Temporal subtraction of dual-energy chest radiographs

Abstract

Temporal subtraction and dual-energy imaging are two enhanced radiography techniques that are receiving increased attention in chest radiography. Temporal subtraction is an image processing technique that facilitates the visualization of pathologic change across serial chest radiographic images acquired from the same patient; dual-energy imaging exploits the differential relative attenuation of x-ray photons exhibited by soft-tissue and bony structures at different x-ray energies to generate a pair of images that accentuate those structures. Although temporal subtraction images provide a powerful mechanism for enhancing visualization of subtle change, misregistration artifacts in these images can mimic or obscure abnormalities. The purpose of this study was to evaluate whether dual-energy imaging could improve the quality of temporal subtraction images. Temporal subtraction images were generated from 100 pairs of temporally sequential standard radiographic chest images and from the corresponding 100 pairs of dual-energy, soft-tissue radiographic images. The registration accuracy demonstrated in the resulting temporal subtraction images was evaluated subjectively by two radiologists. The registration accuracy of the soft-tissue-based temporal subtraction images was rated superior to that of the conventional temporal subtraction images. Registration accuracy also was evaluated objectively through an automated method, which achieved an area-under-the-ROC-curve value of 0.92 in the distinction between temporal subtraction images that demonstrated clinically acceptable and clinically unacceptable registration accuracy. By combining dual-energy soft-tissue images with temporal subtraction, misregistration artifacts can be reduced and superior image quality can be obtained.

Evaluation of a template-based algorithm for markerless lung tumour localization on single- and dual-energy kilovoltage images

“…DE imaging enhances visualization of soft-tissue abnormalities, such as lung tumours, in chest radiographs by taking advantage of the different degrees to which tissues attenuate high-and low-energy photons. [30][31][32][33][34][35][36][37][38][39][40][41][42] The DE process involves obtaining two different radiographs, one at low energy (such as 60 kVp) and one at high energy (such as 120 kVp). Using these images, a weighted logarithmic subtraction is performed that removes obscuring bony anatomy (ribs and vertebral bodies), thus creating a third image that highlights soft tissue, such as lung tumours.…”

Anniversary Paper: Image processing and manipulation through the pages ofMedical Physics

“…9͒. Armato et al 113 used energy subtraction chest images as input to a temporal subtraction process to demonstrate the potential of these combined enhanced visualization techniques.…”

Technical Note: Estimation of lung tumor thickness from planar dual‐energy kV images

“…DE imaging has been used by radiologists primarily to aid in the diagnosis of lung disease. [1][2][3] By selectively suppressing the bones (i.e., ribs), DE imaging has been shown to improve the visibility of small lung tumors on planar x-ray images.…”