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Okanovic M, Hillig B, Breuer F, Jakob P, Blaimer M. Time-of-flight MR-angiography with a helical trajectory and slice-super-resolution reconstruction. Magn Reson Med 2018. [PMID: 29527736 DOI: 10.1002/mrm.27167] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE To improve 2D noncontrast-enhanced MRA by using a helical time-of-flight (TOF) acquisition technique and a slice-super-resolution reconstruction. METHODS The TOF technique is combined with a helical trajectory with golden-angle-based radial projection reordering. A continuous spatial shift in slice direction is realized by adjusting the frequency of the excitation pulse between the individual projections. The limited resolution along the shift direction is improved by a deconvolution with simulated slice profile. The helical TOF (hTOF) was compared in vivo with a conventional 2D and 3D TOF. RESULTS Results from in vivo experiments on the carotid show that the visual resolution in slice direction can be improved by using hTOF and the slice-super-resolution reconstruction. The vessels appear up to 1.5 times sharper and can be better separated from each other. Compared to 2D TOF images, the stair step artifacts are strongly reduced in reformatted hTOF images, whereas measurement time is decreased by at least 35%. Compared to 3D TOF, the hTOF offers a higher blood-to-background contrast, better visualization of smaller vessels, and reduced measurement time. CONCLUSION The hTOF benefits from a 2D acquisition and a 3D reconstruction, which makes it a promising technique for the noncontrast-enhanced imaging of the carotid.
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Affiliation(s)
- Melisa Okanovic
- Department of Experimental Physics 5, University of Wuerzburg, Wuerzburg, Germany
| | - Burghard Hillig
- Institute of Automation Technology, Chair of Measurement and Information Technology, Helmut-Schmidt-University, Hamburg, Germany
| | - Felix Breuer
- Fraunhofer Institute for Integrated Circuits (IIS), Development Center for X-ray Technology (EZRT), Wuerzburg, Germany
| | - Peter Jakob
- Department of Experimental Physics 5, University of Wuerzburg, Wuerzburg, Germany
| | - Martin Blaimer
- Fraunhofer Institute for Integrated Circuits (IIS), Development Center for X-ray Technology (EZRT), Wuerzburg, Germany
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Sengupta S, Smith DS, Gifford A, Welch EB. Whole-body continuously moving table fat-water MRI with dynamic B0 shimming at 3 Tesla. Magn Reson Med 2015. [PMID: 26198380 DOI: 10.1002/mrm.25848] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
PURPOSE The purpose of this work was to develop a rapid and robust whole-body fat-water MRI (FWMRI) method using a continuously moving table (CMT) with dynamic field corrections at 3 Tesla. METHODS CMT FWMRI was developed at 3 Tesla with a multiecho golden angle (GA) radial trajectory and dynamic B0 field shimming. Whole-body imaging was performed with 4 echoes and superior-inferior coverage of 1.8 meters without shims in 90 s. 716 axial images were reconstructed with GA profile binning followed by B0 field map generation using fast three-point seeded region growing fat-water separation and slice-specific 0(th) and 1(st) order shim calculation. Slice-specific shims were applied dynamically in a repeated CMT FWMRI scan in the same session. The resulting images were evaluated for field homogeneity improvements and quality of fat-water separation with a whole-image energy optimized algorithm. RESULTS GA sampling allowed high quality whole-body FWMRI from multiecho CMT data. Dynamic B0 shimming greatly improved field homogeneity in the body and produced high quality water and fat only images as well as fat signal fraction and R2 * relaxivity maps. CONCLUSION A rapid and robust technique for whole-body fat-water quantification has been developed with CMT MRI with dynamic B0 field correction. Magn Reson Med 76:183-190, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Saikat Sengupta
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - David S Smith
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Aliya Gifford
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Chemical and Physical Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - E Brian Welch
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
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Sengupta S, Smith DS, Welch EB. Continuously moving table MRI with golden angle radial sampling. Magn Reson Med 2014; 74:1690-7. [PMID: 25461600 DOI: 10.1002/mrm.25531] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 10/13/2014] [Accepted: 10/24/2014] [Indexed: 11/09/2022]
Abstract
PURPOSE Continuously moving table (CMT) MRI is a high throughput technique that has multiple applications in whole-body imaging. In this work, CMT MRI based on golden angle (GA, 111.246° azimuthal step) radial sampling is developed at 3 Tesla (T), with the goal of increased flexibility in image reconstruction using arbitrary profile groupings. THEORY AND METHODS CMT MRI with GA and linear angle (LA) schemes were developed for whole-body imaging at 3T with a table speed of 20 mm/s. Imaging was performed in phantoms and a human volunteer with extended z fields of view of up to 1.8 meters. Four separate LA and a single GA scan were performed to enable slice reconstructions at four different thicknesses. RESULTS GA CMT MRI produced high image quality in phantoms and humans and allowed complete flexibility in reconstruction of slices with arbitrary slice thickness and position from a single data set. LA CMT MRI was constrained by predetermined parameters, required multiple scans and suffered from stair step artifacts that were not present in GA images. CONCLUSION GA sampling provides a robust flexible approach to CMT whole-body MRI with the ability to reconstruct slices at arbitrary positions and thicknesses from a single scan.
