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Chandra Sekhar P, Rangasami R, Andrew C, Natarajan P. Measurement of apparent diffusion coefficient (ADC) in fetal organs and placenta using 3 Tesla magnetic resonance imaging (MRI) across gestational ages. Sci Rep 2024; 14:23811. [PMID: 39394357 PMCID: PMC11470107 DOI: 10.1038/s41598-024-73902-x] [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: 05/21/2024] [Accepted: 09/23/2024] [Indexed: 10/13/2024] Open
Abstract
Diffusion-weighted imaging (DWI) is a technique used to probe the random microscopic motion of water protons in living tissue, represented by a parameter measurement of apparent diffusion coefficient (ADC) values. This study aimed to measure the ADC values of various fetal organs and placenta using 3T at various gestational ages. This was a prospective observational study. A total of 103 singleton pregnancies from 20 to 38 weeks of gestational age were included. Diffusion-weighted imaging was performed in the axial plane from the fetal head to the trunk with the following parameters: TR: 2000-2500 ms; TE: 88 ms; FOV: 250 mm; 256 matrix; slice thickness: 4 mm with a 0 mm gap; acquisition time: 1 min, 18 s. Diffusion gradient values were b = 0 and b = 700 s/mm2. ADC was measured in fetal brain regions (frontal white matter, occipital white matter, centrum semiovale, pons, thalamus, cerebellum, and fetal organs (lungs, kidney, and placenta). ANOVA was used to calculate the mean ADC values. Karl Pearson's coefficient of correlation was used to evaluate the correlation between ADC values and increasing gestational age. The mean ADC values of brain regions were: frontal white matter (1.64 ± 0.08 × 10- 3 mm2 /s, F-39.10,p-<0.001), occipital white matter (1.64 ± 0.06 × 10- 3 mm2/s, F-26.14, p-<0.001), centrum semiovale (1.62 ± 0.03 × 10- 3 mm2/s, F-49.88,p-<0.001, pons (1.23 ± 0.09 × 10- 3 mm2/s F-9.14,p-<0.001) ), Thalamus (1.21 ± 0.07 × 10- 3 mm2/s, F-13.54,p-<0.001) and cerebellum (1.36 ± 0.10 × 10- 3 mm2 /s, F-4.19,p-<0.001). The mean ADC values of fetal organs were lung (1.92 ± 0.15 × 10- 3 mm2 /s, F-28.24, p-<0.001), kidney (1.34 ± 0.11 × 10- 3 mm2 /s, F-1.05, p- 0.37) and placenta (1.94 ± 0.11 × 10- 3 mm2 /s, F-160.33, p-<0.001). White-matter regions showed a significant positive correlation with increasing gestational age. Statistically, a negative correlation was observed between increasing gestational age and ADC measurements obtained in the thalamus, cerebellum, pons, and kidney. This will be one of the first few studies to provide the ADC values of the fetal brain and fetal organs using 3T MRI. The current study shows that diffusion-weighted MRI can offer a promising technique to evaluate the structural development of fetal organs and can potentially lead to a biomarker for predicting the functionality of the fetal organs in abnormalities.
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Affiliation(s)
- Priyanka Chandra Sekhar
- Department of Radiology, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, 600116, India.
- Department of Allied Health Sciences, The Apollo University, Chittoor, India.
| | - Rajeswaran Rangasami
- Department of Radiology, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, 600116, India
| | - Chitra Andrew
- Department of Fetal Medicine, Sri Ramachandra Institute of Higher Education and Research, Chennai, 600116, India
| | - Paarthipan Natarajan
- Department of Radiology, Saveetha Medical College and Hospital, Chennai, 602105, India
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Danzer E, Peña-Trujillo V, Gallo-Bernal S, Gee MS, Victoria T. Neonatal Anthropometric Measurements: A Comparison of Neonates With 3-T Fetal MRI Exposure, With 1.5-T Fetal MRI Exposure, and Without In-Utero MRI Exposure. AJR Am J Roentgenol 2024. [PMID: 39230404 DOI: 10.2214/ajr.24.31647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
Background: Fetal MRI is increasingly performed at 3 T. Nonetheless, safety concerns persist regarding potential increased risk of intrauterine growth restriction from in-utero 3-T MRI exposure. Objective: To compare neonatal anthropometric measurements between newborns who underwent 3-T fetal MRI, newborns who underwent 1.5-T fetal MRI, and newborns without in utero MRI exposure. Methods: This single-center retrospective study included gravid patients who underwent fetal ultrasound and possible 1.5-T or 3-T fetal MRI within 10 days from January 2017 to January 2022. For each included patient who also underwent 3-T fetal MRI, one matched patient who also underwent 1.5-T MRI and two matched patients without in-utero MRI exposure, were randomly selected. Matching was based on gestational age per the fetal ultrasound. Neonatal anthropometric characteristics were compared among groups. Results: The final sample included 416 patients (mean age, 32±5 years), 104 in the 3-T MRI group, 104 in the 1.5-T MRI group, and 208 in the MRI-unexposed group. Mean gestational age at the time of fetal ultrasound used for matching was 27 weeks 2 days in the 3-T group, 25 weeks 2 days in the 1.5-T group, and 26 weeks 0 days in the MRI-unexposed group (p=.07). The distribution of indications for fetal MRI was not significantly different between the 3-T and 1.5-T groups (p=.62). Mean gestational age at delivery was 37 weeks 5 days in the 3-T group, 38 weeks 0 day in the 1.5-T group, and 38 weeks 2 days in the unexposed group (p=.51). No significant difference (p=.09) was observed among groups in mean neonatal weight (3-T: 3120±753 g; 1.5-T: 3104±704 g; unexposed: 2967±614 g); neonatal weight percentile (3-T: 45±27; 1.5-T: 42±26; MRI: 41±24); neonatal head circumference (3-T: 34±3 cm; 1.5-T: 34±3 cm; unexposed: 34±2 cm), or neonatal head circumference percentile (3-T: 48±29; 1.5-T: 42±23; unexposed: 43±30). Conclusion: There were no significant differences in neonatal anthropometric measurements among newborns who underwent in-utero 3-T MRI, newborns who underwent in-utero 1.5-T MRI, and newborns without in-utero MRI exposure. Clinical Impact: The results support the safety of 3-T MRI with respect to growth of the developing fetus.
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Affiliation(s)
- Enrico Danzer
- Division of Pediatric Surgery, Memorial Sloan Kettering Cancer Center, Weill Cornell Medical College, New York, NY
- Division of Neonatal and Developmental Medicine, Stanford University School of Medicine and Lucile Packard Children's Hospital, Palo Alto, CA
| | - Valeria Peña-Trujillo
- Department of Pediatric Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA
- Pediatric Imaging Research Center (PIRC), Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Sebastian Gallo-Bernal
- Department of Pediatric Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA
- Pediatric Imaging Research Center (PIRC), Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Medicine, NYC Health + Hospitals, Icahn School of Medicine at Mount Sinai, Elmhurst, NY, USA
| | - Michael S Gee
- Department of Pediatric Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA
- Pediatric Imaging Research Center (PIRC), Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Teresa Victoria
- Department of Pediatric Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA
- Pediatric Imaging Research Center (PIRC), Massachusetts General Hospital, Boston, Massachusetts, USA
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Peña-Trujillo V, Gallo-Bernal S, Kirsch J, Victoria T, Gee MS. 3 Tesla Fetal MR Imaging Quality and Safety Considerations. Magn Reson Imaging Clin N Am 2024; 32:385-394. [PMID: 38944429 DOI: 10.1016/j.mric.2024.02.007] [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: 07/01/2024]
Abstract
Medical imaging, particularly fetal MR imaging, has undergone a transformative shift with the introduction of 3 Tesla (3T) clinical MR imaging systems. The utilization of higher static magnetic fields in these systems has resulted in remarkable advancements, including superior soft tissue contrast, improved spatial and temporal resolution, and reduced image acquisition time. Despite these notable benefits, safety concerns have emerged, stemming from the elevated static magnetic field strength, amplified acoustic noise, and increased radiofrequency power deposition. This article provides an overview of fetal MR imaging at 3T, its benefits and drawbacks, and the potential safety issues.
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Affiliation(s)
- Valeria Peña-Trujillo
- Department of Radiology, Massachusetts General Hospital, 55 Fruit Strret, Boston, MA 02114, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA; Pediatric Imaging Research Center (PIRC), Massachusetts General Hospital, 55 Fruit Strret, Boston, MA 02114, USA
| | - Sebastian Gallo-Bernal
- Department of Radiology, Massachusetts General Hospital, 55 Fruit Strret, Boston, MA 02114, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA; Pediatric Imaging Research Center (PIRC), Massachusetts General Hospital, 55 Fruit Strret, Boston, MA 02114, USA; Department of Medicine, NYC Health + Hospitals/Queens, Icahn School of Medicine at Mount Sinai, 79-01 Broadway, Queens, NY 11373, USA
| | - John Kirsch
- Department of Radiology, Massachusetts General Hospital, 55 Fruit Strret, Boston, MA 02114, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA; A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 13th, Chartlestown, MA 02129, USA
| | - Teresa Victoria
- Department of Radiology, Massachusetts General Hospital, 55 Fruit Strret, Boston, MA 02114, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA; Pediatric Imaging Research Center (PIRC), Massachusetts General Hospital, 55 Fruit Strret, Boston, MA 02114, USA
| | - Michael S Gee
- Department of Radiology, Massachusetts General Hospital, 55 Fruit Strret, Boston, MA 02114, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA; Pediatric Imaging Research Center (PIRC), Massachusetts General Hospital, 55 Fruit Strret, Boston, MA 02114, USA.
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Zhong N, Mi Q, Lu M, Jiang H, Zhang Y. Evaluation of twin fetal exposure to radiofrequency field during magnetic resonance imaging. RADIATION PROTECTION DOSIMETRY 2024; 200:791-801. [PMID: 38777801 DOI: 10.1093/rpd/ncae119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 02/17/2024] [Accepted: 04/14/2024] [Indexed: 05/25/2024]
Abstract
Fetal development is essential to the human lifespan. As more and more multifetal gestations have been reported recently, clinical diagnosis using magnetic resonance imaging (MRI), which introduced radiofrequency (RF) exposure, raised public concerns. The present study developed two whole-body pregnant models of 31 and 32 gestational weeks (GWs) with twin fetuses and explored RF exposure by 1.5 and 3.0 T MRI. Differences in the relative position of the fetus and changes in fetal weight can cause differences in fetal peak local specific absorption rate averaged over 10 g tissue (pSAR10g). Variation of pSAR10g due to different fetal positions can be ~35%. Numerically, twin and singleton fetal pSAR10g results were not significantly different, however twin results exceeded the limit in some cases (e.g. fetuses of 31 GW at 1.5 T), which indicated the necessity for further research employing anatomically correct twin-fetal models coming from various GWs and particular sequence to be applied.
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Affiliation(s)
- Nan Zhong
- China Academy of Information and Communications Technology, No. 52 Huayuanbei Road, Haidian District, Beijing 100191, China
| | - Qunzheng Mi
- China Academy of Information and Communications Technology, No. 52 Huayuanbei Road, Haidian District, Beijing 100191, China
| | - Meng Lu
- China Academy of Information and Communications Technology, No. 52 Huayuanbei Road, Haidian District, Beijing 100191, China
| | - Haoyu Jiang
- China Academy of Information and Communications Technology, No. 52 Huayuanbei Road, Haidian District, Beijing 100191, China
| | - Yi Zhang
- China Academy of Information and Communications Technology, No. 52 Huayuanbei Road, Haidian District, Beijing 100191, China
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Yetisir F, Abaci Turk E, Adalsteinsson E, Wald LL, Grant PE. Local SAR management strategies to use two-channel RF shimming for fetal MRI at 3 T. Magn Reson Med 2024; 91:1165-1178. [PMID: 37929768 PMCID: PMC10843691 DOI: 10.1002/mrm.29913] [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: 07/12/2023] [Revised: 10/10/2023] [Accepted: 10/16/2023] [Indexed: 11/07/2023]
Abstract
PURPOSE This study evaluates the imaging performance of two-channel RF-shimming for fetal MRI at 3 T using four different local specific absorption rate (SAR) management strategies. METHODS Due to the ambiguity of safe local SAR levels for fetal MRI, local SAR limits for RF shimming were determined based on either each individual's own SAR levels in standard imaging mode (CP mode) or the maximum SAR level observed across seven pregnant body models in CP mode. Local SAR was constrained either indirectly by further constraining the whole-body SAR (wbSAR) or directly by using subject-specific local SAR models. Each strategy was evaluated by the improvement of the transmit field efficiency (average |B1 + |) and nonuniformity (|B1 + | variation) inside the fetus compared with CP mode for the same wbSAR. RESULTS Constraining wbSAR when using RF shimming decreases B1 + efficiency inside the fetus compared with CP mode (by 12%-30% on average), making it inefficient for SAR management. Using subject-specific models with SAR limits based on each individual's own CP mode SAR value, B1 + efficiency and nonuniformity are improved on average by 6% and 13% across seven pregnant models. In contrast, using SAR limits based on maximum CP mode SAR values across seven models, B1 + efficiency and nonuniformity are improved by 13% and 25%, compared with the best achievable improvement without SAR constraints: 15% and 26%. CONCLUSION Two-channel RF-shimming can safely and significantly improve the transmit field inside the fetus when subject-specific models are used with local SAR limits based on maximum CP mode SAR levels in the pregnant population.
