American College of Physicians: Internal Medicine — Doctors for Adults ®

Thursday, July 17, 2014

They do make an ultrasound probe that plugs into a USB port!

“They should make an ultrasound probe that plugs into your laptop. It could just hook into a USB port.”

Ultrasound technology has become progressively more accessible to doctors who aren’t radiologists. During my training, some obstetricians imaged the bellies of their pregnant patients to quickly see how the baby was lying in the womb and assess its progress. Other than that, ultrasound resided in the realm of the radiologists, who lived in dark rooms and interpreted blurry pictures for the rest of us.

Since ultrasound is not expensive and has many potential applications, far beyond just seeing fetuses, other specialties have adopted it and doctors in resource poor countries where there are no radiologists have come to rely on it for all sorts of information. Trauma surgeons and emergency physicians can use it to rule in or out life threatening conditions, and internal medicine physicians like me can improve on the accuracy of our physical exams and sometimes avoid the cost of more complex and dangerous imaging procedures. Ultrasound can be used to guide procedures, making them safer. The machines have become smaller and are even pocket sized. It’s all so very exciting.

So why not an app for the iPhone? Why not Google glasses with which one can see ultrasound images of the patient in front of me? Why not a wireless ultrasound transducer?

The possible avenues of progress in very portable ultrasound technology have been slow for various reasons. First, many people are happy with radiologists imaging the body and cardiologists imaging the heart using large and expensive machines. The system works. It doesn’t require the rest of us to learn ultrasound and the pictures are good and the rather large charges benefit hospitals. Bedside, ultrasonographers are looking for inexpensive machines and it is unclear how much the use of these will increase the revenue stream which drives much of what happens in research and development in medicine.

Having wandered through the health care device industry’s displays at many ultrasound conferences and having surfed the Internet I thought I knew what kind of technology was available for doing bedside ultrasound imaging. I had seen an ultrasound transducer that plugged into an iPhone made by a company called Mobisante, and had seen their iPad/transducer combo. The software was buggy and the pictures were not impressive and the whole package did not end up being handy or attractive. I bought the GE Vscan machine which is about the size of my hand, and like my hand, fits in my pocket. The pictures are good and it does most of what I want it to do. So when people asked about just buying a transducer for a laptop and plugging it in I told them that clearly that was a great idea but it didn’t exist.

Except that I was wrong. The company Interson, out of the Bay Area in California, makes transducers for imaging blood vessels, deeper structures such as abdominal organs, and cavities such as the throat and vagina/uterus. I had the opportunity to try their abdominal probe in the last few weeks. It is definitely a clever and versatile device, despite several drawbacks.

The probe is called SeeMore, which will probably not help sell the product. It is about as heavy as a small hardback book and it is a little big to have comfortably in a pocket. It has an inescapable resemblance to a personal vibrator which will also not help sell it. It is actually the same transducer that Mobisante used in their iPhone device. On the very positive side, though, it gives really good pictures of the abdomen, uterus and bladder. Its resolution is good enough that it could be used to rule in or out a pneumothorax, which my Vscan is not quite up to. Its image acquisition is slow so when looking at the heart it is not possible to see the delicate movement of the heart walls or valves, though it is possible to see grossly abnormal cardiac function or pericardial effusion from an abdominal approach. It does not do color Doppler, so it cannot give any indication of blood flow. It has its own software that loads quickly onto a laptop and it could be used with a tablet so long as it has a windows operating system.

The USB attachment can go into a USB to mini-USB converter so the tablet doesn’t even need to have a full size USB port. Once the software is loaded it has calculations that are user friendly and intuitive calipers for measurements plus all of the usual gain adjustments that a person might want. There is a button on the transducer that freezes and unfreezes the image. After images are stored they can be printed or transmitted easily as JPEGs.

If I worked in a bush hospital somewhere and needed my ultrasound just to evaluate unborn babies or critically ill or traumatized patients, this transducer would be just the ticket. If I used a laptop as I went from room to room, as I did at my last job, I can imagine information from this device being integrated seamlessly into my documentation as I examined the patient. The transducer I tried does not visualize superficial structures, like blood vessels or bones or tendons, abscesses or thyroids, but Interson makes a linear transducer that does. Each transducer costs $4000 new, and the software, support and hefty plastic case with tiny tube of ultrasound gel are included. My Vscan cost over $8000 and the cheapest portable ultrasound machine that hospitals in the US buy costs over $40,000 new. (Veterinary ultrasound machines and ones that are used in developing countries can cost much less than this, even in the sub $1,000 range for a used machine.) From where I stand this USB transducer is an affordable alternative for point of care ultrasound, though I do like a machine that gives better pictures of the heart.

What about the Google glasses thing? I think somebody has a patent for that, though it’s not commercially available. What about the wireless transducer? Yes. It exists. It is not Bluetooth, a proprietary short distance wireless connection that uses ultra-high frequency radio waves. It uses a different proprietary ultra wide band wireless connection which can handle more information. The one that I found is called the Freestyle, by Acuson, which is now owned by Siemens. It looks like a TV remote and I think it’s just for superficial structures.

As there is demand, these machines will get lighter, cheaper, more versatile and attractive. The potential is awesome and I’m looking forward to trying out new toys that will allow me more capably to help my patients.


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Anonymous Anonymous said...

How are you planning on using ultrasound with little-to-no training? You do realise that sonographers and radiologists train for years in the art of ultrasound, and have an in depth understanding of the physics behind it to allow them to get the best quality images. I doubt you even know the difference between B-mode and M-mode, let alone power wave doppler and harmonics. In my experience people using these portable ultrasound machines inevitably a) find something that isn't there or b) miss something that is there, and in my years of experience at a busy imaging department we have had to do countless repeat ultrasounds to confirm/deny apparent findings done by untrained people on these inadequate machines. I've seen GPs refer people in for AAA seen on their ultrasound - turned out to be the bloody gallbladder!

Fine - go ahead, but don't tell your patient what you are doing is a replacement for a proper ultrasound with a decent machine under skilled hands. It's not.

July 17, 2014 at 3:28 PM  
Anonymous Anonymous said...

Bedside ultrasound is a different procedure than an ultrasound performed by a radiology technician and read by a radiologist. It is really an extension of the physical exam, and as such, often requires another imaging study to clarify what we think we see. As a clinician and bedside ultrasonographer I have a detailed history and physical to temper my interpretation of what I see. I also have less experience than technicians and a machine that gives pictures with less resolution than the larger and more expensive machines radiologists use. I try to limit my interpretation to those things which I am very confident about, and ask for more imaging when I am unsure. I have completed the certification as a sonographer, so I do know what M-mode and power doppler are, but that is neither necessary nor sufficient for competency in bedside ultrasound. As a group, we internists need to develop some guidelines about how to train ourselves adequately and how to define competence and scope of practice. This little device is just one of many that is on the market to make it convenient to bring ultrasound into the clinic and to the bedside. The implications are a big issue and one that I have addressed elsewhere, and will need ongoing work. In the meantime, bedside ultrasound, here in the US and overseas, is making a huge and positive impact on improving diagnosis and treatment.

July 18, 2014 at 3:50 PM  

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