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Rietsch SHG, Brunheim S, Orzada S, Voelker MN, Maderwald S, Bitz AK, Gratz M, Ladd ME, Quick HH. Development and evaluation of a 16-channel receive-only RF coil to improve 7T ultra-high field body MRI with focus on the spine. Magn Reson Med 2019; 82:796-810. [PMID: 30924181 DOI: 10.1002/mrm.27731] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/02/2019] [Accepted: 01/27/2019] [Indexed: 12/21/2022]
Abstract
PURPOSE A 16-channel receive (16Rx) radiofrequency (RF) array for 7T ultra-high field body MR imaging is presented. The coil is evaluated in conjunction with a 16-channel transmit/receive (16TxRx) coil and additionally with a 32-channel transmit/receive (32TxRx) remote body coil for RF transmit and serving as receive references. METHODS The 16Rx array consists of 16 octagonal overlapping loops connected to custom-built detuning boards with preamplifiers. Performance metrics like noise correlation, g-factors, and signal-to-noise ratio gain were compared between 4 different RF coil configurations. In vivo body imaging was performed in volunteers using radiofrequency shimming, time interleaved acquisition of modes (TIAMO), and 2D spatially selective excitation using parallel transmit (pTx) in the spine. RESULTS Lower g-factors were obtained when using the 16Rx coil in addition to the 16TxRx array coil configuration versus the 16TxRx array alone. Distinct signal-to-noise ratio gain using the 16Rx coil could be demonstrated in the spine region both for a comparison with the 16TxRx coil (>50% gain) in vivo and the 32TxRx coil (>240% gain) in a phantom. The 16Rx coil was successfully applied to improve anatomical imaging in the abdomen and 2D spatially selective excitation in the spine of volunteers. CONCLUSION The novel 16-channel Rx-array as an add-on to multichannel TxRx RF coil configurations provides increased signal-to-noise ratio, lower g-factors, and thus improves 7T ultra-high field body MR imaging.
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Affiliation(s)
- Stefan H G Rietsch
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany.,High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
| | - Sascha Brunheim
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany.,High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
| | - Stephan Orzada
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany
| | - Maximilian N Voelker
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany.,High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
| | - Stefan Maderwald
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany
| | - Andreas K Bitz
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Electromagnetic Theory and Applied Mathematics, Faculty of Electrical Engineering and Information Technology, University of Applied Sciences Aachen, Aachen, Germany
| | - Marcel Gratz
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany.,High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
| | - Mark E Ladd
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany.,Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Faculty of Physics and Astronomy and Faculty of Medicine, University of Heidelberg, Heidelberg, Germany
| | - Harald H Quick
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany.,High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
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Alizai H, Chang G, Regatte RR. MR Imaging of the Musculoskeletal System Using Ultrahigh Field (7T) MR Imaging. PET Clin 2019; 13:551-565. [PMID: 30219187 DOI: 10.1016/j.cpet.2018.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
MR imaging is an indispensable instrument for the diagnosis of musculoskeletal diseases. In vivo MR imaging at 7T offers many advantages, including increased signal-to-noise ratio, higher spatial resolution, improved spectral resolution for spectroscopy, improved sensitivity for X-nucleus imaging, and decreased image acquisition times. There are also however technical challenges of imaging at a higher field strength compared with 1.5 and 3T MR imaging systems. We discuss the many potential opportunities as well as the challenges presented by 7T MR imaging systems and highlight recent developments in in vivo research imaging of musculoskeletal applications in general and cartilage, skeletal muscle, and bone in particular.
