Wednesday, December 12, 2007

The Squawkie and the Cymbal
...A Hypothetical Post About A Hypothetical Machine

In the vacuum of my once-productive mind, there occasionally forms some strange ideas. I wondered what might happen if one tried to combine Ultrasound and CT scanners to form an US/CT device. This idea could have some interesting consequences, and following is a fictional account of how this might play out in the marketplace... Note that the machines are not real, no one has one, and no one will ever get one.

Trying to stay at the leading edge of technology is difficult at best, and expensive to say the least. The hospitals down the road, across town, or on the other side of the country are always trying to one-up each other, buying the latest and greatest, usually to be leap-frogged by the next great development.

Here at my above-average hospital in a large town in the North, we have caught the bug to buy one of the new hybrid ultrasound/computed tomography scanners, the US/CT. This is really incredible technology, which will allow us, for example, to definitively diagnose renal lesions and declare them cystic or solid on the spot. The CT image helps orient the ultrasound and can provide depth and echogenicity adjustments.

As with most advanced products of this nature, there are several choices. Black and Decker produces a rather small and relatively compact unit called the Squawkie (UltraSOUND, noise, squawk, get it?). This is a very elegant machine, with a tiny x-ray tube mounted to the hand-held ultrasound transducer. An x-ray detector belt is placed around the patient, and both the CT and the U/S images are formed as the sonographer (wearing lead gloves) performs the exam.

Bosch, on the other hand, has their own version, called the Cymbal (Cymbals make noise like UltraSound, yes?), which, typical for European engineering, takes a battle-ship like approach, mating an automated U/S transducer on an articulated arm to a full-size CT scanner. There is a continuous flow of ultrasound gel through a port near the transducer face.

These two machines obviously represent rather diverse approaches to the problem. Which to choose? My inclination is to go with the Bosch, as I like their fuel injectors, and so I would assume their US/CT device is just as well made. But the Black and Decker folks have been very persuasive. They sent a number of articles outlining the dangers of too much CT radiation, which is kind of funny since they sell a lot of regular old CT's. But they very correctly point out that the minimalist CT approach found in the little Squawkie has less CT radiation than the full-CT of the Bosch. And there's the problem. The Squawkie's limited CT doesn't produce a great image, and no one expects it to do so given its limited radiation. Supposedly it's CT is good enough to enhance the U/S image, and some say it will work better for this purpose. BUT, to the guy looking at the study, a very important factor is the ability to match the U/S to the CT, and for that, a diagnostic quality CT is needed. Black and Decker points out that the patient has probably already had one on another machine, which may or may not be true. If they have, B&D suggests simply using the computer to match the U/S to the CT, but that doesn't always work well. Heck, even the example they have in their literature shows a pretty bad misregistration of part of the U/S relative to the CT. I don't trust that approach. But we all agree, I guess, that a diagnostic CT is needed somewhere along the line. And everyone who has a Squawkie, including the academic center in the hills north of us, says that it's CT images are, ummmmm, not diagnostic.

Bosch's approach with the Cymbal assumes that the diagnostic CT is such an important part of the study that it should be included with the U/S. So, with a little planning, the patient could have the U/S and the diagnostic CT all in one sitting, and eliminate the small but extra CT dose that he would have to have with the Squawkie. To me, that is the more logical way to do it. But that's just my opinion......

Decisions, decisions......

No comments :