New Logo!

Time to add a little color...

Dalai's PACS Group

At the bottom of the left column you will find a link to my newest web-feature, Dalai's PACS Group! Sign up and feel free to discuss any (preferably PACS) issue that comes to mind.

A Note From Sectra

Dr. John Goble, President of Sectra North America, posted this on AuntMinnie.com:

Sectra has been in the US for nearly ten years, and we have a superb service and support team. In addition to Philips Medical Systems, we provide Level II support for our other partners, selected dealers and comprehensive support for our direct sales.

Our PACS products for the Orthopedics and Mammography markets are extremely well received by the US market. While Philips' acquisition of Stentor will undeniably impact our revenue in the short term, we intend to aggressively bid for service on our products and continue to protect the investment of customers who have purchased Sectra PACS... whether under the Philips label or directly from us.

Sectra will continue to innovate and bring industry leading products to market in the US. If you have questions about support for your system, extensions to your Sectra PACS or have a new opportunity, we'd be happy to talk with you.

John Goble, Ph.D., President, Sectra North America, Inc. Call us at 800.307.4425.

Sounds pretty promising for Sectra customers. We'll see how it works.

Farewell, Scotty

Today, we Star Trek fans say goodbye to James Doohan, who will be forever known as Scotty, the Chief Engineer of the Starship Enterprise. He died of complications from pneumonia and Alzheimer's disease at age 85. His ashes will be rocketed into orbit later this year. (That's not a joke, by the way; he will join Star Trek creator Gene Roddenberry, whose ashes were intered into space several years ago.) I guess we tend to forget that the characters of Star Trek are getting on up there in years. DeForest Kelly, who played Dr. McCoy, died in 1999 at age 79. Even Kirk (William Shatner) and Spock (Leonard Nimoy) are in their early seventies now. I had the chance to spend 10 seconds in their presence last summer at the Star Trek convention (yes, I admit I went), while posing with my son for this photo. I call it three old Jewish guys and a kid.

Many say Jimmy Doohan was the most beloved of all the Star Trek actors. I think we can rest assured that he was beamed up and not down to his Final Frontier.

One Brief and Shining Moment....

My apologies to the late Richard Harris....

I am really amazed at the traffic generated by the AuntMinnie.com article. Comments have been generally positive, usually something like, "I didn't know PACS could be funny!" I seem to have the attention of a significant number of those in the PACS community, and I would like to put that to good use while it lasts.

It seems clear that there is a disconnect between the designers and (Radiologist) users of PACS interfaces. I'm not sure why this is the case, as it seems logical to consult your end users before creating a huge software product. I don't want to indict any one particular company, but some do a better job than others of giving us the clear interface and powerful tools we need to slog through the day's work.

For the moment, lots of users, and not a few vendors are dropping by to see what foolish thing I have posted this time. Now I'm sure you all realize that is is possible for you to post comments here, and I really, really, REALLY encourage you to do so. It's simple; just click the word "COMMENTS" at the end of each posting. Perhaps this blog might be considered a "safer" place to post complaints or suggestions for the vendors, and for them to post answers. This happens on the AuntMinnie.com boards to some extent, but I think some are hesitant to post there. So, come here and let it all hang out. Don't hold back, say what you really think. I certainly haven't even begun to describe everything that would go into a perfect system, but if I can get input from as many of you as possible, maybe we can get closer to that ideal product.

Now, if you will excuse me, the boys want me to get back to the Roundtable, I mean my PACS station, and generate some revenue.

Northwest, One Last Time

Ms. Michelle Mohr
Northwest Airlines Complaint Department
Dear Ms. Mohr:

