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Shetty AS, Ludwig DR, Ippolito JE, Andrews TJ, Narra VR, Fraum TJ. Low-Field-Strength Body MRI: Challenges and Opportunities at 0.55 T. Radiographics 2023; 43:e230073. [PMID: 37917537 DOI: 10.1148/rg.230073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
Advances in MRI technology have led to the development of low-field-strength (hereafter, "low-field") (0.55 T) MRI systems with lower weight, fewer shielding requirements, and lower cost than those of traditional (1.5-3 T) systems. The trade-offs of lower signal-to-noise ratio (SNR) at 0.55 T are partially offset by patient safety and potential comfort advantages (eg, lower specific absorption rate and a more cost-effective larger bore diameter) and physical advantages (eg, decreased T2* decay, shorter T1 relaxation times). Image reconstruction advances leveraging developing technologies (such as deep learning-based denoising) can be paired with traditional techniques (such as increasing the number of signal averages) to improve SNR. The overall image quality produced by low-field MRI systems, although perhaps somewhat inferior to 1.5-3 T MRI systems in terms of SNR, is nevertheless diagnostic for a broad variety of body imaging applications. Effective low-field body MRI requires (a) an understanding of the trade-offs resulting from lower field strengths, (b) an approach to modifying routine sequences to overcome SNR challenges, and (c) a workflow for carefully selecting appropriate patients. The authors describe the rationale, opportunities, and challenges of low-field body MRI; discuss important considerations for low-field imaging with common body MRI sequences; and delineate a variety of use cases for low-field body MRI. The authors also include lessons learned from their preliminary experience with a new low-field MRI system at a tertiary care center. Finally, they explore the future of low-field MRI, summarizing current limitations and potential future developments that may enhance the clinical adoption of this technology. ©RSNA, 2023 Supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center. See the invited commentary by Venkatesh in this issue.
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Affiliation(s)
- Anup S Shetty
- From the Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S Kingshighway Blvd, Campus Box 8131, St. Louis, MO 63110
| | - Daniel R Ludwig
- From the Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S Kingshighway Blvd, Campus Box 8131, St. Louis, MO 63110
| | - Joseph E Ippolito
- From the Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S Kingshighway Blvd, Campus Box 8131, St. Louis, MO 63110
| | - Trevor J Andrews
- From the Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S Kingshighway Blvd, Campus Box 8131, St. Louis, MO 63110
| | - Vamsi R Narra
- From the Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S Kingshighway Blvd, Campus Box 8131, St. Louis, MO 63110
| | - Tyler J Fraum
- From the Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S Kingshighway Blvd, Campus Box 8131, St. Louis, MO 63110
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Eisenmenger LB, Peret A, Roberts GS, Spahic A, Tang C, Kuner AD, Grayev AM, Field AS, Rowley HA, Kennedy TA. Focused Abbreviated Survey MRI Protocols for Brain and Spine Imaging. Radiographics 2023; 43:e220147. [PMID: 37167089 PMCID: PMC10262597 DOI: 10.1148/rg.220147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 10/12/2022] [Accepted: 10/18/2022] [Indexed: 05/13/2023]
Abstract
There has been extensive growth in both the technical development and the clinical applications of MRI, establishing this modality as one of the most powerful diagnostic imaging tools. However, long examination and image interpretation times still limit the application of MRI, especially in emergent clinical settings. Rapid and abbreviated MRI protocols have been developed as alternatives to standard MRI, with reduced imaging times, and in some cases limited numbers of sequences, to more efficiently answer specific clinical questions. A group of rapid MRI protocols used at the authors' institution, referred to as FAST (focused abbreviated survey techniques), are designed to include or exclude emergent or urgent conditions or screen for specific entities. These FAST protocols provide adequate diagnostic image quality with use of accelerated approaches to produce imaging studies faster than traditional methods. FAST protocols have become critical diagnostic screening tools at the authors' institution, allowing confident and efficient confirmation or exclusion of actionable findings. The techniques commonly used to reduce imaging times, the imaging protocols used at the authors' institution, and future directions in FAST imaging are reviewed to provide a practical and comprehensive overview of FAST MRI for practicing neuroradiologists. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.
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Affiliation(s)
| | | | - Grant S. Roberts
- From the Departments of Radiology (L.B.E., A.P., A.D.K., A.M.G.,
A.S.F., H.A.R., T.A.K.) and Medical Physics (G.S.R., A.S., C.T.), University of
Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI
53792-3252
| | - Alma Spahic
- From the Departments of Radiology (L.B.E., A.P., A.D.K., A.M.G.,
A.S.F., H.A.R., T.A.K.) and Medical Physics (G.S.R., A.S., C.T.), University of
Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI
53792-3252
| | - Chenwei Tang
- From the Departments of Radiology (L.B.E., A.P., A.D.K., A.M.G.,
A.S.F., H.A.R., T.A.K.) and Medical Physics (G.S.R., A.S., C.T.), University of
Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI
53792-3252
| | - Anthony D. Kuner
- From the Departments of Radiology (L.B.E., A.P., A.D.K., A.M.G.,
A.S.F., H.A.R., T.A.K.) and Medical Physics (G.S.R., A.S., C.T.), University of
Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI
53792-3252
| | - Allison M. Grayev
- From the Departments of Radiology (L.B.E., A.P., A.D.K., A.M.G.,
A.S.F., H.A.R., T.A.K.) and Medical Physics (G.S.R., A.S., C.T.), University of
Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI
53792-3252
| | - Aaron S. Field
- From the Departments of Radiology (L.B.E., A.P., A.D.K., A.M.G.,
A.S.F., H.A.R., T.A.K.) and Medical Physics (G.S.R., A.S., C.T.), University of
Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI
53792-3252
| | - Howard A. Rowley
- From the Departments of Radiology (L.B.E., A.P., A.D.K., A.M.G.,
A.S.F., H.A.R., T.A.K.) and Medical Physics (G.S.R., A.S., C.T.), University of
Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI
53792-3252
| | - Tabassum A. Kennedy
- From the Departments of Radiology (L.B.E., A.P., A.D.K., A.M.G.,
A.S.F., H.A.R., T.A.K.) and Medical Physics (G.S.R., A.S., C.T.), University of
Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI
53792-3252
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Ferumoxytol-enhanced MR demonstration of changes to internal placental structure in placenta accreta spectrum: Preliminary findings. Placenta 2023; 134:1-8. [PMID: 36807998 DOI: 10.1016/j.placenta.2023.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 02/04/2023] [Accepted: 02/07/2023] [Indexed: 02/12/2023]
Abstract