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Affiliation(s)
- Hamza Alizai
- Department of Radiology, New York University Langone Medical Center, 660 First Avenue, New York, NY 10016, USA.
| | - Gregory Chang
- Department of Radiology, New York University Langone Medical Center, 660 First Avenue, New York, NY 10016, USA
| | - Ravinder R Regatte
- Department of Radiology, New York University Langone Medical Center, 660 First Avenue, New York, NY 10016, USA
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3
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Haraguchi N, Ota K, Nishida N, Ozeki T, Yoshida T, Tsutaya A. T1ρ mapping of articular cartilage grafts after autologous osteochondral transplantation for osteochondral lesions of the talus: A longitudinal evaluation. J Magn Reson Imaging 2018; 48:398-403. [PMID: 29457299 DOI: 10.1002/jmri.25962] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/19/2018] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Clinical results of autologous osteochondral transplantation (AOT) for treatment of osteochondral lesions of the talus have been mixed. T1ρ imaging can be used to noninvasively detect early cartilage degeneration. PURPOSE OR HYPOTHESIS To quantitatively assess, by means of T1ρ imaging, changes over time in the biochemical health of grafted cartilage after AOT for osteochondral lesions of the talus. STUDY TYPE Retrosepctive case series. POPULATION The study group comprised nine patients who underwent AOT for an osteochondral lesion of the talus and in whom T1ρ mapping was performed 1 and 2 years postoperatively. FIELD STRENGTH/SEQUENCE 3 Tesla. T1ρ-weighted turbo field echo. ASSESSMENT The mean T1ρ value of full-thickness cartilage at the repair site and that of full-thickness cartilage elsewhere in the same image (far-field cartilage) were determined. Clinical assessment was based on the American Orthopaedic Foot & Ankle Society (AOFAS) scale. Correlation between the T1ρ ratios (grafted-to-far-field cartilage T1ρ values) and clinical outcomes was examined. STATISTICAL TESTS Mixed effects model. Pearson correlation analysis. RESULTS At 1 year, a significant difference existed between the mean T1ρ value of the grafted cartilage (57.0 ± 7.7 ms) and that of the far-field cartilage (41.8 ± 4.6 ms) (P < 0.001). At 2 years, the mean T1ρ value of the grafted cartilage (49.1 ± 6.4 ms) was significantly lower than that at 1 year (P = 0.011). Moderate negative correlation was found between the 1-year T1ρ ratio and 1-year AOFAS score (r = -0.60) and between the 2-year T1ρ ratio and 2-year AOFAS score (r = -0.50). DATA CONCLUSION Our observation of substantial restoration of the proteoglycan content of the grafted cartilage approximately 2 years after AOT for osteochondral lesions of the talus indicates that the content changes gradually and that the cartilage reparation process is slower than previously believed. LEVEL OF EVIDENCE 3 Technical Efficacy: Stage 3 J. MAGN. RESON. IMAGING 2018;48:398-403.
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Affiliation(s)
- Naoki Haraguchi
- Department of Orthopaedic Surgery, Tokyo Metropolitan Police Hospital, Tokyo, Japan
| | - Koki Ota
- Department of Orthopaedic Surgery, Tokyo Metropolitan Police Hospital, Tokyo, Japan
| | - Naoki Nishida
- Department of Orthopaedic Surgery, Tokyo Metropolitan Police Hospital, Tokyo, Japan
| | - Takuma Ozeki
- Department of Orthopaedic Surgery, Tokyo Metropolitan Police Hospital, Tokyo, Japan
| | - Takashige Yoshida
- Department of Radiology, Tokyo Metropolitan Police Hospital, Tokyo, Japan
| | - Atsushi Tsutaya
- Department of Radiology, Tokyo Metropolitan Police Hospital, Tokyo, Japan
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Rietsch SHG, Pfaffenrot V, Bitz AK, Orzada S, Brunheim S, Lazik-Palm A, Theysohn JM, Ladd ME, Quick HH, Kraff O. An 8-channel transceiver 7-channel receive RF coil setup for high SNR ultrahigh-field MRI of the shoulder at 7T. Med Phys 2017; 44:6195-6208. [PMID: 28976586 DOI: 10.1002/mp.12612] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 08/11/2017] [Accepted: 09/15/2017] [Indexed: 12/16/2022] Open
Abstract
PURPOSE In this work, we present an 8-channel transceiver (Tx/Rx) 7-channel receive (Rx) radiofrequency (RF) coil setup for 7 T ultrahigh-field MR imaging of the shoulder. METHODS A C-shaped 8-channel Tx/Rx coil was combined with an anatomically close-fitting 7-channel Rx-only coil. The safety and performance parameters of this coil setup were evaluated on the bench and in phantom experiments. The 7 T MR imaging performance of the shoulder RF coil setup was evaluated in in vivo measurements using a 3D DESS, a 2D PD-weighted TSE sequence, and safety supervision based on virtual observation points. RESULTS Distinct SNR gain and acceleration capabilities provided by the additional 7-channel Rx-only coil were demonstrated in phantom and in vivo measurements. The power efficiency indicated good performance of each channel and a maximum B1+ of 19 μT if the hardware RF power limits of the MR system were exploited. MR imaging of the shoulder was demonstrated with clinically excellent image quality and submillimeter spatial resolution. CONCLUSIONS The presented 8-channel transceiver 7-channel receive RF coil setup was successfully applied for in vivo 7 T MRI of the shoulder providing a clear SNR gain vs the transceiver array without the additional receive array. Homogeneous images across the shoulder region were obtained using 8-channel subject-specific phase-only RF shimming.