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Affiliation(s)
- Saikat Sengupta
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - David S Smith
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - E Brian Welch
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
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Han Y, Weigel M, Huff S, Ludwig U. Whole-body diffusion-weighted imaging with a continuously moving table acquisition method: Preliminary results. Magn Reson Med 2011; 65:1557-63. [DOI: 10.1002/mrm.22833] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Revised: 10/11/2010] [Accepted: 12/20/2010] [Indexed: 11/08/2022]
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5
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Huff S, Honal M, Baumann T, Hennig J, Markl M, Ludwig U. Continuously moving table time-of-flight angiography of the peripheral veins. Magn Reson Med 2010; 63:1219-29. [DOI: 10.1002/mrm.22296] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Sandra Huff
- Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany.
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6
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Honal M, Leupold J, Huff S, Baumann T, Ludwig U. Compensation of breathing motion artifacts for MRI with continuously moving table. Magn Reson Med 2010; 63:701-12. [DOI: 10.1002/mrm.22162] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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7
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Koken P, Dries SP, Keupp J, Bystrov D, Pekar V, Börnert P. Towards automatic patient positioning and scan planning using continuously moving table MR imaging. Magn Reson Med 2009; 62:1067-72. [DOI: 10.1002/mrm.22069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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8
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Zenge MO, Ladd ME, Quick HH. Novel reconstruction method for three-dimensional axial continuously moving table whole-body magnetic resonance imaging featuring autocalibrated parallel imaging GRAPPA. Magn Reson Med 2009; 61:867-73. [DOI: 10.1002/mrm.21859] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Baumann T, Ludwig U, Pache G, Fautz HP, Kotter E, Langer M, Schaefer O. Continuously moving table MRI with sliding multislice for rectal cancer staging: image quality and lesion detection. Eur J Radiol 2009; 73:579-87. [PMID: 19179029 DOI: 10.1016/j.ejrad.2008.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Revised: 10/04/2008] [Accepted: 12/10/2008] [Indexed: 12/27/2022]
Abstract
PURPOSE To determine image quality and lesion detection of sliding multislice (SMS), a recently developed moving table MRI technique, in patients with rectal cancer. MATERIALS AND METHODS Twenty-seven paired SMS (Avanto, Siemens Medical Solutions) and MDCT (Sensation 64, Siemens Medical Solutions) examinations of abdomen and pelvis were performed in patients with rectal cancer and compared for detection of liver, lymph node and bone metastases by two independent observers. A contrast-enhanced, fat saturated 2D gradient echo sequence (TE, 2.0 ms; TR, 102 ms; slice, 5 mm) was acquired with SMS and a standard contrast-enhanced protocol (100 ml @ 2.5 ml/s; slice, 5 mm) was used for abdominal MDCT. Standard of reference consisted of a consensus evaluation of SMS, MDCT, and all available follow-up examinations after a period of 6 months. Artifact burden and image quality of SMS was assessed in comparison to stationary gradient echo sequences obtained in an age-matched group of 27 patients. RESULTS Whereas SMS achieved a mean quality score of 3.65 (scale, 0-4) for the liver, representing very good diagnostic properties, strong breathing artifacts in the intestinal region were observed in 19 cases by both observers. The retroperitoneum still achieved a mean quality score of 3.52, although breathing artifacts were noted in 12 and 15 cases (observers 1 and 2, respectively). The sensitivities of SMS to detect hepatic metastases were 91.2% and 94.1% for both observers, respectively, compared to 98.5%/98.5% for MDCT. The sensitivities for lymph node metastases were 87.5%/81.3% for SMS compared to 78.1%/81.3% for MDCT. The sensitivities for bone metastases were 91.7%/100% for SMS compared to 8.3%/16.7% for MDCT. CONCLUSION With slightly reduced image quality in the intestinal region, SMS exhibits equal detection of lymph node and liver metastases compared to MDCT. SMS MRI proved to be superior to MDCT in detection of bone metastases.