INTRODUCTION The goal of this pilot study is to determine if ferumoxytol-enhanced MR might provide a new approach to the diagnosis of placenta accreta spectrum (PAS), and if so, to identify signs of PAS. METHODS Ten pregnant women were referred for MRI evaluation for PAS. MR studies consisted of pre-contrast SSFSE, SSFP, DWI, and ferumoxytol-enhanced sequences. Post-contrast images were rendered as MIP and MinIP images to separately display the maternal and fetal circulations respectively. Two readers examined the images for architectural changes to placentone (fetal cotyledon) that might distinguish PAS cases from normal. Attention was given to the size and morphology of the placentone, villous tree, and vascularity. In addition, the images were examined for evidence of fibrin/fibrinoid, intervillous thrombus, basal and chorionic plate bulges. Interobserver agreement was characterized with kappa coefficients and levels of confidence for feature identification was recorded on a 10-point scale. RESULTS At delivery, there were five normal placentas and five with PAS (one accreta, two increta, two percreta). The ten changes of placental architecture in PAS included: focal/regional expansion of placentone(s); lateral displacement and compression of the villous tree; disruption of a regular pattern of normal placentones; bulging of the basal plate; bulging of the chorionic plate; transplacental stem villi; linear/nodular bands at basal plate; non-tapering villous branches; intervillous hemorrhage; and dilated subplacental vessels. All these changes were more common in PAS; the first five achieved statistical significance in this small sample. The interobserver agreement and confidence for the identification of these features was good to excellent except for dilated subplacental vessels. DISCUSSION Ferumoxytol-enhanced MR imaging appears to depict derangements of the internal architecture of placentas with PAS, thereby suggesting a promising new strategy to diagnose PAS.
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Kliewer MA, Bagley AR, Reeder SB, Iruretagoyena JI, Bockoven CG, Fritsch MK. Normal placental structural anatomy: ultrasound and doppler features elucidated with US-MR image fusion and ferumoxytol-enhanced MRI. Abdom Radiol (NY) 2023; 48:744-751. [PMID: 36462034 DOI: 10.1007/s00261-022-03758-0] [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: 10/25/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 12/05/2022]
Abstract
PURPOSE To elucidate ultrasound features of normal placental anatomy through correlation of gray-scale and ultrasound Doppler with ferumoxytol-enhanced MRI features using US-MR image fusion. METHODS All patients referred to MR for ultrasound findings worrisome for PAS (placenta accreta spectrum) were included in this retrospective study. MR studies included a ferumoxytol-enhanced T1-weighted MRI. Ultrasound imaging included gray-scale, color Doppler, power Doppler, and spectral Doppler techniques. After the MR, US-MRI fusion was performed by co-registering a MR acquisition to real-time US, which allowed precise, point-to-point correlation of placental features. RESULTS Fourteen patients at risk for PAS were studied using the US-MR image fusion. At delivery, there were six cases without PAS (gestational age range: 24 weeks 3 days to 34 weeks 0 days), and these composed the study cohort. Placental features that were on high signal intensity on post-ferumoxytol acquisitions represent spaces with maternal blood flow and corresponded to hypoechoic areas on ultrasound created by a paucity of reflective interfaces (villi). Color and spectral Doppler allowed the separation of maternal and fetal circulations in individual perfusional domains and demonstrated spiral artery inflow, circulation around the villous tree, and return of blood flow to the basal plate. Recognizable histopathologic features by ultrasound included the central cavity, villous tree, and venous return channels. CONCLUSION Internal placental architecture can be discerned on ultrasound. This anatomy can be correlated and confirmed with ferumoxytol-MR through US-MR fusion. Understanding this structural anatomy on ultrasound could serve as a basis to identify normal and abnormal placental features.
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Affiliation(s)
- Mark A Kliewer
- Department of Radiology, University of Wisconsin - Madison, E3/311, 600 Highland Avenue, Madison, WI, 53792-3252, USA.
| | - Anjuli R Bagley
- Department of Radiology, The University of Vermont, 111 Colchester Avenue, Main Campus, McClure, Level 1, Burlington, VT, 05401-1473, USA
| | - Scott B Reeder
- Department of Radiology, University of Wisconsin - Madison, E3/311, 600 Highland Avenue, Madison, WI, 53792-3252, USA
| | - Jesus Igor Iruretagoyena
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Wisconsin Medical School, 4th Floor McConnell Hall, 1010 Mound St, Madison, WI, 53715, USA
| | - Crystal G Bockoven
- Department of Pathology and Laboratory Medicine, University of WI-Madison, E3/311, 600 Highland Avenue, Madison, WI, 53792-8550, USA
| | - Michael K Fritsch
- Department of Pathology and Laboratory Medicine, University of WI-Madison, E3/311, 600 Highland Avenue, Madison, WI, 53792-8550, USA
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Herrmann J, Nickel D, Mugler JP, Arberet S, Gassenmaier S, Afat S, Nikolaou K, Othman AE. Development and Evaluation of Deep Learning-Accelerated Single-Breath-Hold Abdominal HASTE at 3 T Using Variable Refocusing Flip Angles. Invest Radiol 2021; 56:645-652. [PMID: 33965966 DOI: 10.1097/rli.0000000000000785] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Deep learning (DL) reconstruction enables substantial acceleration of image acquisition while maintaining diagnostic image quality. The aims of this study were to overcome the drawback of specific absorption rate (SAR)-related limitations at 3 T and to develop a DL-accelerated single-breath-hold half-Fourier acquisition single-shot turbo spin echo (HASTE) sequence for 2-dimesional T2-weighted fat-suppressed magnetic resonance imaging of the abdomen at 3 T using a variable flip angle (FA) evolution for the refocusing radiofrequency pulses, as well as to evaluate its feasibility and image quality in comparison to state-of-the-art T2-weighted fat-suppressed imaging technique (BLADE). MATERIALS AND METHODS First, a suitable FA evolution with low cardiac motion-related signal loss (CRSL) and low SAR was determined through a prospective volunteer study with 11 participants. Image quality and diagnostic confidence with 5 different FA evolutions of a HASTEDL were assessed to identify the most suitable FA evolution. Second, the identified FA evolution was implemented clinically and evaluated in 51 patients undergoing a clinically indicated liver magnetic resonance imaging at 3 T. Two radiologists assessed the HASTEDL and standard sequences regarding overall image quality, noise, contrast, sharpness, artifacts, CRSL, and diagnostic confidence using a Likert scale ranging from 1 to 4, with 4 being the best. Comparative analyses were conducted to assess the differences between HASTEDL (acquisition time, 21 seconds; single breath-hold) and the routinely used T2-weighted BLADE sequence (acquisition time, 4 minutes; respiratory triggering). RESULTS From the volunteer study, the FA evolution characterized by the control points 130-90-110-130 degrees (HASTEDL) was identified as optimal among the 5 evolutions evaluated and was implemented in our clinical protocol. In all 51 patients, HASTEDL was successfully acquired at 3 T and showed excellent image quality (median, 4; interquartile range, 3-4). Although BLADE was rated significantly higher for overall image quality, noise, contrast, sharpness, artifacts, CRSL, and diagnostic confidence than HASTEDL, no differences were found concerning the number (n = 102) and measured diameter of the detected hepatic lesions between the 2 sequences BLADE and HASTEDL. CONCLUSIONS The proposed single-breath-hold abdominal HASTEDL with variable refocusing FAs is feasible at 3 T within SAR limits and yields high image quality and diagnostic confidence as compared with a standard T2-weighted acquisition technique, at a 10th of the acquisition time.
