Virtual Deep Throat

Image: Courtesy of Drs. ERIC A. HOFFMAN and GEOFFREY McLANNAN of the University of Iowa and WILLIAM HIGGINS of Pennsylvania State University. MONTAGE of virtual bronchoscopy work, completed at the University of Iowa, in collaboration with Pennsylvania State University.

Instead of sticking a bronchoscope down a patient's throat, some researchers are now generating three dimensional images of the lungs and airways using virtual bronchoscopy.

In addition to being much more comfortable for patients, virtual bronchoscopy can image structures outside the boundaries of the airways--something impossible with conventional bronchoscopy. Studies have found that this technique is just as capable of picking up some of the same abnormalities diagnosed by bronchoscopy, such as small masses, narrowing of the airways or blockages in some of the airway branches. Summers of the NIH estimates that perhaps several hundred virtual bronchoscopies have been performed in the U.S. alone.

Planning Surgery

The real benefit of virtual bronchoscopy may lie in its ability to help doctors plan and execute medical interventions. When tumors push against the airways, doctors often insert a stent to keep breathing passages open. The stent must be exactly the right size: too small, and it could be coughed out or sucked into the lung; too big, and it won¿t fully expand in the airways, and could block breathing even more. Using virtual bronchoscopy, researchers at the University of Iowa are trying to improve the success of their intervention by measuring the exact size of the airway before inserting the stent, to assure a perfect fit.

Some surgeons are now relying on virtual endoscopy to plan surgeries in advance. Because virtual bronchoscopy can image structures outside of the airways, when it finds outlying tumors, doctors can plan and practice different ways to biopsy masses from a bronchoscope confined to the airways.

Francois I. Luks and colleagues at Brown University recently published a paper in the American Journal of Obstetrics and Gynecology about how they used virtual imaging to save two sets of twin fetuses inside two mothers. In both cases, one twin was pumping some of its blood into the other; when blood exchange is unbalanced, the donor twin doesn¿t have enough resources to grow, so Luks decided to seal off the blood vessels connecting the twins. Normally, there is only a 50 percent chance both twins will survive the procedure, but Luks used the three-dimensional images of the mother¿s abdomen to carry out "what if" scenarios, allowing him to fine-tune the procedure beforehand.

And both sets of twins--like many other patients who've benefited from virtual endoscopy--survived.