1
|
So YH, Lee W, Park EA, Kim PK. Investigation of the Characteristics of New, Uniform, Extremely Small Iron-Based Nanoparticles as T1 Contrast Agents for MRI. Korean J Radiol 2021; 22:1708-1718. [PMID: 34402245 PMCID: PMC8484154 DOI: 10.3348/kjr.2020.1455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 04/06/2021] [Accepted: 05/10/2021] [Indexed: 11/21/2022] Open
Abstract
Objective The purpose of this study was to evaluate the magnetic resonance (MR) characteristics and applicability of new, uniform, extremely small iron-based nanoparticles (ESIONs) with 3–4-nm iron cores using contrast-enhanced magnetic resonance angiography (MRA). Materials and Methods Seven types of ESIONs were used in phantom and animal experiments with 1.5T, 3T, and 4.7T scanners. The MR characteristics of the ESIONs were evaluated via phantom experiments. With the ESIONs selected by the phantom experiments, animal experiments were performed on eight rabbits. In the animal experiments, the in vivo kinetics and enhancement effect of the ESIONs were evaluated using half-diluted and non-diluted ESIONs. The between-group differences were assessed using a linear mixed model. A commercially available gadolinium-based contrast agent (GBCA) was used as a control. Results All ESIONs showed a good T1 shortening effect and were applicable for MRA at 1.5T and 3T. The relaxivity ratio of the ESIONs increased with increasing magnetic field strength. In the animal experiments, the ESIONs showed peak signal intensity on the first-pass images and persistent vascular enhancement until 90 minutes. On the 1-week follow-up images, the ESIONs were nearly washed out from the vascular structures and organs. The peak signal intensity on the first-pass images showed no significant difference between the non-diluted ESIONs with 3-mm iron cores and GBCA (p = 1.000). On the 10-minutes post-contrast images, the non-diluted ESIONs showed a significantly higher signal intensity than did the GBCA (p < 0.001). Conclusion In the phantom experiments, the ESIONs with 3–4-nm iron oxide cores showed a good T1 shortening effect at 1.5T and 3T. In the animal experiments, the ESIONs with 3-nm iron cores showed comparable enhancement on the first-pass images and superior enhancement effect on the delayed images compared to the commercially available GBCA at 3T.
Collapse
Affiliation(s)
- Young Ho So
- Department of Radiology, SMG-SNU Boramae Medical Center, Seoul, Korea.,Department of Radiology, Seoul National University College of Medicine, Seoul, Korea
| | - Whal Lee
- Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.,Department of Radiology, Seoul National University Hospital, Seoul, Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.
| | - Eun Ah Park
- Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.,Department of Radiology, Seoul National University Hospital, Seoul, Korea
| | - Pan Ki Kim
- Department of Radiology and Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| |
Collapse
|
2
|
Abstract
MR imaging hardware and software improvements have led to new applications for contrast-enhanced and noncontrast-enhanced magnetic resonance angiography in the abdomen and pelvis. Higher magnetic field strength MR imaging scanners have greater signal-to-noise ratio and contrast-to-noise ratio, which is used to improve spatial resolution or temporal resolution for these techniques. New noncontrast-enhanced sequences offer high-resolution magnetic resonance angiography without contrast and provide additional hemodynamic information. Magnetic resonance angiography is particularly well suited to imaging patients with chronic mesenteric ischemia, renal vascular disease, pelvic congestion syndrome, and vascular malformations.
Collapse
Affiliation(s)
- Christopher J François
- Department of Radiology, University of Wisconsin, 600 Highland Avenue, Madison, WI 53792, USA.
| |
Collapse
|
3
|
Allen BD, Schiebler ML, François CJ. Pulmonary Vascular Disease Evaluation with Magnetic Resonance Angiography. Radiol Clin North Am 2020; 58:707-719. [PMID: 32471539 DOI: 10.1016/j.rcl.2020.02.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Pulmonary vascular assessment commonly relies on computed tomography angiography (CTA), but continued advances in magnetic resonance angiography have allowed pulmonary magnetic resonance angiography (pMRA) to become a reasonable alternative to CTA without exposing patients to ionizing radiation. pMRA allows the evaluation of pulmonary vascular anatomy, hemodynamic physiology, lung parenchymal perfusion, and (optionally) right and left ventricular function with a single examination. This article discusses pMRA techniques and artifacts; performance in commonly encountered pulmonary vascular diseases, specifically pulmonary embolism and pulmonary hypertension; and recent advances in both contrast-enhanced and noncontrast pMRA.
