Cinema observers have noted that 3-D comes to the theaters in waves. In the 1950s, a couple of decades before the technology for polarized glasses was brought to the movies, teens lined up for "Creature from the Black Lagoon" and other cheesy flicks. A mini-craze erupted briefly in the 80s ("Jaws 3-D," anyone?), and now in a post-"Avatar" world we're seeing a glut of 3-D films made by studios hoping to charge viewers a few extra bucks for the privilege of seeing such immortal works of cinema as "Wrath of the Titans" (which opened last month) in all three dimensions.

While for the pictures, 3-D glasses have rarely been more than a gimmick, they shouldn't be written off just yet. In medicine, some researchers think they can help doctors and surgeons do their job. And one company even hopes they could help radiologists spot breast cancer.

3-D in medicine

That company is Fujifilm Medical Systems, and this weekend at a radiology conference in Japan, it's demonstrating a mammography workstation that comes with polarized glasses and lets radiologists review breast images in stereoscopic 3-D.

What good is stereo 3-D? Robert Held, a post-doctoral researcher at the University of California, Berkeley who has studied stereo 3-D displays in medicine (but who has not worked with this machine and has no connection to Fujifilm), says doctors have been using stereo 3-D monitors in a small way for decades, although they aren't always necessary.

"Quite often the case is that people think stereo is going to help you no matter what, but it's important to realize there are specific situations where the stereo information will help you out," he tells DOTmed News.

Mostly, these are situations with few monocular depth cues -- the signs of depth you could pick up even if you lacked stereo vision. For instance, if you're walking down the street, you would gain a pretty robust guide to depth just by noticing the relative size of objects, the fact that objects farther away appear smaller, and by taking into account linear perspective, in which parallel lines appear to converge in the distance.

But these cues are generally absent in many medical situations, such as for surgeons looking through monitors while performing laparoscopic surgeries or while controlling surgical robots.

"Once you get into anatomy, there are very irregular structures, so you lose a lot of that monocular information that you get from a typical object," Held says.

But surgeons could still potentially benefit from knowledge of depth as they make tricky cuts and snips. That's partly why Intuitive Surgical's pricey Da Vinci surgical robot, for instance, presents images in 3-D to the surgeons operating it. But surgery isn't the only case where stereo 3-D could be useful.

"Mammograms project all of the structures on top each other, which essentially makes monocular depth cues useless," Held says.

Mammo in 3-D

As Fujifilm explains it, looking at a stereo 3-D image of a mammogram could give you better visualization of masses or microcalcifications hiding behind overlapping tissues, something that might be especially important for women with mammographically dense breasts. "3-D images enable the internal anatomical breast structures to be identified more clearly than in a 2-D image," the company said on its website.

Stereo information also could help you tell if a mass you're looking at is just one mass or actually two regions, with one in front of the other, Held says. "If you're looking at one image, it could be a brighter spot, it looks like one mass, but with stereo, you'd be more likely to resolve if that bright region was one mass or two masses superimposed on each other," he says.

How the Fujifilm system works

So how does Fujifilm's system work?

First, doctors would have to take X-ray images of the breast, using Fujifilm's digital mammography unit, the Aspire HD Plus (known as the Amulet f abroad, not available yet in the U.S., and sold separately from the workstation). In the model described by Fujifilm, the scanner acquires two images of the breast, each image taken about four degrees apart.

The images are then displayed on the workstation, called the Mammoascent Bi-V 3D. This features two screens, one facing the viewer and another jutting out horizontally from its top, as though it were a kind of visor. The screen on the top gets the image for the right eye, while the screen on the bottom for the left eye. Midway between the two screens is what the company calls a half mirror. By looking through this half mirror while wearing the polarized 3D glasses, a stereoscopic image is created, Fujifilm said.

It should be noted the technique does mean exposing women to 1.3 times the dose of a typical Fujifilm 2-D X-ray mammogram and it takes slightly longer to capture the image, the company said. However, Fujifilm said that the average glandular dose, at 1.39 mGy, is actually lower than a typical digital mammogram scan performed in the U.S., at 1.5 mGy. Also, the company says if the product works as planned, it could lead to a reduction in false positives, and thus less of a need to get a follow-up scan.

Proving effectiveness

Even if 3-D mammography, in principle, has certain advantages, how does it work in practice?

Fujifilm says it's busy acquiring clinical evidence. David Hotchkiss, director of product marketing modality solutions with Fujifilm, told DOTmed News in an emailed statement that the company will have three sites collecting images in the U.S. for clinical trials by the middle of this month. Fuji has also already started studies in Japan in 2010 and in Europe, where the device is commercially available.

But the company says there's already some clinical evidence out there for 3-D mammography, citing a 2008 study published in Lecture Notes in Computer Science, and run by Emory University researchers, which found stereoscopic digital mammography upped sensitivity and specificity of exams. According to the study, which involved about 1,450 patients, stereoscopic mammo increased its ability to find breast lesions by 23 percent, and to rule out false positives by about 46 percent.

Drawbacks

Hotchkiss said no drawbacks have been reported in the studies so far, but there are some potential limitations. One is that about 2 to 3 percent of people lack full stereo vision, often for neurological reasons, according to Held, the Berkeley researcher.

Also, if you remember the launch of Nintendo's 3DS game system -- a portable game console with a glasses-free 3D screen -- some people using 3-D for extended lengths of time reported eye strain and headaches. "One of the main causes of fatigue is that your eyes have to work hard to stay focused at a different distance than where your eyes are pointed," Held says.

However, in a paper Held co-authored with Tiffany T. Hui in Academic Radiology last year, he noted that this problem, known as the vergence-accommodation conflict, mostly affects those under 50, as the lens of the eye hardens with age. Viewer discomfort can also be mitigated by product design and by the user adopting a proper posture, Held said. And Hotchkiss said as far as their product was concerned, physiological studies conducted in Japan found no difference between 2-D and 3-D reads.

Of course, more will be known when the device, reported to cost around $181,000 in Japan (U.S. prices have not been released), finally reaches American markets. Hotchkiss said the scanner that you need to work with it, the Aspire HD Plus, would be launched probably in the late summer. But Fujifilm still needs to file a premarket approval submission with the Food and Drug Administration for the mammography workstation itself, something they expect to do by 2013.

If you're in Japan, however, you'll have a chance to get an earlier look at it. Fujifilm is expected to show the device at the International Technical Exhibition of Medical Imaging 2012, which is being held at the Pacifico Yokohama Exhibition Hall, starting Friday.