1
|
Quist B, Hargreaves BA, Daniel BL, Saranathan M. Balanced SSFP Dixon imaging with banding-artifact reduction at 3 Tesla. Magn Reson Med 2014; 74:706-15. [PMID: 25227766 DOI: 10.1002/mrm.25449] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 08/20/2014] [Accepted: 08/21/2014] [Indexed: 01/10/2023]
Abstract
PURPOSE To develop a three-dimensional (3D) balanced steady-state free-precession (bSSFP) two-point Dixon method with banding-artifact suppression to offer robust high-resolution 3D bright-fluid imaging. METHODS A complex sum reconstruction that combines phase-cycled bSSFP images acquired at specific echo times for robust fat/water separation without banding was investigated and compared with a magnitude-based method. Bloch simulations using both single-peak and multiple-peak fat models were performed to predict the performance of these methods for a wide range of echo times and repetition times. The quality and degree of fat/water separation was evaluated in both simulations and using in vivo imaging. RESULTS Simulations predicted that both effective banding-artifact suppression and substantial improvements in fat/water separation are possible at echo times that are different from conventional echo times, enabling improved spatial resolution. Comparisons between various echo times and repetition times in vivo validated the improved fat/water separation and effective banding-artifact removal predicted by the simulations. CONCLUSION The proposed complex sum Dixon 3D bSSFP method is able to effectively separate fat and water at different sets of echo times, while removing banding-artifacts, providing a fast, high-resolution, T2 -like sequence without blurring.
Collapse
Affiliation(s)
- Brady Quist
- Department of Radiology, Stanford University, Stanford, California, USA.,Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | | | - Bruce L Daniel
- Department of Radiology, Stanford University, Stanford, California, USA
| | | |
Collapse
|
2
|
Kojima S, Suzuki K, Hirata M, Shinohara H, Ueno E. Depicting the semicircular canals with inner-ear MRI: a comparison of the SPACE and TrueFISP sequences. J Magn Reson Imaging 2012; 37:652-9. [PMID: 23172691 DOI: 10.1002/jmri.23863] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2012] [Accepted: 09/04/2012] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To assess the ability of magnetic resonance imaging (MRI) to depict the semicircular canals of the inner ear by comparing results from the sampling perfection with application-optimized contrasts by using different flip angle evolutions (SPACE) sequence with those from the true free induction with steady precession (TrueFISP) sequence. MATERIALS AND METHODS A 1.5-T MRI system was used to perform an in vivo study of 10 healthy volunteers and 17 patients. A three-point visual score was employed for assessing the depiction of the semicircular canals and facial and vestibulocochlear nerves and the contrast-to-noise ratio (CNR) was computed for the vestibule and pons on images with the SPACE and TrueFIPS sequences. RESULTS There were no susceptibility artifact-related filling defects with the SPACE sequence. However, the TrueFISP sequence showed filling defects for at least one semicircular canal on both sides in seven cases for healthy subjects and in 10 cases for patients. The CNR with the SPACE sequence was significantly higher than with the TrueFISP sequence (P < 0.05). There was no statistically significant difference in depicting the facial and the vestibulocochlear nerves (P = 0.32). CONCLUSION For the depiction of the semicircular canal, the SPACE sequence is superior to the TrueFISP sequence.
Collapse
Affiliation(s)
- Shinya Kojima
- Department of Radiology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan.
| | | | | | | | | |
Collapse
|
3
|
Hargreaves BA. Rapid gradient-echo imaging. J Magn Reson Imaging 2012; 36:1300-13. [PMID: 23097185 DOI: 10.1002/jmri.23742] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 05/24/2012] [Indexed: 11/07/2022] Open
Abstract
Gradient-echo sequences are widely used in magnetic resonance imaging (MRI) for numerous applications ranging from angiography to perfusion to functional MRI. Compared with spin-echo techniques, the very short repetition times of gradient-echo methods enable very rapid 2D and 3D imaging, but also lead to complicated "steady states." Signal and contrast behavior can be described graphically and mathematically, and depends strongly on the type of spoiling: fully balanced (no spoiling), gradient spoiling, or radiofrequency (RF)-spoiling. These spoiling options trade off between high signal and pure T(1) contrast, while the flip angle also affects image contrast in all cases, both of which can be demonstrated theoretically and in image examples. As with spin-echo sequences, magnetization preparation can be added to gradient-echo sequences to alter image contrast. Gradient-echo sequences are widely used for numerous applications such as 3D perfusion imaging, functional MRI, cardiac imaging, and MR angiography.
