Magnetic Resonance Imaging (MRI) is among the most important medical imaging techniques available today. There is an installed base of approximately 15,000 MRI scanners worldwide. Each of these ...scanners is capable of running many different "pulse sequences", which are governed by physics and engineering principles, and implemented by software programs that control the MRI hardware. To utilize an MRI scanner to the fullest extent, a conceptual understanding of its pulse sequences is crucial. This book offers a complete guide that can help the scientists, engineers, clinicians, and technologists in the field of MRI understand and better employ their scanner.
·Explains pulse sequences, their components, and the associated image reconstruction methods commonly used in MRI·Provides self-contained sections for individual techniques·Can be used as a quick reference guide or as a resource for deeper study·Includes both non-mathematical and mathematical descriptions ·Contains numerous figures, tables, references, and worked example problems
The origin of modern science is often located in Europe and the West. This Euro/West-centrism relegates emergent practices elsewhere to the periphery, undergirding analyses of contemporary ...transnational science and technology with traditional but now untenable hierarchical categories. In this book, Amit Prasad examines features of transnationality in science and technology through a study of MRI research and development in the United States, Britain, and India. In an analysis that is both theoretically nuanced and empirically robust, Prasad unravels the entangled genealogies of MRI research, practice, and culture in these three countries. Prasad follows sociotechnical trails in relation to five aspects of MRI research: invention, industrial development, market, history, and culture. He first examines the well-known dispute between American scientists Paul Lauterbur and Raymond Damadian over the invention of MRI, then describes the post-invention emergence of the technology, as the center of MRI research shifted from Britain to the U.S; the marketing of the MRI and the transformation of MRI research into a corporate-powered "Big Science"; and MRI research in India, beginning with work in India's nuclear magnetic resonance (NMR) laboratories in the 1940s. Finally, he explores the different dominant technocultures in each of the three countries, analyzing scientific cultures as shifting products of transnational histories rather than static products of national scientific identities and cultures. Prasad's analysis offers not only an innovative contribution to current debates within science and technology studies but also an original postcolonial perspective on the history of cutting-edge medical technology.
BACKGROUND AND PURPOSE—If magnetic resonance imaging (MRI) is to compete with computed tomography for evaluation of patients with acute ischemic stroke, there is a need for further improvements in ...acquisition speed.
METHODS—Inclusion criteria for this prospective, single institutional study were symptoms of acute ischemic stroke within 24 hours onset, National Institutes of Health Stroke Scale ≥3, and absence of MRI contraindications. A combination of echo-planar imaging (EPI) and a parallel acquisition technique were used on a 3T magnetic resonance (MR) scanner to accelerate the acquisition time. Image analysis was performed independently by 2 neuroradiologists.
RESULTS—A total of 62 patients met inclusion criteria. A repeat MRI scan was performed in 22 patients resulting in a total of 84 MRIs available for analysis. Diagnostic image quality was achieved in 100% of diffusion-weighted imaging, 100% EPI-fluid attenuation inversion recovery imaging, 98% EPI-gradient recalled echo, 90% neck MR angiography and 96% of brain MR angiography, and 94% of dynamic susceptibility contrast perfusion scans with interobserver agreements (k) ranging from 0.64 to 0.84. Fifty-nine patients (95%) had acute infarction. There was good interobserver agreement for EPI-fluid attenuation inversion recovery imaging findings (k=0.78; 95% confidence interval, 0.66–0.87) and for detection of mismatch classification using dynamic susceptibility contrast-Tmax (k=0.92; 95% confidence interval, 0.87–0.94). Thirteen acute intracranial hemorrhages were detected on EPI-gradient recalled echo by both observers. A total of 68 and 72 segmental arterial stenoses were detected on contrast-enhanced MR angiography of the neck and brain with k=0.93, 95% confidence interval, 0.84 to 0.96 and 0.87, 95% confidence interval, 0.80 to 0.90, respectively.
CONCLUSIONS—A 6-minute multimodal MR protocol with good diagnostic quality is feasible for the evaluation of patients with acute ischemic stroke and can result in significant reduction in scan time rivaling that of the multimodal computed tomographic protocol.
.2661 Preamble This document was developed by the American College of Cardiology Foundation (ACCF) Task Force on Clinical Expert Consensus Documents (ECDs) and cosponsored by the American College of ...Radiology (ACR), American Heart Association (AHA), North American Society for Cardiovascular Imaging (NASCI), and the Society for Cardiovascular Magnetic Resonance (SCMR), to provide a perspective on the current state of cardiovascular magnetic resonance (CMR). Often the topic is the subject of ongoing investigation. ...the reader should view the ECD as the best attempt of the ACCF and document cosponsors to inform and guide clinical practice in areas where rigorous evidence may not be available or the evidence to date is not widely accepted. ...some topics covered by ECDs will be addressed subsequently by the ACCF/AHA Practice Guidelines Committee. Peer Reviewer Representation Consultant Speaker Ownership/Partnership/Principal Research Institutional, Organizational, or Other Financial Benefit Expert Witness Dr. James C. Carr Official Reviewer--North American Society for Cardiovascular Imaging None None None None None None Dr. Michael G. Del Core Official Reviewer--ACCF Board of Governors None None None None None None Dr. Andre Duerinckx Official Reviewer--American College of Radiology None None None Philips Medical Systems Schering-Plough None None Dr. Mark J. Eisenberg Official Reviewer--ACCF Task Force on Clinical Expert Consensus Documents None None None None None None Dr. Victor A. Ferrari Official Reviewer-- Society for Cardiovascular Magnetic Resonance Imaging None None None None None None Dr. Gautham Reddy Official Reviewer--American College of Radiology None None None None None None Dr. Orlando Simonetti Official Reviewer--North American Society for Cardiovascular Imaging None None * Siemens Healthcare None None None Dr. James E. Udelson Official Reviewer--ACCF Board of Trustees; American Heart Association None None None None None None Dr. Sanjay Kaul Content Reviewer--ACCF Task Force on Clinical Expert Consensus Documents None None None None None None Dr. Debabrata Mukherjee Content Reviewer--ACCF Task Force on Clinical Expert Consensus Documents None None None None None None Dr. Robert S. Rosenson Content Reviewer--ACCF Task Force on Clinical Expert Consensus Documents Abbott Anthera AstraZeneca* Daiichi Sankyo LipoScience* Roche None LipoScience* None Grain Board None Dr. Jonathan W. Weinsaft Content Reviewer--*Individual None None None Lantheus Medical Imaging None None * This table represents the relevant relationships with industry and other entities that were disclosed by reviewers at the time of peer review. A person is deemed to have a significant interest in a business if the interest represents ownership of 5% or more of the voting stock or share of the business entity, or ownership of $10 000 or more of the fair market value of the business entity; or if funds received by the person from the business entity exceed 5% of the person's gross income for the previous year.
