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Seginer A, Niry D, Furman-Haran E, Kolb H, Schmidt R. Reducing blood flow pulsation artifacts in 3D time-of-flight angiography by locally scrambling the order of the acquisition at 3 T and 7 T. Magn Reson Med 2024; 92:2081-2090. [PMID: 38923628 DOI: 10.1002/mrm.30196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 05/01/2024] [Accepted: 06/03/2024] [Indexed: 06/28/2024]
Abstract
PURPOSE Non-contrast-enhanced time of flight (TOF) is a standard method for magnetic resonance angiography used to depict vessel morphology. TOF is commonly performed with a 3D steady-state acquisition, employing a short repetition time to support high resolution imaging. At 7 T, TOF exhibits substantial increase in SNR and contrast, improving its clinical value. However, one of the remaining challenges, exacerbated at 7 T, is the presence of artifacts due to pulsatile blood flow, especially near major blood vessels. In this study we examine a method to significantly reduce these artifacts. METHODS We recently introduced a new "local-scrambling" approach that semi-randomizes the acquisition order of the phase encodes, to achieve a controllable cutoff frequency above which the artifacts are drastically reduced. With this approach, artifacts resulting from fast local fluctuations such as cardiac pulsation are significantly reduced. In this study, we explore the ability of this local-scrambling approach to reduce pulsatile blood flow artifacts in a 3D TOF acquisition. Cartesian line-by-line and center-out ordering, with and without local-scrambling, were compared in simulations and in human brain imaging at 3 and 7 T scanners. RESULTS In the simulations the artifact intensity showed a 10-fold reduction using local-scrambling compared to line-by-line and 4-fold compared to center-out ordering. In vivo results show that artifacts are much more pronounced at 7 T compared to 3 T, and in both cases they are effectively reduced by local-scrambling. CONCLUSION Local-scrambling improves image quality for both line-by-line and center-out ordering. This approach can easily be implemented in the scanner without any changes to the reconstruction.
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Affiliation(s)
- Amir Seginer
- Weizmann Institute of Science, Life Sciences Core Facilities, Rehovot, Israel
- The Azrieli National Institute for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel
| | - Dana Niry
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Radiology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Edna Furman-Haran
- Weizmann Institute of Science, Life Sciences Core Facilities, Rehovot, Israel
- The Azrieli National Institute for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel
| | - Hadar Kolb
- Neuroimmunology service, Division of Neurology, Tel Aviv Sourasky Medical Center, Tel-Aviv, Israel
| | - Rita Schmidt
- The Azrieli National Institute for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel
- Weizmann Institute of Science, Department of Brain Sciences, Rehovot, Israel
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Sasaki G, Uetani H, Nakaura T, Nakahara K, Morita K, Nagayama Y, Kidoh M, Iwashita K, Yoshida N, Hokamura M, Yamashita Y, Nakajima M, Ueda M, Hirai T. Optimizing High-Resolution MR Angiography: The Synergistic Effects of 3D Wheel Sampling and Deep Learning-Based Reconstruction. J Comput Assist Tomogr 2024; 48:819-825. [PMID: 38346820 DOI: 10.1097/rct.0000000000001590] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/20/2024]
Abstract
OBJECTIVE The aim of this study was to assess the utility of the combined use of 3D wheel sampling and deep learning-based reconstruction (DLR) for intracranial high-resolution (HR)-time-of-flight (TOF)-magnetic resonance angiography (MRA) at 3 T. METHODS This prospective study enrolled 20 patients who underwent head MRI at 3 T, including TOF-MRA. We used 3D wheel sampling called "fast 3D" and DLR for HR-TOF-MRA (spatial resolution, 0.39 × 0.59 × 0.5 mm 3 ) in addition to conventional MRA (spatial resolution, 0.39 × 0.89 × 1 mm 3 ). We compared contrast and contrast-to-noise ratio between the blood vessels (basilar artery and anterior cerebral artery) and brain parenchyma, full width at half maximum in the P3 segment of the posterior cerebral artery among 3 protocols. Two board-certified radiologists evaluated noise, contrast, sharpness, artifact, and overall image quality of 3 protocols. RESULTS The contrast and contrast-to-noise ratio of fast 3D-HR-MRA with DLR are comparable or higher than those of conventional MRA and fast 3D-HR-MRA without DLR. The full width at half maximum was significantly lower in fast 3D-MRA with and without DLR than in conventional MRA ( P = 0.006, P < 0.001). In qualitative evaluation, fast 3D-MRA with DLR had significantly higher sharpness and overall image quality than conventional MRA and fast 3D-MRA without DLR (sharpness: P = 0.021, P = 0.001; overall image quality: P = 0.029, P < 0.001). CONCLUSIONS The combination of 3D wheel sampling and DLR can improve visualization of arteries in intracranial TOF-MRA.
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Affiliation(s)
- Goh Sasaki
- From the Departments of Diagnostic Radiology
| | | | | | - Keiichi Nakahara
- Neurology, Graduate School of Medical Sciences, Kumamoto University
| | - Kosuke Morita
- Central Radiology Section, Kumamoto University Hospital, Kumamoto
| | | | | | | | | | | | - Yuichi Yamashita
- MRI Clinical Strategy Group, MRI Sales Department, Canon Medical Systems Corporation, Kanagawa, Japan
| | - Makoto Nakajima
- Neurology, Graduate School of Medical Sciences, Kumamoto University
| | - Mitsuharu Ueda
- Neurology, Graduate School of Medical Sciences, Kumamoto University
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Sui B, Sannananja B, Zhu C, Balu N, Eisenmenger L, Baradaran H, Edjlali M, Romero JM, Rajiah PS, Li R, Mossa-Basha M. Report from the society of magnetic resonance angiography: clinical applications of 7T neurovascular MR in the assessment of intracranial vascular disease. J Neurointerv Surg 2024; 16:846-851. [PMID: 37652689 PMCID: PMC10902184 DOI: 10.1136/jnis-2023-020668] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Accepted: 08/16/2023] [Indexed: 09/02/2023]
Abstract
In recent years, ultra-high-field magnetic resonance imaging (MRI) applications have been rapidly increasing in both clinical research and practice. Indeed, 7-Tesla (7T) MRI allows improved depiction of smaller structures with high signal-to-noise ratio, and, therefore, may improve lesion visualization, diagnostic capabilities, and thus potentially affect treatment decision-making. Incremental evidence emerging from research over the past two decades has provided a promising prospect of 7T magnetic resonance angiography (MRA) in the evaluation of intracranial vasculature. The ultra-high resolution and excellent image quality of 7T MRA allow us to explore detailed morphological and hemodynamic information, detect subtle pathological changes in early stages, and provide new insights allowing for deeper understanding of pathological mechanisms of various cerebrovascular diseases. However, along with the benefits of ultra-high field strength, some challenges and concerns exist. Despite these, ongoing technical developments and clinical oriented research will facilitate the widespread clinical application of 7T MRA in the near future. In this review article, we summarize technical aspects, clinical applications, and recent advances of 7T MRA in the evaluation of intracranial vascular disease. The aim of this review is to provide a clinical perspective for the potential application of 7T MRA for the assessment of intracranial vascular disease, and to explore possible future research directions implementing this technique.
