences of drug seeking can paradoxically potentiate opioid craving and relapse. We propose the dopamine stabilizer (-)-OSU6162 may serve as an adjunct pharmacological treatment to prevent relapse in male opioid users.
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