Lung Nodules: Improved Detection with Software That Suppresses the Rib and Clavicle on Chest Radiographs

Abstract

Purpose:To demonstrate possible superiority in the performance of a radiologist who is tasked with detecting actionable nodules and aided by the bone suppression and soft-tissue visualization algorithm of a new software program that produces a modifi ed image by suppressing the ribs and clavicles, fi ltering noise, and equalizing the contrast in the area of the lungs. Materials and Methods:The study and use of anonymized and deidentifi ed data received approval from the MedStar-Georgetown University Oncology Institutional Review Board. Informed consent was obtained from 15 study radiologists. The study radiologists participated as observers in a reader study of 368 patients in an approximately 2:1 cancer-free-to-cancer ratio. The localized receiver operating characteristic (LROC) method was used for analyses. Images were rerandomized for each radiologist. Each patient image was sequentially read, fi rst with the standard radiograph and then with the software-aided image. Normal studies were confi rmed with computed tomography (CT), follow-up, and/or panel consensus. Results:Each reader and the combined scores of the 15 readers showed improvement. The area under the combined LROC curve increased signifi cantly from 0.460 unaided to 0.558 aided by visualization software ( P = .0001). When measured according to the reader's indication that a case should be sent or not sent for CT or biopsy, sensitivity for cancer detection increased from 49.5% unaided to 66.3% aided by software ( P , .0001); specifi city decreased from 96.1% to 91.8% ( P = .004). Seventy-four percent of the aided detections occurred in cancers with 70% or greater overlap of the bone and the nodule. Conclusion:The radiologists using visualization software signifi cantly increased their detection of lung cancers and benign nodules.Clinical trial registration no. NCT00906789q RSNA, 2011Supplemental material: http://radiology.rsna.org/lookup /suppl

A Comparison of Computer-Aided Detection (CAD) Effectiveness in Pulmonary Nodule Identification Using Different Methods of Bone Suppression in Chest Radiographs

“…The results of this study suggest that the number of ROI and FPPI has been dramatically reduced from earlier versions of CAD used in conjunction with DESR [11,12,14] and also when compared to earlier software-based methods of bone suppression [13]. Additionally, sensitivity and specificity were found to be improved over previous versions evaluated in the literature [11,13,14]. The majority of false-positives recorded by the CAD/bone suppression systems tested were caused by misidentification of remnant rib crossings and shadows.…”

“…Other authors, [10][11][12] indicated that hardware-based bone suppression (DESR) removed the presence of bony structures in digital chest radiographs and significantly improved the sensitivity of CAD performance in pathology-proven cases with pulmonary nodules while reducing the false-positive rate. Similarly, Freedman et al [13] suggested that softwarebased removal of bony structures also improved the rate of lung cancer detection. The results of these studies suggest that both methods of bone suppression when used with digital chest images improve the diagnostic efficacy of CAD by improving sensitivity and reducing the number of false-positives.…”

Comparison of Dual-Energy Subtraction and Electronic Bone Suppression Combined With Computer-Aided Detection on Chest Radiographs: Effect on Human Observers' Performance in Nodule Detection

“…This technique can be used on any digital radiographs or even on secondarily digitalized chest radiographs and does not require a dual-energy subtraction system for image data acquisition. Freedman et al [1] recently reported a higher nodule detection rate with BSI compared with chest radiography alone. Li et al [23] found that BSI improved radiologists' accuracy for the detection of small lung cancers on chest radiographs but that dual-energy subtraction provided even further improvements.…”

“…By subtracting this bone image from the original radiograph followed by noise reduction and contrast equalization, the software forms a soft-tissue image similar to the image formed by a dualenergy system. However, in contrast to dual-energy subtraction, this algorithm does not require two separate images obtained at different energy levels with a dedicated unit and it suppresses ribs and clavicles only within the rib cage [1,2].…”

“…In past decades, several technical innovations were introduced to improve the sensitivity of this modality. In addition to dual-energy subtraction radiography, other new software techniques have been shown to be capable of decreasing or completely removing the overprojection of bones, mainly of the clavicles and ribs, that significantly hampers the detection of pulmonary nodules on projection radiographs [1][2][3][4][5][6]. On the other hand, computer-aided detection (CAD) techniques have been developed for chest radiography, analogous to those used with chest CT, to aid in the detection of lung nodules.…”