Accomplishments and challenges in stem cell imaging in vivo.

Stem cell therapies have demonstrated promising preclinical results, but very few applications have reached the clinic owing to safety and efficacy concerns. Translation would benefit greatly if stem cell survival, distribution and function could be assessed in vivo post-transplantation, particularly in patients. Advances in molecular imaging have led to extraordinary progress, with several strategies being deployed to understand the fate of stem cells in vivo using magnetic resonance, scintigraphy, PET, ultrasound and optical imaging. Here, we review the recent advances, challenges and future perspectives and opportunities in stem cell tracking and functional assessment, as well as the advantages and challenges of each imaging approach

MRI of the lung (3/3)-current applications and future perspectives

BACKGROUND: MRI of the lung is recommended in a number of clinical indications. Having a non-radiation alternative is particularly attractive in children and young subjects, or pregnant women. METHODS: Provided there is sufficient expertise, magnetic resonance imaging (MRI) may be considered as the preferential modality in specific clinical conditions such as cystic fibrosis and acute pulmonary embolism, since additional functional information on respiratory mechanics and regional lung perfusion is provided. In other cases, such as tumours and pneumonia in children, lung MRI may be considered an alternative or adjunct to other modalities with at least similar diagnostic value. RESULTS: In interstitial lung disease, the clinical utility of MRI remains to be proven, but it could provide additional information that will be beneficial in research, or at some stage in clinical practice. Customised protocols for chest imaging combine fast breath-hold acquisitions from a "buffet" of sequences. Having introduced details of imaging protocols in previous articles, the aim of this manuscript is to discuss the advantages and limitations of lung MRI in current clinical practice. CONCLUSION: New developments and future perspectives such as motion-compensated imaging with self-navigated sequences or fast Fourier decomposition MRI for non-contrast enhanced ventilation- and perfusion-weighted imaging of the lung are discussed. Main Messages • MRI evolves as a third lung imaging modality, combining morphological and functional information. • It may be considered first choice in cystic fibrosis and pulmonary embolism of young and pregnant patients. • In other cases (tumours, pneumonia in children), it is an alternative or adjunct to X-ray and CT. • In interstitial lung disease, it serves for research, but the clinical value remains to be proven. • New users are advised to make themselves familiar with the particular advantages and limitations

Focal Spot, Fall/Winter 2000

https://digitalcommons.wustl.edu/focal_spot_archives/1086/thumbnail.jp

Characterization of a preclinical PET insert in a 7 tesla MRI scanner: beyond NEMA testing