Collapse
Affiliation(s)
- Brian A Hargreaves
- Department of Radiology, Stanford University, Stanford, California, USA.
| |
Collapse
|
4
|
Hargreaves BA, Bangerter NK, Shimakawa A, Vasanawala SS, Brittain JH, Nishimura DG. Dual-acquisition phase-sensitive fat–water separation using balanced steady-state free precession. Magn Reson Imaging 2006; 24:113-22. [PMID: 16455400 DOI: 10.1016/j.mri.2005.10.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Accepted: 10/22/2005] [Indexed: 10/25/2022]
Abstract
Balanced steady-state free precession (SSFP) sequences use fully re-focussed gradient waveforms to achieve a high signal and useful image contrast in short scan times. Despite these strengths, the clinical feasibility of balanced SSFP is still limited both by bright fat signal and by the signal voids that result from off-resonance effects such as field or susceptibility variations. A new method, dual-acquisition phase-sensitive SSFP, combines the signals from two standard balanced SSFP acquisitions to separate fat and water while simultaneously reducing the signal voids. The acquisitions are added in quadrature and then phase corrected using a simple algorithm before fat and water can be identified simply by the sign of the signal. This method is especially useful for applications at high field, where the RF power deposition, spatial resolution requirements and gradient strength limit the minimum repetition times. Finally, dual-acquisition phase-sensitive SSFP can be combined with other magnetization preparation schemes to produce specific image contrast in addition to separating fat and water signals.
Collapse
Affiliation(s)
- Brian A Hargreaves
- Department of Radiology, Stanford University, Stanford, CA 94305-5488, USA
| | | | | | | | | | | |
Collapse
|
5
|
Wiet GJ, Schmalbrock P, Powell K, Stredney D. Use of ultra-high-resolution data for temporal bone dissection simulation. Otolaryngol Head Neck Surg 2006; 133:911-5. [PMID: 16360513 DOI: 10.1016/j.otohns.2005.05.655] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Accepted: 05/31/2005] [Indexed: 11/21/2022]
Abstract
OBJECTIVES For the past 5 years, our group has been developing a virtual temporal bone dissection environment for training otologic surgeons. Throughout the course of our development, a recurring challenge is the acquisition of high-resolution, multimodal, and multi-scale data sets that are used for the visual as well as haptic (sense of touch) display. This study presents several new techniques in temporal bone imaging and their use as data for surgical simulation. METHODS At our institution (OSU), we are fortunate to have a high-field (8 Tesla) magnetic resonance imaging (MRI) research magnet that provides an order of magnitude higher resolution compared to clinical 1.5T MRI scanners. Magnetic resonance imaging has traditionally been superb at delineating soft tissue structure, and certainly, the 8T unit does indeed do this at a resolution of 100-200 microm(3). To delineate the bony structure of the mastoid and middle ear, computed tomography (CT) has traditionally been used because of the high signal-to-noise ratio delineating bone signal from air and soft tissue. We have partnered with researchers at other institutions (CCF) to make use of a "microCT" that provides a resolution of 214 x 214 x 390 micrometers of bony structure. RESULTS This report provides a description of the 2 methodologies and presentation of the striking image data capable of being generated. See images presented. CONCLUSIONS Using these 2 new and innovative imaging modalities, we provide an order of magnitude greater resolution to the visual and haptic display in our temporal bone dissection simulation environment.
Collapse
Affiliation(s)
- Gregory J Wiet
- Department of Otolaryngology, Children's Hospital, Columbus, Ohio 43205, USA.
