Orthopaedic MRI Research Articles

Analysis and Evaluation of a Deep Learning Reconstruction Approach with Denoising for Orthopedic MRI.

To evaluate two settings (noise reduction of 50% or 75%) of a deep learning (DL) reconstruction model relative to each other and to conventional MR image reconstructions on clinical orthopedic MRI datasets. This retrospective study included 54 patients who underwent two-dimensional fast spin-echo MRI for hip (n = 22; mean age, 44 years ± 13 [standard deviation]; nine men) or shoulder (n = 32; mean age, 56 years ± 17; 17 men) conditions between March 2019 and June 2020. MR images were reconstructed with conventional methods and the vendor-provided and commercially available DL model applied with 50% and 75% noise reduction settings (DL 50 and DL 75, respectively). Quantitative analytics, including relative anatomic edge sharpness, relative signal-to-noise ratio (rSNR), and relative contrast-to-noise ratio (rCNR) were computed for each dataset. In addition, the image sets were randomized, blinded, and presented to three board-certified musculoskeletal radiologists for ranking based on overall image quality and diagnostic confidence. Statistical analysis was performed with a nonparametric hypothesis comparing derived quantitative metrics from each reconstruction approach. In addition, inter- and intrarater agreement analysis was performed on the radiologists' rankings. Both denoising settings of the DL reconstruction showed improved edge sharpness, rSNR, and rCNR relative to the conventional reconstructions. The reader rankings demonstrated strong agreement, with both DL reconstructions outperforming the conventional approach (Gwet agreement coefficient = 0.98). However, there was lower agreement between the readers on which DL reconstruction denoising setting produced higher-quality images (Gwet agreement coefficient = 0.31 for DL 50 and 0.35 for DL 75). The vendor-provided DL MRI reconstruction showed higher edge sharpness, rSNR, and rCNR in comparison with conventional methods; however, optimal levels of denoising may need to be further assessed.Keywords: MRI Reconstruction Method, Deep Learning, Image Analysis, Signal-to-Noise Ratio, MR-Imaging, Neural Networks, Hip, Shoulder, Physics, Observer Performance, Technology Assessment Supplemental material is available for this article. © RSNA, 2021.

Performance Test of 1.5 T Cryogen-Free Orthopedic MRI Magnet

A 1.5 T cryogen-free superconducting magnet for a dedicated orthopedic MRI of human extremities was developed and tested. The magnet has a compact cryostat cooled by a pulse tube coldhead with cooling power of 1 W at 4.2 K. The warm bore of a cryostat is 325 mm in diameter and 600 mm in length. Cost effective NbTi wire was used for making superconducting coils. The magnet is actively shielded. A novel approach has been implemented to decrease the cool down time of the magnet. According to it, the coldhead was placed in the separate sleeve filled with the gaseous helium. It was shown experimentally that the convection of helium gas in the coldhead sleeve speeds up the cool down significantly, more than by 40% in this case. Cooling down the magnet from ambient to operating temperature takes about 100 h. The magnet operates in persistent mode with magnetic field stability of better than 0.01 ppm/h. Special tests have been performed to investigate the magnet behavior in case the coldhead is switched off . The magnet has shown steady operation at 1.5 T in case the coldhead was switched off for 4 min or even longer.

WE-C-213A-01: ACR MRI Accreditation: Medical Physicist Role in the Application Process

The medical physicist plays an important role in several aspects of the ACR MRI accreditation program. In 2008 significant program changes were made. The new program is modular so that facilities can apply for accreditation in any or all of six clinical modules depending on the practice. Each of the modules allows flexible protocol choices for clinical image submission, while setting minimum requirements for spatial resolution, temporal resolution, and total scan time. Two phantoms are now available to allow accreditation of both large bore magnets and small bore orthopedic MRI systems. During the application or renewal process the physicist can provide expertise to MRI facilities by acquiring the phantom images and assessing whether phantom image quality will meet ACR requirements. When image quality measures fall below standards, the physicist can identify the cause and offer recommendations for corrective action. In addition, prior to acquiring clinical images for accreditation, the physicist can determine whether the site's clinical protocols provide adequate spatial and temporal resolution. Learning Objectives: 1. Present an overview of the new modular ACR MRI Accreditation program as it applies to phantom image acquisition for accreditation application. 2. Discuss phantom image quality failures, possible causes and potential remedies. 3. Provide advice for avoiding common pitfalls in the phantom image submission process.

An “Openable,” High-Strength Gradient Set for Orthopedic MRI

A novel three-axis gradient set and RF resonator for orthopedic MRI has been designed and constructed. The set is openable and may be wrapped around injured joints. The design methodology used was the minimization of magnetic field spherical harmonics by simulated annealing. Splitting of the longitudinal coil presents the major design challenge to a fully openable gradient set and in order to efficiently design such coils, we have developed a new fast algorithm for determining the magnetic field spherical harmonics generated by an arc of multiturn wire. The algorithm allows a realistic impression of the effect of split longitudinal designs. A prototype set was constructed based on the new designs and tested in a 2-T clinical research system. The set generated 12 mT/m/A with a linear region of 12 cm and a switching time of 100 μs, conforming closely with theoretical predictions. Preliminary images from the set are presented.

Book Reviews

Australasian RadiologyVolume 36, Issue 2 p. 182-187 Book Reviews First published: May 1992 https://doi.org/10.1111/j.1440-1673.1992.tb03118.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Book reviewed in this article: An Introduction to Radiobiology. Endosonography in Obstetrics and Gynaecology. Cervical Spine: Tricks and Traps. Magnetic Resonance Imaging of the Paediatric Brain: An Anatomical Atlas. Emergency Interventional Radiology. MRI of the Musculoskeletal System. Differential Diagnosis in Conventional Radiology 2nd Edition. Cranial MRI: A Teaching File Approach. Manual of Clinical Magnetic Resonance Imaging. Frontiers in Radiation Therapy and Oncology - The Role of High Energy Electrons in the Treatment of Cancer. Radiology of the Trachea. Carpal Injuries — Anatomy, Radiology, Current Treatment. Orthopaedic MRI — A Teaching File. The Raven MRI Teaching File. Measurements in Pediatric Radiology. Surgical Neuro-angiographg (3): Functional Vascular Anatomy of Brain, Spinal Cord and Spine. The Radiotherapy of Malignant Disease. (Second Edition). R.C.S. Pointon. Atlas of Radiology of the Chest. Radiology of Trauma. Magnetic Resonance of the Cardiovascular System. Volume36, Issue2May 1992Pages 182-187 RelatedInformation