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Affiliation(s)
- Tobias Baumann
- Department of Diagnostic Radiology, University Hospital Freiburg, Freiburg, Germany.
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10
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Börnert P, Aldefeld B. Principles of whole-body continuously-moving-table MRI. J Magn Reson Imaging 2008; 28:1-12. [DOI: 10.1002/jmri.21339] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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11
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Ladd SC, Ladd ME. Perspectives for preventive screening with total body MRI. Eur Radiol 2007; 17:2889-97. [PMID: 17549492 DOI: 10.1007/s00330-007-0657-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 02/19/2007] [Accepted: 03/27/2007] [Indexed: 10/23/2022]
Abstract
Radiology has started to increasingly recognise its potential for screening with the advent of "whole-body" imaging techniques. This article briefly reviews prerequisites for successful screening, presents a quick summary of single-organ screening with magnetic resonance (MR) imaging, and introduces how this knowledge can be integrated into whole-body MR (wb-MR) screening. MR colonography has demonstrated its potential for screening. Wb-MR in the form of wb-MR angiography has already entered both clinical and screening settings; also, the search for metastases with wb-MR has been evaluated and has performed well when compared with other imaging modalities. But screening a group of healthy subjects requires more than feasibility and high accuracy of the screening test; thus, technical and ethical considerations are also presented. Wb-MR is only at its beginning and will in the near future certainly inspire many new research activities as well as transform the radiological market.
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Affiliation(s)
- Susanne C Ladd
- Department of Diagnostic and Interventional Radiology, University Hospital Essen, Hufelandstrasse 55, 45122, Essen, Germany.
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Vogt FM, Zenge MO, Ladd ME, Herborn CU, Brauck K, Luboldt W, Barkhausen J, Quick HH. Peripheral Vascular Disease: Comparison of Continuous MR Angiography and Conventional MR Angiography—Pilot Study. Radiology 2007; 243:229-38. [PMID: 17329687 DOI: 10.1148/radiol.2431052098] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The aim of this study was to prospectively assess the accuracy of three-dimensional magnetic resonance (MR) angiography for evaluation of stenosis in the peripheral arterial system with a continuous moving table technique, with conventional MR angiography as reference. This study was approved by the local institutional review board; informed consent was obtained. Five healthy male volunteers (mean age, 27 years; range, 24-35 years) and four men and one woman (mean age, 63 years; range, 46-78 years) with peripheral arterial occlusive disease were examined. Images obtained with both techniques showed excellent concordance (Cohen kappa = 0.75). Images obtained with a conventional protocol had higher quality compared with those obtained with the continuous technique (mean, 1.07 +/- 0.25 [standard deviation] vs 1.58 +/- 0.6; P < .05); small vessels appeared sharper on them. For detection of significant stenosis and occlusion, accuracy, sensitivity, and specificity of the continuous technique were 92.8%, 100%, and 89.2%, respectively.
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Affiliation(s)
- Florian M Vogt
- Department of Diagnostic and Interventional Radiology, University Hospital Essen, Hufelandstrasse 55, D-45122 Essen, Germany.
