student research day - Case Western Reserve University School of ...

Jason Balkman
Dual Energy Subtraction Digital Radiography Improves Performance of a
Commerical Computer-aided Detection Program
Jason Balkman and Robert C. Gilkeson
Department of Radiology, University Hospitals
Skeletal structures are a significant source of anatomic noise on a chest radiograph, making them a major limiting
factor for the detection of subtle lung nodules for both physicians and computer-aided detection (CAD) programs. Dual
energy subtraction (DES) enables the acquisition of a soft tissue only chest radiograph and has shown potential to
improve physician performance in the detection of subtle cancers. Few studies have used DES to examine its effect on
CAD performance, which is often poor because of difficulties distinguishing bony structures. The purpose of this study
was to apply a commercial CAD program to the analysis of both standard posteroanterior (PA) and DES chest
radiography, and compare the sensitivity and number of false-positive marks achieved by the CAD system in both
cases.
One hundred and two patient records were retrospectively identified as having DES radiographs and pulmonary
nodules confirmed by CT. Those patients with biopsy proven lung carcinoma (n=45) were selected and the panel was
narrowed to identify patients with lung nodules 8-30 mm in size (n = 36) to satisfy the search criteria for the CAD
system. The final panel of 36 patients with a total of 48 nodules was evaluated.
The sensitivity of the CAD program with the standard PA was 46% (22 of 48 nodules) compared to 67% (32 of 48
nodules) using the DES soft tissue, or bone-subtracted view (P=0.064). The average number of false positives per
image (FPPI) identified by CAD was significantly lower using DES (FPPI ST=1.64) when compared to the standard PA
chest radiograph (FPPI PA=2.39) (P