Collapse
Affiliation(s)
- Bradley D Allen
- Department of Radiology, Northwestern University Feinberg School of Medicine, 737 North Michigan Avenue, Suite 1600, Chicago, IL 60611, USA.
| | - Mark L Schiebler
- Department of Radiology, University of Wisconsin, 600 Highland Avenue, Madison, WI 53792, USA
| | - Christopher J François
- Department of Radiology, University of Wisconsin, 600 Highland Avenue, Madison, WI 53792, USA
| |
Collapse
|
4
|
Sparse Parallel MRI Based on Accelerated Operator Splitting Schemes. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:1724630. [PMID: 27746824 PMCID: PMC5056009 DOI: 10.1155/2016/1724630] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 08/29/2016] [Indexed: 11/17/2022]
Abstract
Recently, the sparsity which is implicit in MR images has been successfully exploited for fast MR imaging with incomplete acquisitions. In this paper, two novel algorithms are proposed to solve the sparse parallel MR imaging problem, which consists of l1 regularization and fidelity terms. The two algorithms combine forward-backward operator splitting and Barzilai-Borwein schemes. Theoretically, the presented algorithms overcome the nondifferentiable property in l1 regularization term. Meanwhile, they are able to treat a general matrix operator that may not be diagonalized by fast Fourier transform and to ensure that a well-conditioned optimization system of equations is simply solved. In addition, we build connections between the proposed algorithms and the state-of-the-art existing methods and prove their convergence with a constant stepsize in Appendix. Numerical results and comparisons with the advanced methods demonstrate the efficiency of proposed algorithms.
Collapse
|
5
|
Riederer SJ, Haider CR, Borisch EA, Weavers PT, Young PM. Recent advances in 3D time-resolved contrast-enhanced MR angiography. J Magn Reson Imaging 2015; 42:3-22. [PMID: 26032598 DOI: 10.1002/jmri.24880] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 12/31/2014] [Indexed: 11/11/2022] Open
Abstract
Contrast-enhanced magnetic resonance angiography (CE-MRA) was first introduced for clinical studies approximately 20 years ago. Early work provided 3-4 mm spatial resolution with acquisition times in the 30-second range. Since that time there has been continuing effort to provide improved spatial resolution with reduced acquisition time, allowing high resolution 3D time-resolved studies. The purpose of this work is to describe how this has been accomplished. Specific technical enablers have been: improved gradients allowing reduced repetition times, improved k-space sampling and reconstruction methods, parallel acquisition, particularly in two directions, and improved and higher count receiver coil arrays. These have collectively made high-resolution time-resolved studies readily available for many anatomic regions. Depending on the application, ∼1 mm isotropic resolution is now possible with frame times of several seconds. Clinical applications of time-resolved CE-MRA are briefly reviewed.
Collapse
|
6
|
Abstract
Magnetic resonance (MR) angiography of the pulmonary arteries is a rapidly evolving technique with proven clinical usefulness. Multiple-step protocols, such as MR perfusion followed by high-spatial resolution MR angiography, seem to be a good approach for the assessment of different vascular diseases affecting the pulmonary arteries. In combination with other imaging sequences, MR imaging is one of the most comprehensive potential noninvasive imaging techniques available.
Collapse
Affiliation(s)
- Sebastian Ley
- Diagnostic and Interventional Radiology, Chirurgische Klinik Dr Rinecker, Am Isarkanal 30, Munich 81379, Germany; Department of Clinical Radiology, Ludwig Maximilians University, Marchioninistrasse 15, Munich 81377, Germany.
| |
Collapse
|
7
|
Stinson EG, Borisch EA, Johnson CP, Trzasko JD, Young PM, Riederer SJ. Vascular masking for improved unfolding in 2D SENSE-accelerated 3D contrast-enhanced MR angiography. J Magn Reson Imaging 2013; 39:1161-70. [PMID: 23897776 DOI: 10.1002/jmri.24266] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 05/16/2013] [Indexed: 11/05/2022] Open
Abstract
PURPOSE To describe and evaluate the method we refer to as "vascular masking" for improving signal-to-noise ratio (SNR) retention in sensitivity encoding (SENSE)-accelerated contrast-enhanced magnetic resonance angiography (CE-MRA). MATERIALS AND METHODS Vascular masking is a technique that restricts the SENSE unfolding of an accelerated subtraction angiogram to the voxels within the field of view known to have enhancing signal. This is a more restricted voxel set than that identified with conventional masking, which excludes only voxels in the air around the object. Thus, improved retention of SNR is expected. Evaluation was done in phantom and in vivo studies by comparing SNR and the g-factor in results reconstructed using vascular versus conventional masking. A radiological evaluation was also performed comparing conventional and vascular masking in R = 8 accelerated CE-MRA studies of the thighs (n = 21) and calves (n = 13). RESULTS Images reconstructed with vascular masking showed a significant reduction in g-factor and improved retention of SNR versus those reconstructed with conventional masking. In the radiological evaluation, vascular masking consistently provided reduced background noise, improved luminal signal smoothness, and better small vessel conspicuity. CONCLUSION Vascular masking provides improved SNR retention and improved depiction of the vasculature in accelerated, subtraction 3D CE-MRA of the thighs and calves.
Collapse
|
8
|
Hansmann J, Apfaltrer P, Zoellner FG, Henzler T, Meyer M, Weisser G, Schoenberg SO, Attenberger UI. Correlation analysis of dual-energy CT iodine maps with quantitative pulmonary perfusion MRI. World J Radiol 2013; 5:202-207. [PMID: 23805370 PMCID: PMC3692965 DOI: 10.4329/wjr.v5.i5.202] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 03/28/2013] [Accepted: 05/17/2013] [Indexed: 02/06/2023] Open
Abstract
AIM: To correlate dual-energy computed tomography (DECT) pulmonary angiography derived iodine maps with parameter maps of quantitative pulmonary perfusion magnetic resonance imaging (MRI).