| | | | | | | |
Collapse
|
6
|
Rabinov JD, Barker FG, McKenna MJ, Curtin HD. Virtual cisternoscopy: 3D MRI models of the cerebellopontine angle for lesions related to the cranial nerves. Skull Base 2005; 14:93-9; discussion 99. [PMID: 16145590 PMCID: PMC1151677 DOI: 10.1055/s-2004-828701] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
This study was conducted to show that high-resolution magnetic resonance imaging (MRI) can aid in the neurosurgical approach to lesions affecting the cranial nerves (CNs) in the cerebellopontine angle (CPA). Three patients with symptomatology related to CNs VII and VIII underwent MRI examinations performed on a 1.5-Tesla Siemens MR scanner. As part of these routine examinations, the imaging technique of constructive interference in the steady state (CISS) was used to collect a volume of data through the brainstem and internal auditory canals. This high-resolution technique acquires a three-dimensional (3D) volume of data at 0.7-mm intervals. Parameters included TR 12.3/TE 5.9, number of acquisitions of 2, a matrix of 230 x 512, bandwidth of 130 Hz per pixel, and time of 8:40. Data were transferred to a commercially available GE workstation and reconstructed into a 3D surface-rendered model. This interactive method allows the model to be visualized from any angle, including that of a standard skull base approach of suboccipital craniotomy for access to the CPA cistern. The images shown include the CPA cistern as seen from the suboccipital surgical approach. CNs V, VII, and VIII can easily be seen in relation to the pons and petrous face. The relationship between the CNs and acoustic neuromas and skull base tumors can be evaluated. Vascular structures, which are often seen in relation to CNs VII and VIII, can be viewed in a 3D format to determine the need for microvascular decompression. Direct intraoperative photographs taken through the operating microscope confirmed the anatomic accuracy of the 3D models. Imaging used for interactive neurosurgical planning must demonstrate a high degree of anatomic detail. Virtual cisternoscopy using CISS MRI technique can achieve the required resolution. Reconstruction algorithms to create surface rendering can generate images with similar 3D anatomic detail to that seen during neurosurgical approaches to the CPA cistern.
Collapse
Affiliation(s)
- James D Rabinov
- Massachusetts General Hospital, Department of Neuroradiology, Boston, Massachusetts 02114, USA.
| | | | | | | |
Collapse
|
7
|
Schmalbrock P. Comparison of three-dimensional fast spin echo and gradient echo sequences for high-resolution temporal bone imaging. J Magn Reson Imaging 2000; 12:814-25. [PMID: 11105019 DOI: 10.1002/1522-2586(200012)12:6<814::aid-jmri4>3.0.co;2-l] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
T2-weighted high-resolution gradient and fast spin echo sequences are widely used as an alternative or adjunct to contrast-enhanced T1-weighted temporal bone imaging. However, to date no systematic comparison has been presented. The purpose of this work is to identify optimal acquisition parameters and to compare volume gradient and fast spin echo techniques. Signal intensities and scan efficiency were computed for gradient echo segment-interleaved motion-compensated acquisition into steady state (SIMCAST), standard fast spin echo (FSE), and fast recovery fast spin echo (FR-FSE). Computations were compared with inner ear images acquired with cubic voxel sizes of 0.35-0.40 mm(3)in 5-8 minutes. Given otherwise identical conditions, the FR-FSE sequence produces images with improved SNR in shorter scan times than standard FSE. For FR-FSE, the scan efficiency is optimal for specific pairs of TR and echo train length, eg, 400 ms/8, 735 ms/16, and 2,050 ms/48. FR-FSE images with large TR and echo trains, while achieving better SNR, are severely compromised by blurring. Imaging with echo train lengths of 16-24 and TR of 800-1,200 ms is a good compromise, and FR-FSE signal-to-noise ratio (SNR) and scan efficiency become comparable to SIMCAST. In vivo image quality is excellent with both FR-FSE and SIMCAST, but SIMCAST images have slightly higher SNR and are significantly more crisp. J. Magn. Reson. Imaging 2000;12:814-825.
Collapse
Affiliation(s)
- P Schmalbrock
- Department of Radiology, Ohio State University, Columbus, Ohio 43210, USA.
| |
Collapse
|
8
|
Abstract
The phase-encoding scheme can significantly affect the quality of fast spin-echo (FSE) images because the echo amplitude is modulated as a function of the echo position in k-space. The effects of the modulation in two-dimensional FSE imaging include ghosting and blurring artifacts and resolution loss in the phase-encoding (PE) direction. In 3D FSE imaging, the use of two PE directions presents the opportunity for improved PE schemes. A new scheme for assignment of echoes to views in 3D FSE, termed generalized, has been developed. This scheme distributes T(2) effects along both PE directions, allowing considerable flexibility in the selection of blurring artifact appearance. In a set of simulations, phantom experiments, and in vivo experiments, the performance of the generalized PE scheme for 3D FSE imaging was compared with the performance of existing PE schemes. The results demonstrate that the generalized PE scheme can be used to reduce blurring artifacts greatly relative to other PE techniques that are presently in use. This approach to PE can be used to manipulate the blurring artifact appearance and to optimize acquisition time.
