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DOI:10.2214/AJR.07.2875
AJR 2008; 190:886-891
© American Roentgen Ray Society

Original Research

Improved Detection of Small Lung Cancers with Dual-Energy Subtraction Chest Radiography

Feng Li1, Roger Engelmann1, Kunio Doi1 and Heber MacMahon1

1 All authors: Kurt Rossmann Laboratories for Radiologic Image Research and the Department of Radiology, The University of Chicago, 5841 S Maryland Ave., MC-2026, Chicago, IL 60637.

OBJECTIVE. The objective of our study was to retrospectively evaluate whether the use of dual-energy subtraction chest radiographs can improve radiologists' performance for the detection of small previously missed lung cancers.

MATERIALS AND METHODS. Dual-energy subtraction chest radiographs of 19 patients with previously missed nodular cancers, in which the radiology report did not mention a nodule that was visible in retrospect, were selected. Dual-energy subtraction radiographs of 19 patients with cancer and 16 patients without cancer were used for an observer study. Six radiologists indicated their confidence level regarding the presence of a lung cancer and, if they thought a cancer was present, also marked the most likely position for each lung, first using standard posteroanterior and lateral chest radiographs and then using both soft-tissue and bone dual-energy subtraction images along with standard radiographs. Receiver operating characteristic (ROC) curves were used to evaluate the observers' performance. The indicated locations of cancers and false-positives were also analyzed.

RESULTS. The average area under the ROC curve (Az) value for the six radiologists was improved from 0.718 to 0.816, a statistically significant amount (p = 0.004), and the average sensitivity (correct localizations) for 19 previously missed cancers was also significantly improved from 40% to 59% (p = 0.008) with the aid of dual-energy subtraction images. The average number of false-positive (incorrect) localizations on 70 lungs was 10 without and nine with dual-energy subtraction images (p = 0.785).

CONCLUSION. Dual-energy subtraction chest radiography has the potential to improve radiologists' performance for the detection of small missed lung cancers.

Keywords: diagnostic radiology • digital radiography • dual-energy subtraction radiography • lung neoplasms • observer performance study






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