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Affiliation(s)
- Judith Herrmann
- From the Department of Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, Tuebingen
| | - Dominik Nickel
- MR Applications Predevelopment, Siemens Healthcare GmbH, Erlangen, Germany
| | - John P Mugler
- Department of Radiology and Medical Imaging, University of Virginia School of Medicine, Charlottesville, VA
| | - Simon Arberet
- Digital Technology & Innovation, Siemens Healthineers, Princeton, NJ
| | - Sebastian Gassenmaier
- From the Department of Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, Tuebingen
| | - Saif Afat
- From the Department of Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, Tuebingen
| | - Konstantin Nikolaou
- From the Department of Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, Tuebingen
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Gui B, Cambi F, Micco M, Sbarra M, Petta F, Autorino R, De Vincenzo R, Valentini V, Scambia G, Manfredi R. MRI in pregnant patients with suspected abdominal and pelvic cancer: a practical guide for radiologists. ACTA ACUST UNITED AC 2021; 26:183-192. [PMID: 32071031 DOI: 10.5152/dir.2019.19343] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The incidence of abdominal and pelvic cancer in pregnancy is low, but it is rising as the population of pregnant women gets older. Depending on disease stage, gestational age and patient's preference, active surveillance as well as surgery and chemotherapy are feasible options during pregnancy. Correct diagnosis and staging of the tumor is crucial for choosing the best therapeutic approach. Moreover, a reproducible modality to assess the treatment response is requested. Magnetic resonance imaging (MRI) is commonly used with good results for the local staging and treatment response evaluation of most abdominal and pelvic cancers in nonpregnant patients, and it is considered relatively safe during pregnancy. The purpose of this article is to analyze the most relevant topics regarding the use of MRI in pregnant women with abdominal and pelvic cancer. We discuss MRI safety during pregnancy, including the use of gadolinium-based contrast agents (GBCAs), how to prepare the patient for the exam and MRI technique. This will be followed by a brief review on the most common malignancies diagnosed during pregnancy and their MRI appearance.
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Affiliation(s)
- Benedetta Gui
- General Diagnostic and Interventional Radiology, Diagnostic Imaging Area, Department of Diagnostic Imaging, Radiation Oncology and Hematology, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italy
| | - Francesco Cambi
- General Diagnostic and Interventional Radiology, Diagnostic Imaging Area, Department of Diagnostic Imaging, Radiation Oncology and Hematology, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italy;Institute of Radiology, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Maura Micco
- General Diagnostic and Interventional Radiology, Diagnostic Imaging Area, Department of Diagnostic Imaging, Radiation Oncology and Hematology, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italy
| | - Martina Sbarra
- General Diagnostic and Interventional Radiology, Diagnostic Imaging Area, Department of Diagnostic Imaging, Radiation Oncology and Hematology, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italy;Institute of Radiology, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Federica Petta
- General Diagnostic and Interventional Radiology, Diagnostic Imaging Area, Department of Diagnostic Imaging, Radiation Oncology and Hematology, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italy;Institute of Radiology, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Rosa Autorino
- Radiation Oncology, Radiation Oncology Area, Department of Diagnostic Imaging, Radiation Oncology and Hematology, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italy
| | - Rosa De Vincenzo
- Department of Woman and Child Health Sciences, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italy;Institute of Obstetric and Gynaecology Clinic, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Vincenzo Valentini
- Radiation Oncology, Radiation Oncology Area, Department of Diagnostic Imaging, Radiation Oncology and Hematology, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italy;Institute of Radiation Oncology, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Giovanni Scambia
- Department of Woman and Child Health Sciences, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italy;Institute of Obstetric and Gynaecology Clinic, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Riccardo Manfredi
- General Diagnostic and Interventional Radiology, Diagnostic Imaging Area, Department of Diagnostic Imaging, Radiation Oncology and Hematology, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italy;Institute of Radiology, Università Cattolica del Sacro Cuore, Roma, Italy
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Soewondo W, Kusumaningrum S, Putro PS, Indriyani I, Maryetty IP, Rosati A, Yuliantara EE. The use of FIESTA sequence MRI in successful management of abdominal pregnancy. Clin Imaging 2021; 77:117-121. [PMID: 33667944 DOI: 10.1016/j.clinimag.2021.01.005] [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: 10/31/2020] [Revised: 12/30/2020] [Accepted: 01/06/2021] [Indexed: 11/19/2022]
Abstract
Identification of fetal location and its relations to abdominal organs is extremely important in reducing fetal and maternal morbidity in rare cases of abdominal pregnancy. Ultrasound examination is inadequate for helping to successfully manage such cases. In this case report, FIESTA sequence MRI is used to provide high-resolution, better contrast, and higher signal-to-noise ratio fetal and abdominal images. A case of advanced abdominal pregnancy with a live fetus is reported. The surgery was conducted successfully on 34 weeks of gestation.