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13
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Fautz HP, Honal M, Saueressig U, Schäfer O, Kannengiesser SAR. Artifact reduction in moving-table acquisitions using parallel imaging and multiple averages. Magn Reson Med 2007; 57:226-32. [PMID: 17191244 DOI: 10.1002/mrm.21117] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Two-dimensional (2D) axial continuously-moving-table imaging has to deal with artifacts due to gradient nonlinearity and breathing motion, and has to provide the highest scan efficiency. Parallel imaging techniques (e.g., generalized autocalibrating partially parallel acquisition GRAPPA)) are used to reduce such artifacts and avoid ghosting artifacts. The latter occur in T(2)-weighted multi-spin-echo (SE) acquisitions that omit an additional excitation prior to imaging scans for presaturation purposes. Multiple images are reconstructed from subdivisions of a fully sampled k-space data set, each of which is acquired in a single SE train. These images are then averaged. GRAPPA coil weights are estimated without additional measurements. Compared to conventional image reconstruction, inconsistencies between different subsets of k-space induce less artifacts when each k-space part is reconstructed separately and the multiple images are averaged afterwards. These inconsistencies may lead to inaccurate GRAPPA coil weights using the proposed intrinsic GRAPPA calibration. It is shown that aliasing artifacts in single images are canceled out after averaging. Phantom and in vivo studies demonstrate the benefit of the proposed reconstruction scheme for free-breathing axial continuously-moving-table imaging using fast multi-SE sequences.
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Affiliation(s)
- H P Fautz
- Department of Diagnostic Radiology, University Hospital Freiburg, Freiburg, Germany.
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14
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Zenge MO, Vogt FM, Brauck K, Jökel M, Barkhausen J, Kannengiesser S, Ladd ME, Quick HH. High-resolution continuously acquired peripheral MR angiography featuring partial parallel imaging GRAPPA. Magn Reson Med 2007; 56:859-65. [PMID: 16964615 DOI: 10.1002/mrm.21033] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Continuously-moving-table MRI, in contrast to traditional multistation techniques, potentially can improve the scan time efficiency of whole-body applications and provide seamless images of an extended field of view (FOV). Contrast-enhanced MR angiography (CE-MRA) in particular requires high spatial resolution and at the same time has rigid scan time constraints due to the limited arterial contrast window. In this study a reconstruction method for continuously acquired 3D data sets during table movement was combined with a self-calibrated partial parallel imaging algorithm (generalized autocalibrating partially parallel acquisitions (GRAPPA)). The method was applied to peripheral CE-MRA and compared with a standard continuously-moving-table MRA protocol. The gain in scan time was used to increase the data acquisition matrix and decrease the slice thickness. The method was evaluated in five healthy volunteers and applied to one patient with peripheral arterial occlusive disease (PAOD). The protocols were intraindividually compared with respect to the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in selected vessel segments, as well as overall vessel depiction. The combination of the continuously-moving-table technique with parallel imaging enabled the acquisition of seamless peripheral 3D MRA with increased resolution and an overall crisper appearance.
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Affiliation(s)
- Michael O Zenge
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany.
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15
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Sabati M, Lauzon ML, Mahallati H, Frayne R. Interactive continuously moving table (iCMT) large field-of-view real-time MRI. Magn Reson Med 2006; 55:1202-9. [PMID: 16586450 DOI: 10.1002/mrm.20848] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Continuously moving table (CMT) MRI is a new method that is capable of generating 3D, seamless, large field-of-view (FOV) images by acquiring readouts along the patient superior-inferior axis as the subject is translated through the scanner. For applications that require artifact-free images, such as arterial-phase contrast-enhanced (CE) angiography of the legs, a major challenge is to match the MR data acquisition and patient table motion with the dynamics of blood flow in the region of interest (ROI). Instead of restricting the CMT to predetermined constant table speeds, we adopted a more general approach in which the table motion is decoupled from the phase-encoding order. In our approach the table moves adaptively and in response to operator-provided feedback obtained from viewing real-time preview (or fluoroscopic) images. This interactivity is accomplished by integrating high temporal-spatial resolution encoding of the table position with real-time hybrid-space filling and image reconstruction. Experimental results obtained using our prototype interactive CMT (iCMT) system on a peripheral vascular phantom and five healthy volunteers demonstrate the feasibility of this robust and rapid imaging method for acquiring 3D large-FOV continuous images with patient-specific adaptive table motion profiles.