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Affiliation(s)
- Stefan H G Rietsch
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, 45141, Germany.,High Field and Hybrid MR Imaging, University Hospital Essen, Essen, 45147, Germany
| | - Viktor Pfaffenrot
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, 45141, Germany.,High Field and Hybrid MR Imaging, University Hospital Essen, Essen, 45147, Germany
| | - Andreas K Bitz
- Faculty of Electrical Engineering and Information Technology, Electromagnetic Theory and Applied Mathematics, University of Applied Sciences Aachen, Aachen, Germany
| | - Stephan Orzada
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, 45141, Germany
| | - Sascha Brunheim
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, 45141, Germany.,High Field and Hybrid MR Imaging, University Hospital Essen, Essen, 45147, Germany
| | - Andrea Lazik-Palm
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, 45147, Germany
| | - Jens M Theysohn
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, 45147, Germany
| | - Mark E Ladd
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, 45141, Germany.,Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Harald H Quick
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, 45141, Germany.,High Field and Hybrid MR Imaging, University Hospital Essen, Essen, 45147, Germany
| | - Oliver Kraff
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, 45141, Germany
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5
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Wang L, Regatte RR. T₁ρ MRI of human musculoskeletal system. J Magn Reson Imaging 2014; 41:586-600. [PMID: 24935818 DOI: 10.1002/jmri.24677] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 06/03/2014] [Indexed: 12/21/2022] Open
Abstract
Magnetic resonance imaging (MRI) offers the direct visualization of the human musculoskeletal (MSK) system, especially all diarthrodial tissues including cartilage, bone, menisci, ligaments, tendon, hip, synovium, etc. Conventional MRI techniques based on T1 - and T2 -weighted, proton density (PD) contrast are inconclusive in quantifying early biochemically degenerative changes in MSK system in general and articular cartilage in particular. In recent years, quantitative MR parameter mapping techniques have been used to quantify the biochemical changes in articular cartilage, with a special emphasis on evaluating joint injury, cartilage degeneration, and soft tissue repair. In this article we focus on cartilage biochemical composition, basic principles of T1ρ MRI, implementation of T1ρ pulse sequences, biochemical validation, and summarize the potential applications of the T1ρ MRI technique in MSK diseases including osteoarthritis (OA), anterior cruciate ligament (ACL) injury, and knee joint repair. Finally, we also review the potential advantages, challenges, and future prospects of T1ρ MRI for widespread clinical translation.