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Affiliation(s)
- Binbin Sui
- Tiantan Neuroimaging Center of Excellence, China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Bhagya Sannananja
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Chengcheng Zhu
- Department of Radiology, University of Washington, Seattle, Washington, USA
| | - Niranjan Balu
- Department of Radiology, University of Washington, Seattle, Washington, USA
- Vascular Imaging Lab, University of Washington School of Medicine, Seattle, Washington, USA
| | | | - Hediyeh Baradaran
- Department of Radiology & Imaging Sciences, University of Utah, Salt Lake City, Utah, USA
| | | | - Javier M Romero
- Department of Radiology, Division of Neuroradiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Rui Li
- Center for Biomedical Imaging Research, Tsinghua University, Beijing, China
| | - Mahmud Mossa-Basha
- Department of Radiology, University of Washington, Seattle, Washington, USA
- Vascular Imaging Lab, University of Washington School of Medicine, Seattle, Washington, USA
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Cosottini M, Calzoni T, Lazzarotti GA, Grigolini A, Bosco P, Cecchi P, Tosetti M, Biagi L, Donatelli G. Time-of-flight MRA of intracranial vessels at 7 T. Eur Radiol Exp 2024; 8:68. [PMID: 38844683 PMCID: PMC11156832 DOI: 10.1186/s41747-024-00463-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 04/03/2024] [Indexed: 06/09/2024] Open
Abstract
BACKGROUND Three-dimensional time-of-flight magnetic resonance angiography (TOF-MRA) is a largely adopted non-invasive technique for assessing cerebrovascular diseases. We aimed to optimize the 7-T TOF-MRA acquisition protocol, confirm that it outperforms conventional 3-T TOF-MRA, and compare 7-T TOF-MRA with digital subtraction angiography (DSA) in patients with different vascular pathologies. METHODS Seven-tesla TOF-MRA sequences with different spatial resolutions acquired in four healthy subjects were compared with 3-T TOF-MRA for signal-to-noise and contrast-to-noise ratios as well as using a qualitative scale for vessel visibility and the quantitative Canny algorithm. Four patients with cerebrovascular disease (primary arteritis of the central nervous system, saccular aneurism, arteriovenous malformation, and dural arteriovenous fistula) underwent optimized 7-T TOF-MRA and DSA as reference. Images were compared visually and using the complex-wavelet structural similarity index. RESULTS Contrast-to-noise ratio was higher at 7 T (4.5 ± 0.8 (mean ± standard deviation)) than at 3 T (2.7 ± 0.9). The mean quality score for all intracranial vessels was higher at 7 T (2.89) than at 3 T (2.28). Angiogram quality demonstrated a better vessel border detection at 7 T than at 3 T (44,166 versus 28,720 pixels). Of 32 parameters used for diagnosing cerebrovascular diseases on DSA, 27 (84%) were detected on 7-T TOF-MRA; the similarity index ranged from 0.52 (dural arteriovenous fistula) to 0.90 (saccular aneurysm). CONCLUSIONS Seven-tesla TOF-MRA outperformed conventional 3-T TOF-MRA in evaluating intracranial vessels and exhibited an excellent image quality when compared to DSA. Seven-tesla TOF-MRA might improve the non-invasive diagnostic approach to several cerebrovascular diseases. RELEVANCE STATEMENT An optimized TOF-MRA sequence at 7 T outperforms 3-T TOF-MRA, opening perspectives to its clinical use for noninvasive diagnosis of paradigmatic pathologies of intracranial vessels. KEY POINTS • An optimized 7-T TOF-MRA protocol was selected for comparison with clinical 3-T TOF-MRA for assessing intracranial vessels. • Seven-tesla TOF-MRA outperformed 3-T TOF-MRA in both quantitative and qualitative evaluation. • Seven-tesla TOF-MRA is comparable to DSA for the diagnosis and characterization of intracranial vascular pathologies.
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Affiliation(s)
- Mirco Cosottini
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.
- Neuroradiology Unit, Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy.
| | - Tommaso Calzoni
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | | | | | - Paolo Bosco
- Laboratory of Medical Physics and Magnetic Resonance, IRCCS Stella Maris, Pisa, Italy
| | - Paolo Cecchi
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
- Imago7 Research Foundation, Pisa, Italy
| | - Michela Tosetti
- Laboratory of Medical Physics and Magnetic Resonance, IRCCS Stella Maris, Pisa, Italy
| | - Laura Biagi
- Laboratory of Medical Physics and Magnetic Resonance, IRCCS Stella Maris, Pisa, Italy
| | - Graziella Donatelli
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
- Imago7 Research Foundation, Pisa, Italy
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Suh PS, Jung SC, Moon HH, Roh YH, Song Y, Kim M, Lee J, Choi KM. Diagnosis of Unruptured Intracranial Aneurysms Using Proton-Density Magnetic Resonance Angiography: A Comparison With High-Resolution Time-of-Flight Magnetic Resonance Angiography. Korean J Radiol 2024; 25:575-588. [PMID: 38807339 PMCID: PMC11136948 DOI: 10.3348/kjr.2023.1241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/08/2024] [Accepted: 04/03/2024] [Indexed: 05/30/2024] Open
Abstract
OBJECTIVE Differentiating intracranial aneurysms from normal variants using CT angiography (CTA) or MR angiography (MRA) poses significant challenges. This study aimed to evaluate the efficacy of proton-density MRA (PD-MRA) compared to high-resolution time-of-flight MRA (HR-MRA) in diagnosing aneurysms among patients with indeterminate findings on conventional CTA or MRA. MATERIALS AND METHODS In this retrospective analysis, we included patients who underwent both PD-MRA and HR-MRA from August 2020 to July 2022 to assess lesions deemed indeterminate on prior conventional CTA or MRA examinations. Three experienced neuroradiologists independently reviewed the lesions using HR-MRA and PD-MRA with reconstructed voxel sizes of 0.253 mm3 or 0.23 mm3, respectively. A neurointerventionist established the gold standard with digital subtraction angiography. We compared the performance of HR-MRA, PD-MRA (0.253-mm3 voxel), and PD-MRA (0.23-mm3 voxel) in diagnosing aneurysms, both per lesion and per patient. The Fleiss kappa statistic was used to calculate inter-reader agreement. RESULTS The study involved 109 patients (average age 57.4 ± 11.0 years; male:female ratio, 11:98) with 141 indeterminate lesions. Of these, 78 lesions (55.3%) in 69 patients were confirmed as aneurysms by the reference standard. PD-MRA (0.253-mm3 voxel) exhibited significantly higher per-lesion diagnostic performance compared to HR-MRA across all three readers: sensitivity ranged from 87.2%-91.0% versus 66.7%-70.5%; specificity from 93.7%-96.8% versus 58.7%-68.3%; and accuracy from 90.8%-92.9% versus 63.8%-69.5% (P ≤ 0.003). Furthermore, PD-MRA (0.253-mm3 voxel) demonstrated significantly superior per-patient specificity and accuracy compared to HR-MRA across all evaluators (P ≤ 0.013). The diagnostic accuracy of PD-MRA (0.23-mm3 voxel) surpassed that of HR-MRA and was comparable to PD-MRA (0.253-mm3 voxel). The kappa values for inter-reader agreements were significantly higher in PD-MRA (0.820-0.938) than in HR-MRA (0.447-0.510). CONCLUSION PD-MRA outperformed HR-MRA in diagnostic accuracy and demonstrated almost perfect inter-reader consistency in identifying intracranial aneurysms among patients with lesions initially indeterminate on CTA or MRA.
