Abstract Archives of the RSNA, 2003
498-p
Effect of Temporal Subtraction Images on the Detection of Lung Cancer on Low-Dose CT
Scientific Posters
Presented on December 3, 2003
Presented as part of L03: Chest Lung Nodules
Hiroyuki Abe MD, PhD, PRESENTER: Nothing to Disclose
Abstract:
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Purpose: Temporal subtraction is an effective image processing technique
which can enhance selectively areas of interval changes by using the previous
image as a subtraction mask. Although the usefulness of this technique on chest
radiographs has been demonstrated, it is unclear if the temporal subtraction in
CT images can improve radiologists' performance in the detection of lung
cancer. The purpose of this study is to evaluate the effect of temporal
subtraction on low-dose CT on the detection of early primary lung cancer by an
observer study.
Methods and Materials: We selected 14 cases with primary lung cancer and 16
normal cases for this study from our database of low-dose CT images, which were
obtained from a CT screening program for lung cancer on 7,847 cases including
87 cases with primary lung cancer. Images were obtained with a single helical
CT scanner with a 10 mm collimation and 2:1 pitch. Each case had previous and
current CT scans. Temporal subtraction technique included a global matching
technique, in which the previous image was adjusted its position in order to
correct for the difference between the previous and the current image, and an
iterative image warping technique, in which the previous image was nonlinearly
warped for the best match with the current image. Seven radiologists, including
four attendings and three residents, participated in this study. First,
radiologists marked their confidence levels for the presence or absence of lung
cancer by reading previous and current CT together, and then the temporal
subtraction image was shown. Their confidence levels were marked again, if
different from the initial result. Receiver operating characteristic (ROC)
analysis was employed to compare their performance without and with temporal
subtraction images.
Results: The results indicated that diagnostic accuracy was significantly
improved with the use of temporal subtraction images. The mean Az values (area
under the ROC curve) of the observers without and with temporal subtraction
were 0.87 and 0.93, respectively (p<0.01). Temporal subtraction images were
especially useful when the nodule was present near the pulmonary hilum, where
radiologists tended to overlook the nodule.
Conclusion: The temporal subtraction technique can significantly improve the
sensitivity and specificity for detection of lung cancer on low-dose CT. (S.K.
and K.D. are shareholders in R2 Technology, Inc., Los Altos, CA. K.D. is a
shareholder in Deus Technologies, Inc., Rockville, MD.)
Questions about this event email: habe@uchicago.edu
Abe MD, PhD, H,
Effect of Temporal Subtraction Images on the Detection of Lung Cancer on Low-Dose CT. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3102958.html