METHODS: Eighteen patients with pulmonary perfusion defects detected on DECT derived iodine maps were included in this prospective study and additionally underwent time-resolved contrast-enhanced pulmonary MRI [dynamic contrast enhanced (DCE)-MRI]. DCE-MRI data were quantitatively analyzed using a pixel-by-pixel deconvolution analysis calculating regional pulmonary blood flow (PBF), pulmonary blood volume (PBV) and mean transit time (MTT) in visually normal lung parenchyma and perfusion defects. Perfusion parameters were correlated to mean attenuation values of normal lung and perfusion defects on DECT iodine maps. Two readers rated the concordance of perfusion defects in a visual analysis using a 5-point Likert-scale (1 = no correlation, 5 = excellent correlation).
RESULTS: In visually normal pulmonary tissue mean DECT and MRI values were: 22.6 ± 8.3 Hounsfield units (HU); PBF: 58.8 ± 36.0 mL/100 mL per minute; PBV: 16.6 ± 8.5 mL; MTT: 17.1 ± 10.3 s. In areas with restricted perfusion mean DECT and MRI values were: 4.0 ± 3.9 HU; PBF: 10.3 ± 5.5 mL/100 mL per minute, PBV: 5 ± 4 mL, MTT: 21.6 ± 14.0 s. The differences between visually normal parenchyma and areas of restricted perfusion were statistically significant for PBF, PBV and DECT (P < 0.0001). No linear correlation was found between MRI perfusion parameters and attenuation values of DECT iodine maps (PBF: r = 0.35, P = 0.15; PBV: r = 0.34, P = 0.16; MTT: r = 0.41, P = 0.08). Visual analysis revealed a moderate correlation between perfusion defects on DECT iodine maps and the parameter maps of DCE-MRI (mean score 3.6, κ 0.45).
CONCLUSION: There is a moderate visual but not statistically significant correlation between DECT iodine maps and perfusion parameter maps of DCE-MRI.
Collapse
|
9
|
Kramer JH, Arnoldi E, François CJ, Wentland AL, Nikolaou K, Wintersperger BJ, Grist TM. Dynamic and static magnetic resonance angiography of the supra-aortic vessels at 3.0 T: intraindividual comparison of gadobutrol, gadobenate dimeglumine, and gadoterate meglumine at equimolar dose. Invest Radiol 2013; 48:121-8. [PMID: 23211552 PMCID: PMC3818529 DOI: 10.1097/rli.0b013e31827752b4] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE The purpose of this study was the intraindividual comparison of a 1.0 M and two 0.5 M gadolinium-based contrast agents (GBCA) using equimolar dosing in dynamic and static magnetic resonance angiography (MRA) of the supra-aortic vessels. MATERIALS AND METHODS In this institutional review board-approved study, a total of 20 healthy volunteers (mean ± SD age, 29 ± 6 years) underwent 3 consecutive supra-aortic MRA examinations on a 3.0 T magnetic resonance system. The order of GBCA (Gadobutrol, Gadobenate dimeglumine, and Gadoterate meglumine) was randomized with a minimum interval of 48 hours between the examinations. Before each examination and 45 minutes after each examination, circulatory parameters were recorded. Total GBCA dose per MRA examination was 0.1 mmol/kg with a 0.03 mmol/kg and 0.07 mmol/kg split for dynamic and static MRA, respectively, injected at a rate of 2 mL/s. Two blinded readers qualitatively assessed static MRA data sets independently using pairwise rankings (superior, inferior, and equal). In addition, quantitative analysis was performed with signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) evaluation as well as vessel sharpness analysis of static MRA using an in-house-developed semiautomated tool. Dynamic MRA was evaluated for maximal SNR. Statistical analysis was performed using the Cohen κ, the Wilcoxon rank sum tests, and mixed effects models. RESULTS No significant differences of hemodynamic parameters were observed. In static MRA, Gadobutrol was rated superior to Gadoterate meglumine (P < 0.05) and equal to Gadobenate dimeglumine (P = 0.06) with good to excellent reader agreement (κ, 0.66-0.83). In static MRA, SNR was significantly higher using 1.0 M Gadobutrol as compared with either 0.5 M agent (P < 0.05 and P < 0.05) and CNR was significantly higher as compared with Gadoterate meglumine (P < 0.05), whereas CNR values of Gadobutrol data sets were not significantly different as compared with Gadobenate dimeglumine (P = 0.13). Differences in CNR between Gadobenate dimeglumine and Gadoterate meglumine were not significant (P = 0.78). Differences in vessel sharpness between the different GBCAs were also not significant (P > 0.05). Maximal SNR in dynamic MRA using Gadobutrol was significantly higher than both comparators at the level of the proximal and distal internal carotid artery (P < 0.05 and P < 0.05; P < 0.05 and P < 0.05). CONCLUSIONS At equimolar doses, 1.0 M Gadobutrol demonstrates higher SNR/CNR than do Gadobenate dimeglumine and Gadoterate meglumine, with superior image quality as compared with Gadoterate meglumine for dynamic and static carotid MRA. Despite the shortened bolus with Gadobutrol, no blurring of vessel edges was observed.