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Affiliation(s)
- Ligong Wang
- Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, School for Radiological and Interdisciplinary Sciences (RAD-X), Soochow University, Suzhou, Jiangsu, China
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Pachowsky ML, Trattnig S, Apprich S, Mauerer A, Zbyn S, Welsch GH. Impact of different coils on biochemical T2 and T2* relaxation time mapping of articular patella cartilage. Skeletal Radiol 2013; 42:1565-72. [PMID: 23974465 DOI: 10.1007/s00256-013-1699-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 07/15/2013] [Accepted: 07/22/2013] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The purpose of our study was to assess T2 and T2* relaxation time values of patella cartilage in healthy volunteers using three different coils at 3.0 Tesla MRI and their influence on the quantitative values. METHODS Fifteen volunteers were examined on the same 3-Tesla MR unit using three different coils: (i) a dedicated eight-channel knee phased-array coil; (ii) an eight-channel multi-purpose coil, and (iii) a one-channel 1H surface coil. T2 and T2* relaxation time measurements were prepared by a multi-echo spinecho respectively a gradient-echo sequence. A semi-automatic region-of-interest analysis was performed for patella cartilage. To allow stratification, a subregional analysis was carried out (deep-superficial cartilage layer). Statistical analysis-of-variance was performed. RESULTS The mean quantitative T2 values showed statistically significant differences in all comparison combinations. The differences between the mean quantitative T2* values were slightly less pronounced than the T2 evaluation and only the comparison between (i) and (ii) showed a significant difference. The results of T2 and T2* values showed, independent of the used coil, higher values in the superficial zone compared to the deep zone (p < 0.05). Looking at the signal alterations, all coils showed clearly higher values (and thus more signal alterations as a sign of noise) in the deep layer. The validation of the reliability showed a high intra-class correlation coefficient and hence a very high plausibility (ICC was between 0.870 and 0.905 for T2 mapping and between 0.879 and 0.888 for T2* mapping). CONCLUSIONS The present results demonstrate that biochemical T2 and T2* mapping is significantly dependent on the utilized coil.
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Affiliation(s)
- Milena L Pachowsky
- MR Center, Department of Radiology, Medical University of Vienna, Lazarettgasse 14, Vienna, Austria,
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7
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Madelin G, Babb J, Xia D, Chang G, Krasnokutsky S, Abramson SB, Jerschow A, Regatte RR. Articular cartilage: evaluation with fluid-suppressed 7.0-T sodium MR imaging in subjects with and subjects without osteoarthritis. Radiology 2013; 268:481-91. [PMID: 23468572 DOI: 10.1148/radiol.13121511] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PURPOSE To assess the potential use of sodium magnetic resonance (MR) imaging of cartilage, with and without fluid suppression by using an adiabatic pulse, for classifying subjects with versus subjects without osteoarthritis at 7.0 T. MATERIALS AND METHODS The study was approved by the institutional review board and was compliant with HIPAA. The knee cartilage of 19 asymptomatic (control subjects) and 28 symptomatic (osteoarthritis patients) subjects underwent 7.0-T sodium MR imaging with use of two different sequences: one without fluid suppression (radial three-dimensional sequence) and one with fluid suppression (inversion recovery [IR] wideband uniform rate and smooth truncation [WURST]). Fluid suppression was obtained by using IR with an adiabatic inversion pulse (WURST pulse). Mean sodium concentrations and their standard deviations were measured in the patellar, femorotibial medial, and lateral cartilage regions over four consecutive sections for each subject. The minimum, maximum, median, and average means and standard deviations were calculated over all measurements for each subject. The utility of these measures in the detection of osteoarthritis was evaluated by using logistic regression and the area under the receiver operating characteristic curve (AUC). Bonferroni correction was applied to the P values obtained with logistic regression. RESULTS Measurements from IR WURST were found to be significant predicators of all osteoarthritis (Kellgren-Lawrence score of 1-4) and early osteoarthritis (Kellgren-Lawrence score of 1 or 2). The minimum standard deviation provided the highest AUC (0.83) with the highest accuracy (>78%), sensitivity (>82%), and specificity (>74%) for both all osteoarthritis and early osteoarthritis groups. CONCLUSION Quantitative sodium MR imaging at 7.0 T with fluid suppression by using adiabatic IR is a potential biomarker for osteoarthritis.