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Affiliation(s)
- M Sabati
- Department of Electrical and Computer Engineering, University of Calgary, Calgary, Alberta, Canada
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Madhuranthakam AJ, Hu HH, Kruger DG, Riederer SJ. Numerical equilibration of signal intensity and spatial resolution in time-resolved continuously moving table imaging. Magn Reson Med 2006; 55:694-9. [PMID: 16450354 DOI: 10.1002/mrm.20800] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Time-resolved continuously moving table imaging techniques have been previously developed to observe a dynamically changing phenomenon over an extended field-of-view. The acquisition involves differential k-space sampling and view sharing. Since the table is continuously moving during data acquisition, the k-space for any longitudinal position is sampled only sparsely for the first reconstruction timeframe and is progressively more fully sampled for subsequent frames. Consequently, the signal intensity increases and the lateral spatial resolution improves from frame to frame even for static materials, which can mask true dynamically changing phenomena. This work provides a description of this effect and a means for signal correction in the early reconstruction frames, thus permitting any residual variation in signal intensity to be primarily attributed to true dynamic processes. The method is tested experimentally on a static phantom and in a peripheral vascular study designed to observe the leading edge of the contrast bolus.
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Affiliation(s)
- Ananth J Madhuranthakam
- MR Research Lab and Dept. of Radiology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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Fautz HP, Kannengiesser SAR. Sliding multislice (SMS): a new technique for minimum FOV usage in axial continuously moving-table acquisitions. Magn Reson Med 2006; 55:363-70. [PMID: 16408283 DOI: 10.1002/mrm.20762] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A novel technique for axial continuously moving-table scans is described that minimizes the required extension of the scanner's field of view (FOV) along the direction of table motion (z) by applying a segmented multislice acquisition technique. Any anatomical slice is acquired by applying the same phase-encoding steps at the same spatial positions along the scanner FOV. The full k-space data set of any anatomical slice is collected while the slice moves through the scanner from one scan position to the next. Simultaneous acquisition of multiple slices is realized by shifting the acquisition trajectories of different slices in time. It is demonstrated how the image artifact behavior that relates to varying imaging properties along the distance the table traverses during the acquisition of any given anatomical slice can be optimized simultaneously for all images. Discontinuities between the images along the slice axis are avoided because all z-dependent scan properties are encoded identically for all slices. Flexible spatial acquisition patterns are proposed to enable data oversampling and overlapping slice acquisitions at reduced table speeds. A framework of equations is presented by which matched parameter combinations for sliding multislice acquisitions can be applied to both single- and multiecho sequences. The new technique is validated on phantom and in vivo measurements using a T1-weighted fast low-angle shot (FLASH) sequence as well as a T2-weighted multi-spin-echo sequence of variable echo train lengths.
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Affiliation(s)
- H-P Fautz
- Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany.
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Hu HH, Madhuranthakam AJ, Kruger DG, Glockner JF, Riederer SJ. Continuously moving table MRI with SENSE: application in peripheral contrast enhanced MR angiography. Magn Reson Med 2006; 54:1025-31. [PMID: 16149061 PMCID: PMC2716116 DOI: 10.1002/mrm.20639] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An integration of SENSitivity Encoding (SENSE) with continuously moving table (CMT) MRI for extended field-of-view (FOV) acquisitions is described. In this work, the approach in which receiver coils are attached to the object and move in synchrony with the scanner table is considered. Technical issues dealing with the implementation of SENSE-CMT are addressed, including coil calibration, correction for non-uniform magnetic gradients, and specific reconstruction steps. An explanation of combining SENSE with gradient non-linearity correction is given, as the latter becomes necessary in CMT acquisitions where a large sampling FOV is used. It is hypothesized that SENSE can provide at least a 2-fold improvement in lateral spatial resolution compared to non-accelerated CMT acquisitions. The hypothesis is tested in phantoms, where the effectiveness of both SENSE and gradient non-linearity correction to improve spatial resolution is shown. The SENSE-CMT technique is further demonstrated in vivo with contrast-enhanced MR angiography of the peripheral vasculature.