Collapse
Affiliation(s)
- Jens Harald Kramer
- Institute for Clinical Radiology, Ludwig Maximilians University Hospital Munich, Munich, Germany.
| | | | | | | | | | | | | |
Collapse
|
10
|
Contrast-enhanced magnetic resonance angiography in rabbits: evaluation of the gadolinium-based agent p846 and the iron-based blood pool agent p904 in comparison with gadoterate meglumine. Invest Radiol 2011; 46:524-9. [PMID: 21577130 DOI: 10.1097/rli.0b013e31821ae21f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES : To evaluate the performance of a gadolinium-based contrast compound (P846) as well as an ultra-small particle of iron oxide agent (P904) in contrast-enhanced magnetic resonance angiography (MRA) in rabbits and to compare those agents with gadoterate meglumine (Gd-DOTA) for first pass and steady state imaging. MATERIALS AND METHODS : A total of 6 rabbits underwent contrast-enhanced MRA of the aorta and its branches at 3 different time points. All examinations were performed on a 1.5T MR (Siemens HealthCare, Magnetom Espree), and the contrast agents were applied in random order. Image data were acquired using a time-resolved MRA sequence (time-resolved angiography with stochastic trajectories) during the first pass to assess the bolus phase and a high-resolution MRA sequence followed by repetitive measurements over the next 10 minutes for all 3 agents to evaluate the postbolus phase. Two radiologists reviewed the images in consensus blinded to the contrast agent used. Signal-to-noise ratio and contrast-to-noise ratio for three-dimensional high-resolution MRA were calculated for each time point and agent. Image quality was consensually evaluated on a 4-point Likert scale. A Wilcoxon-Mann-Whitney U test was used for comparison with P < 0.05 as level of statistical significance. RESULTS : All agents led to diagnostic MR angiograms in all 6 rabbits. The time-resolved angiography with stochastic trajectories datasets provided detailed information about the bolus phase for all the 3 agents. During the first pass, P904 and P846 proved to be superior to Gd-DOTA with the highest peak enhancement for P846. In the postbolus phase up to 10 minutes postcontrast injection, P904 proved to be superior to the other agents. All the agents led to excellent image quality, with no statistical difference to a maximum of 3 minutes postinjection, whereas thereafter images with Gd-DOTA and P846 were assessed as nondiagnostic. CONCLUSIONS : P846 and P904 proved to be superior to Gd-DOTA for time-resolved MRA. The ultra-small particle of iron oxide compound P904 showed continuous high signal over 10 minutes and seems to be best suited for first pass and steady-state imaging.
Collapse
|
11
|
Londy FJ, Lowe S, Stein PD, Weg JG, Eisner RL, Leeper KV, Woodard PK, Sostman HD, Jablonski KA, Fowler SE, Hales CA, Hull RD, Gottschalk A, Naidich DP, Chenevert TL. Comparison of 1.5 and 3.0 T for contrast-enhanced pulmonary magnetic resonance angiography. Clin Appl Thromb Hemost 2011; 18:134-9. [PMID: 21993980 DOI: 10.1177/1076029611419840] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE In a recent multi-center trial of gadolinium contrast-enhanced magnetic resonance angiography (Gd-MRA) for diagnosis of acute pulmonary embolism (PE), two centers utilized a common MRI platform though at different field strengths (1.5T and 3T) and realized a signal-to-noise gain with the 3T platform. This retrospective analysis investigates this gain in signal-to-noise of pulmonary vascular targets. METHODS Thirty consecutive pulmonary MRA examinations acquired on a 1.5T system at one institution were compared to 30 consecutive pulmonary MRA examinations acquired on a 3T system at a different institution. Both systems were from the same MRI manufacturer and both used the same Gd-MRA pulse sequence, although there were some protocol adjustments made due to field strength differences. Region-of-interests were manually defined on the main pulmonary artery, 4 pulmonary veins, thoracic aorta, and background lung for objective measurement of signal-to-noise, contrast-to-noise, and bolus timing bias between centers. RESULTS The 3T pulmonary MRA protocol achieved higher spatial resolution yet maintained significantly higher signal-to-noise ratio (≥13%, p = 0.03) in the main pulmonary vessels relative to 1.5T. There was no evidence of operator bias in bolus timing or patient hemodynamic differences between groups. CONCLUSION Relative to 1.5T, higher spatial resolution Gd-MRA can be achieved at 3T with a sustained or greater signal-to-noise ratio of enhanced vasculature.