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Affiliation(s)
- Guillaume Madelin
- Department of Radiology, New York University Langone Medical Center, 660 First Ave, 4th Floor, New York, NY 10016, USA.
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Magnetic resonance imaging of the knee at 3 and 7 Tesla: a comparison using dedicated multi-channel coils and optimised 2D and 3D protocols. Eur Radiol 2012; 22:1852-9. [DOI: 10.1007/s00330-012-2450-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 02/20/2012] [Indexed: 10/28/2022]
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Madelin G, Chang G, Otazo R, Jerschow A, Regatte RR. Compressed sensing sodium MRI of cartilage at 7T: preliminary study. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 214:360-5. [PMID: 22204825 PMCID: PMC3278671 DOI: 10.1016/j.jmr.2011.12.005] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 12/01/2011] [Accepted: 12/03/2011] [Indexed: 05/11/2023]
Abstract
Sodium MRI has been shown to be highly specific for glycosaminoglycan (GAG) content in articular cartilage, the loss of which is an early sign of osteoarthritis (OA). Quantitative sodium MRI techniques are therefore under development in order to detect and assess early biochemical degradation of cartilage, but due to low sodium NMR sensitivity and its low concentration, sodium images need long acquisition times (15-25 min) even at high magnetic fields and are typically of low resolution. In this preliminary study, we show that compressed sensing can be applied to reduce the acquisition time by a factor of 2 at 7 T without losing sodium quantification accuracy. Alternatively, the nonlinear reconstruction technique can be used to denoise fully-sampled images. We expect to even further reduce this acquisition time by using parallel imaging techniques combined with SNR-improved 3D sequences at 3T and 7 T.
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Affiliation(s)
- Guillaume Madelin
- Quantitative Multinuclear Musculoskeletal Imaging Group (QMMIG), Center for Biomedical Imaging, Radiology Department, New York University Langone Medical Center, New York, NY, USA
- Chemistry Department, New York University, New York, NY, USA
| | - Gregory Chang
- Quantitative Multinuclear Musculoskeletal Imaging Group (QMMIG), Center for Biomedical Imaging, Radiology Department, New York University Langone Medical Center, New York, NY, USA
| | - Ricardo Otazo
- Center for Biomedical Imaging, Radiology Department, New York University Langone Medical Center, New York, NY, USA
| | - Alexej Jerschow
- Chemistry Department, New York University, New York, NY, USA
- Corresponding author: Chemistry Department, New York University, New York, NY 10012.
| | - Ravinder R. Regatte
- Quantitative Multinuclear Musculoskeletal Imaging Group (QMMIG), Center for Biomedical Imaging, Radiology Department, New York University Langone Medical Center, New York, NY, USA
- Corresponding author: Quantitative Multinuclear Musculoskeletal Imaging Group (QMMIG), Center for Biomedical Imaging, New York University Medical Center, 660 First Avenue, 4th Floor, New York, NY 10016, USA.
