Ultrasound Elastography: The New Frontier in Direct Measurement of Muscle Stiffness
Authors: Joline E. Brandenburg, MD, Sarah F. Eby, Pengfei Song, Heng Zhao, PhD, Jeffrey S. Brault, DO, Shigao Chen, PhD, and Kai-Nan An, PhD
Published in: Arch Phys Med Rehabil. 2014 November ; 95(11): 2207–2219. doi:10.1016/j.apmr.2014.07.007.
The use of brightness-mode ultrasound and Doppler ultrasound in physical medicine and rehabilitation has increased dramatically. The continuing evolution of ultrasound technology has also produced ultrasound elastography, a cutting-edge technology that can directly measure the mechanical properties of tissue, including muscle stiffness. Its real-time and direct measurements of muscle stiffness can aid the diagnosis and rehabilitation of acute musculoskeletal injuries and chronic myofascial pain. It can also help monitor outcomes of interventions affecting muscle in neuromuscular and musculoskeletal diseases, and it can better inform the functional prognosis. This technology has implications for even broader use of ultrasound in physical medicine and rehabilitation practice, but more knowledge about its uses and limitations is essential to its appropriate clinical implementation. In this review, we describe different ultrasound elastography techniques for studying muscle stiffness, including strain elastography, acoustic radiation force impulse imaging, and shear-wave elastography. We discuss the basic principles of these techniques, including the strengths and limitations of their measurement capabilities. We review the current muscle research, discuss physiatric clinical applications of these techniques, and note directions for future research.
Power and Color Doppler Ultrasound Settings for Inflammatory Flow: Impact on Scoring of Disease Activity in Patients With Rheumatoid Arthritis
Authors: Søren Torp-Pedersen, Robin Christensen, Marcin Szkudlarek, Karen Ellegaard, Maria Antonietta D’Agostino, Annamaria Iagnocco, Esperanza Naredo, Peter Balint, Richard J. Wakefield, Arendse Torp-Pedersen, and Lene Terslev
Published in: ARTHRITIS & RHEUMATOLOGY, Vol. 67, No. 2, February 2015, pp 386–395
Objective. To determine how settings for power and color Doppler ultrasound sensitivity vary on different high- and intermediate-range ultrasound machines and to evaluate the impact of these changes on Doppler scoring of inflamed joints.
Methods. Six different types of ultrasound machines were used. On each machine, the factory setting for superficial musculoskeletal scanning was used unchanged for both color and power Doppler modalities. The settings were then adjusted for increased Doppler sensitivity, and these settings were designated study settings. Eleven patients with rheumatoid arthritis (RA) with wrist involvement were scanned on the 6 machines, each with 4 settings, generating 264 Doppler images for scoring and color quantification. Doppler sensitivity was measured with a quantitative assessment of Doppler activity: color fraction. Higher color fraction indicated higher sensitivity.
Results. Power Doppler was more sensitive on half of the machines, whereas color Doppler was more sensitive on the other half, using both factory settings and study settings. There was an average increase in Doppler sensitivity, despite modality, of 78% when study settings were applied. Over the 6 machines, 2 Doppler modalities, and 2 settings, the grades for each of 7 of the patients varied between 0 and 3, while the grades for each of the other 4 patients varied between 0 and 2.
Conclusion. The effect of using different machines, Doppler modalities, and settings has a considerable influence on the quantification of inflammation.
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Shear-Wave Elastography: Basic Physics and Musculoskeletal Applications
Authors: Mihra S. Taljanovic, MD, PhD, Lana H. Gimber, MD, MPH, Giles W. Becker, MD, L. Daniel Latt, MD, PhD, Andrea S. Klauser, MD, David M. Melville, MD, Liang Gao, PhD, Russell S. Witte, PhD
In the past 2 decades, sonoelastography has been progressively used as a tool to help evaluate soft-tissue elasticity and add to information obtained with conventional gray-scale and Doppler ultrasonographic techniques. Recently introduced on clinical scanners, shearwave elastography (SWE) is considered to be more objective, quantitative,
and reproducible than compression sonoelastography with increasing applications to the musculoskeletal system. SWE uses an acoustic radiation force pulse sequence to generate shear waves, which propagate perpendicular to the ultrasound beam, causing transient displacements. The distribution of shear-wave velocities at each pixel is directly related to the shear modulus, an absolute measure of the tissue’s elastic properties. Shear-wave images are automatically coregistered with standard B-mode images to provide quantitative color elastograms with anatomic specificity. Shear waves propagate faster through stiffer contracted tissue, as well as along the long axis of tendon and muscle. SWE has a promising role in determining the severity of disease and treatment followup of various musculoskeletal tissues including tendons, muscles, nerves, and ligaments. This article describes the basic ultrasound physics of SWE and its applications in the evaluation of various traumatic and pathologic conditions of the musculoskeletal system.