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Affiliation(s)
- Filiz Yetisir
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children’s Hospital, Boston, MA, USA
| | - Esra Abaci Turk
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children’s Hospital, Boston, MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Elfar Adalsteinsson
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Lawrence L. Wald
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - P. Ellen Grant
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children’s Hospital, Boston, MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
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Thanh Thi Nguyen T, Mai Duy Le H, Thanh Nguyen D, Quang Nguyen H, Hoang Nguyen N, Tan Vo D, Cong Phan C. The Role of Magnetic Resonance Pulse Sequences in the Diagnosis of Acute Appendicitis in Pregnant Women. Cureus 2023; 15:e51312. [PMID: 38288189 PMCID: PMC10823294 DOI: 10.7759/cureus.51312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2023] [Indexed: 01/31/2024] Open
Abstract
INTRODUCTION Acute appendicitis (AA) is one of the most common surgical emergencies, with a lifetime risk estimated at 7-8%. Pregnant women with appendicitis can have a difficult diagnosis because many signs and symptoms could overlap with other causes of acute abdominal pain. Although magnetic resonance imaging (MRI) is not contraindicated at all gestational ages for units with a field strength of three Tesla or less, there is still much discussion regarding the best protocol to follow in order to minimize survey time and maximize diagnostic efficiency. The purpose of this study was to assess how well different MR pulse sequences can diagnose AA. METHODS This retrospective study involved 179 pregnant females. All patients treated and admitted to the University Medical Center, Ho Chi Minh City, Vietnam, between January 2016 and October 2023 had their MR scans and medical data examined. MRI results were assessed and compared with surgical and histopathological findings. RESULTS The mean age of the population was 29.7 ± 4.8 years (range, 18-46 years). On T1-weighted (T1W) and T2-weighted (T2W) sequences, the appendix was clearly visualized at rates of 81.8% and 89.9%, respectively. The sensitivity and specificity of the T2W in diagnosing AA were 93.5% and 92.3%, and when combined with T1W and diffusion-weighted (DW) images, the sensitivity and specificity further increased, being 96.8% and 94.9%, respectively. The predictive value of non-AA of the T1 bright appendix sign was 95.6%. CONCLUSION Our study supports the use of MRI as an imaging test to identify appendicitis during pregnancy, as it has been shown to be a useful method for diagnosing the condition in pregnant women. The T2W pulse sequence is a useful tool for diagnosing appendicitis because of its high sensitivity and specificity. When identifying appendicitis from T2W alone proves challenging, T1W with the T1 bright sign and DW to take advantage of the appendix lumen and/or wall's diffusion features can yield additional information and boost diagnostic confidence.
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Affiliation(s)
- Thien Thanh Thi Nguyen
- Department of Diagnostic Imaging, University Medical Center of Ho Chi Minh City, Ho Chi Minh, VNM
| | - Huyen Mai Duy Le
- Department of Diagnostic Imaging, University Medical Center of Ho Chi Minh City, Ho Chi Minh, VNM
| | - Duy Thanh Nguyen
- Department of Diagnostic Imaging, University Medical Center of Ho Chi Minh City, Ho Chi Minh, VNM
| | - Hieu Quang Nguyen
- Department of Diagnostic Imaging, University Medical Center of Ho Chi Minh City, Ho Chi Minh, VNM
| | - Nam Hoang Nguyen
- Department of Diagnostic Imaging, University Medical Center of Ho Chi Minh City, Ho Chi Minh, VNM
| | - Duc Tan Vo
- Department of Diagnostic Imaging, University Medical Center of Ho Chi Minh City, Ho Chi Minh, VNM
| | - Chien Cong Phan
- Department of Diagnostic Imaging, University Medical Center of Ho Chi Minh City, Ho Chi Minh, VNM
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Maralani PJ, Pai V, Ertl-Wagner BB. Safety of Magnetic Resonance Imaging in Pregnancy. RADIOLOGIE (HEIDELBERG, GERMANY) 2023; 63:34-40. [PMID: 37747489 DOI: 10.1007/s00117-023-01207-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/24/2023] [Indexed: 09/26/2023]
Abstract
Magnetic resonance imaging is being increasingly used to diagnose and follow up a variety of medical conditions in pregnancy, both for maternal and fetal indications. However, limited data regarding its safe use in pregnancy may be a source of anxiety and avoidance for both patients and their healthcare providers. In this review, we critically discuss the main safety concerns of Magnetic Resonance Imaging (MRI) in pregnancy including energy deposition, acoustic noise, and use of contrast agents, supported by data from animal and human studies. Use of maternal sedatives and concerns related to occupational exposure in pregnant personnel are also addressed. Exposure to gadolinium-based contrast agents and sedation for MRI during pregnancy should be avoided whenever feasible.
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Affiliation(s)
- Pejman Jabehdar Maralani
- Department of Medical Imaging, Sunnybrook Health Sciences Centre, Bayview Avenue, Room AG270C, 2075, Toronto, Ontario, Canada.
| | - Vivek Pai
- Department of Medical Imaging, University of Toronto, The Hospital for Sick Children, 555 University Ave, M5G 1X8, Toronto, ON, Canada
| | - Birgit B Ertl-Wagner
- Department of Medical Imaging, University of Toronto, The Hospital for Sick Children, 555 University Ave, M5G 1X8, Toronto, ON, Canada
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DastAmooz S, Broujeni ST, Sarahian N. A primary study on rat fetal development and brain-derived neurotrophic factor levels under the control of electromagnetic fields. J Public Health Afr 2023; 14:2347. [PMID: 37538938 PMCID: PMC10395370 DOI: 10.4081/jphia.2023.2347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 12/22/2022] [Indexed: 08/05/2023] Open
Abstract
Background In previous researches, electromagnetic fields have been shown to adversely affect the behavior and biology of humans and animals; however, body growth and brain-derived neurotrophic factor levels were not evaluated. Objective The original investigation aimed to examine whether Electromagnetic Fields (EMF) exposure had adverse effects on spatial learning and motor function in rats and if physical activity could diminish the damaging effects of EMF exposure. In this study, we measured anthropometric measurements and brain-derived neurotrophic factor (BDNF) levels in pregnant rats' offspring to determine if Wi-Fi EMF also affected their growth. These data we report for the first time in this publication. Methods Twenty Albino-Wistar pregnant rats were divided randomly into EMF and control (CON) groups, and after delivery, 12 male fetuses were randomly selected. For assessing the body growth change of offspring beginning at delivery, then at 21 postnatal days, and finally at 56 post-natal days, the crown-rump length of the body was assessed using a digital caliper. Examining BDNF factor levels, an Enzyme-linked immunosorbent assay ELISA kit was taken. Bodyweight was recorded by digital scale. Results Outcomes of the anthropometric measurements demonstrated that EMF blocked body growth in rats exposed to EMF. The results of the BDNF test illustrated that the BDNF in the EMF liter group was remarkably decreased compared to the CON group. The results indicate that EMF exposure could affect BDNF levels and harm body growth in pregnant rats' offspring. Conclusions The results suggest that EMF exposure could affect BDNF levels and impair body growth in pregnant rats' offspring.
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Affiliation(s)
- Sima DastAmooz
- Department of Sport Science and Physical Education, Chinese University of Hong Kong, China
| | - Shahzad Tahmasebi Broujeni
- Department of Behavioral and Cognitive Sciences in Sport, Faculty of Sport Sciences and Health, University of Tehran, Iran
| | - Nahid Sarahian
- Neuroscience Research Center, Shahid Beheshti University of Medical Science, Tehran, Iran
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Cook N, Shelton N, Gibson S, Barnes P, Alinaghi-Zadeh R, Jameson MG. ACPSEM position paper: the safety of magnetic resonance imaging linear accelerators. Phys Eng Sci Med 2023; 46:19-43. [PMID: 36847966 PMCID: PMC10030425 DOI: 10.1007/s13246-023-01224-9] [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] [Accepted: 01/19/2023] [Indexed: 03/01/2023]
Abstract
Magnetic Resonance Imaging linear-accelerator (MRI-linac) equipment has recently been introduced to multiple centres in Australia and New Zealand. MRI equipment creates hazards for staff, patients and others in the MR environment; these hazards must be well understood, and risks managed by a system of environmental controls, written procedures and a trained workforce. While MRI-linac hazards are similar to the diagnostic paradigm, the equipment, workforce and environment are sufficiently different that additional safety guidance is warranted. In 2019 the Australasian College of Physical Scientists and Engineers in Medicine (ACPSEM) formed the Magnetic Resonance Imaging Linear-Accelerator Working Group (MRILWG) to support the safe clinical introduction and optimal use of MR-guided radiation therapy treatment units. This Position Paper is intended to provide safety guidance and education for Medical Physicists and others planning for and working with MRI-linac technology. This document summarises MRI-linac hazards and describes particular effects which arise from the combination of strong magnetic fields with an external radiation treatment beam. This document also provides guidance on safety governance and training, and recommends a system of hazard management tailored to the MRI-linac environment, ancillary equipment, and workforce.
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Affiliation(s)
- Nick Cook
- Christchurch Hospital, Christchurch, New Zealand
| | - Nikki Shelton
- Olivia Newton-John Cancer Wellness and Research Centre, Heidelberg, VIC Australia
| | | | | | - Reza Alinaghi-Zadeh
- Olivia Newton-John Cancer Wellness and Research Centre, Heidelberg, VIC Australia
| | - Michael G. Jameson
- GenesisCare, Sydney, NSW Australia
- University of New South Wales, Sydney, Australia
| | - on behalf of the ACPSEM Magnetic Resonance Imaging Linac Working Group (MRILWG)
- Christchurch Hospital, Christchurch, New Zealand
- Olivia Newton-John Cancer Wellness and Research Centre, Heidelberg, VIC Australia
- Townsville Cancer Centre, Douglas, QLD Australia
- Austin Health, Heidelberg, VIC Australia
- GenesisCare, Sydney, NSW Australia
- University of New South Wales, Sydney, Australia
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Hakim A, Kurmann C, Pospieszny K, Meinel TR, Shahin MA, Heldner MR, Umarova R, Jung S, Arnold M, El-Koussy M. Diagnostic Accuracy of High-Resolution 3D T2-SPACE in Detecting Cerebral Venous Sinus Thrombosis. AJNR Am J Neuroradiol 2022; 43:881-886. [PMID: 35618422 DOI: 10.3174/ajnr.a7530] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 04/12/2022] [Indexed: 12/26/2022]
Abstract
BACKGROUND AND PURPOSE Assessment of cerebral venous sinus thrombosis on MR imaging can be challenging. The aim of this study was to evaluate the diagnostic accuracy of high-resolution 3D T2 sampling perfection with application-optimized contrasts by using different flip angle evolution (SPACE) in patients with cerebral venous sinus thrombosis and to compare its performance with contrast-enhanced 3D T1-MPRAGE. MATERIALS AND METHODS We performed a blinded retrospective analysis of T2-SPACE and contrast-enhanced MPRAGE sequences from patients with cerebral venous sinus thrombosis and a control group. The results were compared with a reference standard, which was based on all available sequences and clinical history. Subanalyses were performed according to the venous segment involved and the clinical stage of the thrombus. RESULTS Sixty-three MR imaging examinations from 35 patients with cerebral venous sinus thrombosis and 51 examinations from 40 control subjects were included. The accuracy, sensitivity, and specificity calculated from the initial MR imaging examination for each patient were 100% each for T2-SPACE and 95%, 91%, and 98%, respectively, for contrast-enhanced MPRAGE. The interrater reliability was high for both sequences. In the subanalysis, the accuracy for each venous segment involved and if subdivided according to the clinical stage of thrombus was ≥95% and ≥85% for T2-SPACE and contrast-enhanced MPRAGE, respectively. CONCLUSIONS Both T2-SPACE and contrast-enhanced MPRAGE offer high accuracy for the detection and exclusion of cerebral venous sinus thrombosis; however, T2-SPACE showed a better overall performance and thus could be a useful tool if included in a multiparametric MR imaging protocol for the diagnosis of cerebral venous sinus thrombosis, especially in scenarios where gadolinium administration is contraindicated.