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Affiliation(s)
| | | | | | | | - Stephen J. Riederer
- Correspondence to: Stephen J. Riederer, Ph.D., Magnetic Resonance Laboratory, Mayo Clinic College of Medicine, 200 First Street S.W., Rochester, MN 55905, USA. E-mail:
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Abstract
The motivations for developing MR-guided minimally invasive therapy include its excellent soft tissue contrast, tomographic imaging in any direction (as opposed to projection imaging as in fluoroscopy), the absence of ionizing radiation,the abundance of contrast mechanisms (including bright blood pulse sequences that lead to excellent vessel conspicuity without exogenous contrast agent injection), the ability to obtain physiologic information such as perfusion, and an overall excellent safety profile. The main pulse sequences used today for interventional MR imaging are T1/T2-weighted FISP and TrueFISP, T2-weighted turbo spin-echo, and T1-weighted FLASH. The specific clinical question, the underlying pathophysiology,and the procedure to be performed dictate which sequence is used. Each of these sequences has been written to acquire data in conventional rectilinear trajectories, radial k-space paths, or even spirals. In many ways, the questions being researched in interventional MR imaging have been dictated by the primary issues in greatest need of resolution or that most directly facilitate new clinical development. A decade ago, research focused on exploration of new scan strategies for contrast and temporal resolution. Advancements in the last decade have made it possible to acquire and display greater than 10 images per second in realtime with millimeter resolution in all three directions. This temporal and spatial resolution is considered high enough to guide most interventions. With this capability, other research has focused on instrument tracking. The field has gone from the capability to track a single coil and superimpose it on a previously acquired roadmap to systems that follow, adapt, and provide high-resolution images due to the advent of multichannel receiver systems, improved graphics, higher processor speeds, and increases in speed and quantity of memory. Hence, instruments can be reliably identified and tracked and the information can be used to update pulse sequence parameters in real time, thereby opening new opportunities for interventional MR imaging that extend from biopsy and thermal therapy to image-guided vascular and cardiac procedures. Today, we see such issues as RF heating of wires used for device localization and the noise generated by rapid switching of MR gradients being significant obstacles yet to overcome to allow the full strength of MR-guided interventions to be realized clinically. It is anticipated that these topics will emerge as critical concepts in the next decade of interventional MR imaging research.
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Affiliation(s)
- Jamal J Derakhshan
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
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Hu HH, Madhuranthakam AJ, Kruger DG, Glockner JF, Riederer SJ. Variable field of view for spatial resolution improvement in continuously moving table magnetic resonance imaging. Magn Reson Med 2005; 54:146-51. [PMID: 15968649 PMCID: PMC2844076 DOI: 10.1002/mrm.20509] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
An approach is described in which the field of view (FOV) along the Y (right/left) phase encoding direction can be dynamically altered during a continuously moving table (CMT) coronal acquisition for extended FOV MRI. We hypothesize that with this method, regions of the anatomy exhibiting significantly different lateral widths can be imaged with a matching local FOV(Y), thereby improving local lateral spatial resolution. k-space raw data from the variable-FOV CMT acquisition do not allow simple Fourier reconstruction due to the presence of a mixture of phase encodes sampled at different Deltak(Y) intervals. In this work, we employ spline interpolation to reregister the mixed data set onto a uniformly sampled k-space grid. Using this interpolation scheme, we present phantom and peripheral contrast-enhanced MR angiography results demonstrating an approximate 45% improvement in local lateral spatial resolution for continuously moving table acquisitions.
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Affiliation(s)
| | | | | | | | - Stephen J. Riederer
- Correspondence to: Stephen J. Riederer, Magnetic Resonance Laboratory, Mayo Clinic College of Medicine, 200 1st Street S.W., Rochester, MN 55905, USA. E-mail:
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Schlemmer HP, Schäfer J, Pfannenberg C, Radny P, Korchidi S, Müller-Horvat C, Nägele T, Tomaschko K, Fenchel M, Claussen CD. Fast Whole-Body Assessment of Metastatic Disease Using a Novel Magnetic Resonance Imaging System. Invest Radiol 2005; 40:64-71. [PMID: 15654249 DOI: 10.1097/01.rli.0000149250.37033.7c] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The objective of this study was to investigate the clinical use of a novel whole-body magnetic resonance imaging (MRI) system for comprehensive assessment of tumor spread in clinical routine. MATERIAL AND METHODS Sixty-five patients with different tumors with known metastatic disease and 6 healthy volunteers were included. High-resolution MRI from head to toe was performed using multiple phased-array surface coil elements, 24 independent receiver channels, and an integrated parallel acquisition technique (iPAT). A total room time of less than 60 minutes was required. Whole-body MRI and conventional spiral computed tomography (CT) were independently evaluated and compared in terms of feasibility, location/number of detected metastases, and therapeutic relevance. RESULTS Whole-body MRI was successfully performed in 68 of 71 subjects. Compared with CT, more metastases were detected by MRI in 11 of 63 patients (17%), particularly in brain, liver, spleen, lymph nodes, bone marrow, muscle, and subcutaneous fat tissue. According to these findings, therapy had to be modified in 6 of 63 patients (10%). CONCLUSIONS High-resolution whole-body MRI is feasible in clinical routine within 1 single examination and offers great potential for fast assessment of individual tumor spread and total tumor burden.