RadioGraphics 2017; 37:855–870
Published online 10.1148/rg.2017160116
READ THE ARTICLE: Shear Wave Elastography Physics Applications
X-ray phase contrast imaging of the breast-advances towards clinical implementation
Citation: Auweter SD, Herzen J, Willner M, Grandl S, Scherer K, Bamberg F, et al. X-ray phase-contrast imaging of the breast—advances towards clinical implementation. Br J Radiol 2014;87:20130606.
Breast cancer constitutes about one-quarter of all cancers and is the leading cause of cancer death in women. To reduce breast cancer mortality, mammographic screening programmes have been implemented in many Western countries. However, these programmes remain controversial because of the associated radiation exposure and the need for improvement in terms of diagnostic accuracy. Phase-contrast imaging is a new X-ray-based technology that has been shown to provide enhanced soft-tissue contrast and improved visualization of cancerous structures. Furthermore, there is some indication that these improvements of image quality can be maintained at reduced radiation doses. Thus, X-ray phase-contrast mammography may significantly contribute to advancements in early breast cancer diagnosis. Feasibility studies of X-ray phase-contrast breast CT have provided images that allow resolution of the fine structure of tissue that can otherwise only be obtained by histology. This implies that X-ray phase-contrast imaging may also lead to the development of entirely new (micro-) radiological applications. This review provides a brief overview of the physical characteristics of this new technology and describes recent developments towards clinical implementation of X-ray phase-contrast imaging of the breast.
Read the Complete Article: Breast Cancer Imaging
Placental Insufficiency in Fetuses That Slow in Growth but Are Born Appropriate for Gestational Age: A Prospective Longitudinal Study
Authors: Nadia Bardien1,5, Clare L. Whitehead1,3, Stephen Tong1,3, Antony Ugoni4, Susan McDonald5, Susan P. Walker1,2*
1 Department of Perinatal Medicine, Mercy Hospital for Women, Melbourne, Australia, 2 Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Australia, 3 Translational Obstetrics Group, University of Melbourne, Melbourne, Australia, 4 School of Physiotherapy, University of Melbourne, Melbourne, Victoria, Australia, 5 La Trobe University, Mercy Hospital for Women, Melbourne, Australia
To determine whether fetuses that slow in growth but are then born appropriate for gestational age (AGA, birthweight >10th centile) demonstrate ultrasound and clinical evidence of placental insufficiency.
Prospective longitudinal study of 48 pregnancies reaching term and a birthweight >10th cen-tile. We estimated fetal weight by ultrasound at 28 and 36 weeks, and recorded birthweight to determine the relative change in customised weight across two time points: 28–36 weeks and 28 weeks-birth. The relative change in weight centiles were correlated with fetoplacental Doppler findings performed at 36 weeks. We also examined whether a decline in growth trajectory in fetuses born AGA was associated with operative deliveries performed for suspected intrapartum compromise.
The middle cerebral artery pulsatility index (MCA-PI) showed a linear association with fetal growth trajectory. Lower MCA-PI readings (reflecting greater diversion of blood supply to the brain) were significantly associated with a decline in fetal growth, both between 28–36 weeks (p = 0.02), and 28 weeks-birth (p = 0.0002). The MCA-PI at 36 weeks was significantly higher among those with a relative weight centile fall <20%, compared to those with a moderate centile fall of 20–30% (mean MCA-PI 1.94 vs 1.61; p<0.05), or severe centile fall of >30% (mean MCA-PI 1.94 vs 1.56; p<0.01). Of 43 who labored, operative delivery for suspected intrapartum fetal compromise was required in 12 cases; 9/18 (50%) cases where growth slowed, and 3/25 (12%) where growth trajectory was maintained (p = 0.01).
Slowing in growth across the third trimester among fetuses subsequently born AGA was associated with ultrasound and clinical features of placental insufficiency. Such fetuses may represent an under-recognised cohort at increased risk of stillbirth.
Published in PLOS One: DOI:10.1371/journal.pone.0142788