Yukihiro Nagatani MD, Presenter: Nothing to Disclose

Masashi Takahashi MD, Abstract Co-Author: Nothing to Disclose

Mitsuru Ikeda MD, Abstract Co-Author: Nothing to Disclose

Tsuneo Yamashiro MD, Abstract Co-Author: Nothing to Disclose

Hisanobu Koyama MD, PhD, Abstract Co-Author: Nothing to Disclose

Mitsuhiro Koyama MD, Abstract Co-Author: Nothing to Disclose

Hiroshi Moriya MD, Abstract Co-Author: Nothing to Disclose

Kiyoshi Murata MD, Abstract Co-Author: Nothing to Disclose

Sadayuki Murayama MD, PhD, Abstract Co-Author: Nothing to Disclose

To compare ground glass nodule detectability (GGND) on computed tomography (CT) with adaptive iterative dose reduction using three dimensional processing (AIDR3D) between ultra-low dose scanning (ULDS) and low dose scanning (LDS) and analyze association of GGND with nodular characteristics and location.

This was part of the Area-detector Computed Tomography for the Investigation of Thoracic Diseases (ACTIVe) Study, a multicenter research project being conducted in Japan. The Institutional Review Board of each institution approved this study and written informed consent was obtained. In a single visit each, 68 subjects underwent multi-detector chest CT (64-row helical mode) at a gantry rotation speed of 0.35-sec with 3 different tube currents: 240,120 and 20 mA (2.51, 1.26 and 0.21mSv, respectively). Axial CT images with 2-mm thickness and increment were reconstructed using AIDR3D. Standard of reference (SOR) as to GGN presence with the longest diameter (LD) of 3mm or more was determined based on CT images at 240mA by consensus reading of 2 radiologists. Another 4 radiologists independently recorded GGN presence and their characteristics by continuously-distributed rating on CT images at 20mA (ULDS) and 120mA (LDS). Receiver-operating characteristic (ROC) analysis was used to evaluate GGND of both methods in total and subgroups classified by nodular LD (>5mm), characteristics (pure and mixed) and locations (ventral/intermediate/dorsal, central/peripheral and upper/middle/lower).

For SOR, 22 mixed and 86 pure GGN were identified. No significant difference in GGND with LD of 5mm or more was shown between both methods, as area under ROC curve was 0.96±0.02 in ULDS and 0.97±0.01 in LDS. For the entire mixed GGN, GGND was almost the same, as area under ROC curve was 0.97±0.02 in both methods. Inter-observer variance of GGND with LD of 5mm or more was not demonstrated among 4 radiologists in 5 locations except for lower, peripheral and intermediate locations.

It was demonstrated that ULDS with AIDR3D had comparable GGND to LDS with AIDR3D except for pure GGN with LD of less than 5mm.

ULDS with AIDR3D has a sufficient potential to be used for GGN screening except for smaller ones without solid part.

Nagatani, Y, Takahashi, M, Ikeda, M, Yamashiro, T, Koyama, H, Koyama, M, Moriya, H, Murata, K, Murayama, S, Ground Glass Nodule Detectability on Ultra-Low dose Computed Tomography (CT) with Adaptive Iterative Dose Reduction Using 3D Processing: Comparison with Low-dose CT by Receiver-Operating Analysis Based on Nodular Characteristics and Location.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14001521.html