[EN] This study evaluates the performance of the Bruker positron emission tomograph (PET) insert combined with a BioSpec 70/30 USR magnetic resonance imaging (MRI) scanner using the manufacturer acceptance protocol and the NEMA NU 4-2008 for small animal PET. The PET insert is made of 3 rings of 8 monolithic LYSO crystals (50 x 50 x 10 mm(3)) coupled to silicon photomultipliers (SiPM) arrays, conferring an axial and transaxial FOV of 15 cm and 8 cm. The MRI performance was evaluated with and without the insert for the following radiofrequency noise, magnetic field homogeneity and image quality. For the PET performance, we extended the NEMA protocol featuring system sensitivity, count rates, spatial resolution and image quality to homogeneity and accuracy for quantification using several MRI sequences (RARE, FLASH, EPI and UTE). The PET insert does not show any adverse effect on the MRI performances. The MR field homogeneity is well preserved (Diameter Spherical Volume, for 20 mm of 1.98 +/- 4.78 without and -0.96 +/- 5.16 Hz with the PET insert). The PET insert has no major effect on the radiofrequency field. The signal-to-noise ratio measurements also do not show major differences. Image ghosting is well within the manufacturer specifications (<2.5%) and no RF noise is visible. Maximum sensitivity of the PET insert is 11.0% at the center of the FOV even with simultaneous acquisition of EPI and RARE. PET MLEM resolution is 0.87 mm (FWHM) at 5 mm off-center of the FOV and 0.97 mm at 25 mm radial offset. The peaks for true/noise equivalent count rates are 410/240 and 628/486 kcps for the rat and mouse phantoms, and are reached at 30.34/22.85 and 27.94/22.58 MBq. PET image quality is minimally altered by the different MRI sequences. The Bruker PET insert shows no adverse effect on the MRI performance and demonstrated a high sensitivity, sub-millimeter resolution and good image quality even during simultaneous MRI acquisition.We acknowledge the KU Leuven core facility, Molecular Small Animal Imaging Center (MoSAIC), for their support with obtaining scientific data presented in this paper. This work was supported by Stichting tegen Kanker (2015-145, Christophe M. Deroose) and Hercules foundation (AKUL/13/029, Uwe Himmelreich) for the purchase of the PET and MRI equipment respectively. The work was supported by the following funding organizations: European Commission for the PANA project (H2020-NMP-2015-two-stage, grant 686009) and the European ERA-NET project 'CryptoView' (3rd call of the FP7 program Infect-ERA).Gsell, W.; Molinos, C.; Correcher, C.; Belderbos, S.; Wouters, J.; Junge, S.; Heidenreich, M.... (2020). Characterization of a preclinical PET insert in a 7 tesla MRI scanner: beyond NEMA testing. Physics in Medicine and Biology. 65(24):1-16. https://doi.org/10.1088/1361-6560/aba08cS1166524Balezeau, F., Eliat, P.-A., Cayamo, A. B., & Saint-Jalmes, H. (2011). Mapping of low flip angles in magnetic resonance. Physics in Medicine and Biology, 56(20), 6635-6647. doi:10.1088/0031-9155/56/20/008Benlloch, J. M., González, A. J., Pani, R., Preziosi, E., Jackson, C., Murphy, J., … Schwaiger, M. (2018). The MINDVIEW project: First results. European Psychiatry, 50, 21-27. doi:10.1016/j.eurpsy.2018.01.002Cal-Gonzalez, J., Rausch, I., Shiyam Sundar, L. K., Lassen, M. L., Muzik, O., Moser, E., … Beyer, T. (2018). Hybrid Imaging: Instrumentation and Data Processing. Frontiers in Physics, 6. doi:10.3389/fphy.2018.00047Clark, D. P., & Badea, C. T. (2014). Micro-CT of rodents: State-of-the-art and future perspectives. Physica Medica, 30(6), 619-634. doi:10.1016/j.ejmp.2014.05.011Drzezga, A., Souvatzoglou, M., Eiber, M., Beer, A. J., Fürst, S., Martinez-Möller, A., … Schwaiger, M. (2012). First Clinical Experience with Integrated Whole-Body PET/MR: Comparison to PET/CT in Patients with Oncologic Diagnoses. Journal of Nuclear Medicine, 53(6), 845-855. doi:10.2967/jnumed.111.098608Gonzalez, A. J., Aguilar, A., Conde, P., Hernandez, L., Moliner, L., Vidal, L. F., … Benlloch, J. M. (2016). A PET Design Based on SiPM and Monolithic LYSO Crystals: Performance Evaluation. IEEE Transactions on Nuclear Science, 63(5), 2471-2477. doi:10.1109/tns.2016.2522179Gonzalez, A. J., Pincay, E. J., Canizares, G., Lamprou, E., Sanchez, S., Catret, J. V., … Correcher, C. (2019). Initial Results of the MINDView PET Insert Inside the 3T mMR. IEEE Transactions on Radiation and Plasma Medical Sciences, 3(3), 343-351. doi:10.1109/trpms.2018.2866899Grant, A. M., Lee, B. J., Chang, C.-M., & Levin, C. S. (2017). Simultaneous PET/MR imaging with a radio frequency-penetrable PET insert. Medical Physics, 44(1), 112-120. doi:10.1002/mp.12031Habte, F., Ren, G., Doyle, T. C., Liu, H., Cheng, Z., & Paik, D. S. (2013). Impact of a Multiple Mice Holder on Quantitation of High-Throughput MicroPET Imaging With and Without Ct Attenuation Correction. Molecular Imaging and Biology, 15(5), 569-575. doi:10.1007/s11307-012-0602-yHammer, B. E., Christensen, N. L., & Heil, B. G. (1994). Use of a magnetic field to increase the spatial resolution of positron emission tomography. Medical Physics, 21(12), 1917-1920. doi:10.1118/1.597178Jadvar, H., & Colletti, P. M. (2014). Competitive advantage of PET/MRI. European Journal of Radiology, 83(1), 84-94. doi:10.1016/j.ejrad.2013.05.028Judenhofer, M. S., Catana, C., Swann, B. K., Siegel, S. B., Jung, W.-I., Nutt, R. E., … Pichler, B. J. (2007). PET/MR Images Acquired with a Compact MR-compatible PET Detector in a 7-T Magnet. Radiology, 244(3), 807-814. doi:10.1148/radiol.2443061756Kinahan, P. E., Townsend, D. W., Beyer, T., & Sashin, D. (1998). Attenuation correction for a combined 3D PET/CT scanner. Medical Physics, 25(10), 2046-2053. doi:10.1118/1.598392Ko, G. B., Yoon, H. S., Kim, K. Y., Lee, M. S., Yang, B. Y., Jeong, J. M., … Lee, J. S. (2016). Simultaneous Multiparametric PET/MRI with Silicon Photomultiplier PET and Ultra-High-Field MRI for Small-Animal Imaging. Journal of Nuclear Medicine, 57(8), 1309-1315. doi:10.2967/jnumed.115.170019Lee, B. J., Grant, A. M., Chang, C.