Collapse
|
12
|
Kramer H, Runge VM, Morelli JN, Williams KD, Naul LG, Nikolaou K, Reiser MF, Wintersperger BJ. Magnetic resonance angiography of the carotid arteries: comparison of unenhanced and contrast enhanced techniques. Eur Radiol 2011; 21:1667-76. [DOI: 10.1007/s00330-011-2110-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 02/02/2011] [Accepted: 02/09/2011] [Indexed: 10/18/2022]
|
13
|
Peldschus K, Hamdorf M, Robert P, Port M, Adam G, Herborn CU. Comparison of the high relaxivity Gd chelates P1152 and Gd-BOPTA for contrast-enhanced MR angiography in rabbits at 1.5 Tesla and 3.0 Tesla. J Magn Reson Imaging 2010; 32:459-65. [DOI: 10.1002/jmri.22261] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
|
14
|
Time-resolved 3D pulmonary perfusion MRI: comparison of different k-space acquisition strategies at 1.5 and 3 T. Invest Radiol 2009; 44:525-31. [PMID: 19652608 DOI: 10.1097/rli.0b013e3181b4c252] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE Time-resolved pulmonary perfusion MRI requires both high temporal and spatial resolution, which can be achieved by using several nonconventional k-space acquisition techniques. The aim of this study is to compare the image quality of time-resolved 3D pulmonary perfusion MRI with different k-space acquisition techniques in healthy volunteers at 1.5 and 3 T. METHODS Ten healthy volunteers underwent contrast-enhanced time-resolved 3D pulmonary MRI on 1.5 and 3 T using the following k-space acquisition techniques: (a) generalized autocalibrating partial parallel acquisition (GRAPPA) with an internal acquisition of reference lines (IRS), (b) GRAPPA with a single "external" acquisition of reference lines (ERS) before the measurement, and (c) a combination of GRAPPA with an internal acquisition of reference lines and view sharing (VS). The spatial resolution was kept constant at both field strengths to exclusively evaluate the influences of the temporal resolution achieved with the different k-space sampling techniques on image quality. The temporal resolutions were 2.11 seconds IRS, 1.31 seconds ERS, and 1.07 VS at 1.5 T and 2.04 seconds IRS, 1.30 seconds ERS, and 1.19 seconds VS at 3 T.Image quality was rated by 2 independent radiologists with regard to signal intensity, perfusion homogeneity, artifacts (eg, wrap around, noise), and visualization of pulmonary vessels using a 3 point scale (1 = nondiagnostic, 2 = moderate, 3 = good). Furthermore, the signal-to-noise ratio in the lungs was assessed. RESULTS At 1.5 T the lowest image quality (sum score: 154) was observed for the ERS technique and the highest quality for the VS technique (sum score: 201). In contrast, at 3 T images acquired with VS were hampered by strong artifacts and image quality was rated significantly inferior (sum score: 137) compared with IRS (sum score: 180) and ERS (sum score: 174). Comparing 1.5 and 3 T, in particular the overall rating of the IRS technique (sum score: 180) was very similar at both field strengths. At 1.5 T the peak signal-to-noise ratio of the ERS was significantly lower in comparison to the IRS and the VS technique (14.6 vs. 26.7 and 39.6 respectively, P < 0.004). CONCLUSION Using the IRS sampling algorithm comparable image quality and SNR can be achieved at 1.5 and 3 T. At 1.5 T VS offers the best possible solution for the conflicting requirements between a further increased temporal resolution and image quality. In consequence the gain of increased scanning efficiency from advanced k[r]-space sampling acquisition techniques can be exploited for a further improvement of image quality of pulmonary perfusion MRI.
Collapse
|
15
|
Henzler T, Dietrich O, Krissak R, Wichmann T, Lanz T, Reiser MF, Schoenberg SO, Fink C. Half-Fourier-acquisition single-shot turbo spin-echo (HASTE) MRI of the lung at 3 Tesla using parallel imaging with 32-receiver channel technology. J Magn Reson Imaging 2009; 30:541-6. [PMID: 19711408 DOI: 10.1002/jmri.21882] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PURPOSE To assess the feasibility of half-Fourier-acquisition single-shot turbo spin-echo (HASTE) of the lung at 3 Tesla (T) using parallel imaging with a prototype of a 32-channel torso array coil, and to determine the optimum acceleration factor for the delineation of intrapulmonary anatomy. MATERIALS AND METHODS Nine volunteers were examined on a 32-channel 3T MRI system using a prototype 32-channel-torso-array-coil. HASTE-MRI of the lung was acquired at both, end-inspiratory and end-expiratory breathhold with parallel imaging (Generalized autocalibrating partially parallel acquisitions = GRAPPA) using acceleration factors ranging between R = 1 (TE = 42 ms) and R = 6 (TE = 16 ms). The image quality of intrapulmonary anatomy and subjectively perceived noise level was analyzed by two radiologists in consensus. In addition quantitative measurements of the signal-to-noise ratio (SNR) of HASTE with different acceleration factors were assessed in phantom measurements. RESULTS Using an acceleration factor of R = 4 image blurring was substantially reduced compared with lower acceleration factors resulting in sharp delineation of intrapulmonary structures in expiratory scans. For inspiratory scans an acceleration factor of 2 provided the best image quality. Expiratory scans had a higher subjectively perceived SNR than inspiratory scans. CONCLUSION Using optimized multi-element coil geometry HASTE-MRI of the lung is feasible at 3T with acceleration factors up to 4. Compared with nonaccelerated acquisitions, shorter echo times and reduced image blurring are achieved. Expiratory scanning may be favorable to compensate for susceptibility associated signal loss at 3T.