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Affiliation(s)
- A Hakim
- From the University Institute of Diagnostic and Interventional Neuroradiology (A.H., C.K., K.P., M.E.), Bern University Hospital, Inselspital, Inselspital, University of Bern, Bern, Switzerland
| | - C Kurmann
- From the University Institute of Diagnostic and Interventional Neuroradiology (A.H., C.K., K.P., M.E.), Bern University Hospital, Inselspital, Inselspital, University of Bern, Bern, Switzerland
| | - K Pospieszny
- From the University Institute of Diagnostic and Interventional Neuroradiology (A.H., C.K., K.P., M.E.), Bern University Hospital, Inselspital, Inselspital, University of Bern, Bern, Switzerland
| | - T R Meinel
- Department of Neurology (T.R.M., M.R.H., R.U., S.J., M.A.), Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - M A Shahin
- Department of Radiodiagnosis (M.A.S.), Faculty of Medicine, Cairo University Hospitals, Cairo, Egypt
| | - M R Heldner
- Department of Neurology (T.R.M., M.R.H., R.U., S.J., M.A.), Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - R Umarova
- Department of Neurology (T.R.M., M.R.H., R.U., S.J., M.A.), Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - S Jung
- Department of Neurology (T.R.M., M.R.H., R.U., S.J., M.A.), Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - M Arnold
- Department of Neurology (T.R.M., M.R.H., R.U., S.J., M.A.), Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - M El-Koussy
- From the University Institute of Diagnostic and Interventional Neuroradiology (A.H., C.K., K.P., M.E.), Bern University Hospital, Inselspital, Inselspital, University of Bern, Bern, Switzerland
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11
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Noetscher GM, Serano P, Wartman WA, Fujimoto K, Makarov SN. Visible Human Project® female surface based computational phantom (Nelly) for radio-frequency safety evaluation in MRI coils. PLoS One 2021; 16:e0260922. [PMID: 34890429 PMCID: PMC8664205 DOI: 10.1371/journal.pone.0260922] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 11/19/2021] [Indexed: 11/19/2022] Open
Abstract
Quantitative modeling of specific absorption rate and temperature rise within the human body during 1.5 T and 3 T MRI scans is of clinical significance to ensure patient safety. This work presents justification, via validation and comparison, of the potential use of the Visible Human Project (VHP) derived Computer Aided Design (CAD) female full body computational human model for non-clinical assessment of female patients of age 50–65 years with a BMI of 30–36 during 1.5 T and 3 T based MRI procedures. The initial segmentation validation and four different application examples have been identified and used to compare to numerical simulation results obtained using VHP Female computational human model under the same or similar conditions. The first application example provides a simulation-to-simulation validation while the latter three application examples compare with measured experimental data. Given the same or similar coil settings, the computational human model generates meaningful results for SAR, B1 field, and temperature rise when used in conjunction with the 1.5 T birdcage MRI coils or at higher frequencies corresponding to 3 T MRI. Notably, the deviation in temperature rise from experiment did not exceed 2.75° C for three different heating scenarios considered in the study with relative deviations of 10%, 25%, and 20%. This study provides a reasonably systematic validation and comparison of the VHP-Female CAD v.3.0–5.0 surface-based computational human model starting with the segmentation validation and following four different application examples.
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Affiliation(s)
- Gregory M. Noetscher
- Department of Electrical and Computer Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
- NEVA Electromagnetics, LLC, Yarmouth Port, Massachusetts, United States of America
- * E-mail:
| | - Peter Serano
- Ansys, Inc., Canonsburg, Pennsylvania, United States of America
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
| | - William A. Wartman
- Department of Electrical and Computer Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Kyoko Fujimoto
- Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Sergey N. Makarov
- Department of Electrical and Computer Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
- NEVA Electromagnetics, LLC, Yarmouth Port, Massachusetts, United States of America
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
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12
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Understanding MNPs Behaviour in Response to AMF in Biological Milieus and the Effects at the Cellular Level: Implications for a Rational Design That Drives Magnetic Hyperthermia Therapy toward Clinical Implementation. Cancers (Basel) 2021; 13:cancers13184583. [PMID: 34572810 PMCID: PMC8465027 DOI: 10.3390/cancers13184583] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/03/2021] [Accepted: 09/07/2021] [Indexed: 12/11/2022] Open
Abstract
Simple Summary Magnetic hyperthermia therapy is an alternative treatment for cancer that complements traditional therapies and that has shown great promise in recent years. In this review, we assess the current applications of this therapy in order to understand why its translation from the laboratory to the clinic has been less smooth than was anticipated, identifying the possible bottlenecks and proposing solutions to the problems encountered. Abstract Hyperthermia has emerged as a promising alternative to conventional cancer therapies and in fact, traditional hyperthermia is now commonly used in combination with chemotherapy or surgery during cancer treatment. Nevertheless, non-specific application of hyperthermia generates various undesirable side-effects, such that nano-magnetic hyperthermia has arisen a possible solution to this problem. This technique to induce hyperthermia is based on the intrinsic capacity of magnetic nanoparticles to accumulate in a given target area and to respond to alternating magnetic fields (AMFs) by releasing heat, based on different principles of physics. Unfortunately, the clinical implementation of nano-magnetic hyperthermia has not been fluid and few clinical trials have been carried out. In this review, we want to demonstrate the need for more systematic and basic research in this area, as many of the sub-cellular and molecular mechanisms associated with this approach remain unclear. As such, we shall consider here the biological effects that occur and why this theoretically well-designed nano-system fails in physiological conditions. Moreover, we will offer some guidelines that may help establish successful strategies through the rational design of magnetic nanoparticles for magnetic hyperthermia.
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13
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Yetisir F, Abaci Turk E, Guerin B, Gagoski BA, Grant PE, Adalsteinsson E, Wald LL. Safety and imaging performance of two-channel RF shimming for fetal MRI at 3T. Magn Reson Med 2021; 86:2810-2821. [PMID: 34240759 DOI: 10.1002/mrm.28895] [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: 04/23/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 11/07/2022]
Abstract
PURPOSE This study investigates whether two-channel radiofrequency (RF) shimming can improve imaging without increasing specific absorption rate (SAR) for fetal MRI at 3T. METHODS Transmit field ( B 1 + ) average and variation in the fetus was simulated in seven numerical pregnant body models. Safety was quantified by maternal and fetal peak local SAR and fetal average SAR. The shim parameter space was divided into improved B 1 + (magnitude and homogeneity) and improved SAR regions, and an overlap where RF shimming improved both classes of metrics compared with birdcage mode was assessed. Additionally, the effect of fetal position, tissue detail, and dielectric properties on transmit field and SAR was studied. RESULTS A region of subject-specific RF shim parameter space improving both B 1 + and SAR metrics was found for five of the seven models. Optimizing only B 1 + metrics improved B 1 + efficiency across models by 15% on average and 28% for the best-case model. B 1 + variation improved by 26% on average and 49% for the best case. However, for these shim settings, fetal SAR increased by up to 106%. The overlap region, where both B 1 + and SAR metrics improve, showed an average B 1 + efficiency improvement of 6% on average across models and 19% for the best-case model. B 1 + variation improved by 13% on average and 40% for the best case. RFS could also decrease maternal/fetal SAR by up to 49%/58%. CONCLUSION RF shimming can improve imaging compared with birdcage mode without increasing fetal and maternal SAR when a patient-specific SAR model is incorporated into the shimming procedure.
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Affiliation(s)
- Filiz Yetisir
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Esra Abaci Turk
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts, USA
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Bastien Guerin
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Borjan A Gagoski
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts, USA
- Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - P Ellen Grant
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts, USA
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
- Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Elfar Adalsteinsson
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Lawrence L Wald
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA
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14
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Jabehdar Maralani P, Kapadia A, Liu G, Moretti F, Ghandehari H, Clarke SE, Wiebe S, Garel J, Ertl-Wagner B, Hurrell C, Schieda N. Canadian Association of Radiologists Recommendations for the Safe Use of MRI During Pregnancy. Can Assoc Radiol J 2021; 73:56-67. [PMID: 34000852 DOI: 10.1177/08465371211015657] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The use of magnetic resonance imaging (MRI) during pregnancy is associated with concerns among patients and health professionals with regards to fetal safety. In this work, the Canadian Association of Radiologists (CAR) Working Group on MRI in Pregnancy presents recommendations for the use of MRI in pregnancy, derived from literature review as well as expert panel opinions and discussions. The working group, which consists of academic subspecialty radiologists and obstetrician-gynaecologists, aimed to provide updated, evidence-based recommendations addressing safety domains related to energy deposition, acoustic noise, and gadolinium-based contrast agent use based on magnetic field strength (1.5T and 3T) and trimester scanned, in addition to the effects of sedative use and occupational exposure.
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Affiliation(s)
| | - Anish Kapadia
- Department of Medical Imaging, 7938University of Toronto, Toronto, Ontario, Canada
| | - Grace Liu
- Department of Obstetrics and Gynecology, 7938University of Toronto, Toronto, Ontario, Canada
| | - Felipe Moretti
- Department of Obstetrics and Gynecology, 12365University of Ottawa, Ottawa, Ontario, Canada
| | - Hournaz Ghandehari
- Department of Medical Imaging, 7938University of Toronto, Toronto, Ontario, Canada
| | - Sharon E Clarke
- Department of Diagnostic Radiology, 3688Dalhousie University, Halifax, Nova Scotia, Canada
| | - Sheldon Wiebe
- Department of Medical Imaging, 12371University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Juliette Garel
- Département de radiologie, radio-oncologie et médecine nucléaire, Université de Montréal, Montréal, Québec, Canada
| | - Birgit Ertl-Wagner
- Department of Medical Imaging, 7938University of Toronto, Toronto, Ontario, Canada
| | - Casey Hurrell
- Research and Policy Development - Canadian Association of Radiologists, Ottawa, Ontario, Canada
| | - Nicola Schieda
- Department of Radiology, 12365University of Ottawa, Ottawa, Ontario, Canada
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15
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Seo Y, Wang ZJ. Measurement and evaluation of specific absorption rate and temperature elevation caused by an artificial hip joint during MRI scanning. Sci Rep 2021; 11:1134. [PMID: 33441883 PMCID: PMC7807097 DOI: 10.1038/s41598-020-80828-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 12/21/2020] [Indexed: 11/25/2022] Open
Abstract
A primary safety concern in a magnetic resonance imaging environment is heating of metallic implants by absorbing radiofrequency (RF) energy during MRI scanning. Experimental measurement in conjunction with computational modeling was used to evaluate the risk of biological tissue injury from the RF heating of artificial hip joints by obtaining both specific absorption rate (SAR) and temperature elevation at 1.5 T and 3 T MRI systems. Simulation result showed that high SAR and high temperature appeared near both head and tail sections of the artificial hip joints. For five different 1.5 T and 3 T MRI systems, measured temperature location showed that high temperature rises occurred near both head and tail regions of the metallic hip joints. Measured SAR value of 24.6 W/kg and the high temperature rise (= 4.22 °C) occurred in the tail region of the hip joint at 1.5 T, which was higher than the limits for temperature required by the international electrotechnical commission 60601-2-33. We have demonstrated the feasibility of evaluating RF heating of metallic hip joints during MRI scans.
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Affiliation(s)
- Youngseob Seo
- Division of Chemical and Biological Metrology, Korea Research Institute of Standards and Science, 267 Gajeong-ro, Doryong-dong, Yuseong-gu, Daejeon, 34113, Republic of Korea.
| | - Zhiyue J Wang
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Children's Health, Dallas, TX, USA
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16
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Deng G, Cai L, Feng J, Duan S, Zhang P, Xin SX. Reliable Method for Fabricating Tissue-Mimicking Materials With Designated Relative Permittivity and Conductivity at 128 MHz. Bioelectromagnetics 2020; 42:86-94. [PMID: 33305868 DOI: 10.1002/bem.22303] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 10/10/2020] [Indexed: 02/01/2023]
Abstract
Artificial materials that can simultaneously mimic the relative permittivity and conductivity of various human tissues are usually used in medical applications. However, the method of precisely designing these materials with designated values of both relative permittivity and conductivity at 3 T MRI resonance frequency is lacking. In this study, a reliable method is established to determine the compositions of artificial dielectric materials with designated relative permittivity and conductivity at 128 MHz. Sixty dielectric materials were produced using oil, sodium chloride, gelatin, and deionized water as the main raw materials. The dielectric properties of these dielectric materials were measured using the open-ended coaxial line method at 128 MHz. Nonlinear least-squares Marquardt-Levenberg algorithm was used to obtain the formula, establishing the relationship between the compositions of the dielectric materials and their dielectric properties at 128 MHz. The dielectric properties of the blood, gall bladder, muscle, skin, lung, and bone at 128 MHz were selected to verify the reliability of the obtained formula. For the obtained formula, the coefficient of determination and the expanded uncertainties with a coverage factor of k = 2 were 0.991% and 4.9% for relative permittivity and 0.992% and 6.4% for conductivity. For the obtained artificial materials measured using the open-ended coaxial line method, the maximal difference of relative permittivity and conductivity were 1.0 and 0.02 S/m, respectively, with respect to the designated values. In conclusion, the compositions of tissue-mimicking material can be quickly determined after the establishment of the formulas with the expanded uncertainties of less than 10%. Bioelectromagnetics. 2021;42:86-94. © 2020 Bioelectromagnetics Society.
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Affiliation(s)
- Guanhua Deng
- Department of Oncology, Guangdong Sanjiu Brain Hospital, Guangzhou, China
| | - Linbo Cai
- Department of Oncology, Guangdong Sanjiu Brain Hospital, Guangzhou, China
| | - Jian Feng
- Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Song Duan
- Department of Radiation Oncology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Ping Zhang
- Department of Oncology, Guangdong Sanjiu Brain Hospital, Guangzhou, China
| | - Sherman X Xin
- School of Medicine, South China University of Technology, Guangzhou, China
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17
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Machado-Rivas F, Jaimes C, Kirsch JE, Gee MS. Image-quality optimization and artifact reduction in fetal magnetic resonance imaging. Pediatr Radiol 2020; 50:1830-1838. [PMID: 33252752 DOI: 10.1007/s00247-020-04672-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 03/09/2020] [Accepted: 03/31/2020] [Indexed: 11/28/2022]
Abstract
Fetal MRI allows for earlier and better detection of complex congenital anomalies. However, its diagnostic utility is often limited by technical barriers that introduce artifacts and reduce image quality. The main determinants of fetal MR image quality are speed of acquisition, spatial resolution and signal-to-noise ratio (SNR). Imaging optimization is a challenge because a change to improve one scan parameter often leads to worsening of another. Moreover, the recent introduction of fetal MRI on 3-tesla (T) scanners to achieve better SNR can amplify some technical issues. Motion, banding artifacts and aliasing artifacts impact the quality of fetal acquisitions at any field strength. High specific absorption rate (SAR) and artifacts from inhomogeneities in the radiofrequency field are important limitations of high-field-strength imaging. We discuss technical barriers that impact image quality and are important limitations to prenatal MRI diagnosis, and propose solutions to improve image quality and reduce artifacts.