Unfortunately, Northwest was unable to live up to the earlier performance on our trip home. In brief, we were delayed leaving Minneapolis/St. Paul on our flight yesterday due to "weather over Detroit", and we idled on the tarmac for almost an hour before taking off, burning a significant amount of expensive jet fuel. After a very late arrival at DTW, we did manage to make our connecting flight home, but all five of our bags did not. We had to sprint to the departing gate, B19, from A70, the longest possible distance at DTW, but made it with a few moments to spare. The fate agents were courteous, and even apologetic but told us we could not take even a minute to walk across the hall and buy a snack, since the gate was about to close. They asked US if WE knew of anyone else trying to make the flight. As it turns out, there were indeed two stragglers who boarded about 10 minutes after we did, and I would be surprised if your computer did not report that these people had arrived at DTW and were en route to the flight. (One of them had a leg injury and was walking with the aid of crutches.) It was very clear that having the aircraft push back from the gate on time was much more important than letting my family grab a quick snack to take onboard (we had not eaten for 8 hours, anticipating an adequate amount of time to do so at DTW, and this flight didn't even have your now-famous $1.00 trail mix available.) This was the last flight of the day to our destination, and the aircraft had nowhere else to go that evening. Your schedule was likely already in shreds due to the "weather problem"; one more minor delay would not have mattered. As it was, the flight arrived home 10 minutes ahead of schedule. To complete the series of unfortunate events, all five of our checked bags did not make the transfer, forcing us to go through the claims process. The only person available at 12:30 AM was George S., one of the baggage handlers, who clearly was trying very hard to do a good job, but just as obviously had never been trained to use the computer system to file a missing baggage claim. Another baggage-handler finally was able to come to his aid, as did Venus R., whom I believe was a Continental agent. Hopefully, our luggage will be delivered sometime today.

Ms. Mohr, I am sad to report this experience, as I had much greater expectations after my last flight with Northwest. It seems that your people can shine if everything in the system is functioning perfectly, but a glitch, such as bad weather or mechanical failure sends everything into a tail-spin. Staffing has obviously been cut to the bone, and the goal of the airline seems to be to meet the on-time deadline of door-closure and pull-back at the expense of the comfort of the passengers. This will be my last flight on Northwest for the foreseeable future.

Thanks for your time. I know there are many good people working for Northwest; it is unfortunate that they are not allowed to perform to their potential.


Addendum: I do have to add praise where praise is due. Rick, the baggage manager for Northwest in my hometown, personally delivered our 5 bags when the local service couldn't get around to it. I wish Northwest would allow the rest of their employees to go the extra mile as Rick did for us.

We ALL have days like this....

PACS preferences: How to push a radiologist's buttons

I've finally made the big-time! This was published on AuntMinnie.com today! For radiology, PACS has been nothing short of a complete and total revolution; PACS now quite literally defines how I perform my job. As a nuclear radiologist, I spend at least 85% to 90% of my day with the microphone in my left hand and the mouse in my right hand. If I'm not talking into the former whilst manipulating the latter, I'm not generating revenue for my group.

My goal in life is to do my work and go home; my PACS system should facilitate this and not get in my way. So what are the elements of a usable, unobtrusive PACS according to this humble rad?

Let's start with some general observations on PACS GUIs and their functions. First and foremost, every part of the darn thing has to work every single time, and that includes all those little buttons that you might use once a year.

The vendors will quote you "uptime" rates of 99.999%, but for some distributed systems, if just one workstation is up, well, that counts as uptime. Given that great uptime, please spare me hourly (or more) lockups and reboots. Been there, done that: we used an early form of a small PACS network that would fail literally on every other study. One of my partners (who still likes the product) determined that pressing thus-and-so button, and right-clicking just there, while holding your left hand in the air and howling at the moon would keep the program from crashing. That may be, but most of us just don't have time for a crash-o-matic solution. The system needs to be bulletproof, and the least-technical member of your group should not be able to bring it down, even if he presses all the keys at the same time (I've seen it happen).

The interface must be clear, without distractions. The whole point of the process is to see the images, right? So why do some programs devote tremendous amounts of screen real estate to everything but the image? If I want the old report, or the demographic page, or the Nasdaq stock ticker, let me bring it up somewhere else, not where it invades the current image.
Some PACS systems out there seem to imitate the bridge of the Starship Enterprise up to and including the "gleeps" and "whirrs" from the controls. As a closet Trekker (we prefer that term to Trekkie, by the way), I love that idea, but not while I'm trying to work, please! Cute, but not what I really need.
Graphics on the various buttons can be a little underdone, too; that same crash-o-matic system I mentioned uses some very primitive low-resolution unintuitive icons on its various buttons, and at least one of those symbols seems to have been lifted from another famous non-PACS, but still copyrighted, source.

