FDA adds transducer check to ultrasound guidance

New ultrasound transducers should include an integrated quality control check that runs every time the probe is turned on, according to final guidance issued by the U.S. Food and Drug Administration (FDA) on August 22.

The FDA plans to incorporate the new transducer check recommendation into the agency's 510(k) compliance policy that covers marketing clearance of diagnostic ultrasound systems and transducers. The new policy -- as well as clarifications to guidelines on when the FDA will require modified probes to receive a new 510(k) application -- was explained in a webinar by Shahram Vaezy, PhD, of the FDA's Center for Devices and Radiological Health.

"This guidance supersedes the FDA's 2008 guidance ... and describes the types of modifications to a diagnostic ultrasound device for which the FDA does not intend to enforce the requirement for a premarket notification," Vaezy said. "[It also] includes a new transducer element check that applies to all ultrasound devices."

Transducer element check

The FDA is recommending that manufacturers integrate into transducers for which they are filing new 510(k) applications a way to test probe performance each time it is activated.

"Each device should include some level of testing," the agency wrote. "This integrated test feature would also generate a report on the performance of the probe under test for documentation ... [and] should also be available to the operators to initiate anytime when a particular probe is suspected of failure."

Developing transducer check features will take time, Vaezy acknowledged.

"The FDA is open to discussions with manufacturers about how to implement transducer checks into devices," he said.

Compliance policy

The FDA clarified that it will not require a new 510(k) for modified ultrasound and transducer devices that have already received an initial 510(k) clearance when all of the following apply:

• The intended use of the modified device is not changed.
• The device is not a reusable device subject to the requirement for the submission of reprocessing labeling and validation data.
• The modes of operation for the modified device are well-established.
• The modifications do not lead to acoustic outputs that exceed the recommended maximum acoustic output levels.
• The modifications do not result in a range of ultrasound interrogation parameters outside a well-known range.
• The modifications do not use novel mechanical or thermal effects for imaging or measurements.
• The measurements and analyses are clearly described, and the user can adjust the associated control parameters.
• Transducer element check is performed.
• Transducer surface temperature falls within a well-defined range.
• Appropriate transducer covers are recommended to users.

During the webinar, Vaezy listed some examples of possible compliance policy applications that would require a new 510(k):

• Adding continuous-wave and pulsed-wave Doppler methods to the device
• Adding an algorithm that measures the volume of an organ based on established image segmentation and volume calculation methods
• Adding a new transducer with similar indications for use and similar acoustic output
• Adding a B-mode noise reduction filter for general imaging use to a system

"The revised final guidance enables manufacturers with an established track record of ultrasound device development, via submission of 510(k)s for their original devices, to add new safety features and make certain modifications to address clinical needs without [having to] submit another 510(k)," he said.