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Affiliation(s)
- Fedel Machado-Rivas
- Department of Radiology, Massachusetts General Hospital, 55 Fruit St., Boston, MA, 02114, USA.,Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Camilo Jaimes
- Department of Radiology, Harvard Medical School, Boston, MA, USA.,Department of Radiology, Boston Children's Hospital, Boston, MA, USA
| | - John E Kirsch
- Department of Radiology, Massachusetts General Hospital, 55 Fruit St., Boston, MA, 02114, USA.,Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Michael S Gee
- Department of Radiology, Massachusetts General Hospital, 55 Fruit St., Boston, MA, 02114, USA. .,Department of Radiology, Harvard Medical School, Boston, MA, USA.
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18
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Barrera CA, Francavilla ML, Serai SD, Edgar JC, Jaimes C, Gee MS, Roberts TPL, Otero HJ, Adzick NS, Victoria T. Specific Absorption Rate and Specific Energy Dose: Comparison of 1.5-T versus 3.0-T Fetal MRI. Radiology 2020; 295:664-674. [PMID: 32255418 DOI: 10.1148/radiol.2020191550] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Background MRI performed at 3.0 T offers greater signal-to-noise ratio and better spatial resolution than does MRI performed at 1.5 T; however, for fetal MRI, there are concerns about the potential for greater radiofrequency energy administered to the fetus at 3.0-T MRI. Purpose To compare the specific absorption rate (SAR) and specific energy dose (SED) of fetal MRI at 1.5 and 3.0 T. Materials and Methods In this retrospective study, all fetal MRI examinations performed with 1.5- and 3.0-T scanners at one institution between July 2012 and October 2016 were evaluated. Two-dimensional (2D) and three-dimensional (3D) steady-state free precession (SSFP), single-shot fast spin-echo, 2D and 3D T1-weighted spoiled gradient-echo (SPGR), and echo-planar imaging sequences were performed. SAR, SED, accumulated SED, and acquisition time were retrieved from the Digital Imaging and Communications in Medicine header. Data are presented as mean ± standard deviation. Two one-sided tests with equivalence bounds of 0.5 (Cohen d effect size) were performed, with statistical equivalence considered at P < .05. Results A total of 2952 pregnant women were evaluated. Mean maternal age was 30 years ± 6 (age range, 12-49 years), mean gestational age was 24 weeks ± 6 (range, 17-40 weeks). A total of 3247 fetal MRI scans were included, with 2784 (86%) obtained at 1.5 T and 463 (14%) obtained at 3.0 T. In total, 93 764 sequences were performed, with 81 535 (87%) performed at 1.5 T and 12 229 (13%) performed at 3.0 T. When comparing 1.5- with 3.0-T MRI sequences, mean SAR (1.09 W/kg ± 0.69 vs 1.14 W/kg ± 0.61), mean SED (33 J/kg ± 27 vs 38 J/kg ± 26), and mean accumulated SED (965 J/kg ± 408 vs 996 J/kg ± 366, P < .001) were equivalent. Conclusion Fetal 1.5- and 3.0-T MRI examinations were found to have equivalent energy metrics in most cases. The 3.0-T sequences, such as two-dimensional T1-weighted spoiled gradient-echo and three-dimensional steady-state free precession, may require modification to keep the energy delivered to the patient as low as possible. © RSNA, 2020 Online supplemental material is available for this article.
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Affiliation(s)
- Christian A Barrera
- From the Departments of Radiology (C.A.B., M.L.F., S.D.S., J.C.E., T.P.L.R., H.J.O., T.V.) and Surgery (N.S.A.), The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa (J.C.E., T.P.L.R.); Department of Radiology, Boston Children's Hospital, Boston, Mass (C.J.); and Department of Radiology, Massachusetts General Hospital, Boston, Mass (M.S.G.)
| | - Michael L Francavilla
- From the Departments of Radiology (C.A.B., M.L.F., S.D.S., J.C.E., T.P.L.R., H.J.O., T.V.) and Surgery (N.S.A.), The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa (J.C.E., T.P.L.R.); Department of Radiology, Boston Children's Hospital, Boston, Mass (C.J.); and Department of Radiology, Massachusetts General Hospital, Boston, Mass (M.S.G.)
| | - Suraj D Serai
- From the Departments of Radiology (C.A.B., M.L.F., S.D.S., J.C.E., T.P.L.R., H.J.O., T.V.) and Surgery (N.S.A.), The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa (J.C.E., T.P.L.R.); Department of Radiology, Boston Children's Hospital, Boston, Mass (C.J.); and Department of Radiology, Massachusetts General Hospital, Boston, Mass (M.S.G.)
| | - J Christopher Edgar
- From the Departments of Radiology (C.A.B., M.L.F., S.D.S., J.C.E., T.P.L.R., H.J.O., T.V.) and Surgery (N.S.A.), The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa (J.C.E., T.P.L.R.); Department of Radiology, Boston Children's Hospital, Boston, Mass (C.J.); and Department of Radiology, Massachusetts General Hospital, Boston, Mass (M.S.G.)
| | - Camilo Jaimes
- From the Departments of Radiology (C.A.B., M.L.F., S.D.S., J.C.E., T.P.L.R., H.J.O., T.V.) and Surgery (N.S.A.), The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa (J.C.E., T.P.L.R.); Department of Radiology, Boston Children's Hospital, Boston, Mass (C.J.); and Department of Radiology, Massachusetts General Hospital, Boston, Mass (M.S.G.)
| | - Michael S Gee
- From the Departments of Radiology (C.A.B., M.L.F., S.D.S., J.C.E., T.P.L.R., H.J.O., T.V.) and Surgery (N.S.A.), The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa (J.C.E., T.P.L.R.); Department of Radiology, Boston Children's Hospital, Boston, Mass (C.J.); and Department of Radiology, Massachusetts General Hospital, Boston, Mass (M.S.G.)
| | - Timothy P L Roberts
- From the Departments of Radiology (C.A.B., M.L.F., S.D.S., J.C.E., T.P.L.R., H.J.O., T.V.) and Surgery (N.S.A.), The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa (J.C.E., T.P.L.R.); Department of Radiology, Boston Children's Hospital, Boston, Mass (C.J.); and Department of Radiology, Massachusetts General Hospital, Boston, Mass (M.S.G.)
| | - Hansel J Otero
- From the Departments of Radiology (C.A.B., M.L.F., S.D.S., J.C.E., T.P.L.R., H.J.O., T.V.) and Surgery (N.S.A.), The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa (J.C.E., T.P.L.R.); Department of Radiology, Boston Children's Hospital, Boston, Mass (C.J.); and Department of Radiology, Massachusetts General Hospital, Boston, Mass (M.S.G.)
| | - N Scott Adzick
- From the Departments of Radiology (C.A.B., M.L.F., S.D.S., J.C.E., T.P.L.R., H.J.O., T.V.) and Surgery (N.S.A.), The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa (J.C.E., T.P.L.R.); Department of Radiology, Boston Children's Hospital, Boston, Mass (C.J.); and Department of Radiology, Massachusetts General Hospital, Boston, Mass (M.S.G.)
| | - Teresa Victoria
- From the Departments of Radiology (C.A.B., M.L.F., S.D.S., J.C.E., T.P.L.R., H.J.O., T.V.) and Surgery (N.S.A.), The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa (J.C.E., T.P.L.R.); Department of Radiology, Boston Children's Hospital, Boston, Mass (C.J.); and Department of Radiology, Massachusetts General Hospital, Boston, Mass (M.S.G.)
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19
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Lum M, Tsiouris AJ. MRI safety considerations during pregnancy. Clin Imaging 2020; 62:69-75. [PMID: 32109683 DOI: 10.1016/j.clinimag.2020.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 02/11/2020] [Accepted: 02/18/2020] [Indexed: 12/12/2022]
Abstract
The use of magnetic resonance imaging (MRI) during pregnancy is on the rise due its ability to provide detailed cross-sectional anatomy without ionizing radiation. Despite the favorable radiation profile, theoretically concerns regarding the safety of MRI and gadolinium-based contrast agent (GBCA) administration have been raised. Currently there are no studies that have shown any attributable harms of MRI during any trimester of pregnancy although prospective and longitudinal studies are lacking. GBCA administration may be associated with a slightly higher rate of neonatal death, although this is based on a single, large cohort study. Understanding the available evidence regarding MRI safety during pregnancy in the context of current society guidelines will help the radiologist serve as a valuable resource to patients and referring providers.
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Affiliation(s)
- Mark Lum
- Department of Radiology, New York Presbyterian Hospital, Weill Cornell Medical Center, 525 E 68th St, New York, NY 10065, United States of America.
| | - A John Tsiouris
- Department of Radiology, New York Presbyterian Hospital, Weill Cornell Medical Center, 525 E 68th St, New York, NY 10065, United States of America
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20
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Ali A, Beckett K, Flink C. Emergent MRI for acute abdominal pain in pregnancy-review of common pathology and imaging appearance. Emerg Radiol 2020; 27:205-214. [PMID: 31902010 DOI: 10.1007/s10140-019-01747-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 12/20/2019] [Indexed: 12/23/2022]
Abstract
Acute abdominal pain in pregnancy remains a clinically challenging presentation, often requiring imaging. The threat of morbidity and mortality to both mother and fetus necessitates quick and accurate imaging diagnosis, often via ultrasound. However, many of the common causes of acute abdominal pain are not readily diagnosed with sonography, and magnetic resonance imaging (MRI) is increasingly favored in this setting. The purpose of this review is to familiarize the reader with common pathologies which may be encountered in pregnant females presenting with acute abdominal pain requiring emergent MRI.
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Affiliation(s)
- Arafat Ali
- Department of Radiology, University of Cincinnati Medical Center, 234 Goodman Street, Cincinnati, OH, 45267, USA.
| | - Katrina Beckett
- Department of Radiology, University of California Los Angeles Medical Center, 10833 Le Conte Avenue, Los Angeles, CA, 90095, USA
| | - Carl Flink
- Department of Radiology, University of Cincinnati Medical Center, 234 Goodman Street, Cincinnati, OH, 45267, USA
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21
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Abaci Turk E, Yetisir F, Adalsteinsson E, Gagoski B, Guerin B, Grant PE, Wald LL. Individual variation in simulated fetal SAR assessed in multiple body models. Magn Reson Med 2019; 83:1418-1428. [PMID: 31626373 DOI: 10.1002/mrm.28006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 08/23/2019] [Accepted: 08/30/2019] [Indexed: 11/06/2022]
Abstract
PURPOSE We generate 12 models from 4 pregnant individuals to evaluate individual differences in local specific absorption rate (SAR) for differing body habitus and fetal and maternal positions. METHODS Structural MR images from 4 pregnant subjects (including supine and left-lateral maternal positions) were manually segmented to create 12 body models by rotating the fetus, modifying the fat content, and altering the maternal arm position in 1 of the subjects. Electromagnetic simulations modeled at 3 Tesla determined the average and peak local SAR in the maternal trunk, fetus, fetal brain, and amniotic fluid. RESULTS We observed a significant range of fetal and maternal peak local SAR across the models (maternal trunk: 19.14-44.03 watts/kg, fetus: 9.93-18.79 watts/kg, fetal brain 3.36-10.3 watts/kg). We found that maternal body habitus changes introduced a significant variation in the maternal peak local SAR but not the fetal local SAR. However, the maternal position (either rotating the mother to left-lateral position or altering the arm position) introduced changes in fetal peak local SAR (range: 11.9-17.9 watts/kg). Rotating the fetus also introduced variation in the fetal and fetal brain peak local SAR. CONCLUSION The observed variation in SAR emphasizes the need for more anatomical models to enable better safety management of individuals during fetal MRI, including a wider range of gestational ages.
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Affiliation(s)
- Esra Abaci Turk
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts
| | - Filiz Yetisir
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts
| | - Elfar Adalsteinsson
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts.,Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts.,Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Borjan Gagoski
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts
| | - Bastien Guerin
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts.,Harvard Medical School, Boston, Massachusetts
| | - P Ellen Grant
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts
| | - Lawrence L Wald
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts.,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts.,Harvard Medical School, Boston, Massachusetts
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Turk EA, Stout JN, Ha C, Luo J, Gagoski B, Yetisir F, Golland P, Wald LL, Adalsteinsson E, Robinson JN, Roberts DJ, Barth WH, Grant PE. Placental MRI: Developing Accurate Quantitative Measures of Oxygenation. Top Magn Reson Imaging 2019; 28:285-297. [PMID: 31592995 PMCID: PMC7323862 DOI: 10.1097/rmr.0000000000000221] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The Human Placenta Project has focused attention on the need for noninvasive magnetic resonance imaging (MRI)-based techniques to diagnose and monitor placental function throughout pregnancy. The hope is that the management of placenta-related pathologies would be improved if physicians had more direct, real-time measures of placental health to guide clinical decision making. As oxygen alters signal intensity on MRI and oxygen transport is a key function of the placenta, many of the MRI methods under development are focused on quantifying oxygen transport or oxygen content of the placenta. For example, measurements from blood oxygen level-dependent imaging of the placenta during maternal hyperoxia correspond to outcomes in twin pregnancies, suggesting that some aspects of placental oxygen transport can be monitored by MRI. Additional methods are being developed to accurately quantify baseline placental oxygenation by MRI relaxometry. However, direct validation of placental MRI methods is challenging and therefore animal studies and ex vivo studies of human placentas are needed. Here we provide an overview of the current state of the art of oxygen transport and quantification with MRI. We suggest that as these techniques are being developed, increased focus be placed on ensuring they are robust and reliable across individuals and standardized to enable predictive diagnostic models to be generated from the data. The field is still several years away from establishing the clinical benefit of monitoring placental function in real time with MRI, but the promise of individual personalized diagnosis and monitoring of placental disease in real time continues to motivate this effort.