Make the interface clear and readable, with obvious designations. The same goes for menus. Some of the most sophisticated programs out there suffer from "right-click-orrhea" in which a right-click brings up a huge list of stuff. Now I don't mind if the right-clicker results in a well-organized and helpful submenu, but there are those who pile everything including the kitchen sink into this otherwise hidden area. No thanks. Some systems make that right-click deluge (and about 1,000 additional settings) customizable, and all that for each modality, no less. Most of us would give up and use the default settings that came with the program. Keep it clean, clear, and simple. That's all I ask.

Oh, and by the way, how about having all the buttons work in a consistent manner? It is a real pain if, say, the magnifier works by left-click activation, then actual manipulation with the mouse wheel, while the window/level control is toggled on and off with a left-click and manipulated with moving the mouse immediately thereafter without clicking anything else, etc., etc. See what I mean?

These expensive toys come with a vast number of tools and gadgets, all intended to help us interpret our examinations. Do they really accomplish this goal? Well, let's see. In no particular order, here are some of my favorites (or not as the case may be):

RIS/PACS integration: The new Holy Grail. I don't think this is quite there yet. Yes, it's nice to get your reports brought up within the PACS window, and all systems do that with the appropriate connection. But does the PACS really need to feel the RIS and be the RIS, or could they just go out for dinner and a movie?
Worklist: The unsung hero of PACS. You need to see what you need to read, yes? Well, there's much more to it than that. Tell me what needs reading, what is STAT, what can be put off until after lunch, is someone else reading something so I don't have to, are there prior examinations, and maybe tell me something about the patient like age and what idiot (oops, I mean honored referring clinician) ordered this test.
Hanging protocols: I like to think I'm flexible, but in reality I am set in my ways. I like my studies to come up in the same manner every single time. Hanging protocols are supposed to accomplish this. Properly done, you should simply set up windows and other settings the way you want them for a particular type of exam, click the button, and presto, the next exam comes up in the same way. There are systems out there that require deep, dark, secret programming methods to set up, and somehow, no one ever quite knows how to do it. Hanging protocols can be totally confounded, however, if your techs are inconsistent in labeling the examinations. The PACS is stupid, after all, and can't just look at the image, decide whether it's the patient's head, tail, or something in between, and place it appropriately. Wine and dine your techs and make them swear to label the same image the same way every time. Tell them your happiness is their reward.
3D: Gotta have it for CT and some MRI exams. Period. Some companies have built-in multiplanar reconstruction (MPR), volume rendering, and such, and some let you connect to 3D software (or actual added-on computers). The absolute minimum acceptable to me would be MPR with the ability to do oblique reconstruction, and the ability to MIP (create maximum intensity projections) from there. Volume rendering is really nice to have. It is very helpful to be able to push those renderings back to your PACS, which is often not available without the add-on programs. And by the way, make the included stuff intuitive, if you please. If I point to a lesion on one plane, I want the other planes to show me the same lesion. It's called triangulation, and some of the vendors out there must have slept through that class in high school.
3D cursor: Most MRI studies are done in multiple planes, and the DICOM headers tell you lots of spatial information if you actually look there. A 3D cursor uses this information to triangulate (see above), snapping the images in all sequences to the spot you select. Believe me, this is incredibly helpful.
Spine labeling: Done the easy way using that 3D information there for the taking in multiplanar studies (CT, MRI), I can label the individual vertebral bodies and disk spaces in five seconds. Done the hard way (by another company), it would take me 10 minutes if I were willing to slog through things that way, which I'm not.
Magnification: You thought there wasn't anything new here, right? Surprise! Several companies have figured out that image magnification should not go from the center of the image matrix itself, but should be centered where you select. It doesn't sound like much of a philosophical difference, but it saves the panning step after you've magnified the abnormality off of your screen and have to drag it back.
Linking: If you read a CT or MR that by some miracle has a prior study available, you want to link them together slice by slice. Just about every system will do this based on table position, so if one CT was performed with thicker slices than the other, the images will match up better. A few companies still haven't grasped this simple concept, however. If your potential vendor can't do this, run, don't walk, to the next one. It can be done with one click, especially if you want to display multiple views of the same sequence with different window and level settings, for example. The more clicks, menus, and buttons it takes to make this (or anything else, for that matter) happen, the less likely you are to actually use it. Some systems get bogged down if you link too many windows. That's too bad, because I like to link multiple windows.
Measurement/markup: I have to keep reminding some of my partners not to write on the screens with the red crayons -- that's what the markup tools are for, guys. I like the latest versions that let you place the actual measurement somewhere other than over the thing you're measuring. And if I want to make a hundred measurements on a single slice, I'm going to do just that; one system will only allow two measurements to appear on the screen at once, and that will never do.
Web client: Being rather set in my ways, I really prefer having the same interface at home as I do at work. The Web-based systems allow this; the older model "big-iron" approach is to add on another whole system that taps into the main PACS database (and was usually acquired from some other company anyway).