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Affiliation(s)
- Pae Sun Suh
- Department of Radiology, Research Institute of Radiological Science and Center for Clinical Imaging Data Science, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Seung Chai Jung
- Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea.
| | - Hye Hyeon Moon
- Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea
| | - Yun Hwa Roh
- Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Yunsun Song
- Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea
| | - Minjae Kim
- Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea
| | - Jungbok Lee
- Department of Clinical Epidemiology and Biostatistics, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea
| | - Keum Mi Choi
- Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea
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Radojewski P, Dobrocky T, Branca M, Almiri W, Correia M, Raabe A, Bervini D, Gralla J, Wiest R, Mordasini P. Reply: Diagnosis of Small Unruptured Intracranial Aneurysms: Comparison of 7 T Versus 3 T MRI. Clin Neuroradiol 2024; 34:53-54. [PMID: 37344739 DOI: 10.1007/s00062-023-01322-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 05/30/2023] [Indexed: 06/23/2023]
Affiliation(s)
- P Radojewski
- Institute of Diagnostic and Interventional Neuroradiology, Bern University Hospital, Inselspital, University of Bern, Freiburgstr. 18, 3010, Bern, Switzerland.
- Translational Imaging Center, sitem-insel, Bern, Switzerland.
| | - T Dobrocky
- Institute of Diagnostic and Interventional Neuroradiology, Bern University Hospital, Inselspital, University of Bern, Freiburgstr. 18, 3010, Bern, Switzerland
| | - M Branca
- CTU Bern, University of Bern, Bern, Switzerland
| | - W Almiri
- Institute of Diagnostic and Interventional Neuroradiology, Bern University Hospital, Inselspital, University of Bern, Freiburgstr. 18, 3010, Bern, Switzerland
| | - M Correia
- Institute of Diagnostic and Interventional Neuroradiology, Bern University Hospital, Inselspital, University of Bern, Freiburgstr. 18, 3010, Bern, Switzerland
- Hospital de Santa Maria-Centro Hospitalar Lisboa Norte, Lisbon, Portugal
| | - A Raabe
- Department of Neurosurgery, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - D Bervini
- Department of Neurosurgery, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - J Gralla
- Institute of Diagnostic and Interventional Neuroradiology, Bern University Hospital, Inselspital, University of Bern, Freiburgstr. 18, 3010, Bern, Switzerland
| | - R Wiest
- Institute of Diagnostic and Interventional Neuroradiology, Bern University Hospital, Inselspital, University of Bern, Freiburgstr. 18, 3010, Bern, Switzerland
- Translational Imaging Center, sitem-insel, Bern, Switzerland
| | - P Mordasini
- Institute of Diagnostic and Interventional Neuroradiology, Bern University Hospital, Inselspital, University of Bern, Freiburgstr. 18, 3010, Bern, Switzerland
- Netzwerk Radiologie, Kantonsspital St. Gallen, St. Gallen, Switzerland
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Hokamura M, Uetani H, Nakaura T, Matsuo K, Morita K, Nagayama Y, Kidoh M, Yamashita Y, Ueda M, Mukasa A, Hirai T. Exploring the impact of super-resolution deep learning on MR angiography image quality. Neuroradiology 2024; 66:217-226. [PMID: 38148334 DOI: 10.1007/s00234-023-03271-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 12/14/2023] [Indexed: 12/28/2023]
Abstract
PURPOSE The aim of this study is to assess the effect of super-resolution deep learning-based reconstruction (SR-DLR), which uses k-space properties, on image quality of intracranial time-of-flight (TOF) magnetic resonance angiography (MRA) at 3 T. METHODS This retrospective study involved 35 patients who underwent intracranial TOF-MRA using a 3-T MRI system with SR-DLR based on k-space properties in October and November 2022. We reconstructed MRA with SR-DLR (matrix = 1008 × 1008) and MRA without SR-DLR (matrix = 336 × 336). We measured the signal-to-noise ratio (SNR), contrast, and contrast-to-noise ratio (CNR) in the basilar artery (BA) and the anterior cerebral artery (ACA) and the sharpness of the posterior cerebral artery (PCA) using the slope of the signal intensity profile curve at the half-peak points. Two radiologists evaluated image noise, artifacts, contrast, sharpness, and overall image quality of the two image types using a 4-point scale. We compared quantitative and qualitative scores between images with and without SR-DLR using the Wilcoxon signed-rank test. RESULTS The SNRs, contrasts, and CNRs were all significantly higher in images with SR-DLR than those without SR-DLR (p < 0.001). The slope was significantly greater in images with SR-DLR than those without SR-DLR (p < 0.001). The qualitative scores in MRAs with SR-DLR were all significantly higher than MRAs without SR-DLR (p < 0.001). CONCLUSION SR-DLR with k-space properties can offer the benefits of increased spatial resolution without the associated drawbacks of longer scan times and reduced SNR and CNR in intracranial MRA.
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Affiliation(s)
- Masamichi Hokamura
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Chuo-ku, Kumamoto-shi, Kumamoto, 860-8556, Japan
| | - Hiroyuki Uetani
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Chuo-ku, Kumamoto-shi, Kumamoto, 860-8556, Japan
| | - Takeshi Nakaura
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Chuo-ku, Kumamoto-shi, Kumamoto, 860-8556, Japan.
