RSNA 2003 

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

Participants

Hiroyuki Abe MD, PhD, PRESENTER: Nothing to Disclose

Abstract: HTML 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

Cite This Abstract

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