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Kraff O, Bitz AK, Dammann P, Ladd SC, Ladd ME, Quick HH. An eight-channel transmit/receive multipurpose coil for musculoskeletal MR imaging at 7 T. Med Phys 2011; 37:6368-76. [PMID: 21302794 DOI: 10.1118/1.3517176] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE MRI plays a leading diagnostic role in assessing the musculoskeletal (MSK) system and is well established for most questions at clinically used field strengths (up to 3 T). However, there are still limitations in imaging early stages of cartilage degeneration, very fine tendons and ligaments, or in locating nerve lesions, for example. 7 T MRI of the knee has already received increasing attention in the current published literature, but there is a strong need to develop new radiofrequency (RF) coils to assess more regions of the MSK system. In this work, an eight-channel transmit/receive RF array was built as a multipurpose coil for imaging some of the thus far neglected regions. An extensive coil characterization protocol and first in vivo results of the human wrist, shoulder, elbow, knee, and ankle imaged at 7 T will be presented. METHODS Eight surface loop coils with a dimension of 6 x 7 cm2 were machined from FR4 circuit board material. To facilitate easy positioning, two coil clusters, each with four loop elements, were combined to one RF transmit/receive array. An overlapped and shifted arrangement of the coil elements was chosen to reduce the mutual inductance between neighboring coils. A phantom made of body-simulating liquid was used for tuning and matching on the bench. Afterward, the S-parameters were verified on a human wrist, elbow, and shoulder. For safety validation, a detailed compliance test was performed including full wave simulations of the RF field distribution and the corresponding specific absorption rate (SAR) for all joints. In vivo images of four volunteers were assessed with gradient echo and spin echo sequences modified to obtain optimal image contrast, full anatomic coverage, and the highest spatial resolution within a reasonable acquisition time. The performance of the RF coil was additionally evaluated by in vivo B1 mapping. RESULTS A comparison of B1 per unit power, flip angle distribution, and anatomic images showed a fairly homogeneous excitation for the smaller joints (elbow, wrist, and ankle), while for the larger joints, the shoulder and especially the knee, B1 inhomogeneities and limited penetration depth were more pronounced. However, the greater part of the shoulder joint could be imaged. In vivo images rendered very fine anatomic details such as fascicles of the median nerve and the branching of the nerve bundles. High-resolution images of cartilage, labrum, and tendons could be acquired. Additionally, turbo spin echo (TSE) and inversion recovery sequences performed very well. CONCLUSIONS This study demonstrates that the concept of two four-channel transmit/receive RF arrays can be used as a multipurpose coil for high-resolution in vivo MR imaging of the musculoskeletal system at 7 T. Not only gradient echo but also typical clinical and SAR-intensive sequences such as STIR and TSE performed well. Imaging of small structures and peripheral nerves could in particular benefit from this technique.
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Affiliation(s)
- Oliver Kraff
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, 45141 Essen, Germany.
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Orzada S, Bitz AK, Schäfer LC, Ladd SC, Ladd ME, Maderwald S. Open design eight-channel transmit/receive coil for high-resolution and real-time ankle imaging at 7 T. Med Phys 2011; 38:1162-7. [DOI: 10.1118/1.3553399] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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12
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Jia G, Takayama Y, Flanigan DC, Kaeding CC, Zhou J, Chaudhari A, Clark D, Sammet S, Liang J, Choi S, Knopp MV. Quantitative assessment of mobile protein levels in human knee synovial fluid: feasibility of chemical exchange saturation transfer (proteinCEST) MRI of osteoarthritis. Magn Reson Imaging 2011; 29:335-41. [PMID: 21292419 DOI: 10.1016/j.mri.2010.10.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 09/16/2010] [Accepted: 10/23/2010] [Indexed: 11/26/2022]
Abstract
PURPOSE To establish the feasibility of chemical exchange saturation transfer (proteinCEST) MRI in the differentiation of osteoarthritis (OA) knee joints from non-OA joints by detecting mobile protein and peptide levels in synovial fluid by determining their relative distribution. MATERIALS AND METHODS A total of 25 knees in 11 men and 12 women with knee injuries were imaged using whole knee joint proteinCEST MRI sequence at 3 T. The joint synovial fluid was segmented and the asymmetric magnetization transfer ratio at 3.5 ppm MTR(asym) (3.5 ppm) was calculated to assess protein content in the synovial fluid. The 85th percentile of synovial fluid MTR(asym) (3.5 ppm) distribution profile was compared using the independent Student's t test. The diagnostic performance of the 85th percentile of synovial fluid MTR(asym) (3.5 ppm) in differentiating OA and non-OA knee joints was evaluated. RESULTS The 85th percentile of synovial fluid MTR(asym) (3.5 ppm) in knee joints with OA was 8.6%±3.4% and significantly higher than that in the knee joints without OA (6.3%±1.4%, P<.05). A knee joint with an 85th percentile of synovial fluid MTR(asym) (3.5 ppm) greater than 7.7% was considered to be an OA knee joint. With the threshold, the sensitivity, specificity and overall accuracy for differentiating knee joints with OA from the joints without OA were 54% (7/13), 92% (11/12) and 72% (18/25), respectively. CONCLUSION proteinCEST MRI appears feasible as a quantitative methodology to determine mobile protein levels in synovial fluid and identify patterns characteristic for OA disease.