| | - Kensei Matsuo
- Department of Central Radiology, Kumamoto University Hospital, Honjo 1-1-1, Kumamoto, 860-8556, Japan
| | - Kosuke Morita
- Department of Central Radiology, Kumamoto University Hospital, Honjo 1-1-1, Kumamoto, 860-8556, Japan
| | - Yasunori Nagayama
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Chuo-ku, Kumamoto-shi, Kumamoto, 860-8556, Japan
| | - Masafumi Kidoh
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Chuo-ku, Kumamoto-shi, Kumamoto, 860-8556, Japan
| | - Yuichi Yamashita
- Canon Medical Systems Corporation, 70-1, Yanagi-cho, Saiwai-ku, Kawasaki-shi, Kanagawa, 212-0015, Japan
| | - Mitsuharu Ueda
- Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, 860-8556, Japan
| | - Akitake Mukasa
- Department of Neurosurgery, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, 860-8556, Japan
| | - Toshinori Hirai
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Chuo-ku, Kumamoto-shi, Kumamoto, 860-8556, Japan
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Seginer A, Schmidt R. Messing up to clean up: Semi-randomized frequency selective space-filling curves to suppress physiological signal fluctuations in MRI. Magn Reson Med 2023; 90:2275-2289. [PMID: 37448104 DOI: 10.1002/mrm.29790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023]
Abstract
PURPOSE Rapid 3D steady-state sequences are widely used but are also known to be sensitive to semi-periodic physiological signal fluctuations due to, for example, cardiac pulsation, breathing, and eye/eyelids movement. This semi-periodicity results in repeating artifacts in the image whose intensity depends on the scan parameters. The purpose of this study is to design a reordering of the 2D phase encodes (within the 3D acquisition) that reduces these artifacts. METHODS A randomized order of the phase encodes can suppress repeating artifact but may also introduce its own apparent noise, for example, in cases of slow subject movement or gradual changes in eddy currents. In a new design a semi-randomized space-filling curve is generated by scrambling the local order of the phase encodes to achieve a controlled frequency selective effect, that is, eliminating artifacts above a chosen (fluctuation) frequency threshold while leaving lower frequencies untouched, thus overcoming the limitations of a randomized order. The method was characterized in simulations and substantiated by human brain imaging at 7 T using two steady-state gradient echo variants that suffer from pulsation, either near blood vessels or near the ventricles. RESULTS The simulations with a point source show that the maximum artifact intensity can be reduced by factors of 10-50 depending on the scan parameters. In human scanning, the new approach drastically reduced physiologically induced artifacts and was superior in this regard to both full randomization and a generalized Hilbert curve, another semi-randomized approach. CONCLUSION The phase-encodes reordering presented here effectively removes artifacts arising from local fluctuations.
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Affiliation(s)
- Amir Seginer
- Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel
- The Azrieli National Institute for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel
| | - Rita Schmidt
- The Azrieli National Institute for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
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9
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Morita K, Uetani H, Nakaura T, Yoneyama M, Nagayama Y, Kidoh M, Shinojima N, Hamasaki T, Mukasa A, Hirai T. Accelerating TOF-MRA: The impact of the combined use of compressed sensitivity encoding and spiral imaging. Magn Reson Imaging 2023; 103:28-36. [PMID: 37406743 DOI: 10.1016/j.mri.2023.06.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 06/29/2023] [Accepted: 06/29/2023] [Indexed: 07/07/2023]
Abstract
PURPOSE To evaluate the image quality of the combined technique of compressed sensitivity encoding (CS) and spiral imaging in time-of-flight magnetic resonance angiography (TOF-MRA), which is approximately 2.5 times faster than conventional methods. METHODS Twenty volunteers underwent four TOF-MRA sequences: sensitivity encoding (SENSE) with acceleration factor of 4 (acquisition time: 4:55 min), CS with acceleration factor of 10.9, and spiral and CS-spiral (both 1:55 min). A quantitative image analysis (signal-to-noise ratio [SNR], contrast, and full width at half maximum [FWHM] edge criterion measurements) was performed on four TOF sequences. For qualitative image analysis, two board-certified radiologists evaluated the overall depiction of the proximal, intermediate, and distal branches in CS, spiral, and CS-spiral images using SENSE as a reference. RESULTS The SNR of BA in spiral and CS-spiral imaging was significantly lower than that in SENSE (p = 0.009). The contrasts of ACA and BA in CS-spiral were significantly higher and those in spiral were significantly lower than those in SENSE (p < 0.001). The FWHM in the CS image was significantly higher than that of SENSE; however, no significant differences were observed between the spiral or CS-spiral and SENSE. In qualitative analysis, the depiction of proximal vascular branches was significantly impaired in spiral than in others and that of distal vascular branches was significantly impaired in CS than in others (p < 0.001). CONCLUSIONS In TOF-MRA, which is approximately 2.5 times faster than conventional methods, the combined use of CS and spiral imaging demonstrated an improvement in image quality compared to either CS or spiral imaging alone. SUMMARY STATEMENT The image quality of Compressed SENSE and spiral imaging is particularly poor in the proximal and distal vascular branches, respectively at an extremely high acceleration factor; however, CS-spiral provided stable image quality in all regions as compared with the SENSE technique.
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Affiliation(s)
- Kosuke Morita
- Department of Radiology, Kumamoto University Hospital, Honjo 1-1-1, Kumamoto, Japan
| | - Hiroyuki Uetani
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Japan
| | - Takeshi Nakaura
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Japan.
| | | | - Yasunori Nagayama
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Japan
| | - Masafumi Kidoh
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Japan
| | - Naoki Shinojima
- Department of Neurosurgery, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Japan
| | - Tadashi Hamasaki
- Department of Neurosurgery, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Japan
| | - Akitake Mukasa
- Department of Neurosurgery, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Japan
| | - Toshinori Hirai
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Japan
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10
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Huang P, Chen K, Liu C, Zhen Z, Zhang R. Visualizing Cerebral Small Vessel Degeneration During Aging and Diseases Using Magnetic Resonance Imaging. J Magn Reson Imaging 2023; 58:1323-1337. [PMID: 37052571 DOI: 10.1002/jmri.28736] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 03/28/2023] [Accepted: 03/30/2023] [Indexed: 04/14/2023] Open
Abstract
Cerebral small vessel disease is a major contributor to brain disorders in older adults. It is associated with a much higher risk of stroke and dementia. Due to a lack of clinical and fluid biomarkers, diagnosing and grading small vessel disease are highly dependent on magnetic resonance imaging. In the past, researchers mostly used brain parenchymal imaging markers to represent small vessel damage, but the relationships between these surrogate markers and small vessel pathologies are complex. Recent progress in high-resolution magnetic resonance imaging methods, including time-of-flight MR angiography, phase-contrast MR angiography, black blood vessel wall imaging, susceptibility-weighted imaging, and contrast-enhanced methods, allow for direct visualization of cerebral small vessel structures. They could be powerful tools for understanding aging-related small vessel degeneration and improving disease diagnosis and treatment. This article will review progress in these imaging techniques and their application in aging and disease studies. Some challenges and future directions are also discussed. EVIDENCE LEVEL: 4. TECHNICAL EFFICACY: 3.
