By Sean Fenske, Editor-in-Chief

The use of diagnostic imaging is growing rapidly as its value increases exponentially with each new advancement and innovation that improves performance. Physicians can gain critical insights into a patient’s condition or a specific area of concern through its use. In addition, imaging technologies can help aid with the navigation of instruments during medical procedures.

While ultrasound is still often commonly associated with pregnancy and enabling parents an opportunity to view their developing baby, it proves to be a valuable tool for an array of other clinical applications. Ensuring the utmost quality for these other situations will often require a specialized needle to enhance the visual result for the physician. Development of such an instrument requires a company with specific skills.

To help further explain the development and considerations involved with these needles, Balaji Janardhanan, Senior Managing, Engineering, at Elevaris Medical Devices, shared several comments. In the following Q&A, he explains what echogenicity is, how it impacts ultrasound innovations, and where the needle fits into the equation with this technology.

Sean Fenske: Can you first please explain what echogenicity is?

Balaji Janardhanan: Sure thing. Echogenicity is the ability to reflect sound waves to produce an ultrasound image. The National Institutes of Health explains it as, “the brightness of an image caused by the reflection of soundwaves and is influenced by sound beam characteristics and tissue density.” In addition, the ability is usually categorized in one of three ways.

• Hyperechoic, which is highly reflective
• Hypoechoic, which reflects fewer sound waves than the surrounding tissue
• Anechoic, which lacks echogenicity altogether, so no sound waves are reflected

Fenske: How is echogenicity used in ultrasound to improve imaging results?

Janardhanan: The variation in echogenicity creates the contrasts needed to distinguish tissues and identify any abnormalities during an ultrasound. So, for instance, hyperechoic tissues reflect more sound waves than surrounding tissue, appearing brighter or whiter on an ultrasound image. Some examples of tissues that would do that are bone, calcifications, and fat. Hypoechoic tissues like lymph nodes or tumors would appear darker on ultrasound images. And anechoic tissue, such as cysts and water, would appear as a completely black image on an ultrasound image. Effectively, the greater the difference in acoustic impedance between two adjacent tissues, the more pronounced the reflection of ultrasound waves and the higher echogenicity.

Medical procedures often rely on needle positioning, and ultrasound with echocardiography is a major imaging technology used for positioning and visualization within the body. This depends on echogenicity, which becomes crucial for guiding various medical procedures, such as biopsies, injections, and catheter placements. Therefore, effective use of medical devices with precise targeting of the tissues is made possible by echogenicity, which makes real-time ultrasound imaging work.

In the procedures where needles are used, the opposing needs of increased echogenicity on thin needles are at play for visualization. Increasing demand for smaller needles with thinner walls and smoother profiles, while also having increased visualization of the apex of the needle, poses a unique challenge, for which we have few established novel solutions.

Fenske: What type of procedures typically use echogenic needles? What types of diseases and/or clinical conditions are being identified?

Janardhanan: Echogenic needles are commonly used in radiofrequency procedures, like those used to treat back pain. They are also used in pre-surgery nerve-block procedures. In addition, they can be used in interventional spine procedures to guide needle placement in the spinal space, and they’re also used in interventional radiology.

Fenske: What factors impact the quality or results from echogenicity?

Janardhanan: Great question. Many needles may be echogenic, but not all echogenicity is equal. Some factors that come to mind are the needle’s shape, material, finish, and positioning in relation to the ultrasound probe, as well as tissue density, tissue composition, and imaging instrument and probe.

The key to creating superior echogenicity is in developing a feature or surface that maximizes the reflection of the ultrasound waves. There are multiple methods with which to accomplish this. Dimples and ablations can be created through grit blasting, mechanical dimpling, and laser dimpling, or ablating, where the needle is processed in a machine that creates these features that reflect the ultrasound waves.

Fenske: As a manufacturer of procedural needles, can you please explain the physical characteristics of a needle that promote improved echogenicity?

Janardhanan: Absolutely. To help improve echogenicity in a bare metal needle—for example, a guide wire Introducer needle—the distal tip (or patient-contacting end) is the portion of the needle that is treated. The treatment typically occurs on the outer surface of the cannula of the needle and extends to various shapes of the tip—for example, Touhy or Quincke—and various lengths of the tip. This treatment is especially useful because it enables clinicians to monitor the distal tip for more precise placement as the needle penetrates the body of the patient.

Fenske: Why are echogenic needles better for diagnostic imaging?

Janardhanan: Simply put, they allow for better patient experience. Clinicians can guide highly echogenic needles with minimal errors to eliminate pain at the injection site. Therefore, clinicians can also be precise and efficient while patients experience minimal procedural discomfort.

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