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Affiliation(s)
- Widiastuti Soewondo
- Department of Radiology, Dr. Moewardi Public Hospital, Faculty of Medicine, Universitas Sebelas Maret, Surakarta, Indonesia.
| | - Sulistyani Kusumaningrum
- Department of Radiology, Dr. Moewardi Public Hospital, Faculty of Medicine, Universitas Sebelas Maret, Surakarta, Indonesia
| | - Prasetyo Sarwono Putro
- Department of Radiology, Dr. Moewardi Public Hospital, Faculty of Medicine, Universitas Sebelas Maret, Surakarta, Indonesia
| | - Ifada Indriyani
- Department of Radiology, Dr. Moewardi Public Hospital, Faculty of Medicine, Universitas Sebelas Maret, Surakarta, Indonesia
| | - Ida Prista Maryetty
- Department of Radiology, Dr. Moewardi Public Hospital, Faculty of Medicine, Universitas Sebelas Maret, Surakarta, Indonesia
| | - Ari Rosati
- Department of Radiology, Dr. Moewardi Public Hospital, Faculty of Medicine, Universitas Sebelas Maret, Surakarta, Indonesia
| | - Eric Edwin Yuliantara
- Department of Obstetrics, Dr. Moewardi Public Hospital, Faculty of Medicine, Universitas Sebelas Maret, Surakarta, Indonesia
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Misaka T, Asato N, Ono Y, Ota Y, Kobayashi T, Umehara K, Ota J, Uemura M, Ashikaga R, Ishida T. Image quality improvement of single-shot turbo spin-echo magnetic resonance imaging of female pelvis using a convolutional neural network. Medicine (Baltimore) 2020; 99:e23138. [PMID: 33217817 PMCID: PMC7676607 DOI: 10.1097/md.0000000000023138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
We have developed a deep learning-based approach to improve image quality of single-shot turbo spin-echo (SSTSE) images of female pelvis. We aimed to compare the deep learning-based single-shot turbo spin-echo (DL-SSTSE) images of female pelvis with turbo spin-echo (TSE) and conventional SSTSE images in terms of image quality.One hundred five and 21 subjects were used as training and test sets, respectively. We performed 6-fold cross validation. In the training process, low-quality images were generated from TSE images as input. TSE images were used as ground truth images. In the test process, the trained convolutional neural network was applied to SSTSE images. The output images were denoted as DL-SSTSE images. Apart from DL-SSTSE images, classical filtering methods were adopted to SSTSE images. Generated images were denoted as F-SSTSE images. Contrast ratio (CR) of gluteal fat and myometrium and signal-to-noise ratio (SNR) of gluteal fat were measured for all images. Two radiologists graded these images using a 5-point scale and evaluated the image quality with regard to overall image quality, contrast, noise, motion artifact, boundary sharpness of layers in the uterus, and the conspicuity of the ovaries. CRs, SNRs, and image quality scores were compared using the Steel-Dwass multiple comparison tests.CRs and SNRs were significantly higher in DL-SSTSE, F-SSTSE, and TSE images than in SSTSE images. Scores with regard to overall image quality, contrast, noise, and boundary sharpness of layers in the uterus were significantly higher on DL-SSTSE and TSE images than on SSTSE images. There were no significant differences in the CRs, SNRs, and respective scores between DL-SSTSE and TSE images. The score with regard to motion artifacts was significantly higher on DL-SSTSE, F-SSTSE, and SSTSE images than on TSE images. The score with regard to the conspicuity of ovaries was significantly higher on DL-SSTSE images than on F-SSTSE, SSTSE, and TSE images (P < .001).DL-SSTSE images showed higher image quality as compared with SSTSE images. In comparison with conventional TSE images, DL-SSTSE images had acceptable image quality while keeping the advantage of the motion artifact-robustness and acquisition time efficiency in SSTSE imaging.
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Affiliation(s)
- Tomofumi Misaka
- Department of Medical Physics and Engineering, Graduate School of Medicine, Osaka University, Suita, Osaka
- Department of Radiology, Kindai University Nara Hospital, Otoda-cho, Ikoma, Nara
| | - Nobuyuki Asato
- Department of Radiology, Kindai University Nara Hospital, Otoda-cho, Ikoma, Nara
| | - Yukihiko Ono
- Department of Radiology, Kindai University Nara Hospital, Otoda-cho, Ikoma, Nara
| | - Yukino Ota
- Department of Medical Physics and Engineering, Graduate School of Medicine, Osaka University, Suita, Osaka
| | - Takuma Kobayashi
- Department of Medical Physics and Engineering, Graduate School of Medicine, Osaka University, Suita, Osaka
| | - Kensuke Umehara
- Medical Informatics Section, QST Hospital, National Institutes for Quantum and Radiological Science and Technology
- Applied MRI Research Group, Department of Molecular Imaging and Theranostics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Inage-ku, Chiba, Japan
| | - Junko Ota
- Medical Informatics Section, QST Hospital, National Institutes for Quantum and Radiological Science and Technology
- Applied MRI Research Group, Department of Molecular Imaging and Theranostics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Inage-ku, Chiba, Japan
| | - Masanobu Uemura
- Department of Radiology, Kindai University Nara Hospital, Otoda-cho, Ikoma, Nara
| | - Ryuichiro Ashikaga
- Department of Radiology, Kindai University Nara Hospital, Otoda-cho, Ikoma, Nara
| | - Takayuki Ishida