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Affiliation(s)
- Peiyu Huang
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Kang Chen
- Department of Radiology, Southwest Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Chen Liu
- Department of Radiology, Southwest Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Zhiming Zhen
- Department of Radiology, Southwest Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Ruiting Zhang
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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11
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Zhang Z, Kong Q, Zhang Y, Zhu W, Wei N, Xu Y, Suo Y, Meng X, Liebig P, Zhang Z, Wang Y, Jing J. Improved characterization of lenticulostriate arteries using compressed sensing time-of-flight at 7T. Eur Radiol 2023; 33:6939-6947. [PMID: 37062772 DOI: 10.1007/s00330-023-09629-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 01/22/2023] [Accepted: 02/17/2023] [Indexed: 04/18/2023]
Abstract
OBJECTIVES To evaluate the feasibility of 0.2-mm isotropic lenticulostriate arteries (LSAs) imaging using compressed sensing time-of-flight (CS TOF) at around 10 min on 7T, and compare the delineation and characterization of LSAs using conventional TOF and CS TOF. METHODS Thirty healthy volunteers were examined with CS TOF and conventional TOF at 7T for around 10 min each. CS TOF was optimized to achieve 0.2-mm isotropic LSA imaging. The numbers of LSA stems and branches were counted and compared on a vascular skeleton. The length and distance were measured and compared on the most prominent branch in each hemisphere. Another patient with intracranial artery stenosis was studied to compare LSA delineation in CS TOF and digital subtraction angiography (DSA). RESULTS The number of stems visualized with CS TOF was significantly higher than with conventional TOF in both left (p = 0.002, ICC = 0.884) and right (p < 0.001, ICC = 0.938) hemispheres. The number of branches visualized by conventional TOF was significantly lower than that by CS TOF in both left (p < 0.001, ICC = 0.893) and right (p < 0.001, ICC = 0.896) hemispheres. The lengths were statistically higher in CS TOF than in conventional TOF (left: p < 0.001, ICC = 0.868; right: p < 0.001, ICC = 0.876). CONCLUSIONS The high-resolution CS TOF improves the delineation and characterization of LSAs over conventional TOF. High-resolution LSA imaging using CS TOF can be a promising tool for clinical research and applications in patients with neurologic diseases. KEY POINTS • 0.2-mm isotropic LSA imaging for around 10 min using CS TOF at 7T is feasible. • More stems and branches of LSAs with longer lengths can be delineated with CS TOF than with conventional TOF at the same scan time. • High-resolution CS TOF can be a promising tool for research and applications on LSA.
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Affiliation(s)
- Zhe Zhang
- Tiantan Neuroimaging Center of Excellence, Beijing Tiantan Hospital, Capital Medical University, No 119, South 4th Ring West Road, Fengtai District, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Qingle Kong
- MR Collaboration, Siemens Healthineers Ltd., Beijing, China
| | - Yingkui Zhang
- Tiantan Neuroimaging Center of Excellence, Beijing Tiantan Hospital, Capital Medical University, No 119, South 4th Ring West Road, Fengtai District, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Wanlin Zhu
- Tiantan Neuroimaging Center of Excellence, Beijing Tiantan Hospital, Capital Medical University, No 119, South 4th Ring West Road, Fengtai District, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Ning Wei
- Tiantan Neuroimaging Center of Excellence, Beijing Tiantan Hospital, Capital Medical University, No 119, South 4th Ring West Road, Fengtai District, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Yuyuan Xu
- Tiantan Neuroimaging Center of Excellence, Beijing Tiantan Hospital, Capital Medical University, No 119, South 4th Ring West Road, Fengtai District, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Yue Suo
- Tiantan Neuroimaging Center of Excellence, Beijing Tiantan Hospital, Capital Medical University, No 119, South 4th Ring West Road, Fengtai District, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Xia Meng
- Tiantan Neuroimaging Center of Excellence, Beijing Tiantan Hospital, Capital Medical University, No 119, South 4th Ring West Road, Fengtai District, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | | | - Zihao Zhang
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yongjun Wang
- Tiantan Neuroimaging Center of Excellence, Beijing Tiantan Hospital, Capital Medical University, No 119, South 4th Ring West Road, Fengtai District, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jing Jing
- Tiantan Neuroimaging Center of Excellence, Beijing Tiantan Hospital, Capital Medical University, No 119, South 4th Ring West Road, Fengtai District, Beijing, 100070, China.
- China National Clinical Research Center for Neurological Diseases, Beijing, China.
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
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12
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Ji Y, Wu W, de Buck MHS, Okell T, Jezzard P. Highly accelerated intracranial time-of-flight magnetic resonance angiography using wave-encoding. Magn Reson Med 2023; 90:432-443. [PMID: 37010811 PMCID: PMC10953028 DOI: 10.1002/mrm.29647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 03/03/2023] [Accepted: 03/08/2023] [Indexed: 04/04/2023]
Abstract
PURPOSE To develop an accelerated 3D intracranial time-of-flight (TOF) magnetic resonance angiography (MRA) sequence with wave-encoding (referred to as 3D wave-TOF) and to evaluate two variants: wave-controlled aliasing in parallel imaging (CAIPI) and compressed-sensing wave (CS-wave). METHODS A wave-TOF sequence was implemented on a 3 T clinical scanner. Wave-encoded and Cartesian k-space datasets from six healthy volunteers were retrospectively and prospectively undersampled with 2D-CAIPI sampling and variable-density Poisson disk sampling. 2D-CAIPI, wave-CAIPI, standard CS, and CS-wave schemes were compared at various acceleration factors. Flow-related artifacts in wave-TOF were investigated, and a set of practicable wave parameters was developed. Quantitative analysis of wave-TOF and traditional Cartesian TOF MRA was performed by comparing the contrast-to-background ratio between the vessel and background tissue in source images, and the structural similarity index measure (SSIM) between the maximum intensity projection images from accelerated acquisitions and their respective fully sampled references. RESULTS Flow-related artifacts caused by the wave-encoding gradients in wave-TOF were eliminated by properly chosen parameters. Images from wave-CAIPI and CS-wave acquisitions had a higher SNR and better-preserved contrast than traditional parallel imaging (PI) and CS methods. Maximum intensity projection images from wave-CAIPI and CS-wave acquisitions had a cleaner background, with vessels that were better depicted. Quantitative analyses indicated that wave-CAIPI had the highest contrast-to-background ratio, SSIM, and vessel-masked SSIM among the sampling schemes studied, followed by the CS-wave acquisition. CONCLUSION 3D wave-TOF improves the capability of accelerated MRA and provides better image quality at higher acceleration factors compared to traditional PI- or CS-accelerated TOF, suggesting the potential use of wave-TOF in cerebrovascular disease.
