ARDMS NewsWire November 26, 2010‏

Ultrasound Needle Guidance Improves Performance and Outcomes of Knee Injections

The use of ultrasound needle guidance improves the performance, outcomes and the cost-effectiveness of knee injections in people with osteoarthritis, according to research presented recently at the American College of Rheumatology Annual Scientific Meeting in Atlanta.

Osteoarthritis, or OA as it is commonly called, is the most common joint disease affecting middle-age and older people. It is characterized by progressive damage to the joint cartilage-the cushioning material at the end of long bones-and causes changes in the structures around the joint. These changes can include fluid accumulation, bony overgrowth, and loosening and weakness of muscles and tendons, all of which may limit movement and cause pain and swelling.

Researchers recently set out to determine if the use of ultrasound guidance would affect the outcomes of intraarticular injections-injections of medicine into, or removal of fluid from, arthritic joints-in people with knee OA. "Ultrasound, the use of sound waves to visualize the human body, is useful to physicians to guide the needle into the joint to inject medications to treat arthritis," explained Wilmer Sibbitt, Jr., MD; professor of rheumatology and neurology, University of New Mexico Health Sciences Center, Albuquerque, N.M. and an investigator in the study.

Dr. Sibbitt's research team studied 94 knees, which were randomly selected for injection administered either by the conventional palpation-guided method or by the newer ultrasound-guided method (which allowed researchers to watch, in real time, the needle entering and exiting the joint).

Both the palpation and ultrasound-guided methods involved one needle, with a syringe attached, entering the joint to remove fluid from it. After that was accomplished, the first syringe was removed (with the needle remaining inserted) and a second syringe was used to inject 80mg of a corticosteroid through the same needle. This technique ensured the medication was injected into the correct place. When using the ultrasound-guided method, researchers were able to perform the procedure while confirming needle placement as well as administration of the lidocaine and the corticosteroid by viewing the procedure as it occurred.

Each participant's initial pain, pain during the procedure, and knee pain at the end of two weeks and six months were studied. Researchers looked at who responded to the treatment, the length of time the participants experienced pain relief after the injection, how often participants needed to be reinjected, the total cost of the procedure, and the cost per participant who responded to the treatment.

When compared to the palpation-guided method, researchers found the use of the ultrasound-guided method to provide improved results - including a 107 percent increase in the number of people who responded to the treatment and a 51.6 percent reduction in the number of people who did not.

Additionally, researchers noted a 47 percent reduction in pain during the procedure, a 41.7 percent reduction in pain two weeks after the injection, and a 35.5 percent increase in the length of time the participants experienced pain relief after the injection.

Finally, researchers compared the cost effectiveness of the ultrasound-guided method to the traditional palpation method. They found that the ultrasound method led to a 14.6 percent ($48) reduction in cost per participant per year and a 58.8 percent ($593) reduction in the cost per hospital-outpatient participant who responded to the treatment.

These results have led researchers to believe that the use of ultrasound-guidance in intraarticular injections is an approach that can improve the overall treatment of knee OA, which will improve treatment costs as a patient's need for additional expensive treatments can be reduced.

"The study demonstrates that when physicians use ultrasound and a technique called hydrodissection performed with precise new mechanical syringes to inject the joint, the patient experiences less pain, improved safety, a better response to medications, and less need for other medical therapy," said Dr. Sibbitt. "Rheumatologists are increasingly using ultrasound, and patients should be aware that joint injections may be more effective and less painful if their physician offers this option to them."

Patients should talk to their rheumatologists to determine their best course of treatment.

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Article written by staff at news-medical.net and adapted for the purposes of this newsletter.

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Scientists Find Way to Overcome Limitations of Ultrasound Imaging

University of California, Berkeley, scientists have found a way to overcome one of the main limitations of ultrasound imaging - the poor resolution of the picture.

Everyone who has had an ultrasound, including most pregnant women, is familiar with the impressionistic nature of the images. One of the limits to the detail obtainable with sonography is the frequency of the sound: The basic laws of physics dictate that the smallest objects you can "see" are about the size of the wavelength of the sound waves. For ultrasound of deep tissues in the body, for example, the sound waves are typically 1-5 megahertz - far higher than what humans can hear - which imposes a resolution limit of about a millimeter.

In a paper appearing online this week in the journal Nature Physics, physicists at UC Berkeley and Universidad Autonoma de Madrid in Spain demonstrate how to capture the evanescent waves bouncing off an object to reconstruct detail as small as one-fiftieth of the wavelength of the sound waves.

Evanescent sound waves are vibrations near the object that damp out within a very short distance, as opposed to propagating waves, which can travel over a long distance. "With our device, we can pick up and transmit the evanescent waves, which contain a substantial fraction of the ultra-subwavelength information from the object, so that we can realize super-resolution acoustic imaging," said first author Jie Zhu, a post-doctoral fellow in the Center for Scalable and Integrated NanoManufacturing (SINAM), a National Science Foundation-funded Nano-scale Science and Engineering Center at UC Berkeley.

The researchers refer to their device for capturing evanescent waves as a three-dimensional, holey-structured metamaterial. It consists of 1,600 hollow copper tubes bundled into a 16 centimeter (6 inch) bar with a square cross-section of 6.3 cm (2.5 inches). Placed close to an object, the structure captures the evanescent waves and pipes them through to the opposite end.

In a practical device, Zhu said, the metamaterial could be mounted on the end of an ultrasound probe to vastly improve the image resolution. The device would also improve underwater sonography, or sonar, as well as non-destructive evaluation in industry applications. "For ultrasound detection, the image resolution is generally in the millimeter range," said co-author Xiaobo Yin. "With this device, resolution is only limited by the size of the holes."

In the researchers' experiments, the holes in the copper tubes were about a millimeter in diameter. Using acoustic waves of about 2 kHz, the resolution of an image would normally be limited to the wavelength, or 200 millimeters. With their holey-structured metamaterial, they can resolve the feature size as small as 4 mm, or one-fiftieth of a wavelength. "Without the metamaterial, it would be impossible to detect such a deep sub-wavelength object at all," Yin said.

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Article written by staff at news-medical.net and adapted for the purposes of this newsletter.

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Handheld Ultrasound Market to Exceed $1.2B by 2016

The U.S. handheld ultrasound market is expected to exceed $1.2 billion by 2016, sparked by technological advances in size, imaging quality, ultrasound depth and improvements in both 3D and 4D capabilities, according to marketing research group iData.

While the ultrasound market saw a significant decline in sales during the recession, the report found that the adoption of handheld ultrasound devices and the use of ultrasound in emergency medicine will set the stage for strong growth in the overall U.S. ultrasound market.

In addition to emergency medicine, ultrasound use in breast imaging is expected to double in size by 2016 due to increasing demand for devices in the detection of breast and the lack of ionizing radiation associated with ultrasound, said iData.

The report identified SonoSite, GE and Siemens as the main companies that have presented technological advances and improvements to handheld ultrasound equipment and contributed to the growing market.

"Recent advances in handheld ultrasound devices have allowed for their use in procedures traditionally performed by other modalities such as CT or MRI," explained Kamran Zamanian, PhD, CEO of iData. "As the systems increase the ability to diagnose and treat a greater number of patients, physician preference towards handheld will rise rapidly," Zamanian predicted.