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Affiliation(s)
- Esra Abaci Turk
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children’s Hospital, MA, USA
| | - Jeffrey N. Stout
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children’s Hospital, MA, USA
| | - Christopher Ha
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children’s Hospital, MA, USA
| | - Jie Luo
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Borjan Gagoski
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children’s Hospital, MA, USA
| | - Filiz Yetisir
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children’s Hospital, MA, USA
| | - Polina Golland
- Computer Science and Artificial Intelligence Laboratory (CSAIL), Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Lawrence L. Wald
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
| | - Elfar Adalsteinsson
- Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology, Cambridge, MA, United States
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Julian N. Robinson
- Department of Obstetrics and Gynecology, Brigham and Women’s Hospital, Boston, USA
| | | | - William H. Barth
- Maternal-Fetal Medicine, Obstetrics and Gynecology, Massachusetts General Hospital, Boston, MA, USA
| | - P. Ellen Grant
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children’s Hospital, MA, USA
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van Gemert J, Brink W, Remis R, Webb A. A simulation study on the effect of optimized high permittivity materials on fetal imaging at 3T. Magn Reson Med 2019; 82:1822-1831. [PMID: 31199014 PMCID: PMC6771485 DOI: 10.1002/mrm.27849] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 05/10/2019] [Accepted: 05/19/2019] [Indexed: 12/14/2022]
Abstract
PURPOSE One of the main concerns in fetal MRI is the radiofrequency power that is absorbed both by the mother and the fetus. Passive shimming using high permittivity materials in the form of "dielectric pads" has previously been shown to increase the B 1 + efficiency and homogeneity in different applications, while reducing the specific absorption rate (SAR). In this work, we study the effect of optimized dielectric pads for 3 pregnant models. METHODS Pregnant models in the 3rd, 7th, and 9th months of gestation were used for simulations in a birdcage coil at 3T. Dielectric pads were optimized regions of interest (ROI) using previously developed methods for B 1 + efficiency and homogeneity and were designed for 2 ROIs: the entire fetus and the brain of the fetus. The SAR was evaluated in terms of the whole-body SAR, average SAR in the fetus and amniotic fluid, and maximum 10 g-averaged SAR in the mother, fetus, and amniotic fluid. RESULTS The optimized dielectric pads increased the transmit efficiency up to 55% and increased the B 1 + homogeneity in almost every tested configuration. The B 1 + -normalized whole-body SAR was reduced by more than 31% for all body models. The B 1 + -normalized local SAR was reduced in most scenarios by up to 62%. CONCLUSION Simulations have shown that optimized high permittivity pads can reduce SAR in pregnant subjects at the 3rd, 7th, and 9th month of gestation, while improving the transmit field homogeneity in the fetus. However, significantly more work is required to demonstrate that fetal imaging is safe under standard operating conditions.
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Affiliation(s)
- Jeroen van Gemert
- Circuits & Systems Group, Electrical Engineering, Mathematics and Computer Science Faculty, Delft University of Technology, The Netherlands
| | - Wyger Brink
- Department of Radiology, C.J. Gorter Center for High-Field MRI, Leiden University Medical Center, The Netherlands
| | - Rob Remis
- Circuits & Systems Group, Electrical Engineering, Mathematics and Computer Science Faculty, Delft University of Technology, The Netherlands
| | - Andrew Webb
- Department of Radiology, C.J. Gorter Center for High-Field MRI, Leiden University Medical Center, The Netherlands
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Roy CW, Marini D, Segars WP, Seed M, Macgowan CK. Fetal XCMR: a numerical phantom for fetal cardiovascular magnetic resonance imaging. J Cardiovasc Magn Reson 2019; 21:29. [PMID: 31118056 PMCID: PMC6532268 DOI: 10.1186/s12968-019-0539-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 04/15/2019] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Validating new techniques for fetal cardiovascular magnetic resonance (CMR) is challenging due to random fetal movement that precludes repeat measurements. Consequently, fetal CMR development has been largely performed using physical phantoms or postnatal volunteers. In this work, we present an open-source simulation designed to aid in the development and validation of new approaches for fetal CMR. Our approach, fetal extended Cardiac-Torso cardiovascular magnetic resonance imaging (Fetal XCMR), builds on established methods for simulating CMR acquisitions but is tailored toward the dynamic physiology of the fetal heart and body. We present comparisons between the Fetal XCMR phantom and data acquired in utero, resulting in image quality, anatomy, tissue signals and contrast. METHODS Existing extended Cardiac-Torso models are modified to create maternal and fetal anatomy, combined according to simulated motion, mapped to CMR contrast, and converted to CMR data. To provide a comparison between the proposed simulation and experimental fetal CMR images acquired in utero, images from a typical scan of a pregnant woman are included and simulated acquisitions were generated using matching CMR parameters, motion and noise levels. Three reconstruction (static, real-time, and CINE), and two motion estimation methods (translational motion, fetal heart rate) from data acquired in transverse, sagittal, coronal, and short-axis planes of the fetal heart were performed to compare to in utero acquisitions and demonstrate feasibility of the proposed simulation framework. RESULTS Overall, CMR contrast, morphologies, and relative proportions of the maternal and fetal anatomy are well represented by the Fetal XCMR images when comparing the simulation to static images acquired in utero. Additionally, visualization of maternal respiratory and fetal cardiac motion is comparable between Fetal XCMR and in utero real-time images. Finally, high quality CINE image reconstructions provide excellent delineation of fetal cardiac anatomy and temporal dynamics for both data types. CONCLUSION The fetal CMR phantom provides a new method for evaluating fetal CMR acquisition and reconstruction methods by simulating the underlying anatomy and physiology. As the field of fetal CMR continues to grow, new methods will become available and require careful validation. The fetal CMR phantom is therefore a powerful and convenient tool in the continued development of fetal cardiac imaging.
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Affiliation(s)
- Christopher W. Roy
- Department of Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Vaud Switzerland
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario Canada
- Division of Translational Medicine, Peter Gilgan Centre for Research & Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4 Canada
| | - Davide Marini
- Division of Pediatric Cardiology, The Hospital for Sick Children, Toronto, Ontario Canada
| | - William Paul Segars
- Department of Radiology, Duke University Medical Center, Durham, North Carolina USA
| | - Mike Seed
- Division of Pediatric Cardiology, The Hospital for Sick Children, Toronto, Ontario Canada
- Departments of Pediatrics and Diagnostic Imaging, University of Toronto, Toronto, Ontario Canada
| | - Christopher K. Macgowan
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario Canada
- Division of Translational Medicine, Peter Gilgan Centre for Research & Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4 Canada
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Abstract
Acute abdominopelvic pain, a common symptom in emergency department patients, is challenging given the spectrum of differential diagnoses encompassing multiple organ systems, ranging from benign self-limiting to life-threatening and emergent. Diagnostic imaging is critical given its high accuracy and management guidance. A contrast-enhanced computed tomography (CT) scan is preferred given its widespread availability and speed of acquisition. MR imaging may be appropriate, usually performed for specific indications with tailored protocols. It is accurate for diagnosis and may be an alternative to CT. This article discusses the advantages and disadvantages, protocols, and appearances of MR imaging of common diagnoses.
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Affiliation(s)
- Jennifer W Uyeda
- Department of Radiology, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA.
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26
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Use of Magnetic Resonance Imaging in Evaluating Fetal Brain and Abdomen Malformations during Pregnancy. ACTA ACUST UNITED AC 2019; 55:medicina55020055. [PMID: 30781564 PMCID: PMC6410250 DOI: 10.3390/medicina55020055] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 01/06/2019] [Accepted: 02/11/2019] [Indexed: 01/07/2023]
Abstract
Magnetic resonance imaging (MRI) is used as a clarifying technique after a high-resolution ultrasound examination during pregnancy. Combining ultrasound with MRI, additional diagnostic information is obtained or ultrasound diagnosis is frequently corrected. High spatial resolution provides accurate radiological imaging of internal organs and widens possibilities for detecting perinatal development disorders. The safety of MRI and the use of intravenous contrast agent gadolinium are discussed in this article. There is no currently available evidence that MRI is harmful to the fetus, although not enough research has been carried out to prove enduring safety. MRI should be performed when the benefit outweighs the potential side effects. The narrative review includes several clinical cases of fetal MRI performed in Vilnius University Hospital Santaros Clinics.
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Oppenheimer DC, Mazaheri P, Ballard DH, Yano M, Fowler KJ. Magnetic resonance imaging of the placenta and gravid uterus: a pictorial essay. Abdom Radiol (NY) 2019; 44:669-684. [PMID: 30196361 PMCID: PMC6529811 DOI: 10.1007/s00261-018-1755-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The placenta is commonly overlooked on magnetic resonance imaging of the pregnant patient, which is frequently performed for alternative reasons such as to characterize fetal or uterine anomalies or to investigate the etiology of acute pelvic pain in pregnancy. Placental disorders have potential for significant maternal and fetal morbidity and peripartum complications if not recognized and treated in a timely manner. The radiologist must be familiar with normal placental variants and the spectrum of benign to life-threatening conditions affecting the placenta so that the Obstetrician can be promptly notified and patient management altered, if necessary. In this pictorial essay, we will describe our MR protocol for placental imaging, provide an image-rich review of the normal placenta, placental variants, and a variety of pathological conditions affecting the placenta and gravid uterus.
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Affiliation(s)
- Daniel C Oppenheimer
- Department of Imaging Sciences, University of Rochester Medical Center, 601 Elmwood Ave, P.O. Box no. 648, Rochester, NY, 14642, USA.
| | - Parisa Mazaheri
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd, St. Louis, MO, 63110, USA
| | - David H Ballard
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd, St. Louis, MO, 63110, USA
| | - Motoyo Yano
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd, St. Louis, MO, 63110, USA
| | - Kathryn J Fowler
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd, St. Louis, MO, 63110, USA
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28
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Wi SA, Kim DJ, Cho ES, Kim KA. Diagnostic performance of MRI for pregnant patients with clinically suspected appendicitis. Abdom Radiol (NY) 2018; 43:3456-3461. [PMID: 29869102 DOI: 10.1007/s00261-018-1654-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE To evaluate the accuracy of magnetic resonance imaging (MRI) in the diagnosis of acute appendicitis in pregnant patients and the value of additional diffusion-weighted MRI (DWI). METHODS A total of 125 pregnant patients with clinically suspected appendicitis who underwent 1.5 T MRI were enrolled between May 2011 and January 2016. During this period, two radiologists prospectively predicted acute appendicitis on MRI during daily interpretation. We retrospectively reviewed clinical records, and radiological results were correlated with surgical pathology and clinical outcomes. We calculated the sensitivity, specificity, and accuracy of MRI for diagnosing acute appendicitis. We performed additional DWI between August 2014 and January 2016, and we calculated sensitivity, specificity, and accuracy of MRI with or without DWI. RESULTS The sensitivity, specificity, and accuracy of MRI for acute appendicitis were 100%, 95%, and 96%, respectively. The sensitivity, specificity, and accuracy of MRI without DWI (n = 72) vs. with DWI (n = 53) were 100%, 94.7%, and 95.8% versus 100%, 95%, and 96%, respectively. CONCLUSIONS MRI has high accuracy for the diagnosis of acute appendicitis in pregnant patients. Therefore, MRI is recommended for use as a first-line diagnostic test for pregnant patients with clinically suspected appendicitis.