In my own humble opinion, a PACS needs to let me do my work, and not get in my way. At the same time, it needs to give me a Swiss Army knife (dare I say McGyver-esque?) set of tools to get the job done. These are not mutually exclusive criteria; rather, a properly deployed interface will make my work of interpretation much easier, and make my day much more enjoyable. Well, except for the BEs....

Northwest Redux and Other Random Musings From The North Woods

(My Temporary Shingle)

I try to be flexible when possible, and this week I am playing Pediatrician at my son's camp in northern Wisconsin. The territory up here is nothing short of spectacular, lots of trees and lakes and clear blue skies. The camp itself is a rustic paradise, about as far from a Ritz Carlton as you can get, but still peaceful, placid, and comfortable. Maybe I'll stay up here for a while....

Northwest redeemed itself in getting me here. There were absolutely no glitches whatsoever. Flights were ontime and smooth, and personel were friendly. Special thanks to Sergio at our originating airport, who went out of his way to help us redistribute items in an overweight bag, thus avoiding a penalty. Sergio's behaviour compensated for that of the other Northwest employees to a very significant degree. He "got it" as they say. All I ask is that I be treated with kindness, understanding, and dignity; this is how Sergio treated me, and how I hope I treat my patients.

On the PACS front, the big news is the purchase of Stentor by Philips, for $280 Million. That's a lot of cash, folks. The big question I have is this: What happens to all of those Sectra installs? The Sectra folks seem to be assuming the worst:

Since 1997, Sectra has had a global cooperation with Philips Medical Systems, which has sold Sectra's software for processing digital X-ray images worldwide.

"We have several project agreements with Philips that extend up to ten years and our cooperation will successively be terminated," relates Sectra's President and CEO Jan-Olof Brüer. "We assess that the termination will impact on our sales and earnings in the current fiscal year. At this time, however, it is difficult to provide any reliable view of the financial effects, since this depends on how much time the termination will require."

The change provides Sectra the opportunity to review its sales channels. Sectra's sales of PACS are handled on a proprietary basis in Scandinavia and other selected markets as well as through partners, of which Philips was the largest. Sectra's largest sales together with Philips have been in the US.

"Part of the sales for which Philips is currently responsible will be taken over by other partners that today are active in the same markets as Philips," says Jan-Olof Brüer. "At the same time, we gain the opportunity to advance our positions and will increase our focus on own sales in important key markets, as we do today in Scandinavia, where we have captured more than half of the total PACS market."

Sounds to me like Philips is dropping Sectra (or maybe it will turn out to be the other way around) like a hot potatoe, and Sectra will find some "other way" to service its sites. Uh Oh. I've lived through that sort of thing with our Elscint CT scanners. Elscint sold its CT division to Picker (actually happened while I was visiting their main offices in Haifa, Israel), which then was gobbled up by none other than Philips. Service was pretty good, considering, but it just isn't an optimal situation. In this case, Sectra will have to bring in some other outfit to do its service. Perhaps they should contact Banctec, the outsourced Dell service provider, or maybe the Geek Squad from Best Buy.

