CAD offerings build on clinical performance

Computer-aided detection is evolving from an interesting technological trapping to a standard of care. Part of that process involves the ongoing iterative advancement expected to be on display at the RSNA meeting.

While CAD breast imaging products are being revamped to provide gains in clinical accuracy and utility, CT-oriented product vendors are focusing on high-end visualization and advanced analyses to increase productivity as well as accuracy.

The first CAD mammography products, with detection rates in the high 80% range, did not command much respect. More recent CAD products, however, have raised detection rates to the mid- to upper 90% range, even for difficult-to-spot signs of breast cancers such as microcalcifications and invasive lobular carcinomas.

CAD mammography identified 98% of the microcalcifications and 95% of the invasive lobular carcinomas in a study of 273 women who had histologically confirmed breast cancer, and it spotted 89% of the mixed mass/microcalcification lesions as well as 84% of the masses. The study, which used the Second Look CAD unit from iCAD, was conducted at George Washington University Medical Center.

The iCAD family of Second Look products for screening and diagnostic mammography incorporates an enhanced CAD system, which has an overall sensitivity up to 94% and specifically targets the identification of microcalcifications.

"Calcifications are on the edge of what you can see, so providing a set of 'eyes' that is working at the depth the image is taken gives the radiologist the ability to see much finer detail," said Janet Sterrit, vice president of the mammography business unit for iCAD.

Empirical data and trends analysis of the effectiveness of mammography CAD have been so convincing that Aetna revamped its clinical policies in April to include CAD as an adjunct to mammography. Aetna had previously declined to reimburse for breast cancer screening mammography with CAD.

Several companies have developed workstations with integrated mammography CAD systems. At the RSNA meeting, iCAD will display Second Look 700, a film-to-digital CAD for screening and diagnostic mammography, featuring a built-in monitor. The workstation, designed for use in centers with heavy patient loads, offers an easy-to-use workflow option that is driven by patient lists. The company will also show Second Look Digital, which is compatible with digital systems from GE Healthcare, Hologic, IMS Giotto, and Siemens Medical Solutions. The digital product automatically receives and sends results via a DICOM network without requiring manual interaction, Sterrit said.

CAD for breast MRI is not only proving itself clinically, it is boosting productivity. In papers presented at the 2003 RSNA meeting and the 2005 European Congress of Radiology, CAD for breast MRI achieved 100% sensitivity for detecting enhancement kinetics in malignant breast tumors, 94% correlation with histologic analysis of breast tissue, and a reduction in artifacts during subtraction.

In addition to a study presented at last year's RSNA meeting, which found that CAD for breast MRI could decrease radiologists' time by 80% and technologists' time by 90%, anecdotal reports document dramatic improvements in workflow.

Dr. Nanette Debruhl, an assistant professor of radiology at UCLA Medical Center, used to spend hours interpreting MRI breast studies. While a patient was being imaged, Debruhl would sit with the technologist and decide which calculations to make. Processing and interpreting a single study could take an average of 45 to 60 minutes.

With CADstream, Confirma's CAD system for MR breast imaging, Debruhl can obtain the information she needs to make a diagnosis in less than 15 minutes. All the technologist must do is send the scans to CADstream's Internet address and wait for the postprocessing. Because of CAD, Debruhl's department averages 10 cases a day.

"CADstream allows us to evaluate areas of the breast that take up more contrast relative to the surrounding tissue and magnify the images to look at the borders of a mass clearly," she said. "It has markedly improved the speed of analysis, and with the number of films and studies that are being done now-we do an average of 2000 images per case-speed is important to free up the technologist's time as well as the radiologist's," she said.

Confirma will demonstrate at the RSNA meeting how CAD may play a role in interventional planning and guidance for breast cancer. The vendor will display its latest version of CADstream, as well as the Access Breast Coil, which was shown as a prototype last year and is expected to be approved by the FDA for use with the Siemens 1.5 T MRI by meeting time.

Riverain Medical will make its second appearance at the RSNA meeting with its chest radiography CAD product. Although most lung CAD systems use CT images, there is an important place for CAD in x-ray, which is the first-line imaging strategy for lung cancer, according to Kevin McBride, vice president for marketing. The Riverain system offers both lateral and PA images and can be integrated with a PACS.

Vital Images is showcasing its integrated CAD products. In addition to R2 Technology's lung CT CAD package, the company will exhibit Confirma's CADstream for breast imaging. It also plans to launch a product that integrates the computer-assisted reading software for colon polyps from Medicsight, which has expanded its colon algorithms since it received clearance from the FDA in the fall of 2004. The company is presenting seven abstracts attesting to the performance of its algorithms.

The integrated CAD products are designed to simplify radiologists' daily routine. Rather than having to move from one workstation to another to do advanced analysis and turn on CAD, they can perform both operations on one workstation.

"While radiologists are doing their advanced analysis for any number of applications, they can get their CAD results within the same workflow, without physically going to another place," said Susan A. Wood, executive vice president of marketing and clinical development at Vital Images. "The strategy is to get CAD results outbound. If you take that to the next level, the advanced analysis component is being integrated into the PACS solution, so PACS companies that traditionally don't have this capacity can work together with CAD to optimize workflow for the radiologist."

Karen Sandrick, a contributing editor for Diagnostic Imaging.