-M., Watkins, R. D., Glover, G. H., & Levin, C. S. (2018). MR Performance in the Presence of a Radio Frequency-Penetrable Positron Emission Tomography (PET) Insert for Simultaneous PET/MRI. IEEE Transactions on Medical Imaging, 37(9), 2060-2069. doi:10.1109/tmi.2018.2815620Loening, A. M., & Gambhir, S. S. (2003). AMIDE: A Free Software Tool for Multimodality Medical Image Analysis. Molecular Imaging, 2(3), 131-137. doi:10.1162/153535003322556877Mannheim, J. G., Schmid, A. M., Schwenck, J., Katiyar, P., Herfert, K., Pichler, B. J., & Disselhorst, J. A. (2018). PET/MRI Hybrid Systems. Seminars in Nuclear Medicine, 48(4), 332-347. doi:10.1053/j.semnuclmed.2018.02.011Maramraju, S. H., Smith, S. D., Junnarkar, S. S., Schulz, D., Stoll, S., Ravindranath, B., … Schlyer, D. J. (2011). Small animal simultaneous PET/MRI: initial experiences in a 9.4 T microMRI. Physics in Medicine and Biology, 56(8), 2459-2480. doi:10.1088/0031-9155/56/8/009Molinos, C., Sasser, T., Salmon, P., Gsell, W., Viertl, D., Massey, J. C., … Heidenreich, M. (2019). Low-Dose Imaging in a New Preclinical Total-Body PET/CT Scanner. Frontiers in Medicine, 6. doi:10.3389/fmed.2019.00088Nagy, K., Tóth, M., Major, P., Patay, G., Egri, G., Häggkvist, J., … Gulyás, B. (2013). Performance Evaluation of the Small-Animal nanoScan PET/MRI System. Journal of Nuclear Medicine, 54(10), 1825-1832. doi:10.2967/jnumed.112.119065Nanni, C., & Torigian, D. A. (2008). Applications of Small Animal Imaging with PET, PET/CT, and PET/MR Imaging. PET Clinics, 3(3), 243-250. doi:10.1016/j.cpet.2009.01.002Omidvari, N., Cabello, J., Topping, G., Schneider, F. R., Paul, S., Schwaiger, M., & Ziegler, S. I. (2017). PET performance evaluation of MADPET4: a small animal PET insert for a 7 T MRI scanner. Physics in Medicine & Biology, 62(22), 8671-8692. doi:10.1088/1361-6560/aa910dOmidvari, N., Topping, G., Cabello, J., Paul, S., Schwaiger, M., & Ziegler, S. I. (2018). MR-compatibility assessment of MADPET4: a study of interferences between an SiPM-based PET insert and a 7 T MRI system. Physics in Medicine & Biology, 63(9), 095002. doi:10.1088/1361-6560/aab9d1Raylman, R. R., Majewski, S., Lemieux, S. K., Velan, S. S., Kross, B., Popov, V., … Marano, G. D. (2006). Simultaneous MRI and PET imaging of a rat brain. Physics in Medicine and Biology, 51(24), 6371-6379. doi:10.1088/0031-9155/51/24/006Roncali, E., & Cherry, S. R. (2011). Application of Silicon Photomultipliers to Positron Emission Tomography. Annals of Biomedical Engineering, 39(4), 1358-1377. doi:10.1007/s10439-011-0266-9Schug, D., Lerche, C., Weissler, B., Gebhardt, P., Goldschmidt, B., Wehner, J., … Schulz, V. (2016). Initial PET performance evaluation of a preclinical insert for PET/MRI with digital SiPM technology. Physics in Medicine and Biology, 61(7), 2851-2878. doi:10.1088/0031-9155/61/7/2851Shao, Y., Cherry, S. R., Farahani, K., Meadors, K., Siegel, S., Silverman, R. W., & Marsden, P. K. (1997). Simultaneous PET and MR imaging. Physics in Medicine and Biology, 42(10), 1965-1970. doi:10.1088/0031-9155/42/10/010Steinert, H. C., & von Schulthess, G. K. (2002). Initial clinical experience using a new integrated in-line PET/CT system. The British Journal of Radiology, 75(suppl_9), S36-S38. doi:10.1259/bjr.75.suppl_9.750036Stortz, G., Thiessen, J. D., Bishop, D., Khan, M. S., Kozlowski, P., Retière, F., … Sossi, V. (2017). Performance of a PET Insert for High-Resolution Small-Animal PET/MRI at 7 Tesla. Journal of Nuclear Medicine, 59(3), 536-542. doi:10.2967/jnumed.116.187666Townsend, D. W. (2008). Combined Positron Emission Tomography–Computed Tomography: The Historical Perspective. Seminars in Ultrasound, CT and MRI, 29(4), 232-235. doi:10.1053/j.sult.2008.05.006Vandenberghe, S., & Marsden, P. K. (2015). PET-MRI: a review of challenges and solutions in the development of integrated multimodality imaging. Physics in Medicine and Biology, 60(4), R115-R154. doi:10.1088/0031-9155/60/4/r115Vaquero, J. J., & Kinahan, P. (2015). Positron Emission Tomography: Current Challenges and Opportunities for Technological Advances in Clinical and Preclinical Imaging Systems. Annual Review of Biomedical Engineering, 17(1), 385-414. doi:10.1146/annurev-bioeng-071114-040723Von Schulthess, G. K., & Schlemmer, H.-P. W. (2008). A look ahead: PET/MR versus PET/CT. European Journal of Nuclear Medicine and Molecular Imaging, 36(S1), 3-9. doi:10.1007/s00259-008-0940-9Wehner, J., Weissler, B., Dueppenbecker, P. M., Gebhardt, P., Goldschmidt, B., Schug, D., … Schulz, V. (2015). MR-compatibility assessment of the first preclinical PET-MRI insert equipped with digital silicon photomultipliers. Physics in Medicine and Biology, 60(6), 2231-2255. doi:10.1088/0031-9155/60/6/2231Wehrl, H. F., Judenhofer, M. S., Thielscher, A., Martirosian, P., Schick, F., & Pichler, B. J. (2010). Assessment of MR compatibility of a PET insert developed for simultaneous multiparametric PET/MR imaging on an animal system operating at 7 T. Magnetic Resonance in Medicine, 65(1), 269-279. doi:10.1002/mrm.22591Yamamoto, S., Imaizumi, M., Kanai, Y., Tatsumi, M., Aoki, M., Sugiyama, E., … Hatazawa, J. (2010). Design and performance from an integrated PET/MRI system for small animals. Annals of Nuclear Medicine, 24(2), 89-98. doi:10.1007/s12149-009-0333-6Yamamoto, S., Watabe, T., Watabe, H., Aoki, M., Sugiyama, E., Imaizumi, M., … Hatazawa, J. (2011). Simultaneous imaging using Si-PM-based PET and MRI for development of an integrated PET/MRI system. Physics in Medicine and Biology, 57(2), N1-N13. doi:10.1088/0031-9155/57/2/n1Zaidi, H., Montandon, M.-L., & Alavi, A. (2008). The Clinical Role of Fusion Imaging Using PET, CT, and MR Imaging. PET Clinics, 3(3), 275-291. doi:10.1016/j.cpet.2009.03.00