Collapse
Affiliation(s)
- Thomas Henzler
- Department of Clinical Radiology and Nuclear Medicine, University of Heidelberg, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Abstract
This article discusses the role of magnetic resonance angiography (MRA) in evaluating the pulmonary arterial system. For depiction of pulmonary arterial anatomy and morphology, MRA techniques are compared with CT angiography and digital subtraction x-ray angiography. Perfusion, flow, and function are emphasized, as the integrated MR examination offers a comprehensive assessment of vascular morphology and function. Advances in MR technology that improve spatial and temporal resolution and compensate for potential artifacts are reviewed as they pertain to pulmonary MRA. Current and emerging gadolinium contrast-enhanced and non-contrast-enhanced MRA techniques are discussed. The role of pulmonary MRA, clinical protocols, imaging findings, and interpretation pitfalls are reviewed for clinical indications.
Collapse
Affiliation(s)
- Elizabeth M Hecht
- Department of Radiology, New York University School of Medicine, 560 First Avenue, TCH-HW202, New York, NY 10016, USA.
| | | |
Collapse
|
17
|
Mayerhoefer ME, Szomolanyi P, Jirak D, Berg A, Materka A, Dirisamer A, Trattnig S. Effects of Magnetic Resonance Image Interpolation on the Results of Texture-Based Pattern Classification. Invest Radiol 2009; 44:405-11. [DOI: 10.1097/rli.0b013e3181a50a66] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
18
|
Tomasian A, Salamon N, Krishnam MS, Finn JP, Villablanca JP. 3D high-spatial-resolution cerebral MR venography at 3T: a contrast-dose-reduction study. AJNR Am J Neuroradiol 2009; 30:349-55. [PMID: 18945800 DOI: 10.3174/ajnr.a1319] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The effect of various contrast-dose regimens for cerebral MR venography (MRV) has not been previously evaluated at 3T, to our knowledge. Our purpose was to evaluate and compare the diagnostic image quality resulting from half-versus-full-dose contrast regimens for high-spatial-resolution 3D cerebral MRV at 3T. MATERIALS AND METHODS Forty consecutive patients with known or suggested cerebrovascular disease underwent 3D high-spatial-resolution (0.7 x 0.6 x 0.9 mm(3)) cerebral contrast-enhanced MRV (CE-MRV) at 3T, by using an identical acquisition protocol. Patients were assigned to 1 of 2 groups: 1) full-dose (approximately 0.1 mmol/kg), and 2) half-dose (approximately 0.05 mmol/kg). Two readers evaluated the resulting images for overall image quality, venous structure definition, and arterial contamination. Signal intensity-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) were evaluated in 8 consistent sites. Statistical analysis was performed by using Mann-Whitney U, Wilcoxon signed rank, and t tests and a kappa coefficient. RESULTS Both readers scored venous-structure definition as excellent or sufficient for diagnosis in approximately 90% of segments for the full-dose group (kappa = 0.87) and in approximately 80% of segments for the half-dose group (kappa = 0.85). Delineation grades were significantly lower for small venous segments, including the middle cerebral, septal, superior cerebellar, inferior vermian, posterior tonsillar, and thalamostriate veins in the half-dose group (P < .01). No significant difference existed for arterial contamination grades between the 2 groups (P > .05). SNR and CNR values were lower in the half-dose group (P < .01). CONCLUSIONS At 3T, high-spatial-resolution cerebral MRV can be performed with contrast doses as low as 7.5 mL, without compromising image quality as compared with full-dose protocols, except in the smallest veins, and without compromise of acquisition speed or spatial resolution.
Collapse
Affiliation(s)
- A Tomasian
- Department of Radiological Sciences, University of California, Los Angeles, Los Angeles, Calif., USA.