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Affiliation(s)
- Sung Ah Wi
- Department of Radiology, CHA Bundang Medical Center, CHA University, 351 Yatap-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-712, Korea
| | - Dae Jung Kim
- Department of Radiology, CHA Bundang Medical Center, CHA University, 351 Yatap-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-712, Korea.
| | - Eun-Suk Cho
- Department of Radiology, Yonsei University College of Medicine, Gangnam Severance Hospital, Seoul, Korea
| | - Kyoung Ah Kim
- Department of Radiology, CHA Bundang Medical Center, CHA University, 351 Yatap-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-712, Korea
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DastAmooz S, Tahmasebi Boroujeni S, Shahbazi M, Vali Y. Physical activity as an option to reduce adverse effect of EMF exposure during pregnancy. Int J Dev Neurosci 2018; 71:10-17. [DOI: 10.1016/j.ijdevneu.2018.07.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 07/21/2018] [Accepted: 07/23/2018] [Indexed: 12/13/2022] Open
Affiliation(s)
- Sima DastAmooz
- Department of Motor Behavior, Faculty of Physical Education and Sport SciencesUniversity of TehranTehranIran
| | - Shahzad Tahmasebi Boroujeni
- Department of Motor Behavior, Faculty of Physical Education and Sport SciencesUniversity of TehranTehranIran
| | - Mehdi Shahbazi
- Department of Motor Behavior, Faculty of Physical Education and Sport SciencesUniversity of TehranTehranIran
| | - Yasamin Vali
- Department of Radiology and Surgery, Faculty of Veterinary MedicineUniversity of TehranTehranIran
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Li Q, Liao C, Ye H, Chen Y, Cao X, Yuan L, He H, Zhong J. Squeezed Trajectory Design for Peak RF and Integrated RF Power Reduction in Parallel Transmission MRI. IEEE TRANSACTIONS ON MEDICAL IMAGING 2018; 37:1809-1821. [PMID: 29993630 DOI: 10.1109/tmi.2018.2828112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
High peak RF amplitude and excessive specific absorption rate (SAR) are two critical concerns for hardware implementation and patient safety in scientific and clinical research for high field MRI using parallel transmissions (pTX). In this paper, we introduce a squeezing strategy to reduce peak RF amplitude and integrated RF power via direct reshaping of the k-space trajectory. In the existing peak RF / integrated RF power optimization methods gradient amplitude or slew rate is reduced, but the k-space trajectory remains unchanged. Unlike these traditional methods, we worked directly in the excitation k-space to reshape k-space traversal by a squeezing vector in order to achieve peak RF and total RF power optimization, using a particle swarm optimization algorithm. The squeezing strategy was applied to the conventional variable density spiral (CVDS) and the variable rate selective excitation (VERSE) trajectories, dubbed SVDS (squeezed variable density spiral) and SVERSE (squeezing trajectory with VERSE), respectively, for different excitation profiles of small or large tip angles. Pulse acceleration and off-resonance effects were evaluated for an 8-ch pTX via Bloch simulation. CVDS, VERSE, SVDS, and SVERSE pulses were implemented on a 3T scanner with a 2-ch pTX. Phantom and in vivo experiments were performed for reduced FOV (rFOV) imaging. The results show that SVDS pulses simultaneously reduce integrated RF power and peak RF by about 30% on average compared to CVDS pulses for a square pattern ( $80\times80$ mm2) with flip angles of 30°, 90°, and 180°. Compared with the VERSE method under the same peak RF constraints, the SVDS method reduces integrated RF power by an average of 20% for small tip excitations for profiles of slice, rectangular, square, and circle, and has slightly reduced excitation accuracy slightly (about 0.6%, from 6.8% to 7.4%). The SVERSE method shortens the duration of the VERSE pulse by 12.8% at large ti p angle (180°). Feasibility for rFOV imaging was demonstrated with phantom and in vivo experiments with squeezed pulses.
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Razjouyan A, Park BS, Kainz W, Rajan SS, Angelone LM. Computational assessment of radiofrequency energy absorption of fetus during an MRI scan. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aac9a8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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32
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Ferrazzi G, Price AN, Teixeira RPAG, Cordero-Grande L, Hutter J, Gomes A, Padormo F, Hughes E, Schneider T, Rutherford M, Kuklisova Murgasova M, Hajnal JV. An efficient sequence for fetal brain imaging at 3T with enhanced T 1 contrast and motion robustness. Magn Reson Med 2017; 80:137-146. [PMID: 29193244 PMCID: PMC5900721 DOI: 10.1002/mrm.27012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 10/25/2017] [Accepted: 10/26/2017] [Indexed: 11/11/2022]
Abstract
PURPOSE Ultrafast single-shot T2 -weighted images are common practice in fetal MR exams. However, there is limited experience with fetal T1 -weighted acquisitions. This study aims at establishing a robust framework that allows fetal T1 -weighted scans to be routinely acquired in utero at 3T. METHODS A 2D gradient echo sequence with an adiabatic inversion was optimized to be robust to fetal motion and maternal breathing optimizing grey/white matter contrast at the same time. This was combined with slice to volume registration and super resolution methods to produce volumetric reconstructions. The sequence was tested on 22 fetuses. RESULTS Optimized grey/white matter contrast and robustness to fetal motion and maternal breathing were achieved. Signal from cerebrospinal fluid (CSF) and amniotic fluid was nulled and 0.75 mm isotropic anatomical reconstructions of the fetal brain were obtained using slice-to-volume registration and super resolution techniques. Total acquisition time for a single stack was 56 s, all acquired during free breathing. Enhanced sensitivity to normal anatomy and pathology with respect to established methods is demonstrated. A direct comparison with a 3D spoiled gradient echo sequence and a controlled motion experiment run on an adult volunteer are also shown. CONCLUSION This paper describes a robust framework to perform T1 -weighted acquisitions and reconstructions of the fetal brain in utero. Magn Reson Med 80:137-146, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
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Affiliation(s)
- Giulio Ferrazzi
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, Division of Imaging Sciences and Biomedical Engineering, King's College, London, UK
| | - Anthony N Price
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, Division of Imaging Sciences and Biomedical Engineering, King's College, London, UK
| | - Rui Pedro A G Teixeira
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, Division of Imaging Sciences and Biomedical Engineering, King's College, London, UK
| | - Lucilio Cordero-Grande
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, Division of Imaging Sciences and Biomedical Engineering, King's College, London, UK
| | - Jana Hutter
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, Division of Imaging Sciences and Biomedical Engineering, King's College, London, UK
| | - Ana Gomes
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, Division of Imaging Sciences and Biomedical Engineering, King's College, London, UK
| | - Francesco Padormo
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, Division of Imaging Sciences and Biomedical Engineering, King's College, London, UK.,Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Emer Hughes
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, Division of Imaging Sciences and Biomedical Engineering, King's College, London, UK
| | | | - Mary Rutherford
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, Division of Imaging Sciences and Biomedical Engineering, King's College, London, UK
| | - Maria Kuklisova Murgasova
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, Division of Imaging Sciences and Biomedical Engineering, King's College, London, UK
| | - Joseph V Hajnal
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, Division of Imaging Sciences and Biomedical Engineering, King's College, London, UK
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Park BS, Razjouyan A, Angelone LM, McCright B, Rajan SS. RF Safety Evaluation of a Breast Tissue Expander Device for MRI: Numerical Simulation and Experiment. IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY 2017; 59:1390-1399. [PMID: 29456260 PMCID: PMC5814144 DOI: 10.1109/temc.2017.2678201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
This study describes the MRI-related radio frequency (RF) safety evaluation of breast tissue expander devices to establish safety criteria. Numerical simulations and experimental measurements were performed at 64 MHz with a gel phantom containing a breast expander. Additionally, computational modeling was performed (64 and 128 MHz) with an adult female model, containing a virtually implanted breast tissue expander device for four imaging landmark positions. The presence of the breast tissue expander device led to significant alterations in specific absorption rate (SAR) and|B1+|distributions. The main source of SAR alterations with the use of the breast expander device was the saline-filled pouch of the expander. Conversely, the variation of RF magnetic field (B1+) was mainly caused by the metallic port. The measured values of electric field magnitude did not increase significantly due to the introduction of the expander device. The maximum 1g- or 10g-averaged SAR values in tissues near the implant were lower than those expected in other regions of the patient body with normalization of both|B1+|equal to 2 μT at the coil isocenter and whole body averaged SAR equal to 4W/kg.
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Affiliation(s)
- Bu S Park
- U.S. FDA, CBER, OTAT Division of Cellular and Gene Therapies, Silver Spring, MD 20993-0002 USA
| | - Amir Razjouyan
- U.S. FDA, CDRH, OSEL, Division of Biomedical Physics, Silver Spring, MD 20993-0002 USA
| | - Leonardo M Angelone
- U.S. FDA, CDRH, OSEL, Division of Biomedical Physics, Silver Spring, MD 20993-0002 USA
| | - Brent McCright
- U.S. FDA, CBER, OTAT Division of Cellular and Gene Therapies, Silver Spring, MD 20993-0002 USA
| | - Sunder S Rajan
- U.S. FDA, CDRH, OSEL, Division of Biomedical Physics, Silver Spring, MD 20993-0002 USA
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Yanamadala J, Noetscher GM, Makarov SN, Pascual-Leone A. Estimates of peak electric fields induced by Transcranial magnetic stimulation in pregnant women as patients using an FEM full-body model. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:1441-1444. [PMID: 29060149 DOI: 10.1109/embc.2017.8037105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Transcranial magnetic stimulation (TMS) for treatment of depression during pregnancy is an appealing alternative to fetus-threatening drugs. However, no studies to date have been performed that evaluate the safety of TMS for a pregnant mother patient and her fetus. A full-body FEM model of a pregnant woman with about 100 tissue parts has been developed specifically for the present study. This model allows accurate computations of induced electric field in every tissue given different locations of a shape-eight coil, a biphasic pulse, common TMS pulse durations, and using different values of the TMS intensity measured in SMT (Standard Motor Threshold) units. Our simulation results estimate the maximum peak values of the electric field in the fetal area for every fetal tissue separately and for the TMS intensity of one SMT unit.
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Plowman RS, Javidan-Nejad C, Raptis CA, Katz DS, Mellnick VM, Bhalla S, Cornejo P, Menias CO. Imaging of Pregnancy-related Vascular Complications. Radiographics 2017; 37:1270-1289. [DOI: 10.1148/rg.2017160128] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- R. Scooter Plowman
- From the Department of Radiology, Mayo Clinic Arizona, Phoenix, Ariz (R.S.P., C.O.M.); Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.J.N., C.A.R., V.M.M., S.B.); Department of Radiology, NYU Winthrop Hospital, Mineola, NY (D.S.K.); Stony Brook University School of Medicine, Stony Brook, NY (D.S.K.); and Neuroradiology Section, Department of Radiology, Phoenix Children’s Hospital, Phoenix, Ariz (P.C.)
| | - Cylen Javidan-Nejad
- From the Department of Radiology, Mayo Clinic Arizona, Phoenix, Ariz (R.S.P., C.O.M.); Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.J.N., C.A.R., V.M.M., S.B.); Department of Radiology, NYU Winthrop Hospital, Mineola, NY (D.S.K.); Stony Brook University School of Medicine, Stony Brook, NY (D.S.K.); and Neuroradiology Section, Department of Radiology, Phoenix Children’s Hospital, Phoenix, Ariz (P.C.)
| | - Constantine A. Raptis
- From the Department of Radiology, Mayo Clinic Arizona, Phoenix, Ariz (R.S.P., C.O.M.); Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.J.N., C.A.R., V.M.M., S.B.); Department of Radiology, NYU Winthrop Hospital, Mineola, NY (D.S.K.); Stony Brook University School of Medicine, Stony Brook, NY (D.S.K.); and Neuroradiology Section, Department of Radiology, Phoenix Children’s Hospital, Phoenix, Ariz (P.C.)
| | - Douglas S. Katz
- From the Department of Radiology, Mayo Clinic Arizona, Phoenix, Ariz (R.S.P., C.O.M.); Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.J.N., C.A.R., V.M.M., S.B.); Department of Radiology, NYU Winthrop Hospital, Mineola, NY (D.S.K.); Stony Brook University School of Medicine, Stony Brook, NY (D.S.K.); and Neuroradiology Section, Department of Radiology, Phoenix Children’s Hospital, Phoenix, Ariz (P.C.)
| | - Vincent M. Mellnick
- From the Department of Radiology, Mayo Clinic Arizona, Phoenix, Ariz (R.S.P., C.O.M.); Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.J.N., C.A.R., V.M.M., S.B.); Department of Radiology, NYU Winthrop Hospital, Mineola, NY (D.S.K.); Stony Brook University School of Medicine, Stony Brook, NY (D.S.K.); and Neuroradiology Section, Department of Radiology, Phoenix Children’s Hospital, Phoenix, Ariz (P.C.)
| | - Sanjeev Bhalla
- From the Department of Radiology, Mayo Clinic Arizona, Phoenix, Ariz (R.S.P., C.O.M.); Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.J.N., C.A.R., V.M.M., S.B.); Department of Radiology, NYU Winthrop Hospital, Mineola, NY (D.S.K.); Stony Brook University School of Medicine, Stony Brook, NY (D.S.K.); and Neuroradiology Section, Department of Radiology, Phoenix Children’s Hospital, Phoenix, Ariz (P.C.)
| | - Patricia Cornejo
- From the Department of Radiology, Mayo Clinic Arizona, Phoenix, Ariz (R.S.P., C.O.M.); Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.J.N., C.A.R., V.M.M., S.B.); Department of Radiology, NYU Winthrop Hospital, Mineola, NY (D.S.K.); Stony Brook University School of Medicine, Stony Brook, NY (D.S.K.); and Neuroradiology Section, Department of Radiology, Phoenix Children’s Hospital, Phoenix, Ariz (P.C.)
| | - Christine O. Menias
- From the Department of Radiology, Mayo Clinic Arizona, Phoenix, Ariz (R.S.P., C.O.M.); Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.J.N., C.A.R., V.M.M., S.B.); Department of Radiology, NYU Winthrop Hospital, Mineola, NY (D.S.K.); Stony Brook University School of Medicine, Stony Brook, NY (D.S.K.); and Neuroradiology Section, Department of Radiology, Phoenix Children’s Hospital, Phoenix, Ariz (P.C.)