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Affiliation(s)
- Guang Jia
- Department of Radiology and Wright Center of Innovation in Biomedical Imaging, The Ohio State University, Columbus, OH 43210, USA
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Madelin G, Jerschow A, Regatte RR. Sodium MRI with fluid suppression: will it improve early detection of osteoarthritis? ACTA ACUST UNITED AC 2011. [DOI: 10.2217/iim.10.70] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Welsch GH, Apprich S, Zbyn S, Mamisch TC, Mlynarik V, Scheffler K, Bieri O, Trattnig S. Biochemical (T2, T2* and magnetisation transfer ratio) MRI of knee cartilage: feasibility at ultra-high field (7T) compared with high field (3T) strength. Eur Radiol 2010; 21:1136-43. [PMID: 21153551 DOI: 10.1007/s00330-010-2029-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 10/15/2010] [Accepted: 10/18/2010] [Indexed: 02/02/2023]
Abstract
OBJECTIVE This study compares the performance and the reproducibility of quantitative T2, T2* and the magnetisation transfer ratio (MTR) of articular cartilage at 7T and 3T. METHODS Axial MRI of the patella was performed in 17 knees of healthy volunteers (25.8 ± 5.7 years) at 3T and 7T using a comparable surface coil and whole-body MR systems from the same vendor, side-by-side. Thirteen knee joints were assessed once, and four knee joints were measured three times to assess reproducibility. T2 relaxation was prepared by a multi-echo, spin-echo sequence and T2* relaxation by a multi-echo, gradient-echo sequence. MTR was based on a magnetisation transfer-sensitized, steady-state free precession approach. Statistical analysis-of-variance and coefficient-of-variation (CV) were prepared. RESULTS For T2 and T2*, global values were significantly lower at 7T compared with 3T; the zonal evaluation revealed significantly less pronounced stratification at 7T (p < 0.05). MTR provided higher values at 7T (p < 0.05). CV, indicating reproducibility, showed slightly lower values at 7T, but only for T2 and T2*. CONCLUSION Although lower T2 and T2* relaxation times were expected at 7T, the differences in stratification between the field strengths were reported for the first time. The assessment of MT is feasible at 7T, but requires further investigation.
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Affiliation(s)
- Goetz H Welsch
- MR Center, Department of Radiology, Medical University of Vienna, Lazarettgasse 14, Vienna, A-1090, Austria.
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Trattnig S, Welsch GH, Juras V, Szomolanyi P, Mayerhoefer ME, Stelzeneder D, Mamisch TC, Bieri O, Scheffler K, Zbýn S. 23Na MR imaging at 7 T after knee matrix-associated autologous chondrocyte transplantation preliminary results. Radiology 2010; 257:175-84. [PMID: 20713608 DOI: 10.1148/radiol.10100279] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To evaluate the feasibility of sodium 7-T magnetic resonance (MR) imaging in repaired tissue and native cartilage of patients after matrix-associated autologous chondrocyte transplantation (MACT) and compare results with delayed gadolinium-enhanced MR imaging of cartilage (dGEMRIC) at 3 T. MATERIALS AND METHODS Ethical approval was provided by the local ethics committee; written informed consent was obtained from all patients. Six women and six men (mean age, 32.8 year ± 8.2 [standard deviation] and 32.3 years ± 12.7, respectively) were included. Mean time between MACT and MR was 56 months ± 28. A variable three-dimensional (3D) gradient-echo (GRE) dual-flip-angle technique was used for T1 mapping before and after contrast agent administration at 3 T. All patients were also examined at 7 T (mean delay, 70.5 days ± 80.1). A sodium 23-only transmit-receive knee coil was used with the 3D GRE sequence. A statistical analysis of variance and Pearson correlation were applied. RESULTS Mean signal-to-noise ratio (SNR) was 24 in native cartilage and was 16 in transplants (P < .001). Mean sodium signal intensities normalized with the reference sample were 174 ± 53 and 267 ± 42 for repaired tissue in the cartilage transplant and healthy cartilage, respectively (P < .001). Mean postcontrast T1 values were 510 msec ± 195 and 756 msec ± 188 for repaired tissue and healthy cartilage, respectively (P = .005). Mean score of MR observation of cartilage repair tissue was 75 ± 14. Association between postcontrast T1 and normalized sodium signal values showed a high Pearson correlation coefficient (R) of 0.706 (P = .001). A high correlation of R = 0.836 (P = .001) was found between ratios of normalized sodium values and ratios of T1 postcontrast values. CONCLUSION With the modified 3D GRE sequence at 7 T, a sufficiently high SNR in sodium images was achieved, allowing for differentiation of repaired tissue from native cartilage after MACT. A strong correlation was found between sodium imaging and dGEMRIC in patients after MACT.