I know of several sites that had purchased Philips/Sectra, or were close to doing so. Wouldn't go there at this point, at least until the market stabilizes. If they were buying because of the Philips name, they would of course still get that, but a completely different product. To buy Sectra means diving into a very murky future. I personally wouldn't go near either one for the time being, but that's just me. Your milage may vary.

I had the chance to play with the Philips/Sectra system, and it isn't bad. It was neither my most or least favorite. The team was (and I emphasize was) a formidible player in the PACS field. I've asked people why they liked the PS system so, and invariably I get one of the following answers:

1. It's made or marketed by a company that makes scanners, so it must be good.
2. It has an easy pull-down preliminary report menu.
3. Their embedded 3D lets you select exact slice thickness on MPR.

My answers to the above are probably predictable. First, GE and Siemens make scanners too...I don't consider the PACS product from either company, um, great at the moment. Secondly, one should never, ever make a major purchase based upon one or two perks. Would you buy a Peugot over a Mercedes because it has, say, a prettier hood-ornament? You have to take all factors into account, not the least of which is the overall usability of the entire system. Having the hots for one specific component has the potential to send you down the completely wrong path. Pull-down preliminary report generators are dandy, and I have a rudimentary version on Agfa Impax 4.5. I rarely use it, because I can type my prelim much faster without any help. As far as MPR slice thickness, I don't know anyone who finds knowing the exact numerical value of the thickness that valuable in actual use. Frankly, I suspect a lot of potential PACS purchasers, especially those who are new to the game, are so overwhelmed by whizbang gadgets, they don't stop to think about how they might actually use said toys.

My advice remains this: use the product as much as you can before making a purchase. Web-based systems lend themselves very well to trial-runs in your own office or home setting. Vendors...can you accomidate this?

Anyway. For the moment, all is well in the North Woods. That is until Sick-Call, which is right after dinner.........

Pod Casting

I saw this in Walt Mossberg's column in the WSJ and I couldn't resist giving it a try. Just click the "Play" button....

Fuji Synapse Not HIPAA Compliant?

CI writes:

Our group of 7 FTE Radiologists is in an interesting predicament. We have been using Fuji Synapse for over 3 years for in-house PACS and we are filmless for all modalities. We do a total of 140K exams a year. For the last three years our group has been pushing the hospital to provide web access to the referring docs using Synapse and they refused claiming that Synapse, outside of the intranet, is not HIPA compliant. (Synapse uses Internet explorer which can leave copies of the downloaded images on the browsing computer). So, the hospital started looking at Stentor a year and half ago. Initially we were all excited but w found out that Stentor was not able to display the Fuji CR images properly on their system. Stentor was able to fix this for new images comparisons still look pretty bad. Most radiologists also do not like the scrolling in stentor (it is too fast when you hold the mouse down or too slow to scroll one image at a time). Our referring docs are finding it a pain to navigate stentor, and clearly it is not as intuitive as Synapse. The rads want to keep Synapse and the hospital is pushing for Stentor. The rest of the hospitals in our system have gone with Stentor. (interestingly none of them have used Synapse before). Any body out there with any experience with these systems or have any general advice please post.....

This is certainly a new one on me! I replied: Yours is the first complaint of that sort I have ever heard about Synapse. It seems an extreme measure to bring in another (expensive) system to do what Synapse will already accomplish for the cost of connection. Your hospital/IT people have taken a view that is more extreme than any other hospital in the country using any web client. They ALL cache stuff on the home computer in some form. It is possible to clear the cache on any IE set-up, and probably this could be automated with a very simple script, thus saving you literally thousands if not millions of dollars. I'll be glad to collect 10% for my trouble.

If your IT folks are correct, every last system using a web-client for call isn't HIPAA compliant, and millions of dollars are out the window. I really don't think so. Yet another example of IT not totally understanding how something in PACS functions, but shoving their view down our throats anyway. I don't know about the HIPAA regs that specifically mention cached images. In general, (and I am far from an expert on this), the regs are there to make sure that images only are available to the intended viewing party. Thus, there should be nothing limiting the access of your rads at all. The only question would come if they temporarily installed Synapse on, say, a friend's computer. In any case, I think your IT department is way, way off base here.