| | | | | | | | | |
Collapse
|
19
|
Griffin M, Grist TM, François CJ. Dynamic Four-Dimensional MR Angiography of the Chest and Abdomen. Magn Reson Imaging Clin N Am 2009; 17:77-90. [DOI: 10.1016/j.mric.2008.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
|
20
|
Tomasian A, Salamon N, Lohan DG, Jalili M, Villablanca JP, Finn JP. Supraaortic arteries: contrast material dose reduction at 3.0-T high-spatial-resolution MR angiography--feasibility study. Radiology 2008; 249:980-90. [PMID: 19011192 DOI: 10.1148/radiol.2493080209] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To evaluate and compare the diagnostic image quality resulting from three contrast agent dose regimens for 3.0-T high-spatial-resolution three-dimensional magnetic resonance (MR) angiography of the supraaortic arteries. MATERIALS AND METHODS Institutional review board approval was obtained; informed consent was waived for this HIPAA-compliant study. One hundred twenty consecutive patients who underwent 3.0-T three-dimensional high-spatial-resolution contrast material-enhanced MR angiography of the supraaortic arteries with an identical acquisition protocol were assigned to either the high-dose (0.154 mmol per kilogram of body weight), intermediate-dose (0.097 mmol/kg), or low-dose (0.047 mmol/kg) group. Two readers evaluated resulting images for arterial definition, venous contamination, and arterial stenosis. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were evaluated at six consistent sites. Statistical analysis was performed with the Kruskal-Wallis, Wilcoxon signed rank, and analysis of variance tests and the kappa coefficient. RESULTS Readers 1 and 2 scored vascular definition as excellent or sufficient for diagnosis in 1311 of 1360 segments and in 1313 of 1360 segments in the high-dose group (kappa = 0.73), in 1321 of 1354 and in 1319 of 1354 segments in the intermediate-dose group (kappa = 0.77), and in 1322 of 1350 and in 1320 of 1350 segments in the low-dose group (kappa= 0.66), respectively. Arterial occlusive disease was detected by reader 1 in 52, 27, and 98 segments in the high-, intermediate-, and low-dose groups, respectively. Arterial occlusive disease was detected by reader 2 in 48, 25, and 100 segments in high-, intermediate-, and low-dose groups, respectively. No significant difference existed among the three groups regarding arterial definition scores (reader 1, P = .21; reader 2, P = .25) and venous contamination scores (reader 1, P = .38; reader 2, P = .35). SNRs and CNRs were lower in the low-dose group (P < .01). CONCLUSION At 3.0 T, high-spatial-resolution MR angiography of the supraaortic arteries can be performed with contrast agent doses as low as 0.047 mmol/kg, without compromising image quality, acquisition speed, or spatial resolution. SUPPLEMENTAL MATERIAL http://radiology.rsnajnls.org/cgi/content/full/249/3/980/DC1http://radiology.rsnajnls.org/cgi/content/full/249/3/980/DC2.
Collapse
Affiliation(s)
- Anderanik Tomasian
- Department of Radiological Sciences, David Geffen School of Medicine, University of California at Los Angeles, Suite 3371, Peter V. Ueberroth Building, 10945 Le Conte Ave, Los Angeles, CA 90095-7206, USA.
| | | | | | | | | | | |
Collapse
|
21
|
|
22
|
Abstract
Current advances in magnetic resonance, as a diagnostic modality, are discussed in the context of publications from Investigative Radiology during 2007 and 2008. The articles relating to this topic, published during the past 2 years, are reviewed by anatomic region. The discussion concludes with a consideration of magnetic resonance contrast media, focusing on studies published in the journal, and examining in particular the potential impact of nephrogenic systemic fibrosis.
Collapse
|
23
|
Intra-individual Crossover Comparison of Gadobenate Dimeglumine and Gadopentetate Dimeglumine for Contrast-Enhanced Magnetic Resonance Angiography of the Supraaortic Vessels at 3 Tesla. Invest Radiol 2008; 43:695-702. [DOI: 10.1097/rli.0b013e31817d1505] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
24
|
Noncontrast 3D steady-state free-precession magnetic resonance angiography of the whole chest using nonselective radiofrequency excitation over a large field of view: comparison with single-phase 3D contrast-enhanced magnetic resonance angiography. Invest Radiol 2008; 43:411-20. [PMID: 18496046 DOI: 10.1097/rli.0b013e3181690179] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To evaluate the feasibility of three-dimensional (3D) steady-state free-precession (SSFP) magnetic resonance angiography (MRA) using nonselective radiofrequency excitation in the assessment of cardiac morphology, thoracic aorta, main pulmonary, and proximal coronary arteries. MATERIAL AND METHODS Thirty consecutive patients (19 males; 11 females; age range, 20-74) with various cardiac and thoracic vascular diseases underwent free-breathing respiratory navigator-gated electrocardiogram-triggered noncontrast SSFP MRA and conventional high-resolution 3D contrast-enhanced MRA (CE-MRA) of the thorax at 1.5 T. Two readers evaluated both datasets for findings, vascular delineation and sharpness (from 0, not visualized to 3, excellent definition), artifacts, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in 14 vascular segments including aorta, supra-aortic, pulmonary, and coronary arteries, and in cardiac chambers. Statistical analysis was performed using Wilcoxon test for vessel delineation, and [kappa] coefficient for interobserver variability. RESULTS 3D SSFP and CE-MRA were successfully performed in all patients. Scan time for SSFP MRA ranged from 5 to 10 minutes (mean +/- standard deviation, 7 +/- 2 minutes). On SSFP MRA, readers 1 and 2 graded 233 (97.1%) and 234 (97.5%) coronary arterial segments and cardiac chambers, and 275 (91.7%) and 278 (92.7%) noncoronary arterial segments with diagnostic definition (grades 2 and 3) (k = 0.86). On conventional CE-MRA, readers 1 and 2 graded 10 (4.2%) and 12 (5%) coronary arterial segments and cardiac chambers, and 272 (90.7%) and 270 (90%) noncoronary arterial segments with diagnostic definition (grades 2 and 3) (k = 0.89). Segmental visibility was higher for aortic root, pulmonary trunk, proximal coronary arteries, and heart chambers (P < 0.001), and lower for supra-aortic arteries (P < 0.001) on SSFP MRA for each reader. SNR and CNR values were higher for aortic root and aorta on SSFP MRA (P < 0.001 for both). No significant difference existed between SNR and CNR values for the other vascular segments and cardiac chambers on SSFP and CE-MRA (P > 0.05 for all). The 2 readers demonstrated vascular stenosis and dilatation/aneurysm in 7 and 35 segments on both datasets, respectively. CONCLUSION Noncontrast 3D SSFP MRA with nonselective radiofrequency excitation provides high image quality and sufficient SNR and CNR for confident assessment of cardiac and thoracic vascular diseases including congenital heart diseases. Our results suggest that noncontrast SSFP MRA outperforms CE-MRA in visualization of cardiac chambers, proximal coronary arteries, pulmonary trunk, and aortic root.