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Affiliation(s)
- Siegfried Trattnig
- Department of Radiology, MR Centre-High Field MR, Medical University of Vienna, Lazarettgasse 14, Vienna, Austria.
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Pepin SR, Griffith CJ, Wijdicks CA, Goerke U, McNulty MA, Parker JB, Carlson CS, Ellermann J, LaPrade RF. A comparative analysis of 7.0-Tesla magnetic resonance imaging and histology measurements of knee articular cartilage in a canine posterolateral knee injury model: a preliminary analysis. Am J Sports Med 2009; 37 Suppl 1:119S-24S. [PMID: 19841141 DOI: 10.1177/0363546509350439] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND There has recently been increased interest in the use of 7.0-T magnetic resonance imaging for evaluating articular cartilage degeneration and quantifying the progression of osteoarthritis. PURPOSE The purpose of this study was to evaluate articular cartilage cross-sectional area and maximum thickness in the medial compartment of intact and destabilized canine knees using 7.0-T magnetic resonance images and compare these results with those obtained from the corresponding histologic sections. STUDY DESIGN Controlled laboratory study. METHODS Five canines had a surgically created unilateral grade III posterolateral knee injury that was followed for 6 months before euthanasia. The opposite, noninjured knee was used as a control. At necropsy, 3-dimensional gradient echo images of the medial tibial plateau of both knees were obtained using a 7.0-T magnetic resonance imaging scanner. Articular cartilage area and maximum thickness in this site were digitally measured on the magnetic resonance images. The proximal tibias were processed for routine histologic analysis with hematoxylin and eosin staining. Articular cartilage area and maximum thickness were measured in histologic sections corresponding to the sites of the magnetic resonance slices. RESULTS The magnetic resonance imaging results revealed an increase in articular cartilage area and maximum thickness in surgical knees compared with control knees in all specimens; these changes were significant for both parameters (P <.05 for area; P <.01 for thickness). The average increase in area was 14.8% and the average increase in maximum thickness was 15.1%. The histologic results revealed an average increase in area of 27.4% (P = .05) and an average increase in maximum thickness of 33.0% (P = .06). Correlation analysis between the magnetic resonance imaging and histology data revealed that the area values were significantly correlated (P < .01), but the values for thickness obtained from magnetic resonance imaging were not significantly different from the histology sections (P > .1). CONCLUSION These results demonstrate that 7.0-T magnetic resonance imaging provides an alternative method to histology to evaluate early osteoarthritic changes in articular cartilage in a canine model by detecting increases in articular cartilage area. CLINICAL RELEVANCE The noninvasive nature of 7.0-T magnetic resonance imaging will allow for in vivo monitoring of osteoarthritis progression and intervention in animal models and humans for osteoarthritis.
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Affiliation(s)
- Scott R Pepin
- University of Minnesota Orthopaedic Biomechanics Laboratory, Department of Orthopaedic Surgery, University of Minnesota, 2450 Riverside Avenue South, Minneapolis, MN 55454, USA
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