The Integration of Positron Emission Tomography With Magnetic Resonance Imaging

A number of laboratories and companies are currently exploring the development of integrated imaging systems for magnetic resonance imaging (MRI) and positron emission tomography (PET). Scanners for both preclinical and human research applications are being pursued. In contrast to the widely distributed and now quite mature PET/computed tomography technology, most PET/MRI designs allow for simultaneous rather than sequential acquisition of PET and MRI data. While this offers the possibility of novel imaging strategies, it also creates considerable challenges for acquiring artifact-free images from both modalities. This paper discusses the motivation for developing combined PET/MRI technology, outlines the obstacles in realizing such an integrated instrument, and presents recent progress in the development of both the instrumentation and of novel imaging agents for combined PET/MRI studies. The performance of the first-generation PET/MRI systems is described. Finally, a range of possible biomedical applications for PET/MRI are outlined

Focal Spot, Winter 2005/2006

https://digitalcommons.wustl.edu/focal_spot_archives/1101/thumbnail.jp

Antimicrobial resistance: a biopsychosocial problem requiring innovative interdisciplinary and imaginative interventions

To date, antimicrobials have been understood through largely biomedical perspectives. There has been a tendency to focus upon the effectiveness of pharmaceuticals within individual bodies. However, the growing threat of antimicrobial resistance demands we reconsider how we think about antimicrobials and their effects. Rather than understanding them primarily within bodies, it is increasingly important to consider their effects between bodies, between species and across environments. We need to reduce the drivers of antimicrobial resistance (AMR) at a global level, focusing on the connections between prescribing in one country and resistance mechanisms in another. We need to engage with the ways antimicrobials within the food chain will impact upon human healthcare. Moreover, we need to realise what happens within the ward will impact upon the environment (through waste water). In the future, imaginative interventions will be required that must make the most of biomedicine but draw equally across a wider range of disciplines (e.g. engineering, ecologists) and include an ever-increasing set of professionals (e.g. nurses, veterinarians and farmers). Such collective action demands a shift to working in new interdisciplinary, inter-professional ways. Mutual respect and understanding is required to enable each perspective to be combined to yield synergistic effects