- Department of Medical Physics and Engineering, Graduate School of Medicine, Osaka University, Suita, Osaka
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de Paula WD, Rodrigues MP, Ferreira NMC, Passini VV, Melo-Silva CA. Lung MRI to predict response or lack of response to treatment in interstitial lung disease: initial observations on SSFSE/PROPELLER T2 match/mismatch. Expert Rev Respir Med 2020; 15:285-292. [PMID: 32993387 DOI: 10.1080/17476348.2020.1828070] [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] [Indexed: 10/23/2022]
Abstract
BACKGROUND Ground-glass opacities (GGO) are frequently found in interstitial lung diseases (ILD) and may represent either active inflammation or subresolution interstitial fibrosis. We sought to investigate the ability of lung MRI to predict treatment response in individuals with ILD presenting with predominant GGO. Methods: prospective cohort, 15 participants presenting with ILD manifested as predominant GGO and referred for a new treatment regimen with a systemic glucocorticoid and/or an immunosuppressive agent, underwent 1.5 T lung MRI. SSFSE/PROPELLER T2 mismatch sign, relative signal intensity on T2-weighted images and relative enhancement of lung lesions were compared to functional response, defined as a greater than 10% increase in forced vital capacity in 10 weeks (primary endpoint). RESULTS SSFSE/PROPELLER T2 match/mismatch was able to discriminate responders from nonresponders for the primary endpoint in 12 of 15 participants (80% accuracy, p = 0.026) for readers 1 and 2, and in 13 of 15 participants (87% accuracy, p = 0.011) for reader 3, with interrater agreement of 87% between readers 1 and 2 (Cohen's kappa coefficient of 0.732) and 93% between readers 1/2 and 3 (Cohen's kappa coefficient of 0.865). CONCLUSIONS SSFSE-PROPELLER T2 match/mismatch was predictive of treatment response status in this group of ILD patients. Abbreviations FVC: forced vital capacityGGO; ground-glass opacities; HRCT: High-Resolution Computed Tomography; ILD: interstitial lung disease; LAVA: Liver Acquisition with Volume Acceleration; mMRC: modified Medical Research Council dyspnea score; MRI: Magnetic Resonance Image; PROPELLER: Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction; SI: signal intensity; SSFSE: Single-Shot Fast Spin Echo.
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Affiliation(s)
- Wagner Diniz de Paula
- Department of Radiology, University Hospital of the University of Brasilia School of Medicine , Brasília, Brazil
| | - Marcelo Palmeira Rodrigues
- Department of Pulmonology, University Hospital of the University of Brasilia School of Medicine , Brasília, Brazil
| | | | - Viviane Vieira Passini
- Department of Pulmonology, University Hospital of the University of Brasilia School of Medicine , Brasília, Brazil
| | - César Augusto Melo-Silva
- Department of Pulmonology, University Hospital of the University of Brasilia School of Medicine , Brasília, Brazil
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Clinical utility and value contribution of an MRI-positive line marker for image-guided brachytherapy in gynecologic malignancies. Brachytherapy 2020; 19:305-315. [DOI: 10.1016/j.brachy.2019.12.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/29/2019] [Accepted: 12/30/2019] [Indexed: 01/19/2023]
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Variable refocusing flip angle single-shot fast spin echo imaging of liver lesions: increased speed and lesion contrast. Abdom Radiol (NY) 2018; 43:593-599. [PMID: 28689221 DOI: 10.1007/s00261-017-1252-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE To evaluate acquisition time and clinical image quality of a variable refocusing flip angle (vrf) single-shot fast spin echo (SSFSE) sequence in comparison with a conventional SSFSE sequence for imaging of liver lesions in patients undergoing whole-body PET/MRI for oncologic staging. METHODS A vrfSSFSE sequence was acquired in 43 patients with known pancreatic neuroendocrine tumors undergoing 68Ga-DOTA-TOC PET on a simultaneous time-of-flight 3.0T PET/MRI. Liver lesions ≥1.5 cm with radionucleotide uptake were analyzed. Contrast-to-noise ratios (CNRs) were measured, and four blinded radiologists assessed overall image quality. Differences in repetition time and CNR were assessed using a paired Student's t test with p < 0.05 considered statistically significant. Inter-reader variability was assessed with Fleiss' kappa statistic. RESULTS 53 eligible lesions in 27 patients were included for analysis. vrfSSFSE demonstrated higher mean lesion CNR compared to SSFSE (9.9 ± 4.1 vs. 6.7 ± 4.1, p < 0.001). Mean repetition time (TR) was 679 ± 97 ms for the vrfSSFSE sequence compared to 1139 ± 106 ms for SSFSE (p < 0.0001), corresponding to a 1.7-fold decrease in acquisition time. Overall quality of liver lesion and common bile duct images with the vrfSSFSE sequence was graded as superior than or equivalent to the SSFSE sequence for 59% and 67% of patients, respectively. CONCLUSIONS Compared to conventional SSFSE, vrfSSFSE resulted in improved lesion contrast on simultaneous PET/MRI in patients with liver metastases. Due to decreased SAR demands, vrfSSFSE significantly decreased TR, allowing coverage of the entire liver in a single twenty-second breath hold. This may have important clinical implications in the setting of PET/MRI, where scan time is limited by the necessity of whole-body image acquisition in addition to bed specific imaging.
