Publications
74 results found
Vogelson MA, Pappas G, Staroswiecki E, et al., 2011, Are Sports Good For Your Knees? An MRI Evaluation of the Effects of Basketball On Knee Health in Division I Collegiate Athletes, ISMRM 19th Annual Meeting
Kaggie JD, Park DJ, Newbould R, et al., 2011, In Vivo Breast Sodium T1 Measurements Using Inversion Recovery 3D Cones, ISMRM 19th Annual Meeting
Park DJ, Javed A, Bangerter N, et al., 2011, Statistical Analysis of B1 Mapping Techniques, ISMRM 19th Annual Meeting
Asher K, Bangerter NK, Watkins RD, et al., 2010, Radiofrequency Coils for Musculoskeletal MRI, Topics in Magnetic Resonance Imaging, ISSN: 0899-3459
Gold G, Shapiro L, Hargreaves B, et al., 2010, Advances in Musculoskeletal Magnetic Resonance Imaging, Topics in Magnetic Resonance Imaging, Vol: 21, Pages: 335-338, ISSN: 0899-3459
Staroswiecki E, Bangerter NK, Gurney PT, et al., 2010, In vivo sodium imaging of human patellar cartilage with a 3D cones sequence at 3 T and 7 T, Journal of Magnetic Resonance Imaging, Vol: 32, Pages: 446-451, ISSN: 1053-1807
<jats:title>Abstract</jats:title><jats:sec><jats:title>Purpose:</jats:title><jats:p>To compare signal‐to‐noise ratios (SNRs) and T*<jats:sub>2</jats:sub> maps at 3 T and 7 T using 3D cones from in vivo sodium images of the human knee.</jats:p></jats:sec><jats:sec><jats:title>Materials and Methods:</jats:title><jats:p>Sodium concentration has been shown to correlate with glycosaminoglycan content of cartilage and is a possible biomarker of osteoarthritis. Using a 3D cones trajectory, 17 subjects were scanned at 3 T and 12 at 7 T using custom‐made sodium‐only and dual‐tuned sodium/proton surface coils, at a standard resolution (1.3 × 1.3 × 4.0 mm<jats:sup>3</jats:sup>) and a high resolution (1.0 × 1.0 × 2.0 mm<jats:sup>3</jats:sup>). We measured the SNR of the images and the T*<jats:sub>2</jats:sub> of cartilage at both 3 T and 7 T.</jats:p></jats:sec><jats:sec><jats:title>Results:</jats:title><jats:p>The average normalized SNR values of standard‐resolution images were 27.1 and 11.3 at 7 T and 3 T. At high resolution, these average SNR values were 16.5 and 7.3. Image quality was sufficient to show spatial variations of sodium content. The average T*<jats:sub>2</jats:sub> of cartilage was measured as 13.2 ± 1.5 msec at 7 T and 15.5 ± 1.3 msec at 3 T.</jats:p></jats:sec><jats:sec><jats:title>Conclusion:</jats:title><jats:p>We acquired sodium images of patellar cartilage at 3 T and 7 T in under 26 minutes using 3D cones with high resolution and acceptable SNR. The SNR improvement at 7 T over 3 T was within the expected range based on the increase in field strength. The measured T*<jats:sub>2</jats:sub> values were also consistent with previously published values. J. Magn. Reson. Imaging 2010;32:446–451. © 2010
Barral JK, Bangerter NK, Hu BS, et al., 2010, In vivo high-resolution magnetic resonance skin imaging at 1.5 T and 3 T, Magnetic Resonance in Medicine, Vol: 63, Pages: 790-796, ISSN: 0740-3194
Gold GE, Chen CA, Koo S, et al., 2009, Recent Advances in MRI of Articular Cartilage, American Journal of Roentgenology, Vol: 193, Pages: 628-638, ISSN: 0361-803X
Çukur T, Lee JH, Bangerter NK, et al., 2009, Non‐contrast‐enhanced flow‐independent peripheral MR angiography with balanced SSFP, Magnetic Resonance in Medicine, Vol: 61, Pages: 1533-1539, ISSN: 0740-3194
<jats:title>Abstract</jats:title><jats:p>Flow‐independent angiography is a non‐contrast‐enhanced technique that can generate vessel contrast even with reduced blood flow in the lower extremities. A method is presented for producing these angiograms with magnetization‐prepared balanced steady‐state free precession (bSSFP). Because bSSFP yields bright fat signal, robust fat suppression is essential for detailed depiction of the vasculature. Therefore, several strategies have been investigated to improve the reliability of fat suppression within short scan times. Phase‐sensitive SSFP can efficiently suppress fat; however, partial volume effects due to fat and water occupying the same voxel can lead to the loss of blood signal. In contrast, alternating repetition time (ATR) SSFP minimizes this loss; however, the level of suppression is compromised by field inhomogeneity. Finally, a new double‐acquisition ATR‐SSFP technique reduces this sensitivity to off‐resonance. In vivo results indicate that the two ATR‐based techniques provide more reliable contrast when partial volume effects are significant. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.</jats:p>
Çukur T, Bangerter NK, Nishimura DG, 2007, Enhanced spectral shaping in steady‐state free precession imaging, Magnetic Resonance in Medicine, Vol: 58, Pages: 1216-1223, ISSN: 0740-3194