Objective
Treatment response assessment in high-grade gliomas uses contrast enhanced T1-weighted MRI, but is unreliable. Novel advanced MRI techniques have been studied, but the accuracy is not well ...known. Therefore, we performed a systematic meta-analysis to assess the diagnostic accuracy of anatomical and advanced MRI for treatment response in high-grade gliomas.
Methods
Databases were searched systematically. Study selection and data extraction were done by two authors independently. Meta-analysis was performed using a bivariate random effects model when ≥5 studies were included.
Results
Anatomical MRI (five studies, 166 patients) showed a pooled sensitivity and specificity of 68% (95%CI 51–81) and 77% (45–93), respectively. Pooled apparent diffusion coefficients (seven studies, 204 patients) demonstrated a sensitivity of 71% (60–80) and specificity of 87% (77–93). DSC-perfusion (18 studies, 708 patients) sensitivity was 87% (82–91) with a specificity of 86% (77–91). DCE-perfusion (five studies, 207 patients) sensitivity was 92% (73–98) and specificity was 85% (76–92). The sensitivity of spectroscopy (nine studies, 203 patients) was 91% (79–97) and specificity was 95% (65–99).
Conclusion
Advanced techniques showed higher diagnostic accuracy than anatomical MRI, the highest for spectroscopy, supporting the use in treatment response assessment in high-grade gliomas.
Key points
• Treatment response assessment in high-grade gliomas with anatomical MRI is unreliable
• Novel advanced MRI techniques have been studied, but diagnostic accuracy is unknown
• Meta-analysis demonstrates that advanced MRI showed higher diagnostic accuracy than anatomical MRI
• Highest diagnostic accuracy for spectroscopy and perfusion MRI
• Supports the incorporation of advanced MRI in high-grade glioma treatment response assessment
This reprint aims to provide an update on the biomedical imaging technologies that can be used for cardiovascular diseases, including Doppler echocardiography, magnetic resonance imaging and positron ...emission tomography. Cardiovascular disease imaging assessment includes anatomy, hemodynamics, and tissue biomarkers, which aid the stratification of patient risk and therapy. In addition, this Special Issue includes articles that discuss the recent integration of artificial intelligence and machine learning, in order to support novel approaches to personalized image-based diagnosis.
Objective: Improve the reconstructed image with fast and multiclass dictionaries learning when magnetic resonance imaging is accelerated by undersampling the k-space data. Methods: A fast orthogonal ...dictionary learning method is introduced into magnetic resonance image reconstruction to provide adaptive sparse representation of images. To enhance the sparsity, image is divided into classified patches according to the same geometrical direction and dictionary is trained within each class. A new sparse reconstruction model with the multiclass dictionaries is proposed and solved using a fast alternating direction method of multipliers. Results: Experiments on phantom and brain imaging data with acceleration factor up to 10 and various undersampling patterns are conducted. The proposed method is compared with state-of-the-art magnetic resonance image reconstruction methods. Conclusion: Artifacts are better suppressed and image edges are better preserved than the compared methods. Besides, the computation of the proposed approach is much faster than the typical K-SVD dictionary learning method in magnetic resonance image reconstruction. Significance: The proposed method can be exploited in undersampled magnetic resonance imaging to reduce data acquisition time and reconstruct images with better image quality.
Over the past decade, updated definitions for the different stages of prostate cancer and risk for distant disease, along with the advent of new therapies, have remarkably changed the management of ...patients. The two expectations from imaging are accurate staging and appropriate assessment of disease response to therapies. Modern, next‐generation imaging (NGI) modalities, including whole‐body magnetic resonance imaging (WB‐MRI) and nuclear medicine (most often prostate‐specific membrane antigen PSMA positron emission tomography PET/computed tomography CT) bring added value to these imaging tasks. WB‐MRI has proven its superiority over bone scintigraphy (BS) and CT for the detection of distant metastasis, also providing reliable evaluations of disease response to treatment. Comparison of the effectiveness of WB‐MRI and molecular nuclear imaging techniques with regard to indications and the definition of their respective/complementary roles in clinical practice is ongoing. This paper illustrates the evolution of WB‐MRI imaging protocols, defines the current state‐of‐the art, and highlights the latest developments and future challenges. The paper presents and discusses WB‐MRI indications in the care pathway of men with prostate cancer in specific key situations: response assessment of metastatic disease, “all in one” cancer staging, and oligometastatic disease.
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