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Loening AM, Litwiller DV, Saranathan M, Vasanawala SS. Increased Speed and Image Quality for Pelvic Single-Shot Fast Spin-Echo Imaging with Variable Refocusing Flip Angles and Full-Fourier Acquisition. Radiology 2016; 282:561-568. [PMID: 27564132 DOI: 10.1148/radiol.2016151574] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Purpose To assess image quality and speed improvements for single-shot fast spin-echo (SSFSE) with variable refocusing flip angles and full-Fourier acquisition (vrfSSFSE) pelvic imaging via a prospective trial performed in the context of uterine leiomyoma evaluation. Materials and Methods Institutional review board approval and informed consent were obtained. vrfSSFSE and conventional SSFSE sagittal and coronal oblique acquisitions were performed in 54 consecutive female patients referred for 3-T magnetic resonance (MR) evaluation of known or suspected uterine leiomyomas. Two radiologists who were blinded to the image acquisition technique semiquantitatively scored images on a scale from -2 to 2 for noise, image contrast, sharpness, artifacts, and perceived ability to evaluate uterine, ovarian, and musculoskeletal structures. The null hypothesis of no significant difference between pulse sequences was assessed with a Wilcoxon signed rank test by using a Holm-Bonferroni correction for multiple comparisons. Results Because of reductions in specific absorption rate, vrfSSFSE imaging demonstrated significantly increased speed (more than twofold, P < .0001), with mean repetition times compared with conventional SSFSE imaging decreasing from 1358 to 613 msec for sagittal acquisitions and from 1494 to 621 msec for coronal oblique acquisitions. Almost all assessed image quality and perceived diagnostic capability parameters were significantly improved with vrfSSFSE imaging. These improvements included noise, sharpness, and ability to evaluate the junctional zone, myometrium, and musculoskeletal structures for both sagittal acquisitions (mean values of 0.56, 0.63, 0.42, 0.56, and 0.80, respectively; all P values < .0001) and coronal oblique acquisitions (mean values of 0.81, 1.09, 0.65, 0.93, and 1.12, respectively; all P values < .0001). For evaluation of artifacts, there was an insufficient number of cases with differences to allow statistical testing. Conclusion Compared with conventional SSFSE acquisition, vrfSSFSE acquisition increases 3-T imaging speed via reduced specific absorption rate and leads to significant improvements in perceived image quality and perceived diagnostic capability when evaluating pelvic structures. © RSNA, 2016 Online supplemental material is available for this article.
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Affiliation(s)
- Andreas M Loening
- From the Department of Radiology, Stanford University School of Medicine, 300 Pasteur Dr, H1307 MC 5621, Stanford, CA 94305 (A.M.L., S.S.V.); GE Healthcare Global MR Applications and Workflow, Rochester, Minn (D.V.L.); and Department of Medical Imaging, University of Arizona, Tucson, Ariz (M.S.)
| | - Daniel V Litwiller
- From the Department of Radiology, Stanford University School of Medicine, 300 Pasteur Dr, H1307 MC 5621, Stanford, CA 94305 (A.M.L., S.S.V.); GE Healthcare Global MR Applications and Workflow, Rochester, Minn (D.V.L.); and Department of Medical Imaging, University of Arizona, Tucson, Ariz (M.S.)
| | - Manojkumar Saranathan
- From the Department of Radiology, Stanford University School of Medicine, 300 Pasteur Dr, H1307 MC 5621, Stanford, CA 94305 (A.M.L., S.S.V.); GE Healthcare Global MR Applications and Workflow, Rochester, Minn (D.V.L.); and Department of Medical Imaging, University of Arizona, Tucson, Ariz (M.S.)
| | - Shreyas S Vasanawala
- From the Department of Radiology, Stanford University School of Medicine, 300 Pasteur Dr, H1307 MC 5621, Stanford, CA 94305 (A.M.L., S.S.V.); GE Healthcare Global MR Applications and Workflow, Rochester, Minn (D.V.L.); and Department of Medical Imaging, University of Arizona, Tucson, Ariz (M.S.)
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Liu Y, Yin FF, Chen NK, Chu ML, Cai J. Four dimensional magnetic resonance imaging with retrospective k-space reordering: a feasibility study. Med Phys 2015; 42:534-41. [PMID: 25652474 DOI: 10.1118/1.4905044] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
PURPOSE Current four dimensional magnetic resonance imaging (4D-MRI) techniques lack sufficient temporal/spatial resolution and consistent tumor contrast. To overcome these limitations, this study presents the development and initial evaluation of a new strategy for 4D-MRI which is based on retrospective k-space reordering. METHODS We simulated a k-space reordered 4D-MRI on a 4D digital extended cardiac-torso (XCAT) human phantom. A 2D echo planar imaging MRI sequence [frame rate (F) = 0.448 Hz; image resolution (R) = 256 × 256; number of k-space segments (NKS) = 4] with sequential image acquisition mode was assumed for the simulation. Image quality of the simulated "4D-MRI" acquired from the XCAT phantom was qualitatively evaluated, and tumor motion trajectories were compared to input signals. In particular, mean absolute amplitude differences (D) and cross correlation coefficients (CC) were calculated. Furthermore, to evaluate the data sufficient condition for the new 4D-MRI technique, a comprehensive simulation study was performed using 30 cancer patients' respiratory profiles to study the relationships between data completeness (Cp) and a number of impacting factors: the number of repeated scans (NR), number of slices (NS), number of respiratory phase bins (NP), NKS, F, R, and initial respiratory phase at image acquisition (P0). As a proof-of-concept, we implemented the proposed k-space reordering 4D-MRI technique on a T2-weighted fast spin echo MR sequence and tested it on a healthy volunteer. RESULTS The simulated 4D-MRI acquired from the XCAT phantom matched closely to the original XCAT images. Tumor motion trajectories measured from the simulated 4D-MRI matched well with input signals (D = 0.83 and 0.83 mm, and CC = 0.998 and 0.992 in superior-inferior and anterior-posterior directions, respectively). The relationship between Cp and NR was found best represented by an exponential function (CP=1001-e(-0.18NR) , when NS = 30, NP = 6). At a CP value of 95%, the relative error in tumor volume was 0.66%, indicating that NR at a CP value of 95% (NR,95%) is sufficient. It was found that NR,95% is approximately linearly proportional to NP (r = 0.99), and nearly independent of all other factors. The 4D-MRI images of the healthy volunteer clearly demonstrated respiratory motion in the diaphragm region with minimal motion induced noise or aliasing. CONCLUSIONS It is feasible to generate respiratory correlated 4D-MRI by retrospectively reordering k-space based on respiratory phase. This new technology may lead to the next generation 4D-MRI with high spatiotemporal resolution and optimal tumor contrast, holding great promises to improve the motion management in radiotherapy of mobile cancers.
