DOI: 10.1148/radiol.2231010344
(Radiology 2002;223:199-203.)
© RSNA, 2002
Detection of Lung Nodules on Digital Chest Radiographs: Potential Usefulness of a New Contralateral Subtraction Technique1
Shunji Tsukuda, MD,
Atsuko Heshiki, MD,
Shigehiko Katsuragawa, PhD,
Qiang Li, PhD,
Heber MacMahon, MD and
Kunio Doi, PhD
1 From the Department of Radiology, Saitama Medical School, Saitama, Japan (S.T., A.H.); and Kurt Rossmann Laboratories for Radiologic Image Research, Department of Radiology, University of Chicago, 5481 S Maryland Ave, Chicago, IL 60637. From the 1999 RSNA scientific assembly. Received February 6, 2001; revision requested March 1; revision received August 20; accepted September 20. Supported by U.S. Public Health Service grants CA62625 and CA64370. Address correspondence to K.D. (e-mail: k-doi@uchicago.edu).
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Figure 1. Diagram shows overall scheme of a contralateral subtraction technique for posteroanterior chest images.
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Figure 2a. Comparison of chest image and corresponding contralateral subtraction image. (a) On the original chest radiograph, a nodule is noted in the left upper lung overlapping the distal clavicle. (b) On the contralateral subtraction image, symmetrical bone structures are canceled out, and then the nodule is clearly demonstrated without overlapping bone. The nodule is depicted as a dark area on the ipsilateral side (arrows) and as a bright area on the contralateral side. Asymmetrical structures such as the aortic arch and cardiac shadow are demonstrated as a dark area on the ipsilateral side and as white area on the contralateral side. Another dark area in the right upper lung field is an artifact due to misregistration.
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Figure 2b. Comparison of chest image and corresponding contralateral subtraction image. (a) On the original chest radiograph, a nodule is noted in the left upper lung overlapping the distal clavicle. (b) On the contralateral subtraction image, symmetrical bone structures are canceled out, and then the nodule is clearly demonstrated without overlapping bone. The nodule is depicted as a dark area on the ipsilateral side (arrows) and as a bright area on the contralateral side. Asymmetrical structures such as the aortic arch and cardiac shadow are demonstrated as a dark area on the ipsilateral side and as white area on the contralateral side. Another dark area in the right upper lung field is an artifact due to misregistration.
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Figure 3. Graph shows average ROC curves of all observers without (Az = 0.926) and with (Az = 0.962) subtraction images. Diagnostic performance is significantly improved (P = .012) with subtraction images.
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Figure 4. Graph shows ROC curves for residents’ subgroup without (Az = 0.827) and with (Az = 0.926) subtraction images.
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Figure 5. Graph shows ROC curves for attending radiologists’ subgroup without (Az = 0.948) and with (Az = 0.970) subtraction image.
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Figure 6. Graph shows number of cases affected by using subtraction images in nodule cases. Gray bars = beneficial effect, black bars = detrimental effect. Total numbers of cases beneficially affected and detrimentally affected by using subtraction images were 18 and five, respectively.
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Figure 7. Graph shows numbers of cases affected by using subtraction images in nonnodule cases. Gray bars = beneficial effect, black bars = detrimental effect. Total numbers of cases beneficially affected and detrimentally affected by using subtraction images were 25 and 23, respectively.
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Copyright © 2002 by the Radiological Society of North America.