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Zenge MO, Ladd ME, Vogt FM, Brauck K, Barkhausen J, Quick HH. Whole-body magnetic resonance imaging featuring moving table continuous data acquisition with high-precision position feedback. Magn Reson Med 2005; 54:707-11. [PMID: 16086302 DOI: 10.1002/mrm.20598] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A novel setup for whole-body MR imaging with moving table continuous data acquisition has been developed and evaluated. The setup features a manually positioned moving table platform with integrated phased-array surface radiofrequency coils. A high-precision laser position sensor was integrated into the system to provide real-time positional data that were used to compensate for nonlinear manual table translation. This setup enables continuous 2D and 3D whole-body data acquisition during table movement with surface coil image quality. The concept has been successfully evaluated with whole-body steady-state free precession (TrueFISP) anatomic imaging in five healthy volunteers. Seamless coronal and sagittal slices of continually acquired whole-body data during table movement were accurately reconstructed. The proposed strategy is potentially useful for a variety of applications, including whole-body metastasis screening, whole-body MR angiography, large field-of-view imaging in short bore systems, and for moving table applications during MR-guided interventions.
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Affiliation(s)
- Michael O Zenge
- Department of Diagnostic and Interventional Radiology, University Hospital Essen, Germany.
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Abstract
A combination of continuously moving table imaging and parallel imaging based on sensitivity encoding (SENSE) is presented. One specific geometry is considered, where the receiver array is fixed to the MR magnet and does not move with the table, which allows for head-to-toe imaging with a small total number of coils. Sensitivity maps are defined for the enlarged virtual field of view and are composed according to the k-space sampling scheme such that established parallel reconstruction techniques are applicable to good approximation. In vivo experiments show the feasibility of this approach, and simulations determine the application range. Three-dimensional head-to-toe imaging of volunteers is performed in 77 s with a SENSE reduction factor of 2 in a virtual field of view of 1800 x 460 x 100 mm(3).
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Affiliation(s)
- Jochen Keupp
- Philips Research Laboratories, Technical Systems, Röntegenstrasse 24-26, D-22315 Hamburg, Germany.
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Fain SB, Browning FJ, Polzin JA, Du J, Zhou Y, Block WF, Grist TM, Mistretta CA. Floating table isotropic projection (FLIPR) acquisition: A time-resolved 3D method for extended field-of-view MRI during continuous table motion. Magn Reson Med 2004; 52:1093-102. [PMID: 15508171 DOI: 10.1002/mrm.20235] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this work, 3D vastly undersampled isotropic projection (VIPR) acquisition is used simultaneously with continuous table motion to extend the superior/inferior (S/I) FOV for MR angiograms. The new technique is termed floating table isotropic PR (FLIPR). The use of 3D PR in conjunction with table motion obviates the need to locate and prescribe imaging volumes containing the major blood vessels over the large superior-inferior (S/I) ranges encountered in whole-body imaging. In addition, the FLIPR technique provides extended anterior-posterior (A/P) abdominal coverage, isotropic spatial resolution, and temporal resolution. In volunteer studies, FLIPR MR angiograms with 1.6-mm isotropic spatial resolution that approached whole body in extent were acquired in less than 2 min.
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Affiliation(s)
- Sean B Fain
- Department of Medical Physics, University of Wisconsin-Madison, 53792, USA.
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