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Affiliation(s)
- Yilin Liu
- Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710 and Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710
| | - Fang-Fang Yin
- Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710 and Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710
| | - Nan-kuei Chen
- Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710 and Brain Imaging and Analysis Center, Duke University Medical Center, Box 2737, Hock Plaza, Durham, North Carolina 27710
| | - Mei-Lan Chu
- Brain Imaging and Analysis Center, Duke University Medical Center, Box 2737, Hock Plaza, Durham, North Carolina 27710
| | - Jing Cai
- Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710 and Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710
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Loening AM, Saranathan M, Ruangwattanapaisarn N, Litwiller DV, Shimakawa A, Vasanawala SS. Increased speed and image quality in single-shot fast spin echo imaging via variable refocusing flip angles. J Magn Reson Imaging 2015; 42:1747-58. [PMID: 26094580 DOI: 10.1002/jmri.24941] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 04/23/2015] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To develop and validate clinically a single-shot fast spin echo (SSFSE) sequence utilizing variable flip angle refocusing pulses to shorten acquisition times via reductions in specific absorption rate (SAR) and improve image quality. MATERIALS AND METHODS A variable refocusing flip angle SSFSE sequence (vrfSSFSE) was designed and implemented, with simulations and volunteer scans performed to determine suitable flip angle modulation parameters. With Institutional Review Board (IRB) approval/informed consent, patients referred for 3T abdominal magnetic resonance imaging (MRI) were scanned with conventional SSFSE and either half-Fourier (n = 25) or full-Fourier vrfSSFSE (n = 50). Two blinded radiologists semiquantitatively scored images on a scale from -2 to 2 for contrast, noise, sharpness, artifacts, cardiac motion-related signal loss, and the ability to evaluate the pancreas and kidneys. RESULTS vrfSSFSE demonstrated significantly increased speed (∼2-fold, P < 0.0001). Significant improvements in image quality parameters with full-Fourier vrfSSFSE included increased contrast, sharpness, and visualization of pancreatic and renal structures with higher bandwidth technique (mean scores 0.37, 0.83, 0.62, and 0.31, respectively, P ≤ 0.001), and decreased image noise and improved visualization of renal structures when used with an equal bandwidth technique (mean scores 0.96 and 0.35, respectively, P < 0.001). Increased cardiac motion-related signal loss with full-Fourier vrfSSFSE was seen in the pancreas but not the kidney. CONCLUSION vrfSSFSE increases speed at 3T over conventional SSFSE via reduced SAR, and when combined with full-Fourier acquisition can improve image quality, although with some increased sensitivity to cardiac motion-related signal loss.
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Affiliation(s)
- Andreas M Loening
- Department of Radiology, Stanford University School of Medicine, Stanford, California, USA
| | - Manojkumar Saranathan
- Department of Radiology, Stanford University School of Medicine, Stanford, California, USA
| | - Nichanan Ruangwattanapaisarn
- Department of Radiology, Stanford University School of Medicine, Stanford, California, USA.,Department of Diagnostic and Therapeutic Radiology, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Daniel V Litwiller
- GE Healthcare Global MR Applications and Workflow, Rochester, Minnesota, USA
| | - Ann Shimakawa
- GE Healthcare Global MR Applications and Workflow, Menlo Park, California, USA
| | - Shreyas S Vasanawala
- Department of Radiology, Stanford University School of Medicine, Stanford, California, USA
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3D FIESTA pulse sequence for assessing renal artery stenosis: is it a reliable application in unenhanced magnetic resonance angiography? Eur Radiol 2014; 24:3042-50. [DOI: 10.1007/s00330-014-3330-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 06/18/2014] [Accepted: 07/08/2014] [Indexed: 10/25/2022]
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Heyn C, Sue-Chue-Lam D, Jhaveri K, Haider MA. MRI of the pancreas: problem solving tool. J Magn Reson Imaging 2013; 36:1037-51. [PMID: 23090915 DOI: 10.1002/jmri.23708] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Advances in MR hardware and pulse sequence design over the years have improved the quality and robustness of MR imaging of the pancreas. Today, MRI is an indispensible tool for studying the pancreas and can provide useful information not attainable with other noninvasive or minimally invasive imaging techniques. In the present review, specific cases are reviewed where the strengths of MRI demonstrate the utility of this imaging modality as a problem solving tool.
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Affiliation(s)
- Chris Heyn
- Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
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Cai J, Chang Z, Wang Z, Paul Segars W, Yin FF. Four-dimensional magnetic resonance imaging (4D-MRI) using image-based respiratory surrogate: a feasibility study. Med Phys 2012; 38:6384-94. [PMID: 22149822 DOI: 10.1118/1.3658737] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Four-dimensional computed tomography (4D-CT) has been widely used in radiation therapy to assess patient-specific breathing motion for determining individual safety margins. However, it has two major drawbacks: low soft-tissue contrast and an excessive imaging dose to the patient. This research aimed to develop a clinically feasible four-dimensional magnetic resonance imaging (4D-MRI) technique to overcome these limitations. METHODS The proposed 4D-MRI technique was achieved by continuously acquiring axial images throughout the breathing cycle using fast 2D cine-MR imaging, and then retrospectively sorting the images by respiratory phase. The key component of the technique was the use of body area (BA) of the axial MR images as an internal respiratory surrogate to extract the breathing signal. The validation of the BA surrogate was performed using 4D-CT images of 12 cancer patients by comparing the respiratory phases determined using the BA method to those determined clinically using the Real-time position management (RPM) system. The feasibility of the 4D-MRI technique was tested on a dynamic motion phantom, the 4D extended Cardiac Torso (XCAT) digital phantom, and two healthy human subjects. RESULTS Respiratory phases determined from the BA matched closely to those determined from the RPM: mean (± SD) difference in phase: -3.9% (± 6.4%); mean (± SD) absolute difference in phase: 10.40% (± 3.3%); mean (± SD) correlation coefficient: 0.93 (± 0.04). In the motion phantom study, 4D-MRI clearly showed the sinusoidal motion of the phantom; image artifacts observed were minimal to none. Motion trajectories measured from 4D-MRI and 2D cine-MRI (used as a reference) matched excellently: the mean (± SD) absolute difference in motion amplitude: -0.3 (± 0.5) mm. In the 4D-XCAT phantom study, the simulated "4D-MRI" images showed good consistency with the original 4D-XCAT phantom images. The motion trajectory of the hypothesized "tumor" matched excellently between the two, with a mean (± SD) absolute difference in motion amplitude of 0.5 (± 0.4) mm. 4D-MRI was able to reveal the respiratory motion of internal organs in both human subjects; superior-inferior (SI) maximum motion of the left kidney of Subject #1 and the diaphragm of Subject #2 measured from 4D-MRI was 0.88 and 1.32 cm, respectively. CONCLUSIONS Preliminary results of our study demonstrated the feasibility of a novel retrospective 4D-MRI technique that uses body area as a respiratory surrogate.