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Affiliation(s)
- Yang Ji
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of Oxford
OxfordUK
| | - Wenchuan Wu
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of Oxford
OxfordUK
| | - Matthijs H. S. de Buck
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of Oxford
OxfordUK
| | - Thomas Okell
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of Oxford
OxfordUK
| | - Peter Jezzard
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of Oxford
OxfordUK
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Lakhani DA, Zhou X, Tao S, Westerhold EM, Eidelman BH, Singh Sandhu SJ, Middlebrooks EH. Clinical application of ultra-high resolution compressed sensing time-of-flight MR angiography at 7T to detect small vessel pathology. Neuroradiol J 2023; 36:335-340. [PMID: 36173305 PMCID: PMC10268099 DOI: 10.1177/19714009221129576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
3D time-of-flight (TOF) MR angiography (MRA) benefits from ultra-high-field MRI (≥7 T) due to improved contrast and increased signal-to-noise ratio. However, high-resolution TOF MRA at 7T usually requires longer acquisition times. In addition, relatively higher specific absorption rate (SAR) at 7T limits the choice of optimal pulse sequence parameters, especially if venous saturation is employed. Here, we illustrate the clinical application of ultra-high resolution cerebral 7T TOF MRA using compressed sensing in cases of artery of Percheron and lacunar infarcts, which showed superior resolution and exquisite details pertinent to the clinical diagnosis. The technical challenges associated with high-resolution 7T imaging were alleviated by optimization of sequence parameters and utilization of compressed sensing acceleration.
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Affiliation(s)
- Dhairya A Lakhani
- Department of Radiology, West Virginia University, Morgantown, WV, USA
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA
| | - Xiangzhi Zhou
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA
| | - Shengzhen Tao
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA
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14
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Shiraishi K, Nakaura T, Uetani H, Nagayama Y, Kidoh M, Kobayashi N, Morita K, Yamahita Y, Miyamoto T, Hirai T. Combination Use of Compressed Sensing and Deep Learning for Shoulder Magnetic Resonance Imaging With Various Sequences. J Comput Assist Tomogr 2023; 47:277-283. [PMID: 36944152 DOI: 10.1097/rct.0000000000001418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
OBJECTIVE For compressed sensing (CS) to become widely used in routine magnetic resonance imaging (MRI), it is essential to improve image quality. This study aimed to evaluate the usefulness of combining CS and deep learning-based reconstruction (DLR) for various sequences in shoulder MRI. METHODS This retrospective study included 37 consecutive patients who underwent undersampled shoulder MRIs, including T1-weighted (T1WI), T2-weighted (T2WI), and fat-saturation T2-weighted (FS-T2WI) images. Images were reconstructed using the conventional wavelet-based denoising method (wavelet method) and a combination of wavelet and DLR-based denoising methods (hybrid-DLR method) for each sequence. The signal-to-noise ratio and contrast-to-noise ratio of the bone, muscle, and fat and the full width at half maximum of the shoulder joint were compared between the 2 image types. In addition, 2 board-certified radiologists scored the image noise, contrast, sharpness, artifacts, and overall image quality of the 2 image types on a 4-point scale. RESULTS The signal-to-noise ratios and contrast-to-noise ratios of the bone, muscle, and fat in T1WI, T2WI, and FS-T2WI obtained from the hybrid-DLR method were significantly higher than those of the conventional wavelet method (P < 0.001). However, there were no significant differences in the full width at half maximum of the shoulder joint in any of the sequences (P > 0.05). Furthermore, in all sequences, the mean scores of the image noise, sharpness, artifacts, and overall image quality were significantly higher in the hybrid-DLR method than in the wavelet method (P < 0.001), but there were no significant differences in contrast among the sequences (P > 0.05). CONCLUSIONS The DLR denoising method can improve the image quality of CS in T1-weighted images, T2-weighted images, and fat-saturation T2-weighted images of the shoulder compared with the wavelet denoising method alone.
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Affiliation(s)
- Kaori Shiraishi
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Takeshi Nakaura
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Hiroyuki Uetani
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Yasunori Nagayama
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Masafumi Kidoh
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Naoki Kobayashi
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Kosuke Morita
- Department of Radiology, Kumamoto University Hospital, Kumamoto
| | | | - Takeshi Miyamoto
- Department of Orthopaedicsurgery, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Toshinori Hirai
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
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15
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Gast LV, Baier LM, Chaudry O, Meixner CR, Müller M, Engelke K, Uder M, Heiss R, Nagel AM. Assessing muscle-specific potassium concentrations in human lower leg using potassium magnetic resonance imaging. NMR IN BIOMEDICINE 2023; 36:e4819. [PMID: 35994248 DOI: 10.1002/nbm.4819] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 08/17/2022] [Accepted: 08/19/2022] [Indexed: 06/15/2023]
Abstract
Noninvasively assessing tissue potassium concentrations (TPCs) using potassium magnetic resonance imaging (39 K MRI) could give valuable information on physiological processes connected to various pathologies. However, because of inherently low 39 K MR image resolution and strong signal blurring, a reliable measurement of the TPC is challenging. The aim of this work was to investigate the feasibility of a muscle-specific TPC determination with a focus on the influence of a varying residual quadrupolar interaction in human lower leg muscles. The quantification accuracy of a muscle-specific TPC determination was first assessed using simulated 39 K MRI data. In vivo 39 K and corresponding sodium (23 Na) MRI data of healthy lower leg muscles (n = 14, seven females) were acquired on a 7-T MR system using a double-resonant 23 Na/39 K birdcage Tx/Rx RF coil. Additional 1 H MR images were acquired on a 3-T MR system and used for tissue segmentation. Quantification of TPC was performed after a region-based partial volume correction (PVC) using five external reference phantoms. Simulations not only underlined the importance of PVC for correctly assessing muscle-specific TPC values, but also revealed the strong impact of a varying residual quadrupolar interaction between different muscle regions on the measured TPC. Using 39 K T2 * decay curves, we found significantly higher residual quadrupolar interaction in tibialis anterior muscle (TA; ωq = 194 ± 28 Hz) compared with gastrocnemius muscle (medial/lateral head, GM/GL; ωq = 151 ± 25 Hz) and soleus muscle (SOL; ωq = 102 ± 32 Hz). If considered in the PVC, TPC in individual muscles was similar (TPC = 98 ± 11/96 ± 14/99 ± 8/100 ± 12 mM in GM/GL/SOL/TA). Comparison with tissue sodium concentrations suggested that residual quadrupolar interactions might also influence the 23 Na MRI signal of lower leg muscles. A TPC determination of individual lower leg muscles is feasible and can therefore be applied in future studies. Considering a varying residual quadrupolar interaction for PVC of 39 K MRI data is essential to reliably assess potassium concentrations in individual muscles.