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Makarov SN, Noetscher GM, Yanamadala J, Piazza MW, Louie S, Prokop A, Nazarian A, Nummenmaa A. Virtual Human Models for Electromagnetic Studies and Their Applications. IEEE Rev Biomed Eng 2017; 10:95-121. [PMID: 28682265 PMCID: PMC10502908 DOI: 10.1109/rbme.2017.2722420] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/17/2023]
Abstract
Numerical simulation of electromagnetic, thermal, and mechanical responses of the human body to different stimuli in magnetic resonance imaging safety, antenna research, electromagnetic tomography, and electromagnetic stimulation is currently limited by the availability of anatomically adequate and numerically efficient cross-platform computational models or "virtual humans." The objective of this study is to provide a comprehensive review of modern human models and body region models available in the field and their important features.
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Affiliation(s)
- Sergey N. Makarov
- ECE Dept., Worcester Polytechnic Institute, Worcester, MA 01609; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114 ()
| | - Gregory M. Noetscher
- ECE Dept., Worcester Polytechnic Institute, Worcester, MA 01609; Neva Electromagnetics, LLC., Yarmouth Port, MA 02675 ()
| | | | | | | | | | - Ara Nazarian
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02675 ()
| | - Aapo Nummenmaa
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114 ()
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[Magnetic resonance imaging : Recent studies on biological effects of static magnetic and high‑frequency electromagnetic fields]. Radiologe 2017; 57:563-568. [PMID: 28555348 DOI: 10.1007/s00117-017-0260-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PROBLEM During the last few years, new studies on biological effects of strong static magnetic fields and on thermal effects of high-frequency electromagnetic fields used in magnetic resonance imaging (MRI) were published. Many of these studies have not yet been included in the current safety recommendations. METHOD Scientific publications since 2010 on biological effects of static and electromagnetic fields in MRI were researched and evaluated. RESULTS New studies confirm older publications that have already described effects of static magnetic fields on sensory organs and the central nervous system, accompanied by sensory perceptions. A new result is the direct effect of Lorentz forces on ionic currents in the semicircular canals of the vestibular system. Recent studies of thermal effects of high-frequency electromagnetic fields were focused on the development of anatomically realistic body models and a more precise simulation of exposure scenarios. RECOMMENDATION FOR PRACTICE Strong static magnetic fields can cause unpleasant sensations, in particular, vertigo. In addition, they can influence the performance of the medical staff and thus potentially endanger the patient's safety. As a precaution, medical personnel should move slowly within the field gradient. High-frequency electromagnetic fields lead to an increase in the temperature of patients' tissues and organs. This should be considered especially in patients with restricted thermoregulation and in pregnant women and neonates; in these cases exposure should be kept as low as possible.
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Luo M, Hu C, Zhuang Y, Chen W, Liu F, Xin SX. Numerical assessment of the reduction of specific absorption rate by adding high dielectric materials for fetus MRI at 3 T. ACTA ACUST UNITED AC 2017; 61:455-61. [PMID: 26985683 DOI: 10.1515/bmt-2015-0171] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 02/17/2016] [Indexed: 12/16/2022]
Abstract
The specific absorption rate (SAR) is an important issue to be considered in fetus MRI at 3 T due to the high radiofrequency energy deposited inside the body of pregnant woman. The high dielectric material (HDM) has shown its potential for enhancing B1 field and reducing SAR in MRI. The aim of this study is to assess the feasibility of SAR reduction by adding an HDM to the fetus MRI. The feasibility of SAR reduction is numerically assessed in this study, using a birdcage coil in transmission loaded with an electromagnetic pregnant woman model in the SEMCAD-EM solver. The HDMs with different geometric arrangements and dielectric constants are manually optimized. The B1+ ${B_1}^ + $ homogeneity is also considered while calculating the optimized fetus 10 g local SAR among different strategies in the application of HDM. The optimum maximum fetus 10 g local SAR was obtained as 2.25 W/kg, by using two conformal pads placed left and right with the dielectric constant to be 400, reduced by 24.75% compared to that without the HDM. It indicated that the SAR can be significantly reduced with strategic placement of the HDM and the use of HDM may provide a simple, effective and low-cost method for reducing the SAR for the fetus MRI at 3 T.
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Seo Y, Wang ZJ. MRI scanner-independent specific absorption rate measurements using diffusion coefficients. J Appl Clin Med Phys 2017; 18:224-229. [PMID: 28470956 PMCID: PMC5875836 DOI: 10.1002/acm2.12095] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 03/27/2017] [Accepted: 03/29/2017] [Indexed: 01/01/2023] Open
Abstract
Objective The purpose of this study was to measure specific absorption rate (SAR) during MRI scanning using a human torso phantom through quantification of diffusion coefficients independently of those reported by the scanner software for five 1.5 and 3 T clinical MRI systems from different vendors. Methods A quadrature body coil transmitted the RF power and a body array coil received the signals. With diffusion tensor imaging, SAR values for three MRI sequences were measured on the five scanners and compared to the nominal values calculated by the scanners. Results For the GE 1.5 T MRI system, the MRI scanner‐reported SAR value was 1.58 W kg‐1 and the measured SAR value was 1.38 W kg‐1. For the Philips 1.5 T MRI scanner, the MRI system‐reported SAR value was 1.48 W kg‐1 and the measured value was 1.39 W kg‐1. For the Siemens 3 T MRI system, the reported SAR value was 2.5 W kg‐1 and the measured SAR value was 1.96 W kg‐1. For two Philips 3 T MRI scanners, the reported SAR values were 1.5 W kg‐1 and the measured values were 1.94 and 1.96 W kg‐1. The percentage differences between the measured and reported SAR values on the GE 1.5 T, Philips 1.5 T, Siemens 3 T, and Philips 3 T were 13.5, 6.3, 24.2, 25.6, and 26.6% respectively. Conclusion The scanner‐independent SAR measurements using diffusion coefficients described in this study can play a significant role in estimating accurate SAR values as a standardized method.
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Affiliation(s)
- Youngseob Seo
- Medical Metrology Center, Korea Research Institute of Standards and Science, Yuseong-Gu, Daejeon, 34113, Republic of Korea.,Department of Radiology, University of Texas Southwestern Medical Center and Children's Medical Center Dallas, Dallas, TX, 75390, USA
| | - Zhiyue J Wang
- Department of Radiology, University of Texas Southwestern Medical Center and Children's Medical Center Dallas, Dallas, TX, 75390, USA
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Li Z, Deng G, Li Z, Xin SX, Duan S, Lan M, Zhang S, Gao Y, He J, Zhang S, Tang H, Wang W, Han S, Yang QX, Zhuang L, Hu J, Liu F. A large-scale measurement of dielectric properties of normal and malignant colorectal tissues obtained from cancer surgeries at Larmor frequencies. Med Phys 2016; 43:5991. [PMID: 27806614 DOI: 10.1118/1.4964460] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 09/18/2016] [Accepted: 09/26/2016] [Indexed: 07/29/2024] Open
Abstract
PURPOSE Knowledge of dielectric properties of malignant human tissues is necessary for the recently developed magnetic resonance (MR) technique called MR electrical property tomography. This technique may be used in early tumor detection based on the obvious differentiation of the dielectric properties between normal and malignant tissues. However, the dielectric properties of malignant human tissues in the scale of the Larmor frequencies are not completely available in the literature. In this study, the authors focused only on the dielectric properties of colorectal tumor tissue. METHODS The dielectric properties of 504 colorectal malignant samples excised from 85 patients in the scale of the Larmor frequencies were measured using the precision open-ended coaxial probe method. The obtained complex-permittivity data were fitted to the single-pole Cole-Cole model. RESULTS The median permittivity and conductivity for the malignant tissue sample were 79.3 and 0.881 S/m at 128 MHz, which were 14.6% and 17.0% higher, respectively, than those of normal tissue samples. Significant differences between normal and malignant tissues were found for the dielectric properties (p < 0.05). CONCLUSIONS Experimental results indicated that the dielectric properties were significantly different between normal and malignant tissues for colorectal tissue. This large-scale clinical measurement provides more subtle base data to validate the technique of MR electrical property tomography.
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Affiliation(s)
- Zhou Li
- Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, 510280, China
| | - Guanhua Deng
- Biomedical Engineering Department and Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, 510515, China and Department of Oncology, Guangdong 999 Brain Hospital, Guangzhou, Guangdong, 510510, China
| | - Zhe Li
- Biomedical Engineering Department and Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, 510515, China
| | - Sherman Xuegang Xin
- Biomedical Engineering Department and Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, 510515, China
| | - Song Duan
- Biomedical Engineering Department and Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, 510515, China
| | - Maoying Lan
- Biomedical Engineering Department and Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, 510515, China
| | - Sa Zhang
- Biomedical Engineering Department and Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, 510515, China
| | - Yixin Gao
- The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, 510080, China
| | - Jun He
- Shanghai Chenguang Medical Technologies Co., Ltd., Shanghai, 201707, China
| | - Songtao Zhang
- Shanghai Chenguang Medical Technologies Co., Ltd., Shanghai, 201707, China
| | - Hongming Tang
- Shanghai Chenguang Medical Technologies Co., Ltd., Shanghai, 201707, China
| | - Weiwei Wang
- Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, 510280, China
| | - Shuai Han
- Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, 510280, China
| | - Qing X Yang
- Center for NMR Research, Penn State College of Medicine, Hershey, Pennsylvania 17033
| | - Ling Zhuang
- Department of Oncology, School of Medicine, Wayne State University, Detroit, Michigan 48201
| | - Jiani Hu
- Department of Radiology, Wayne State University School of Medicine, Detroit, Michigan 48201
| | - Feng Liu
- School of Information Technology and Electrical Engineering of Queensland University, Brisbane 4702, Australia
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Comparison Between 1.5-T and 3-T MRI for Fetal Imaging: Is There an Advantage to Imaging With a Higher Field Strength? AJR Am J Roentgenol 2016; 206:195-201. [PMID: 26700352 DOI: 10.2214/ajr.14.14205] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Fetal MRI at 3 T is emerging as a promising modality for evaluating fetal anatomy. The objective of this study was to compare the quality of images obtained with commonly used fetal imaging sequences at 1.5 T and 3 T. We hypothesized that the visualization and anatomic detail of fetal structures would be better at 3 T than at 1.5 T. MATERIALS AND METHODS A retrospective search of the radiology department database at our institution identified 58 fetal MRI examinations performed at 3 T to evaluate body abnormalities during the period from July 2012 to February 2014. A blind comparison was conducted between these examinations and 58 1.5-T MRI examinations of age-matched fetuses undergoing evaluation for similar abnormalities during the same period. The anatomic structures analyzed included the bowel, liver, kidney, airway, cartilage, and spine. Scores for the depiction of anatomic structures ranged from 0 to 4, with 4 denoting the best depiction. RESULTS Fetal imaging at 3 T was associated with higher imaging scores in the evaluation of the cartilage and spine when single-shot turbo spin-echo (SSTSE) and steady-state free precession (SSFP) sequences were used and in the assessment of most structures (e.g., bowel, liver, kidney, cartilage, and spine) when SSFP sequences were used. The mean scores for all structures evaluated with the use of SSTSE sequences were higher when MRI was performed at 3 T than at 1.5 T; similar findings were noted when SSFP sequences were used. Evaluation of imaging scores with regard to gestational age showed that scores improved with increasing gestational age on 1.5-T MRI but not on 3-T MRI. Overall, more imaging artifacts were found when imaging was performed at 3 T than at 1.5 T. CONCLUSION An overall advantage to performing fetal imaging at 3 T was made evident by the higher imaging scores obtained with 3-T MRI versus 1.5-T MRI when different fetal anatomic structures were evaluated. These higher scores were predominantly associated with use of SSFP sequences. The findings of this study and future advancements in MRI software and 3-T protocols may allow optimal visualization and examination of fetal pathologic abnormalities, thus better identifying fetal and maternal needs both prenatally and postnatally.
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Abstract
Magnetic resonance imaging (MRI) has a superior soft-tissue contrast compared to other radiological imaging modalities and its physiological and functional applications have led to a significant increase in MRI scans worldwide. A comprehensive MRI safety training to protect patients and other healthcare workers from potential bio-effects and risks of the magnetic fields in an MRI suite is therefore essential. The knowledge of the purpose of safety zones in an MRI suite as well as MRI appropriateness criteria is important for all healthcare professionals who will work in the MRI environment or refer patients for MRI scans. The purpose of this article is to give an overview of current magnetic resonance safety guidelines and discuss the safety risks of magnetic fields in an MRI suite including forces and torque of ferromagnetic objects, tissue heating, peripheral nerve stimulation, and hearing damages. MRI safety and compatibility of implanted devices, MRI scans during pregnancy, and the potential risks of MRI contrast agents will also be discussed, and a comprehensive MRI safety training to avoid fatal accidents in an MRI suite will be presented.
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Affiliation(s)
- Steffen Sammet
- Department of Radiology, University of Chicago Medicine, 5841 South Maryland Avenue, MC2026, Chicago, IL, 60637, USA.
