SUNNYVALE, California-R2 Technology, Inc., has received approval from the US Food and Drug Administration (FDA) for its ImageChecker CT Computer Aided Detection (CAD) Software system to assist radiologists in the detection of solid pulmonary nodules (between 4 mm and 30 mm in diameter) during review of multidetector CT scans of the chest. It is intended to be used as an adjunct, alerting the radiologist- after his or her initial reading of the scan-to regions of interest that may have been initially overlooked. The ImageChecker CAD algorithms examine the complete set of CT images generated during scanning and search for findings with features suggestive of a solid lung nodule. The system marks these candidate nodules for further review by the radiologist. The system workstation is designed to improve radiologist efficiency in reviewing chest CT exams through work-flow-enhancing tools and through automatic measurement and characterization of the detected lung nodules. FDA approved the system based on a clinical study showing that use of the ImageChecker CT CAD system significantly (P = .003) increased the detection of actionable (requiring intervention or short-term follow-up) solid lung nodules by calling attention to potential abnormalities. In the study, 15 radiologists independently reviewed 90 cases from lung CT scans first without the ImageChecker CT system and then again with the system. The system had a false marker rate of only two false marks per case, measured on cases with an average of more than 170 slices per case. The labeling for the ImageChecker CT CAD system includes instructions that the radiologist should always read the film before using the CAD system and never change an original positive reading to a negative one because CAD did not identify the nodule. R2 Technology also announced FDA clearance to market two software packages for use with the ImageChecker CT system. One covers the Temporal Comparison software module, which provides spontaneous three-dimensional registration and the ability to automatically track lung nodule progression or regression over time. Growth rate is an important indicator of clinical significance, and automating this process has potential for significant time savings, the company said. The second clearance is for the Filling Defect Indicator software module, designed to help physicians visualize and evaluate filling defects in pulmonary arteries, such as pulmonary emboli.