The Missing Link

Once in a while (a GREAT while, it seems, for me), one is struck with a simple solution to a complex problem. I have mentioned in earlier posts that linking between a new and an old CT (or MR for that matter) is critical for interpretation. This would be an easy proposition if patients could be very precisely positioned at the same spot on the gantry every single time, and of course if they held completely still. Then there’s the breathing aspect, but I’ve found in general that patients who don’t breathe at all tend not to pay their bills, so we have to live with that.

In the good old days, a couple of years ago that is, the only real option for comparing studies was to link by image number. In other words, if you scrolled down three slices on the new, you would scroll down three slices on the old. This would be OK if your scans were both performed with the same slice thickness. That is not always the case, especially if you have installed a new scanner since the patient’s last exam. So, the modern systems (except, of course, for our friends at Image Technology Laboratories, who don’t think this situation ever occurs) match scans by table position. This represents a considerable improvement, although all it really does is advance the old study intermittently to more or less match the position of the pertinent slice of the new scan. One still has to orient one study with the other. I try to pick some landmark, say the carina, or the SMA, find the slice on each study that demonstrates it well, and then I link the two together.

OK, here’s where my idea comes in. I won’t bother to try to patent it, because it is really just an extension (or a subset) of the fusion software used to match PET’s and CT’s. Those get automatically matched these days because the gantries are combined and the patient (hopefully) doesn’t move much. We have a computer from Hermes that supposedly will stretch and deform and magnify the PET to conform to the CT. Sadly, it doesn’t work very well unless you tweak it to death. But it tries to match without any real help from humans.

My idea is to use a simplified version of this approach to link new and old scans. Instead of having the computer grind away forever trying to match the scans, let the user do it: mark congruent points on each study, say the sternal notch, the carina, the SMA, and the symphysis, just to use my personal favorites. In the simplest implementation, slice incrementation could be adjusted to match the position relative to those marked points, rather than table position per se. The more points you place, the better the match, although I assume most people aren’t going to want to place more than three. The wider the distribution in the z-axis (head-to-toe), the better the match as well. In a really whiz-bang set-up, the scans could be treated as volumes and the old one morphed to the points marked. Some folks from Voxar hinted to me that they were working on a surface-mapping approach to this problem, but so far, several years later, no such luck. My approach is a lot easier, and therefore cheaper, and therefore more likely to appear on a PACS near you.

If someone gets the volumetric approach down, the next step would of course be linked 3D studies, including MPR’s and volume renderings. Again, I have heard that Siemens was working on that sort of thing for InSpace (courtesy of Eliot Fishman responding to my question on, but again, this has yet to see the light of day. My pals at ScImage did create a dual-MPR display (one can do the same with GE AW4.1 and Philips, I mean Sectra). ScI’s program suffers from their usual confusion as to where it thinks you have clicked, not to mention half-a-dozen other problems, and using the dual-MPR is so tedious that I don’t bother with it. Now, watch them be the first to run with my idea. That’s OK, as long as everyone else does so as well.

Phew. Having ideas is hard work. I think I’ll go back to bashing.

A Visit From The General

Three lovely ladies from GE just stopped by our Centricity site to say hello and listen to me whine. And whine I did. Putting on my pompous a$$ hat, I declared that Centricity does several things that are totally unacceptable in a PACS:

  1. It only allowing two measurements on screen at any one time
  2. All caps and a space after the comma are required for searches; without these elements, you are informed that there are no matching studies.
  3. There is very slow refresh on manual cine’ing through linked studies
  4. No 3D.

They listened very politely, and didn’t even laugh. That’s the good news. The better news is that whines 2 and 3 are supposed to be fixed in Centricity 2.1, and we will at least be allowed to demo a 3D package, the long-awaited port of AW software. The number of measurements on a screen problem may take a while, however.

Now dear Dalai has nothing to offer but his credibility. I don’t just bash because it’s fun (although sometimes it is fun), but when I hit a brick wall with a product (or an airline), I can at least vent here on the blog. I promised my visitors that I will accurately relate any and all fixes to my problems. The flip side of course is that I will accurately report if things don’t get fixed. I mentioned my blog (even I have to have a little pride), and you should have seen their faces….

YOU’RE the Dalai Lama?????”

Really, I thought everyone at GE knew. Maybe they were expecting someone better looking. But wait, my photo is over to the left… Oh well, there goes my hiding. Maybe I need a new identity… about “Beelzebub’s PACS Blog?”

