Virtual Reality Promises to Improve Bronchoscopy

CHICAGO--By creating a virtual reality environment, physiciansin the not-too-distant future will be able to move through, around,and into a patient's airways to search for tumors, enlarged lymphnodes, and abnormal masses in the walls of the bronchi and surroundingtissue on a computer screen, David J. Vining, MD, predicted atthe annual scientific meeting of the Radiological Society of NorthAmerica.

"What we're doing right now is relatively crude, but whatwe'll be doing in 5 years will be very sophisticated," saidDr. Vining, assistant professor of radiology, Bowman Gray Schoolof Medicine, Winston-Salem, NC. [A report on Dr. Vining's researchon virtual colonoscopy appeared in the July, 1994, issue of OncologyNews International (ONI), page 29.]

By the turn of the century, virtual reality technology probablywill be advanced enough to be used routinely to obtain three-dimensional(3D) views of the airways that reveal anatomic structures whichnormally remain hidden during bronchoscopy, such as the lymphnodes and blood vessels. It will provide a clear road map physicianscan follow to guide the placement of biopsy needles in suspiciouslymph nodes during standard bronchoscopy, he said.

The technology also will be able to identify patients who shouldnot be subjected to bronchoscopy. "Sometimes, bronchoscopyis unsuccessful because there are blockages in the bronchi thatrestrict access with an endoscope. Other times, there is a tumorthat is situated so it can't be seen with an endoscope. Virtualbronchoscopy will be very good at predicting these things in advance,thus sparing the patient the discomfort and expense of an unsuccessfulexam," Dr. Vining said.

25 Simulations to Date

To date, virtual reality simulations of the interior of the airwayshave been created on more than 25 patients, to provide physicianswith a way of evaluating thin-section spiral computed tomographic(CT) images from the perspective of the bronchoscopist. Specialsoftware converts the CT images into 3D graphic elements thatcan be displayed on a computer console and manipulated by meansof a computer mouse. "With this technology, physicians canview exquisitely detailed reproductions of their patient's anatomyas 3D, movable models on a video screen. The physicians can thensearch for a tumor or other abnormality by 'navigating' throughthe body, using a computer mouse to guide the direction of travel,"Dr. Vining explained.

In a number of ways, virtual reality examination of the airwayshas proved to be more medically illuminating than conventionalbronchoscopy, he added. The technology accurately predicted bronchialinvolvement by mediastinal tumors, identified areas of bronchialstenosis and bronchiectasis, and discovered several unsuspectedconditions, such as multiple aberrant bronchi.

Allows View of Mediastinum

A special feature of the technology causes the bronchial wallsto disappear so that the mediastinum can be viewed on the computerscreen (see figure). "If there is a suspected cancerin the bronchial airways, the physician can push a button, makethe walls of the bronchi transparent, and see the surroundingtissues. When enlarged lymph nodes or abnormal masses are seen,the suspicion of cancer is increased," Dr. Vining said.

In the next few years, Dr. Vining expects that the technologywill acquire improved algorithms to isolate the smaller airwaysand better define lymph nodes, virtual reality computers willoperate more quickly and less expensively, and software will combinemultiplanar reformations with 3D images.