Difficult lung biopsies can now be performed with greater success
A NEW technology enables difficult lung biopsies to be performed with greater success.
When a suspicious nodule or lump in the lung is detected on a CT (computed tomography) scan, the next step is usually to get a small tissue sample to examine if it’s cancerous or harmless.
But collecting a tissue sample deep in the lungs isn’t easy. There is a risk of puncturing the air-filled organ, as well as injury to the heart, aorta and liver – critical organs that lie close by. At the same time, a nodule in the web of airways is difficult to locate, even if a scan clearly shows where it is.
A new technology makes the job easier. Much like a road navigation device such as Google Maps or GPS , the virtual bronchoscopy navigation system is able to plan a route for the doctor to take to accurately reach a lung nodule, said Dr Anantham Devanand, Senior Consultant, Department of Respiratory and Critical Care Medicine, Singapore General Hospital (SGH), and Deputy Head, Singhealth DukeNUS Lung Centre.
“Virtual bronchoscopy navigation improves the diagnostic yield (the information provided by the biopsy to make an accurate diagnosis) by enhancing the planning that occurs before a bronchoscopic biopsy procedure, and by providing guidance during the scope. It is designed to improve diagnostic yield without changing the risks or duration of the procedure,” said Dr Devanand.
“Previously, we had to estimate where to go based on the scans. Now, we know more precisely.”
The hospital has used virtual bronchoscopy navigation under a five year pilot for more than 180 patients undergoing bronchoscopy. The overall diagnostic yield is about 80 per cent for this group, substantially higher than the 50 per cent for such procedures as reported in medical literature. This means that the procedures were able to offer more meaningful diagnoses. In addition, no increased complications were reported.
In virtual bronchoscopy navigation, the coordinator takes a series of CT images, which are then used to map the best of any number of routes for the doctor to take. During the procedure, the coordinator, who is familiar with airway anatomy, prompts the doctor the way to go to reach the nodule.
“The bronchoscope (a thin, flexible tube) is inserted through the windpipe, then she tells me where to go next – go down, turn left, then up, and so on,” said Dr Devanand, who is also Director of SGH’s Bronchoscopy and Interventional Pulmonology Service.
After reaching the target, an endobronchial ultrasound or EB US probe can be inserted via the bronchoscope to confirm that the location is correct. “The EB US has a small rotating ultrasound probe that helps doctors look beyond the walls of the airways to see that we are indeed adjacent to the nodule. There is data to show that the combination of technologies (virtual bronchoscopy navigation and EB US) improves diagnostic yield further,” said Dr Devanand.
As virtual bronchoscopy navigation does not require incisions, only sedation, local anaesthesia and medication to suppress coughing are required. The outpatient procedure is usually completed within 20 to 30 minutes.
Conventional bronchoscopic biopsy is among the safest and least invasive options for patients found to have nodules in their lungs, albeit having a relatively low success rate of positive diagnosis. CT scan-guided needle biopsy, which involves inserting a small needle into the chest, is more accurate but requires hospital admission and can have a higher risk of complications.
Another option is thoracic surgery, where a small part of the lungs is removed – a far more invasive option – for diagnosis. If the nodule is very small, the patient can choose to do nothing but to have it monitored regularly for changes. But repeated scans risk radiation exposure, and if the nodule is indeed cancerous, the disease will advance, and some form of biopsy will still be needed later.
Nodules can suggest not just cancer but tuberculosis or scar tissue. Should nodules be diagnosed as malignant, early diagnosis and treatment have the best chance of success. “But we were frustrated with the imperfect options (for biopsy) available to our patients,” he said.
SGH’s bronchoscopy centre, the busiest in Singapore, has considerable experience in implementing new technologies. “Having a highly trained endoscopy team meant that we had the foundation to try novel approaches to patient care,” said Dr Devanand, who together with Dr Adrian Chan Kwok Wai, another Consultant from his department, applied for a Ministry of Health grant to acquire and test out the virtual bronchoscopy navigation system.
Being the first in Southeast Asia to acquire the technology, Singhealth Lung Centre doctors have lectured specialists in countries such as Taiwan and Indonesia on it. They have also run bronchoscopy workshops for specialists from Australia, New Zealand, the Philippines, Myanmar, Malaysia, India and Macau.