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Affiliation(s)
- Lena V Gast
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Laura-Marie Baier
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Oliver Chaudry
- Department of Medicine 3, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christian R Meixner
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Max Müller
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Klaus Engelke
- Department of Medicine 3, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- Institute of Medical Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Michael Uder
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Rafael Heiss
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Armin M Nagel
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
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16
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de Buck MHS, Jezzard P, Hess AT. Optimization of undersampling parameters for 3D intracranial compressed sensing MR angiography at 7 T. Magn Reson Med 2022; 88:880-889. [PMID: 35344622 PMCID: PMC9314035 DOI: 10.1002/mrm.29236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/23/2022] [Accepted: 02/25/2022] [Indexed: 01/26/2023]
Abstract
PURPOSE 3D time-of-flight MRA can accurately visualize the intracranial vasculature but is limited by long acquisition times. Compressed sensing reconstruction can be used to substantially accelerate acquisitions. The quality of those reconstructions depends on the undersampling patterns used. In this work, we optimize sets of undersampling parameters for various acceleration factors of Cartesian 3D time-of-flight MRA. METHODS Fully sampled datasets, acquired at 7 Tesla, were retrospectively undersampled using variable-density Poisson disk sampling with various autocalibration region sizes, polynomial orders, and acceleration factors. The accuracy of reconstructions from the different undersampled datasets was assessed using the vessel-masked structural similarity index. Identified optimal undersampling parameters were then evaluated in additional prospectively undersampled datasets. Compressed sensing reconstruction parameters were chosen based on a preliminary reconstruction parameter optimization. RESULTS For all acceleration factors, using a fully sampled calibration area of 12 × 12 k-space lines and a polynomial order of 2 resulted in the highest image quality. The importance of parameter optimization of the sampling was found to increase for higher acceleration factors. The results were consistent across resolutions and regions of interest with vessels of varying sizes and tortuosity. The number of visible small vessels increased by 7.0% and 14.2% when compared to standard parameters for acceleration factors of 7.2 and 15, respectively. CONCLUSION The image quality of compressed sensing time-of-flight MRA can be improved by appropriate choice of undersampling parameters. The optimized sets of parameters are independent of the acceleration factor and enable a larger number of vessels to be visualized.
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Affiliation(s)
- Matthijs H. S. de Buck
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
| | - Peter Jezzard
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
| | - Aaron T. Hess
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
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17
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Bollmann S, Mattern H, Bernier M, Robinson SD, Park DJ, Speck O, Polimeni JR. Imaging of the pial arterial vasculature of the human brain in vivo using high-resolution 7T time-of-flight angiography. eLife 2022; 11:71186. [PMID: 35486089 PMCID: PMC9150892 DOI: 10.7554/elife.71186] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 04/28/2022] [Indexed: 11/30/2022] Open
Abstract
The pial arterial vasculature of the human brain is the only blood supply to the neocortex, but quantitative data on the morphology and topology of these mesoscopic arteries (diameter 50–300 µm) remains scarce. Because it is commonly assumed that blood flow velocities in these vessels are prohibitively slow, non-invasive time-of-flight magnetic resonance angiography (TOF-MRA)—which is well suited to high 3D imaging resolutions—has not been applied to imaging the pial arteries. Here, we provide a theoretical framework that outlines how TOF-MRA can visualize small pial arteries in vivo, by employing extremely small voxels at the size of individual vessels. We then provide evidence for this theory by imaging the pial arteries at 140 µm isotropic resolution using a 7 Tesla (T) magnetic resonance imaging (MRI) scanner and prospective motion correction, and show that pial arteries one voxel width in diameter can be detected. We conclude that imaging pial arteries is not limited by slow blood flow, but instead by achievable image resolution. This study represents the first targeted, comprehensive account of imaging pial arteries in vivo in the human brain. This ultra-high-resolution angiography will enable the characterization of pial vascular anatomy across the brain to investigate patterns of blood supply and relationships between vascular and functional architecture.
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Affiliation(s)
- Saskia Bollmann
- Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
| | - Hendrik Mattern
- Department of Biomedical Magnetic Resonance, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | - Michaël Bernier
- Athinoula A Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, United States
| | - Simon D Robinson
- Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
| | - Daniel J Park
- Athinoula A Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, United States
| | - Oliver Speck
- German Center for Neurodegenerative Diseases, Magdeburg, Germany
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18
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Uetani H, Nakaura T, Kitajima M, Morita K, Haraoka K, Shinojima N, Tateishi M, Inoue T, Sasao A, Mukasa A, Azuma M, Ikeda O, Yamashita Y, Hirai T. Hybrid deep-learning-based denoising method for compressed sensing in pituitary MRI: comparison with the conventional wavelet-based denoising method. Eur Radiol 2022; 32:4527-4536. [PMID: 35169896 DOI: 10.1007/s00330-022-08552-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 10/10/2021] [Accepted: 11/07/2021] [Indexed: 11/25/2022]
Abstract
OBJECTIVES This study aimed to evaluate the efficacy of a combined wavelet and deep-learning reconstruction (DLR) method for under-sampled pituitary MRI. METHODS This retrospective study included 28 consecutive patients who underwent under-sampled pituitary T2-weighted images (T2WI). Images were reconstructed using either the conventional wavelet denoising method (wavelet method) or the wavelet and DLR methods combined (hybrid DLR method) at five denoising levels. The signal-to-noise ratio (SNR) of the CSF, hypothalamic, and pituitary images and the contrast between structures were compared between the two image types. Noise quality, contrast, sharpness, artifacts, and overall image quality were evaluated by two board-certified radiologists. The quantitative and the qualitative analyses were performed with robust two-way repeated analyses of variance. RESULTS Using the hybrid DLR method, the SNR of the CSF progressively increased as denoising levels increased. By contrast, with the wavelet method, the SNR of the CSF, hypothalamus, and pituitary did not increase at higher denoising levels. There was a significant main effect of denoising methods (p < 0.001) and denoising levels (p < 0.001), and an interaction between denoising methods and denoising levels (p < 0.001). For all five qualitative scores, there was a significant main effect of denoising methods (p < 0.001) and an interaction between denoising methods and denoising levels (p < 0.001). CONCLUSIONS The hybrid DLR method can provide higher image quality for T2WI of the pituitary with compressed sensing (CS) than the wavelet method alone, especially at higher denoising levels. KEY POINTS • The signal-to-noise ratios of cerebrospinal fluid progressively increased with the hybrid DLR method, with an increase in the denoising level for cerebrospinal fluid in pituitary T2WI with CS. • The signal-to-noise ratios of cerebrospinal fluid using the conventional wavelet method did not increase at higher denoising levels. • All qualitative scores of hybrid deep-learning reconstructions at all denoising levels were higher than those for the wavelet denoising method.
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Affiliation(s)
- Hiroyuki Uetani
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, Japan
| | - Takeshi Nakaura
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, Japan.