Addendum: I just did a Google search...I couldn't answer the question specifically, but I came across the instruction sheet to connect to a Synapse system over the web in the manner we are discussing for three separate radiology groups. I am familiar with two of these groups, and I seriously doubt that your IT people have found something these huge groups have neglected. Ask them why they think Stentor is any better in this regard. I am not a fan of the Synapse interface, as I have posted many times before, and in some ways I am a little surprised that you find iSite harder to use. Still, the key to all this may be in the last lines of your first post, "The rest of the hospitals in our system have gone with Stentor." I'm guessing your IT people would rather have just one platform, and are looking for a way to get the product they know into place. (I'm assuming the same IT people cover all your places...)

There's More than One Way to Scan a PET...

Coincidence scan of a canine, courtesy of: http://ecpi.crump.ucla.edu/vol2/issue4/matwichuk/matwichuk_case-ex.html

Actually, there are numerous options out there for those in the market to purchase a PET scanner. I've directed the purchase of three over the years. My first "PET" scanner was a coincidence device from ADAC, which was replaced with a Siemens ECAT Exact 47, and then with a Siemens Biograph 16 Hybrid PET/CT. As I mentioned in a prior post, GE lobbied me heavily to buy a Discovery ST instead, but I was convinced that the faster LSO crystals in the Biograph made it the best choice.

Fast-forward to the present. My group has today a rather unique situation: we read PET/CT studies from the Siemens I chose, and from a Discovery ST placed several months later at the oncology clinic we cover. So, we can do some near-direct comparisons. I say "near-direct" because we don't have the workstations for the competing systems side by side, and even when a patient has a prior exam, comparisons are done with a CD-ROM or on PACS, which is not the optimal way to do this. (I should, of course, add that about 99% of the time, the new scan is at the clinic and the old was from the hospital, which shouldn't surprise anyone.)

I'll give you the punchline first, and then we'll go into the boring discussion of what's behind it. My educated, although still subjective, opinion is that the Biograph produces better images. Sorry, GE, but Siemens gives us images with less noise which are overall more pleasing and easier to read, again, in my opinion. The faint of heart can leave now.

A word about the proprietary workstations attached to each camera is in order. GE provides the Advantage Workstaton 4.3, the AW, and Siemens uses the Leonardo with eSoft. To be fair, I find the Linux-based AW about the same in ease of use for this application, although it helps that the apps people set me up with my own hanging-protocol. The Windows-based Leo got a slightly different version of my custom display. I don't really like the AW for other purposes, but for PET/CT it works well enough. There are numerous differences in the overall approaches, and I tend to prefer the Leo for CT. Both lack mouse-wheel scrolling, which would be a welcome addition.

The two scanners themselves are quite different in their hearts, their detector crystals, and their approach to the actual acquision of the image.

For those unfamiliar with positron scanning, a very brief primer is in order. Positrons are positively-charged particles that are otherwise identical to negatively-charged electrons. The positron is technically antimatter, which does exist outside of the Star Trek universe. Isotopes that emit positrons when they decay are made by cyclotron, and the most common is 18F, or Flourine-18, which has a half-life of 110 minutes. (Half-life means that half of the stuff is gone or transformed, within that time.) For PET scanning, we label a glucose analogue with 18F to get 18-FDG, fluorodeoxyglucose. This can be used to map metabolism, taking advantage of the fact that most tumors and other bad things burn glucose faster than most normal tissues.

When the 18F decays, it shoots off its positron, which quickly comes in contact with one of the vastly more numerous electrons in the adjacent tissues (or air, or whatever). When a positron meets an electron, they annihilate each other, with a very tiny "bang," and in the process sends out two photons, each with the energy of 511 KeV (Kiloelectron Volts) which just happens to be the amount of energy contained in the mass of the electron or the positron. As it turns out, it is these photons, which are sent out at 180 degrees opposed to each other, which are detected, and not the positrons per se. Thus, we really should call this whole process "Annihilation Imaging" and not PET scanning, but I doubt that anyone would stick their head in an "Annihilation Scanner"!

Siemens uses Lutetium Oxyorthosilicate, or LSO, crystals, pictured below, while GE uses Bismuth Germinate (which looks quite similar.)