<jats:title>Abstract</jats:title><jats:p>Balanced steady‐state free precession (SSFP) is hindered by the inherent off‐resonance sensitivity and unwanted bright fat signal. Multiple‐acquisition SSFP combination methods, where multiple datasets with different fixed RF phase increments are acquired, have been used for shaping the SSFP spectrum to solve both problems. We present a new combination method (weighted‐combination SSFP or WC‐SSFP) that preserves SSFP contrast and enables banding‐reduction and fat‐water separation. Methods addressing the banding artifact have focused on either getting robust banding‐reduction (complex‐sum SSFP) or improved SNR efficiency (sum‐of‐squares SSFP). The proposed method achieves both robust banding‐reduction and an SNR efficiency close to that of the sum‐of‐squares method. A drawback of fat suppression methods that create a broad stop‐band around the fat resonance is the wedge shape of the stop‐band leading to imperfect suppression. WC‐SSFP improves the suppression of the stop‐band without affecting the pass‐band performance, and prevents fat signal from obscuring the tissues of interest in the presence of considerable resonant frequency variations. The method further facilitates the use of SSFP imaging by providing a control parameter to adjust the level of banding‐reduction or fat suppression to application‐specific needs. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.</jats:p>
Gold GE, Hargreaves BA, Reeder SB, et al., 2007, Balanced SSFP imaging of the musculoskeletal system, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 25, Pages: 270-278, ISSN: 1053-1807
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Bangerter NK, Hargreaves BA, Gold GE, et al., 2006, Fluid‐attenuated inversion‐recovery SSFP imaging, Journal of Magnetic Resonance Imaging, Vol: 24, Pages: 1426-1431, ISSN: 1053-1807
<jats:title>Abstract</jats:title><jats:sec><jats:title>Purpose</jats:title><jats:p>To describe and evaluate a fast, fluid‐suppressed 2D multislice steady‐state free precession (SSFP) neuroimaging sequence.</jats:p></jats:sec><jats:sec><jats:title>Materials and Methods</jats:title><jats:p>We developed a fast fluid‐attenuated inversion‐recovery SSFP sequence for use in neuroimaging. The inversion time (TI) was optimized to yield good cerebrospinal fluid (CSF) suppression while conserving white matter (WM)/lesion contrast across a broad range of flip angles. Multiple SSFP acquisitions were combined using the sum‐of‐squares (SOS) method to maximize SNR efficiency while minimizing SSFP banding artifacts. We compared our fluid‐attenuated inversion‐recovery (FLAIR) SSFP sequence with FLAIR fast spin‐echo (FSE) in both normal subjects and a volunteer with multiple sclerosis. SNR measurements were performed to ascertain the SNR efficiency of each sequence.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Our FLAIR SSFP sequence demonstrated excellent CSF suppression and good gray matter (GM)/WM contrast. Coverage of the entire brain (5‐mm slices, 24‐cm FOV, 256 × 192 matrix) was achieved with FLAIR SSFP in less than half the scan time of a corresponding FLAIR FSE sequence with similar SNR, yielding improvements of more than 50% in SNR efficiency. Axial scans of a volunteer with multiple sclerosis show clearly visible plaques and very good visualization of brain parenchyma.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>We have demonstrated the feasibility of a very fast fluid‐suppressed neuroimaging technique using SSFP. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.</jats:p></jats:sec>
Hargreaves BA, Bangerter NK, Shimakawa A, et al., 2006, Dual-acquisition phase-sensitive fat–water separation using balanced steady-state free precession, Magnetic Resonance Imaging, Vol: 24, Pages: 113-122, ISSN: 0730-725X
Bangerter NK, Hargreaves BA, Vasanawala SS, et al., 2004, Analysis of multiple‐acquisition SSFP, Magnetic Resonance in Medicine, Vol: 51, Pages: 1038-1047, ISSN: 0740-3194
<jats:title>Abstract</jats:title><jats:p>Refocused steady‐state free precession (SSFP) is limited by its high sensitivity to local field variation, particularly at high field strengths or the long repetition times (TRs) necessary for high resolution. Several methods have been proposed to reduce SSFP banding artifact by combining multiple phase‐cycled SSFP acquisitions, each differing in how individual signal magnitudes and phases are combined. These include maximum‐intensity SSFP (MI‐SSFP) and complex‐sum SSFP (CS‐SSFP). The reduction in SSFP banding is accompanied by a loss in signal‐to‐noise ratio (SNR) efficiency. In this work a general framework for analyzing banding artifact reduction, contrast, and SNR of any multiple‐acquisition SSFP combination method is presented. A new sum‐of‐squares method is proposed, and a comparison is performed between each of the combination schemes. The sum‐of‐squares SSFP technique (SOS‐SSFP) delivers both robust banding artifact reduction and higher SNR efficiency than other multiple‐acquisition techniques, while preserving SSFP contrast. Magn Reson Med 51:1038–1047, 2004. © 2004 Wiley‐Liss, Inc.</jats:p>
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