Lung CAD Carves a Niche

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Finding lung cancer at its earliest, and thus most treatable, stages is the objective of lung CAD. Advancements in CAD's detection and greater workflow friendliness are helping to boost interest. Clinical sites are running the lung CAD systems that review CT or x-ray images through their paces, while a few vendors are set to launch new options in the next several months.

Since first hitting the market in 2001, lung CAD has been garnering support in the radiology community. Lung CAD systems are available to aid in the detection of suspicious nodules on both x-ray and CT studies. Both types of solutions are showing that they can help detect lung cancer in its earliest and most treatable stages. Some systems incorporate tools that simplify follow-up of suspicious and malignant lesions, such as automatically measuring nodule volume or registering previous scans. The combination of enhanced detection and workflow gains translate into some bold predictions.

"Lung CAD is going to become part of the day-to-day workflow," predicts David Yankelevitz, MD, professor of radiology at Weill Medical College of Cornell University. "Relatively soon, radiologists will be using this technology routinely."

But users agree that lung CAD technology has not yet been perfected, and vendors are working to further boost the utility of the technology. Many are signing partnerships with PACS and 3D vendors that outline plans to integrate CAD into those products. These agreements will facilitate integration and workflow and help lung CAD establish a firm presence in the radiology department.

The chest x-ray route

One option for adding CAD to the lung cancer detection arsenal is to use an x-ray-based CAD system. Supporters of the approach tout the widespread use and low cost of chest x-rays.

Garden City Hospital in Garden City, Mich., has analyzed approximately 700 chest x-rays with Riverain Medical's (formerly Deus Technology) RapidScreen CAD system since installing the system a year ago. The hospital provides CAD free of charge to all chest x-ray patients meeting one of four criteria: smoker, second-hand smoke exposure, asbestos exposure or factory employment.

Analog chest films are digitized and pushed through RapidScreen software. Radiologists typically read the film and CAD print outs simultaneously. Radiology Administrator Jim Williamson notes, "It's important to create a process for reading films and CAD printouts." This links CAD and film results and keeps workflow moving. Williamson says workflow issues are minimal, with CAD adding a maximum of 30 seconds to each exam.

The majority of CAD marks are false positives as the software does pick up tuberculosis scars and rib junctions, which can be readily dismissed by a radiologist. RapidScreen also has picked up one 4 millimeter mass missed by a resident, enabling clinicians to treat a cancer that would have become lethal within months.

For those in the digital realm, Riverain markets RS-Digital for use with digital x-rays, and GE Healthcare has integrated the CAD system into its Revolution DR and CR systems. Both options can process dual-energy subtraction images, which optimizes viewing by reducing obstructions and separating bone and soft tissue images.

Other lung CAD systems focus on CT scans, but the systems are not mutually exclusive as findings on chest x-rays are often followed by CT scans.

The CT option

One of the newest CT CAD options is Medicsight's Lung CAR system. Cornell's Yankelevitz says, "The system performs quite well, finding small lung nodules in the four to five millimeter range, which are often overlooked and the range that you don't want to miss. It is also not missing nodules that turn out to be cancers."

Lung CAR incorporates an adjustability feature that allows sites to fine-tune the system's sensitivity. For example, on an initial screen the radiologist can focus on five to eight millimeter nodules and adjust the "highest sensitivity sweet spot" down on follow-up studies. Or if the radiologist is searching for metastatic diseases in a thyroid cancer patient, the dial can be set for the very small nodules indicative of metastasis. Users also can enhance performance by adjusting slice thickness, dose and speed. Yankelevitz says the adjustability feature is critical in optimizing CAD.

Medicsight has signed agreements with Agfa, Viatronix and Vital Images, outlining plans to integrate Lung CAR into their systems.

R2's ImageChecker CT Lung is another CT CAD option. San