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Sammet S, Sammet CL. Implementation of a comprehensive MR safety course for medical students. J Magn Reson Imaging 2015; 42:1478-86. [PMID: 26172156 PMCID: PMC4713360 DOI: 10.1002/jmri.24993] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 06/18/2015] [Accepted: 06/22/2015] [Indexed: 11/07/2022] Open
Abstract
This review article proposes the design of an educational magnetic resonance (MR) safety course for instructing medical students about basic MR and patient-related safety. The MR safety course material can be implemented as a traditional didactic or interactive lecture in combination with hands-on safety demonstrations. The goal of the course is to ensure that medical students receive a basic understanding of MR principles and safety considerations. This course will prepare medical students for patient screening and safety consultations when ordering MR studies. A multiple-choice exam can be used to document the proficiency in MR safety of the medical students. The course can be used by various medical school programs and may help to ensure consistent quality of teaching materials and MR safety standards.
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Affiliation(s)
| | - Christina L. Sammet
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL
- Northwestern University, Chicago, IL
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Gomes M, Matias A, Macedo F. Risks to the fetus from diagnostic imaging during pregnancy: review and proposal of a clinical protocol. Pediatr Radiol 2015; 45:1916-29. [PMID: 26271622 DOI: 10.1007/s00247-015-3403-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 04/25/2015] [Accepted: 06/01/2015] [Indexed: 11/25/2022]
Abstract
Every day, medical practitioners face the dilemma of exposing pregnant or possibly pregnant patients to radiation from diagnostic examinations. Both doctors and patients often have questions about the risks of radiation. The most vulnerable period is between the 8th and 15th weeks of gestation. Deterministic effects like pregnancy loss, congenital malformations, growth retardation and neurobehavioral abnormalities have threshold doses above 100-200 mGy. The risk is considered negligible at 50 mGy and in reality no diagnostic examination exceeds this limit. The risk of carcinogenesis is slightly higher than in the general population. Intravenous iodinated contrast is discouraged, except in highly selected patients. Considering all the possible noxious effects of radiation exposure, measures to diminish radiation are essential and affect the fetal outcome. Nonionizing procedures should be considered whenever possible and every radiology center should have its own data analysis on fetal radiation exposure. In this review, we analyze existing literature on fetal risks due to radiation exposure, producing a clinical protocol to guide safe radiation use in a clinical setting.
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Affiliation(s)
- Mafalda Gomes
- Faculty of Medicine, University of Porto, Praça de Gomes Teixeira, 4099-002, Porto, Portugal.
| | - Alexandra Matias
- Faculty of Medicine, University of Porto, Praça de Gomes Teixeira, 4099-002, Porto, Portugal
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Lefèvre J, Germanaud D, Dubois J, Rousseau F, de Macedo Santos I, Angleys H, Mangin JF, Hüppi PS, Girard N, De Guio F. Are Developmental Trajectories of Cortical Folding Comparable Between Cross-sectional Datasets of Fetuses and Preterm Newborns? Cereb Cortex 2015; 26:3023-35. [PMID: 26045567 DOI: 10.1093/cercor/bhv123] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Magnetic resonance imaging has proved to be suitable and efficient for in vivo investigation of the early process of brain gyrification in fetuses and preterm newborns but the question remains as to whether cortical-related measurements derived from both cases are comparable or not. Indeed, the developmental folding trajectories drawn up from both populations have not been compared so far, neither from cross-sectional nor from longitudinal datasets. The present study aimed to compare features of cortical folding between healthy fetuses and early imaged preterm newborns on a cross-sectional basis, over a developmental period critical for the folding process (21-36 weeks of gestational age [GA]). A particular attention was carried out to reduce the methodological biases between the 2 populations. To provide an accurate group comparison, several global parameters characterizing the cortical morphometry were derived. In both groups, those metrics provided good proxies for the dramatic brain growth and cortical folding over this developmental period. Except for the cortical volume and the rate of sulci appearance, they depicted different trajectories in both groups suggesting that the transition from into ex utero has a visible impact on cortical morphology that is at least dependent on the GA at birth in preterm newborns.
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Affiliation(s)
- Julien Lefèvre
- Aix-Marseille Université, CNRS, ENSAM, Université de Toulon, LSIS UMR 7296, 13397 Marseille, France Institut de Neurosciences de la Timone UMR 7289, Aix Marseille Université, CNRS, 13385 Marseille, France
| | - David Germanaud
- Service de Neurologie Pédiatrique et Pathologie Métabolique, APHP, Hôpital Robert Debré, DHU PROTECT, 75019 Paris, France Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France CEA, NeuroSpin, UNIACT, UNIPEDIA, 91191 Gif-sur-Yvette, France INSERM, U1129, 75015 Paris, France Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Jessica Dubois
- Cognitive Neuroimaging Unit, INSERM, U992, 91191 Gif-sur-Yvette, France NeuroSpin Center, CEA, 91191 Gif-sur-Yvette, France University Paris Sud, 91400 Orsay, France
| | - François Rousseau
- Institut Mines-Telecom, Telecom Bretagne, INSERM U1101 LaTIM, 29609 Brest, France
| | | | - Hugo Angleys
- Cognitive Neuroimaging Unit, INSERM, U992, 91191 Gif-sur-Yvette, France NeuroSpin Center, CEA, 91191 Gif-sur-Yvette, France University Paris Sud, 91400 Orsay, France
| | | | - Petra S Hüppi
- Department of Pediatrics, Geneva University Hospitals, 1211 Genève 14, Switzerland Department of Neurology, Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Nadine Girard
- Aix Marseille Université, CNRS, CRMBM UMR 7339, 13385 Marseille, France Service de Neuroradiologie, Hôpital de La Timone, 13005 Marseille, France
| | - François De Guio
- CEA, NeuroSpin Center, UNATI, 91191 Gif-sur-Yvette, France Université Paris Diderot, Sorbonne Paris Cité, UMR-S 1161 INSERM, 75010 Paris, France
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Mitter C, Prayer D, Brugger PC, Weber M, Kasprian G. In vivo tractography of fetal association fibers. PLoS One 2015; 10:e0119536. [PMID: 25742520 PMCID: PMC4350986 DOI: 10.1371/journal.pone.0119536] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 01/28/2015] [Indexed: 01/23/2023] Open
Abstract
Association fibers connect different cortical areas within the same hemisphere and constitute an essential anatomical substrate for a diverse range of higher cognitive functions. So far a comprehensive description of the prenatal in vivo morphology of these functionally important pathways is lacking. In the present study, diffusion tensor imaging (DTI) and tractography were used to visualize major association fiber tracts and the fornix in utero in preselected non-motion degraded DTI datasets of 24 living unsedated fetuses between 20 and 34 gestational weeks (GW). The uncinate fasciculus and inferior fronto-occipital fasciculus were depicted as early as 20 GW, while in vivo 3D visualization of the inferior longitudinal fasciculus, cingulum and fornix was successful in older fetuses during the third trimester. Provided optimal scanning conditions, in utero DTI and tractography have the potential to provide a more accurate anatomical definition of developing neuronal networks in the human fetal brain. Knowledge about the normal prenatal 3D association tract morphology may serve as reference for their assessment in common developmental diseases.
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Affiliation(s)
- Christian Mitter
- Department of Biomedical Imaging and Image-guided Therapy, Division of Neuroradiology and Musculoskeletal Radiology, Medical University of Vienna, Vienna, Austria
- * E-mail:
| | - Daniela Prayer
- Department of Biomedical Imaging and Image-guided Therapy, Division of Neuroradiology and Musculoskeletal Radiology, Medical University of Vienna, Vienna, Austria
| | - Peter C. Brugger
- Department of Systematic Anatomy, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Michael Weber
- Department of Biomedical Imaging and Image-guided Therapy, Division of Neuroradiology and Musculoskeletal Radiology, Medical University of Vienna, Vienna, Austria
| | - Gregor Kasprian
- Department of Biomedical Imaging and Image-guided Therapy, Division of Neuroradiology and Musculoskeletal Radiology, Medical University of Vienna, Vienna, Austria
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48
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Tocchio S, Kline-Fath B, Kanal E, Schmithorst VJ, Panigrahy A. MRI evaluation and safety in the developing brain. Semin Perinatol 2015; 39:73-104. [PMID: 25743582 PMCID: PMC4380813 DOI: 10.1053/j.semperi.2015.01.002] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Magnetic resonance imaging (MRI) evaluation of the developing brain has dramatically increased over the last decade. Faster acquisitions and the development of advanced MRI sequences, such as magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI), perfusion imaging, functional MR imaging (fMRI), and susceptibility-weighted imaging (SWI), as well as the use of higher magnetic field strengths has made MRI an invaluable tool for detailed evaluation of the developing brain. This article will provide an overview of the use and challenges associated with 1.5-T and 3-T static magnetic fields for evaluation of the developing brain. This review will also summarize the advantages, clinical challenges, and safety concerns specifically related to MRI in the fetus and newborn, including the implications of increased magnetic field strength, logistics related to transporting and monitoring of neonates during scanning, and sedation considerations, and a discussion of current technologies such as MRI conditional neonatal incubators and dedicated small-foot print neonatal intensive care unit (NICU) scanners.
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Affiliation(s)
- Shannon Tocchio
- Pediatric Imaging Research Center, Department of Radiology Children’s Hospital of Pittsburgh of UPMC, Pittsburgh, PA University of Pittsburgh Medical Center, Pittsburgh, PA
| | - Beth Kline-Fath
- Department of Radiology Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - Emanuel Kanal
- Director, Magnetic Resonance Services; Professor of Neuroradiology; Department of Radiology, University of Pittsburgh Medical Center (UPMC)
| | - Vincent J. Schmithorst
- Pediatric Imaging Research Center, Department of Radiology Children’s Hospital of Pittsburgh of UPMC, Pittsburgh, PA University of Pittsburgh Medical Center, Pittsburgh, PA
| | - Ashok Panigrahy
- Pediatric Imaging Research Center, Department of Radiology Children׳s Hospital of Pittsburgh of UPMC, University of Pittsburgh Medical Center, Pittsburgh, PA.
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49
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Malik SJ, Beqiri A, Price AN, Teixeira JN, Hand JW, Hajnal JV. Specific absorption rate in neonates undergoing magnetic resonance procedures at 1.5 T and 3 T. NMR IN BIOMEDICINE 2015; 28:344-52. [PMID: 25594939 PMCID: PMC5053241 DOI: 10.1002/nbm.3256] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 12/01/2014] [Accepted: 12/09/2014] [Indexed: 05/24/2023]
Abstract
MRI is finding increased clinical use in neonatal populations; the extent to which electromagnetic models used for quantification of specific absorption rate (SAR) by commercial MRI scanners accurately reflect this alternative scenario is unclear. This study investigates how SAR predictions relating to adults can be related to neonates under differing conditions when imaged using 1.5 T and 3 T MRI scanners. Electromagnetic simulations were produced in neonatal subjects of different sizes and positions within a generic MRI body transmit device operating at both 64 MHz and 128 MHz, corresponding to 1.5 T and 3 T MRI scanners, respectively. An adult model was also simulated, as was a spherical salt-water phantom, which was also used in a calorimetry experiment. The SAR in neonatal subjects was found to be less than that experienced in an adult in all scenarios; however, the overestimation factor was variable. For example a 3 T body scan resulting in local 10 g SAR of 10.1 W kg(-1) in an adult would deposit 2.6 W kg(-1) in a neonate: an approximately fourfold difference. The SAR experienced by neonatal subjects undergoing MRI is lower than that in adults in equivalent situations. If the safety of such procedures is assessed using adult-appropriate models then the result is a conservative estimate.
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Affiliation(s)
- Shaihan J Malik
- Centre for the Developing Brain and Department of Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St Thomas' Hospital, London, UK
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50
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Gholipour A, Estroff JA, Barnewolt CE, Robertson RL, Grant PE, Gagoski B, Warfield SK, Afacan O, Connolly SA, Neil JJ, Wolfberg A, Mulkern RV. Fetal MRI: A Technical Update with Educational Aspirations. CONCEPTS IN MAGNETIC RESONANCE. PART A, BRIDGING EDUCATION AND RESEARCH 2014; 43:237-266. [PMID: 26225129 PMCID: PMC4515352 DOI: 10.1002/cmr.a.21321] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Fetal magnetic resonance imaging (MRI) examinations have become well-established procedures at many institutions and can serve as useful adjuncts to ultrasound (US) exams when diagnostic doubts remain after US. Due to fetal motion, however, fetal MRI exams are challenging and require the MR scanner to be used in a somewhat different mode than that employed for more routine clinical studies. Herein we review the techniques most commonly used, and those that are available, for fetal MRI with an emphasis on the physics of the techniques and how to deploy them to improve success rates for fetal MRI exams. By far the most common technique employed is single-shot T2-weighted imaging due to its excellent tissue contrast and relative immunity to fetal motion. Despite the significant challenges involved, however, many of the other techniques commonly employed in conventional neuro- and body MRI such as T1 and T2*-weighted imaging, diffusion and perfusion weighted imaging, as well as spectroscopic methods remain of interest for fetal MR applications. An effort to understand the strengths and limitations of these basic methods within the context of fetal MRI is made in order to optimize their use and facilitate implementation of technical improvements for the further development of fetal MR imaging, both in acquisition and post-processing strategies.
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Affiliation(s)
- Ali Gholipour
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Judith A Estroff
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Carol E Barnewolt
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Richard L Robertson
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - P Ellen Grant
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Borjan Gagoski
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Simon K Warfield
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Onur Afacan
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Susan A Connolly
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Jeffrey J Neil
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Adam Wolfberg
- Boston Maternal Fetal Medicine, Boston, Massachusetts, USA
| | - Robert V Mulkern
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
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