| | - Mika Kitajima
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, Japan
| | - Kosuke Morita
- Department of Radiology, Kumamoto University Hospital, Honjo 1-1-1, Kumamoto, Japan
| | - Kentaro Haraoka
- Sales Engineer Group, MRI Sales Department, Canon Medical Systems Corporation, 70-1, Yanagi-cho, Saiwai-ku, Kawasaki-shi, Kanagawa, 212-0015, Japan
| | - Naoki Shinojima
- Department of Neurosurgery, Faculty of Life Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Japan
| | - Machiko Tateishi
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, Japan
| | - Taihei Inoue
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, Japan
| | - Akira Sasao
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, Japan
| | - Akitake Mukasa
- Department of Neurosurgery, Faculty of Life Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Japan
| | - Minako Azuma
- Department of Radiology, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, 889-1692, Japan
| | - Osamu Ikeda
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, Japan
| | - Yasuyuki Yamashita
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, Japan
| | - Toshinori Hirai
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, Japan
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Meixner CR, Eisen CK, Schmitter S, Müller M, Herrler J, Hensel B, Dörfler A, Uder M, Nagel AM. Hybrid B 1 + -shimming and gradient adaptions for improved pseudo-continuous arterial spin labeling at 7 Tesla. Magn Reson Med 2021; 87:207-219. [PMID: 34411335 DOI: 10.1002/mrm.28982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 08/03/2021] [Accepted: 08/03/2021] [Indexed: 11/09/2022]
Abstract
PURPOSE To improve pseudo-continuous arterial spin labeling (pcASL) at 7T by exploiting a hybrid homogeneity- and efficiency-optimized B 1 + -shim with adapted gradient strength as well as background suppression. METHODS The following three experiments were performed at 7T, each employing five volunteers: (1) A hybrid (ie, homogeneity-efficiency optimized) B 1 + -shim was introduced and evaluated for variable-rate selective excitation pcASL labeling. Therefore, B 1 + -maps in the V3 segment and time-of-flight images were acquired to identify the feeding arteries. For validation, a gradient-echo sequence was applied in circular polarized (CP) mode and with the hybrid B 1 + -shim. Additionally, the gray matter (temporal) signal-to-noise ratio (tSNR) in pcASL perfusion images was evaluated. (2) Bloch simulations for the pcASL labeling were conducted and validated experimentally, with a focus on the slice-selective gradients. (3) Background suppression was added to the B 1 + -shimmed, gradient-adapted 7T sequence and this was then compared to a matched sequence at 3T. RESULTS The B 1 + -shim improved the signal within the labeling plane (23.6%) and the SNR/tSNR increased (+11%/+11%) compared to its value in CP mode; however, the increase was not significant. In accordance with the simulations, the adapted gradients increased the tSNR (35%) and SNR (45%) significantly. Background suppression further improved the perfusion images at 7T, and this protocol performed as well as a resolution-matched protocol at 3T. CONCLUSION The combination of the proposed hybrid B 1 + -phase-shim with the adapted slice-selective gradients and background suppression shows great potential for improved pcASL labeling under suboptimal B 1 + conditions at 7T.
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Affiliation(s)
- Christian R Meixner
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christian K Eisen
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Sebastian Schmitter
- Physikalisch-Technische Bundesanstalt, Braunschweig and Berlin, Germany.,Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Max Müller
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Jürgen Herrler
- Department of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Bernhard Hensel
- Center for Medical Physics and Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Arnd Dörfler
- Department of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Michael Uder
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Armin M Nagel
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.,Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
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Yim Y, Jung SC, Kim JY, Kim SO, Kim BJ, Lee DH, Park W, Park JC, Ahn JS. Added diagnostic values of three-dimensional high-resolution proton density-weighted magnetic resonance imaging for unruptured intracranial aneurysms in the circle-of-Willis: Comparison with time-of-flight magnetic resonance angiography. PLoS One 2020; 15:e0243235. [PMID: 33270756 PMCID: PMC7714200 DOI: 10.1371/journal.pone.0243235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 11/17/2020] [Indexed: 01/18/2023] Open
Abstract
Background Advanced imaging methods can enhance the identification of aneurysms of the infundibula, which can reduce unnecessary follow-ups or further work-up, fear, and anxiety in patients. Purpose This study aimed to evaluate the added diagnostic value of three-dimensional proton density-weighted vessel wall magnetic resonance imaging (3D-PD MRI) in identifying aneurysms from index lesions refer to vascular bulging lesions without vessels arising from the apex, observed using volume-rendered TOF-MRA in the circle-of-Willis compared with time-of-flight magnetic resonance angiography (TOF-MRA). Study type Retrospective. Population A total of 299 patients who underwent 3D-PD MRI, digital subtraction angiography (DSA), and TOF-MRA between January 2012 and December 2016 were retrospectively enrolled in this study. Field strength/sequence 3 Tesla, 3D-PD MRI. Assessment Three neuroradiologists independently evaluated TOF-MRA and 3D-PD MRI combined with TOF-MRA for the determination of intracranial aneurysms in patients with index lesions within the circle of Willis. Final diagnoses were made by another neuroradiologist and neurointerventionist in consensus using DSA as the reference standard. The diagnostic performance and proportions of undetermined lesions on TOF-MRA and 3D-PD MRI with TOF-MRA were assessed based on the final diagnoses. Statistical tests The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for the diagnosis of unruptured intracranial aneurysms were calculated for each imaging modality. Results Of 452 lesions identified on volume-rendered TOF-MRA images, 173 (38%) aneurysms and 276 (61%) infundibula were finally diagnosed on DSA. 3D-PD MRI with TOF-MRA showed superior diagnostic performance (p = .001; accuracy, 85.5% versus 95.4%), superior area under the receiver operating characteristic curve over TOF-MRA (p = .001; 0.837 versus 0.947), and a lower proportion of undetermined lesions than TOF-MRA (p = .001; 25.1% versus 2.3%). Data conclusion For unruptured intracranial aneurysms in the circle of Willis, 3D-PD MRI can complement TOF-MRA to improve diagnostic performance and lower the proportion of undetermined lesions.
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Affiliation(s)
- Younghee Yim
- Department of Radiology, Chung-Ang University Hospital, Seoul, Korea
| | - Seung Chai Jung
- Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
- * E-mail:
| | - Jung Youn Kim
- Department of Radiology, Kangbuk Samsung Hospital, Seoul, Korea
| | - Seon-Ok Kim
- Department of Clinical Epidemiology and Biostatistics, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - Byung Jun Kim
- Department of Radiology, University of Korea College of Medicine, Seoul, Korea
| | - Deok Hee Lee
- Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - Wonhyoung Park
- Department of Neurosurgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - Jung Cheol Park
- Department of Neurosurgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - Jae Sung Ahn
- Department of Neurosurgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
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High-resolution compressed-sensing time-of-flight MRA in a case of acute ICA/MCA dissection. Neuroradiology 2020; 62:753-756. [PMID: 32198564 DOI: 10.1007/s00234-020-02395-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Accepted: 03/04/2020] [Indexed: 12/28/2022]
Abstract
PURPOSE Acute, isolated intracranial dissection (ICD) represents a rare and challenging cause of acute stroke. DSA is considered to be the gold standard imaging modality in patients with ICD. The role of novel, high-resolution (HR) compressed-sensing (CS) time-of-flight (TOF) MRA techniques in ICDs is unclear. METHODS A 22-year-old male patient with an isolated right ICA/MCA intracranial dissection underwent "conventional" 3-T TOF MRA, HR CS TOF MRA and also DSA including digital rotational angiography. RESULTS Unlike the "conventional" TOF MRA, HR CS TOF MRA provided comparable image quality to rotational angiography and a dissection membrane was clearly visible in both techniques. CONCLUSION In this single case study, we demonstrated the feasibility of a novel HR CS TOF in a case of an acute isolated intracranial ICA/MCA dissection, which needs to be validated in a larger case series.
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