Article Summary
Point-of-care ultrasound (POCUS) has become a powerful adjunct in the evaluation and management of patients in many environments. Given the portability of systems and emergence of hand-held systems, various studies have looked at using POCUS in austere environments. Many hand-held systems can transmit images via cellular connection allowing for remote interpretation. However, there may be situations where lack of cellular service would limit the ability to transmit images. The purpose of this study was to evaluate the feasibility of using slow-scan television (SSTV) radio signal as a means of transmitting images.
Image from the original article
The study authors utilized 2 hand-held amateur (HAM) radios operating on the 144 Mhz band and transmitted images from a smartphones equipped with encoding and decoding software. 15 still images were transmitted a distance of 1 mile. The transmitted and received images were reviewed using a 5 point ranking scale for quality and interpretability. 16 individuals at various levels of training reviewed the images.
Table from the original article
Key Data
- The mean score for transmitted images was 3.74.
- The mean score for the received images was 3.60
- The average difference in scores was 3.9% decrease on transmitted images.
The authors also performed a comparison transmission of a single image at 1 mile and at 5 miles
- 100% of respondents indicated that the 1 mile transmission was clinically useable.
- 75% of respondents indicated that the 5 mile transmission was clinically usable. This was due to additional artifacts.
Personal Thoughts
This is a fascinating article about the use of Amateur (HAM) Radio to transmit ultrasound images. As a POCUS user and HAM myself, I was intrigued. It makes sense that radio frequencies can be used to transmit images. I have several thoughts about this study.
1. The images in this study were transmitted at 632x1080 px and received at 340x240 px. They were upscaled to 640x480 px for evaluation. This compression and resizing will result in data loss on the image limiting resolution for small structures or details. Having the ability to receive larger files would be helpful.
2. The study used the 2m (VHF) band. This is a great band for local communications because it is the most popular of the HAM bands and only requires an entry-level license to operate. As such, it is the most widely generalizable to the most number of people. But unless you use a repeater, range will be limited, especially in wooded or rugged terrain. Increasing transmission power and appropriate antennas can help mitigate this problem. But if you want to transmit long distances, dropping down to the 10m or 20m bands would be important. I would be curious to see how this technique works in the HF bands.
3. This study focused only on transmitting still images and not clips. While any image is better than no image, There is a lot that a still image doesn't show. Having the ability to transmit a short video clip would be helpful.
4. Finally, while using HAM radio is a fascinating idea, the question I have is how many situations will this be the only and best form of communication? Cellular networks are expanding worldwide (though while I am writing this I am sitting in my camper with limited cell service). And satellite internet service is available. When these are available, they will offer a better means of transmitting ultrasound images.
Final Verdict
Fascinating study and definitely something that I want to try - if for no other reason than to make the QSL.
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