Collapse
Affiliation(s)
- E G Kholmovski
- Department of Physics, University of Utah, Salt Lake City, Utah, 84112, USA
| | | | | |
Collapse
|
9
|
Abstract
PURPOSE Magnetic susceptibility provides the basis for functional studies and image artifacts in MRI. In this work, magnetic susceptibility and the associated artifacts were analyzed at 8 T in phantoms and in the human head. METHOD A mineral oil phantom was constructed in which three cylindrical air-filled tubes were inserted. This phantom was analyzed with gradient-recalled echo and SE imaging techniques acquired using varying TEs and receiver bandwidths. To visualize the presence of magnetic susceptibility artifacts in the head at 8 T, near axial, coronal, and sagittal GE images were also acquired from human volunteers. RESULTS The use of gradient-recalled echo imaging resulted in the production of significant magnetic susceptibility artifacts. These artifacts could be readily visualized in phantom samples containing air-filled cylindrical tubes. In the human head, susceptibility artifacts produced significant image distortion in the skull base region. In this area, susceptibility artifacts often resulted in the complete loss of MR signal. Magnetic susceptibility artifacts were manifested as bands of varying signal intensity in the frontal lobe and temporal bone region. In addition, they produced clear distortions in the appearance of brain vasculature and seemed to accentuate the relative size of venous structures within the brain. CONCLUSION When using gradient-recalled echo imaging in combination with relatively long TE values, magnetic susceptibility artifacts can be severe at 8 T. These artifacts could be reduced by increasing receiver bandwidths and by lowering effective TEs. As ultra high field MRI provides a fertile ground for the study of susceptibility artifacts in MRI, improvements obtained at this field strength will have a direct impact on studies performed at lower field strengths.
Collapse
Affiliation(s)
- A M Abduljalil
- Center for Advanced Biomedical Imaging, Department of Radiology, Ohio State University, Columbus 43210, USA
| | | |
Collapse
|
10
|
Yang D, Kodama T, Tamura S, Watanabe K. Evaluation of the inner ear by 3D fast asymmetric spin echo (FASE) MR imaging: phantom and volunteer studies. Magn Reson Imaging 1999; 17:171-82. [PMID: 10215471 DOI: 10.1016/s0730-725x(98)00165-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The 3D fast asymmetric spin echo (FASE) method combines the half-Fourier technique and 3D fast spin echo (FSE) sequence. The advantage of this method is that it maintains the same spatial resolution as FSE while markedly reducing the imaging time. The purpose of the present study was to evaluate the usefulness of the 3D FASE technique in displaying the inner ear structure using phantom and volunteer studies. 3D FSE sequence images were obtained for comparison, and the optimum 3D FASE sequence was investigated on a 1.5T MR scanner. The results of phantom experiments showed increased signal-to-noise ratio (SNR) with prolonging repetition time (TR) on both 3D FASE and 3D FSE sequences. Although the SNR of 3D FASE images was 20-25% lower than that of 3D FSE images with the same TR, the SNR per minute with 3D FASE was about twice that with 3D FSE. On 3D FASE images, a higher spatial resolution was obtained with 2- or 4-shot images than with single-shot images. However, no significant difference was observed between 2-shot and 4-shot images. In the volunteer study, 3D FASE images using a TR of 5000 ms and an effective echo time (TEeff) of 250 ms showed a high SNR and spatial resolution and provided excellent contrast between cerebrospinal fluid and nerves in the internal auditory canal. The highest contrast was achieved in the 2-shot/2 number of excitations sequence. 3D FASE provides the same image quality as 3D FSE with a significant reducing in imaging time, and gives strong T2-weighted images. This method enables detailed visualization of the tiny structures of the inner ear.
Collapse
Affiliation(s)
- D Yang
- Department of Radiology, Miyazaki Medical College, Kiyotake, Japan.
| | | | | | | |
Collapse
|