OK, a crystal is a crystal, right? Well, not really. The purpose of the crystal is to turn those 511 KeV photons into light, which is then turned into an electrical signal, and then into the picture. To make a long story short, LSO does a better job of turning the radiation into light, and does it more quickly than BGO, so it can handle a higher amount of radiation. Now, GE insisted that BGO is just as good, and sent me a barrage of articles to prove this. However, GE is working on its own version of LSO, called LYSO, and rumor has it that Duke, the main showsite for GE PET, will not get another PET/CT scanner until GE can deliver the LYSO unit. (The GE people tell me that they are making LYSO to accomodate future PET pharmaceuticals, and BGO is really great for now.)

But there's even more to the story. The PET portion of a PET/CT gantry isn't just a big tube-shaped crystal, but rather a collection of smaller crystals arranged in rings. When a detector senses an annihilation photon, it tries to match it to another one that came in at the same time. The simultaneity allows the machine to figure out where the detonation occurred and then it can paint the picture of the distribution of the tracer. But sometimes the radiation gets scattered within the body, or two unconnected (random) photons happen to hit at the same time. To prevent this, thick lead septa are introduced as in the image below..this is the so-called 2-dimensional approach. With faster crystals, it is theoretically easier to discriminate on the time of arrival, and so one can open up the whole array of detectors to receive all possible photons, the so-called 3-dimensional approach. Siemens LSO PET/CT's use 3D exclusively, while GE's BGO machines can run in either 3D or 2D mode.

“From 3D PET to 3D PET/CT: what did we learn?” Peter Valk Lecture given by David W. Townsend, Ph.D.,
Department of Medicine and Radiology University of Tennessee, Knoxville

All well and good. Again, to make a long story very short, the 3D approach allows a lot more scatter radiation and random counts to be, well, counted. On the other hand, 3D picks up a whole lot more photons overall. Do these balance out? The answer depends on the article you read. Here is one from a recent article in the Journal of Nuclear Medicine by Lodge, et. al.:

Comparisons of 2D and 3D performance are very sensitive to the specific conditions under which the data were acquired. Counting rate, scatter, activity outside the field of view, reconstruction algorithm, and scanner characteristics all influence relative performance. In this study 2D and 3D data were compared under clinically realistic conditions and effects that may introduce bias were minimized. The mean ratio of 3D to 2D image values was 0.94 with 95% limits of agreement of 0.63–1.41. All noise comparisons were made under conditions of matched lesion target-to-background ratio as measured in patient images. A statistically significant reduction in image noise was found with 3D acquisition compared with 2D, suggesting reductions in scan duration of 33% or more are feasible.

Italics are mine, as usual. Now GE cited some other articles contradicting this one. One in particular by Laritizien, et. al., states:

In this study, we performed an AFROC analysis to evaluate the impact of the acquisition mode (2D vs. fully 3D) on human observer detection performances. Three acquisition protocols were selected to provide a fair comparison between the acquisition modes. Results showed that the fully 3D acquisition mode allowed better or equivalent detection performance than the 2D mode for a same injected dose typical of the clinical practice (about 440 MBq) in a standard patient. The 2D acquisition protocol combined with higher injected doses (about 740 MBq) resulted in higher detectability than those achieved with the fully 3D acquisition mode for approximately half the injected dose. Changing the patient size or the PET scanner model will potentially change the lesion detectability results of this study.

Now, wait just a second. This says you have to double the dose to get 2D to work better in the clinical setting than 3D! That's problematic enough, but, BGO has a slower response than LSO, and the "dead time", the time it takes the crystal to "recover" from the last event could get to be a problem if you really crank up the dose. I won't even go into the wisdom of doubling the radiation dose, although 18F is short-lived. Basically, we are not comparing apples and apples here.

