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Every physician and sonographer can understand the importance of image quality and preventing cross contamination when performing TEE ultrasound exams. Without a high-quality image, identifying abnormalities is increasingly difficult and less reliable, which is likely the result of microscopic damage to the TEE transducer that comprises the physical integrity of the probe designed to prevent cross contamination. This makes image quality critically important for proper diagnosis and to quickly identify failing equipment to prevent cross contamination.
Technology Challenges
As with any technology, the TEE transducer’s advanced multidimensional capabilities do not mean it is foolproof when it comes to performance. TEE transducers are very fragile, complex, and prone to many issues from poor image quality and missing information to noise and data-transmission problems. Combined with complicated disinfection processes these transducers can fall victim to physical damage that the naked eye may not see. The result is micro punctures and lacerations that allow fluid ingress and can carry to the next patient. These factors make it particularly important to understand how to use the new TEE ultrasound probes and identify anything amiss. Unfortunately, as sonographers are probably aware, no standard or objective method exists for measuring image quality. Therefore, extensive practice and a trained eye are what sonographers typically rely on to identify artifacts and determine the quality of an image as it is a leading indicator of potential contamination.
However, as with standard ultrasound transducers, there are certain signs sonographers can look for when using the new TEE transducers to spot anything out of the ordinary. Any image noise and color artifact, such as unintended variation in the brightness, color, saturation, or contrast of an image, is cause for suspicion. Some signs, such as image distortion (rearranged material) or color stripes or noise in a nonphysiologic pattern, clearly indicate an equipment problem. Are all of the scan lines parallel? Or are some out of line or fuzzy in comparison to adjacent scan lines? Does the transducer have any dropped elements?
Maintenance
First and foremost, prevention comes from proper maintenance and care of the TEE system. When first receiving new equipment, the sonographer or biomedical engineer should conduct a live-system test to ensure it is in working order. The American College of Radiology (ACR) Technical Standard specifies that acceptance testing must be performed when new equipment is acquired as well as after equipment repairs and major upgrades. For example, the ACR standard notes that tests on transducers should include physical and mechanical inspection, image uniformity and artifact survey, geometric accuracy, system sensitivity, spatial resolution and contrast resolution.
Once the system is accepted, careful handling and sterilization of probes helps control equipment service costs and reduce the risk of cross contamination. The American Institute of Ultrasound in Medicine (AIUM) has posted guidance regarding the cleaning and preparation of external and internal ultrasound probes on its website. It is critical to establish a regular surveillance schedule to guarantee that the transducer is functioning properly over time and with regular use. The AIUM has published recommended or mandatory equipment surveys to be performed, some daily and others at least once a year.
Testing and Repair
Various tools are marketed to test whether a probe is in good shape. Scanners (calibration tools) can be used to identify imaging issues, while certain probe-testing devices can be used to measure and detect any issues related to the acoustic and electrical properties of an ultrasound probe. While these devices may help in certain instances, the best approach to ultrasound equipment testing is live-system testing. Only live-system testing is capable of capturing real images to assess their quality; only live-system testing can reveal the intermittent problems that comprise the majority of issues associated with a probe. Simply stated, there is no substitute for an image-quality test on a live ultrasound system.
Once a problem is identified, biomedical engineers and hospital administrators should first consider a repair. The cost of repairing faulty equipment is much lower than the cost of replacement. Opting to repair rather than replace the technology can maximize its useful life and save health care facilities as much as 97% relative to the cost of original equipment manufacturer replacements. However, it is important to note that the repairability of a compromised TEE transducer decreases rapidly as time passes, due to the corrosion of its materials. For this reason, any technical problems should be acted upon as soon as they are detected to ensure a successful repair.
Prompt repair is particularly important for real-time, multidimensional TEE transducers. Delays in equipment failure diagnosis will make them significantly more difficult to service as the fluid ingress corrodes the fragile internal electronics. Due to their higher power and smaller form factor, damage from electrical shorts from fluid ingress is more catastrophic in addition to the risk of cross contamination. Hospital administrators should therefore seek to partner with a reputable, well-trained team of ultrasound support technicians who can repair equipment down to the component level.
Probe Integrity is Critical
When it comes to accurately assessing and diagnosing cardiac patients, TEE probe integrity should be taken very seriously. This is particularly true when 3D TEE is being used for procedural guidance. As reliance on TEE technology continues to grow and take over functions once dominated by other imaging modalities, ensuring high-quality images will become increasingly important to top-notch patient care. Learning how to spot image anomalies and properly test and care for equipment – and acting at the first sign of any deterioration or failure – will make all the difference. •
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