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Affiliation(s)
- Jing Cai
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710, USA.
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Lee CU, Glockner JF. Vascular staging of renal and adrenal malignancies with a noncontrast enhanced steady state free precession technique. J Magn Reson Imaging 2011; 33:1406-13. [PMID: 21591010 DOI: 10.1002/jmri.22568] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To compare a noncontrast enhanced balanced steady state free precession (bSSFP) MRI technique with a conventional dynamic contrast-enhanced (DCE) three-dimensional (3D) spoiled gradient recalled echo (SPGR) imaging in the vascular staging of renal and adrenal malignancies. MATERIALS AND METHODS Sixty-three MRIs with both bSSFP and DCE acquisitions performed for initial staging of renal and adrenal malignancies were retrospectively evaluated for presence and extent of thrombus in the renal veins and inferior vena cava (IVC). Thrombus characterization was also evaluated. DCE imaging was used as the standard-of-reference. Histopathology was available in 46 of 63 cases as an additional external standard. RESULTS There is very good agreement between bSSFP and DCE imaging for determining the presence or absence of thrombus in the renal veins (r = 0.95; P < 0.0001) and IVC (r = 0.91; P < 0.0001). BSSFP is less successful at distinguishing bland from tumor thrombus. CONCLUSION Noncontrast enhanced bSSFP is an acceptable alternative to DCE imaging for vascular staging of locally advanced renal/adrenal malignancies, with somewhat limited ability to distinguish bland from tumor thrombus.
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Affiliation(s)
- Christine U Lee
- Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA.
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Deeab DA, Dick E, Sergot AA, Sundblon L, Gedroyc W. Magnetic resonance imaging of the small bowel. Radiography (Lond) 2011. [DOI: 10.1016/j.radi.2010.06.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Adamson J, Chang Z, Wang Z, Yin FF, Cai J. Maximum intensity projection (MIP) imaging using slice-stacking MRI. Med Phys 2011; 37:5914-20. [PMID: 21158304 DOI: 10.1118/1.3503850] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To evaluate the feasibility of acquiring maximum intensity projection (MIP) images using a novel slice-stacking MRI (SS-MRI) technique. METHODS The proposed technique employed a steady state acquisition sequence to image multiple axial slices. At each axial slice, the scan is repeated throughout one respiratory cycle. Four objects (small, medium, and large triangles, and a cylinder) moving with a patient breathing trajectory were imaged repeatedly for six times using the slice-stacking MRI and 4D-CT. MIP(SS-MRI) and MIP(4D-CT) were reconstructed. The internal target volume (ITV) was segmented for each object on the six scans and compared between MIP(SS-MRI) and MIP(4D-CT). The medium triangle was also imaged with various motion patterns using slice-stacking MRI, 4D-CT, and sagittal cine-MRI. The corresponding MIP images were reconstructed and volume/area measurements were performed and compared between different imaging methods. Three healthy volunteers underwent the slice-stacking MRI and sagittal cine-MRI scans. A region of interest (ROI) was selected and contoured for each subject in both MIP(SS-MRI) and MIP(cine-MRI). The area of the selected ROI was computed and compared. RESULTS Volume comparison between MIP(SS-MRI) and MIP(4D-CT) showed statistically insignificant (p > 0.05 in all cases) difference in the mean ITVs for all four objects. For the study of the medium triangle with multiple motion patterns, there was a good agreement in the measured ITVs between MIP(SS-MRI) and MIP(4D-CT) (p = 0.46, correlation coefficient = 0.91), with a mean difference of 1.4% +/- 4.4%. The area measurements between MIP(SS-MRI) and MIP(cine-MRI) also showed good agreement (p=0.47, correlation coefficient = 0.97), with a mean difference of 0.2% +/- 2.9%. For the healthy volunteer study, the average difference in the area of selected ROI was -2.5% +/- 2.5% between MIP(SS-MRI) and MIP(cine-MRI). CONCLUSIONS These preliminary results showed good agreement in volume/area measurements between the slice-stacking MRI technique and 4D-CT/cine-MRI, indicating that it is feasible to use this technique for MIP imaging.
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Affiliation(s)
- Justus Adamson
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27707, USA
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Diagnostic accuracy of whole-body MRI/DWI image fusion for detection of malignant tumours: a comparison with PET/CT. Eur Radiol 2010; 21:246-55. [PMID: 20717828 DOI: 10.1007/s00330-010-1929-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 07/15/2010] [Accepted: 07/21/2010] [Indexed: 12/18/2022]
Abstract
OBJECTIVE To prospectively evaluate the diagnostic accuracy of whole-body T2-weighted (wbT2), whole-body diffusion-weighted imaging (wbDWI) and wbT2/wbDWI image fusion for malignant tumour detection compared with PET/CT. METHODS Sixty-eight patients (44 men; 60 ± 14 years) underwent PET/CT for staging of malignancy and were consecutively examined by 1.5-Tesla MRI including wbT2 and wbDWI. Two radiologists independently assessed wbDWI, wbT2, wbT2 + wbDWI (side-by-side) and wbT2 + wbDWI + wbT2/wbDWI image fusion for the presence of malignancy. PET/CT served as a reference standard. RESULTS PET/CT revealed 374 malignant lesions in 48/64 (75%) patients. Detection rates and positive predictive value (PPV) of wbT2 and wbDWI alone were 64% and 84%, and 57% and 93%, respectively. Detection rates and PPV of wbT2 and wbDWI for side-by-side analysis without and with fused images were 72% and 89%, and 74% and 91%, respectively. The detection rate was significantly higher with side-by-side analysis and fused image analysis compared with wbT2 and wbDWI alone (p = .0159; p < .0001). There was no significant difference between fused image interpretation and side-by-side analysis. CONCLUSIONS WbDWI allows detection of malignant lesions with a similar detection rate to wbT2. Side-by-side analysis of wbT2 and wbDWI significantly improves the overall detection rate and fused image data provides no added value.
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