Hyeongmin Jin, Presenter: Nothing to Disclose

Jong Hyo Kim PhD, Abstract Co-Author: Nothing to Disclose

Chang Yong Heo BS, Abstract Co-Author: Nothing to Disclose

The emphysema index (EI) in CT is known to be strongly affected by reconstruction kernel. This study presents an image-based kernel conversion technique which converts CT image of sharp kernel to that of standard kernel and evaluates its impact on EI normalization for images obtained with different kernels.

48 sets of CT data taken at 120kVp, 40mAs, 1mm thickness, of 2 reconstruction kernels (B30f, B50f) were selected from low dose lung cancer screening database. An image-based kernel conversion technique, which converts an image to take effect of different kernel by applying the ratio of kernel MTFs to the Fourier transformed spectral components, was performed to the CT data set of B50f kernel to produce a converted B30f data set. The EI (RA950) was measured with a software package (Pulmonalizer, Seoul, South Korea) and compared between two data sets of B30f kernel and those converted B30f kernel. The accuracy of kernel conversion was evaluated with the mean and standard deviation of pair-wise differences in EI. 

Population mean of EI was 10.57±5.84% for the B30f data set, 28.76±6.24% for B50f data set, and 10.86±6.37% for the converted B30f data set. The mean and standard deviation of pair-wise differences in EI between B30f and the converted B30f 0.85% and 0.76%, respectively. The correlation between the EI of two data sets was 0.987

Our study demonstrates the feasibility of image-based kernel conversion technique for normalization of kernel effect in measurement of EI. 

This technique has a potential to be used in evaluating the longitudinal changes of EI even when the CT was reconstructed with different kernel. 

Jin, H, Kim, J, Heo, C, Image-based Kernel Conversion Technique Normalized the Reconstruction Kernel Effects in the Measurement of Emphysema Index in CT.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13017053.html