Wanted: PACS Guru

Beard and baggy pants optional. My projects are suffering due to the other obligations of hospital personnel, and a few other reasons I won’t go into at the moment. I need someone with proven expertese in PACS, RIS, networking, computers, and especially in dealing with whiny doctors. Experience with Amicas products would be a distinct advantage. My project currently consists of an Amicas server piggy-backed onto an Amicas database SAN at one of our hospitals. I need to expand this, and ultimately create a free-standing system, located off of hospital grounds. This position is equal opportunity for those of all species and planetary origins. It includes full benefits. Salary is commensurate with experience, but unless you are the CIO at your place, it will likely be higher than what you are making now. Please send preliminary responses to “nucleon(at)”. (If you don’t know what to do with the “at”, you ain’t no guru!)

I have had several leads on gurus that didn’t work out, mainly because many of the possible candidates wanted to stay where they were for some strange reason. Some likely possibilities just didn’t yet have the adequate level of expertese to hit the ground running.

This is your chance, folks, to work side by side by side (look at the avatar!) with the most horrible, oops, I mean most honorable, Dalai Lama of PACS! Chances like this don’t come around twice! Well, maybe not three times?

Two, Four, Six, Eight,This Is How We Mensurate!

\Men”su*rate\, v. t. [L. mensuratus, p. p. of mensurare. See Measure, v.] To measure. [Obs.]
Source: Webster’s Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.

Now that we have that straight….

Measurement is one of the most tedious, yet critical operations we radiologists perform on our images. It is very important to know the size of various items, such as (unfortunately) tumors, and whether or not they have changed from the last time they were examined. As with other things in life, size is not the only important issue, and additional factors, such as angle or density might also need evaluation.

The early PACS GUI’s had simple ruler tools. Click the button, point the cursor to one margin of the object in question, left-click-and-drag to the other margin, let go, and voila! The length in centimeters of the badness is produced, though often the number was plopped right over the lesion, just where you didn’t want it.

Many of the newer systems put the numerical measurement somewhere else. I actually like the way ScImage does this to some extent. (That thud you felt was everybody in Los Altos fainting). You click and drag and then drag again to place the number wherever you want it to be. So far, so good, but sadly it doesn’t stop there. ScI’s PICOM viewer has tremendous state problems, i.e., you have to left click in each window or toolbar before it recognizes where you are and what you wish to do. With their version of the venerable ruler (magnificently represented on the tool bar by a line on the button), you can’t let go without deliberate effort. Left click on the first point, then left click again on the second, then left click again to place the number which is (nicely, I might add) flagged to the line of measurement. Personally, I prefer the click and drag routine. Amicas does this, with a fixed-position numerical “flag”. Now, neither lets you reposition the line of measurement. You can erase it, or with Amicas you can actually move the whole line, but you can’t resize it. With Centricity, you can resize by selecting the arrow tool and then pointing at one end of your line. By the way, GE does something completely unacceptable with measurements: only two numbers are displayed on the screen at one time. If you have three (or thirty-seven, for that matter), you must use the arrow and point to the one you wish to see. GE says this is to keep the screen clear. BS. If I want thirty-seven measurements on my screen at once, that’s my problem, and GE should not enforce it’s will on me. But that’s the way GE thinks.

Agfa has some good and bad elements in its ruler tool. You left-click and drag after toggling the tool “on”, then you have the option to click on a grab-box in the center of the line that will let you drag the numerical measurement elsewhere if you wish. Good idea. But you have to right-click to drop the measurement, and two right-clicks drop the tool. Potential for problems with that. Agfa labels each measurement A, B, C, etc, which is helpful as there is no dotted line connecting the number to the line of measurement. GE uses numerals for this.

Now, here is my idea for the perfect ruler… I like the simple left-click-and-drag approach for the measurement itself, and I like the option to move the scalar somewhere else if desired. So, combine Amicas’ and ScImage’s approach to that point. It also would be nice if you could click a line with the ruler tool if you need to adjust it. Here is my great innovation….add magnification to the mix. As noted on an earlier entry, Agfa uses the mouse wheel to magnify within the zoom tool. How about enabling this functionality for the ruler? Amicas actually won’t let you drop a line if it does not cover a sufficient distance (basically if you didn’t move the mouse more than a few pixels), so how about giving you the ability to zoom in on the area of interest while still within the same ruler tool? I think this would work quite well. Who’s going to be the first to implement it???

I’m going to ignore the angle tool. Most systems let you draw two lines in some fashion and then give the angle between them, useful for Cobb angle measurement. Amicas plans to implement this on the next release of LightBeam. I can’t say I’ve noticed its absence.

The ellipse serves many purposes, mainly highlighting an area or giving the average density within that area. Once you get beyond the toggle mentality, I prefer Agfa’s approach. Left-click for the center of the ellipse, left-click-and-drag for one axis, and again for the second. Until the tool is dropped with a right-click, the ellipse can be rotated and resized to your heart’s content. The ellipse grows from the center, not an edge, which turns out to be more intuitive.

Any votes for my next tool-ish remarks?