Collapse
|
25
|
Noncontrast 3D steady state free precession magnetic resonance angiography of the thoracic central veins using nonselective radiofrequency excitation over a large field of view: initial experience. Invest Radiol 2008; 43:306-13. [PMID: 18424951 DOI: 10.1097/rli.0b013e31816be927] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate the feasibility of three-dimensional (3D) steady state free precession (SSFP) magnetic resonance angiography (MRA) using nonselective radiofrequency excitation for the assessment of thoracic central veins. MATERIALS AND METHODS Thirty consecutive patients (17 males, 13 females, age range 22-76) with various cardiac and thoracic vascular diseases underwent free-breathing electrocardiogram-gated noncontrast SSFP MRA and conventional high-resolution 3D contrast-enhanced (CE) MRA of the thorax at 1.5 T. Two readers evaluated both datasets for findings: venous visibility and sharpness (from 0, not visualized to 3, excellent definition); artifacts; signal-to-noise ratio (SNR); and contrast-to-noise ratio (CNR) in 8 venous segments including superior vena cava (SVC), supra-diaphragmatic inferior vena cava, bilateral brachiocephalic, proximal subclavian, and lower internal jugular veins. Statistical analysis was performed using Wilcoxon test for overall image quality and vessel visibility, t test for SNR and CNR analysis, and kappa coefficient for inter-observer variability. RESULTS 3D SSFP and CE-MRA were successfully performed in all patients. Scan time for SSFP MRA ranged from 5 to 10 minutes (mean +/- standard deviation, 7 +/- 2 minutes). Reader 1 (2) graded the overall image quality as excellent and good on SSFP MRA in 23 (25) and 7 (5) patients, and on CE-MRA in 22 (23) and 8 (9) patients, respectively. On SSFP MRA, readers 1 and 2 graded 234 (97.5%) and 233 (97.1%) venous segments with diagnostic definition (grades 2 and 3) (kappa = 0.69), respectively. On conventional CE-MRA, readers 1 and 2 graded 231 (96.3%) and 232 (96.7%) venous segments with diagnostic definition (grades 2 and 3) (kappa = 0.68), respectively. Segmental visibility and sharpness were higher for lower internal jugular veins on CE-MRA for each reader (P < 0.001). No significant difference existed for venous visibility and sharpness scores for other venous segments between the 2 techniques for both readers (P > 0.05). SNR and CNR values were lower for internal jugular veins on SSFP MRA (P < 0.001). No significant difference existed between SNR and CNR values for the other venous segments on SSFP and CE-MRA (P > 0.05 for all). The 2 readers demonstrated patent SVC Glenn shunt to main pulmonary artery (n = 3), patent extra cardiac Fontan shunt from inferior vena cava to pulmonary artery confluence (n = 2), and dilatation and thrombosis of SVC (n = 1) and right brachiocephalic vein (n = 1) on both datasets. CONCLUSION Free breathing navigator-gated noncontrast 3D SSFP MRA with nonselective radiofrequency excitation provides high image quality and sufficient SNR and CNR for confident evaluation of thoracic central veins.
Collapse
|
26
|
Peripheral Magnetic Resonance Angiography (MRA) With Continuous Table Movement at 3.0 T. Invest Radiol 2008; 43:627-34. [PMID: 18708856 DOI: 10.1097/rli.0b013e31817e90e9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
27
|
Validation of Magnetic Resonance Phase-Contrast Flow Measurements in the Main Pulmonary Artery and Aorta Using Perivascular Ultrasound in a Large Animal Model. Invest Radiol 2008; 43:421-6. [DOI: 10.1097/rli.0b013e318169015d] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
28
|
|
29
|
Ley S, Kauczor HU. MR Imaging/Magnetic Resonance Angiography of the Pulmonary Arteries and Pulmonary Thromboembolic Disease. Magn Reson Imaging Clin N Am 2008; 16:263-73, ix. [PMID: 18474331 DOI: 10.1016/j.mric.2008.02.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Sebastian Ley
- Department of Pediatric Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 153, 69120 Heidelberg, Germany.
| | | |
Collapse
|
30
|
|
31
|
Abstract
Advances in clinical magnetic resonance (MR) are discussed in this review in the context of publications from Investigative Radiology during 2006 and 2007. The articles relevant to this topic, published during this 2 year time period, are considered as organized by anatomic region. An additional final focus of discussion is in regards to those studies involving MR contrast media.
Collapse
|