One way to improve your pictures with either system is to scan longer. We had a 2D BGO system, as you may recall, the Siemens ECAT Exact 47, and we scanned at 7-minutes per bed position, i.e., how long each segment of the patient is within the ring of detectors. GE has advised its Discovery ST customers that 2-3 minutes is plenty adequate. Now, I'll grant you that some significant electronics improvements have occured between the introductions of the two devices, but have there been enough to drop scan time by more than half (not counting the time for the attenuation scan, either with the old germanium transmission or with the faster CT version)? I don't know. What I do know is that the images from the Biograph are better, at least to me, than those from the Discovery. That's my story, and I'm sticking to it.

GE made a last ditch effort to change our minds by reminding us that they won the Frost & Sullivan Market Leadership Award for the PET/CT in 2004. This is a monumental achievement, true, but take a look at the press release from Frost & Sullivan:

Frost & Sullivan’s recent analysis, U.S. PET and PET-CT Markets, selected GE Healthcare as the recipient of the 2004 Market Leadership Award. This Award acknowledges the company’s exceptional marketing strategies that helped it capture the largest percentage of the U.S. positron emission tomography-computed tomography (PET-CT) market in 2003 and maintain its robust lead since the market’s inception.

I have to agree 100%. GE certainly has exceptional marketing strategy. No question about that. But I don't think Frost & Sullivan is really qualified to evaluate the scanners themselves. That needs to be left to those of us who actually have to interpret the images. You might ask, "Will the Discovery fail to demonstrate something that the Biograph would show?" Now that's one question I can't honestly answer, and it's probably the most important of all. Time will tell on that one. But you can bet it will become obvious eventually.

1999 Happy Visitors; One Less So

Congratulations to visitor number 2000, from Mesa, Arizona. Maybe someone from AuntMinnie.com?

Sadly, not all of my readers seem to be enjoying my musings. "Anonymous" posted this comment on my entry about the KLAS survey just this afternoon:

Did you ever consider that Blogging in a medical environment would be so crude as to bash vendors. Besides, it is easy to jump on a bandwagon of the top 1, 2 or 3 with little market share and history, yet to bash others in a cowardly fashion is outright fake. What is your total combined compensation (including free meals) for promoting the top 3? Just need to know so I can budget for this when we crush them with slow steady forward progress and you turn your vote. This will remain anonymous so long as you continue to hide your identity behind an outrageous title that should belong to people to have acutally contributed something to the medical profession.
Cheers!

Gee, where do I start? I hate to dignify such a posting with a response, but what the heck. I have to note at the outset that Anonymous' IP localizes him to Milwaukie, WI, the home of GE Medical systems. Coincidence? Gotta wonder... As to the rather personal comments....I would just as soon keep my name off of the blog, but my full name is revealed in the AuntMinnie article, so I am not "hiding" behind anything, thank you. If Anonymous had bothered to read some of the other entries, he would have found that I do indeed deny being in any company's pocket. Adding up all dinners and so on received from PACS vendors (which include Agfa, Amicas, Fuji, and GE) over the past five years would yield the grand total of $500. If I can be bought, it would take a lot more than that! Finally, as to my contributions to medicine, I am responsible for the introduction of PET imaging to South Carolina. Tell me, Anonymous, what have you contributed?

Sigh. I guess you just can't please everyone. But I'll keep trying anyway.

I can't directly link Anonymous to GE, and I should mention that GE PACS headquarters is in Chicago. Perhaps Anonymous owns GE stock (I do too, by the way). He is obviously worried about my "bashing" of big-iron vendors, but in reality, the only vendors I "bash" regularly are GE, Fuji, and ScImage (sorry, guys). I don't push Stentor or DR. My only experience with Stentor was at a past RSNA, where I went through an excellent demo, but concluded that the pricing structure was not what was needed for the hospital that ultimately went with Amicas. We called upon DR Systems once to see if they would be interested in providing an "interim solution" for multislice CT reading. They responded that if they couldn't sell us a full system, we were not worth their time.

I "bash" whom I "bash" usually due to my dislike of their interfaces, which is the part of the PACS I actually use. It is clear in many cases that the products were designed and tested by engineering types (I can say that because I am one) and perhaps a few docs who didn't actually try to do their day-to day work with the system. This is why I am calling for an open exchange of ideas about PACS GUI's. Every PACS system has room for improvement, and the more we work together, the better things will be for the industry and end-users alike.

Cheers!