Ultra-High-Resolution Computed Tomography of the Lung: Image Quality of a Prototype Scanner.

Ryutaro Kakinuma,Hisao Asamura,Masahiro Kazama,Tomohiko Aso,Noriyuki Tomiyama,Koji Tsuta,Osamu Honda,Masahiro Suzuki,Noriyuki Moriyama,Shiho Gomi,Naobumi Tochigi,Masahiro Yanagawa,Kazuto Ashizawa,Hiroyuki Ishikawa,Takaaki Tsuchida,Akiko Miyagi Maeshima,Kazuo Awai,Shinsuke Tsukagoshi,Daisuke Komoto,Naoki Sugihara,Yukio Muramatsu,Masahiko Kusumoto,Yoshihisa Muramatsu,Yasuo Saito,Yoshinori Oshiro ,Hiromichi Nagasawa ,Shun Watanabe ,Shigeto Oda ,Hideshige Moriya ,Noriko Koizumi

doi:10.1371/journal.pone.0137165

Abstract

PurposeThe image noise and image quality of a prototype ultra-high-resolution computed tomography (U-HRCT) scanner was evaluated and compared with those of conventional high-resolution CT (C-HRCT) scanners.Materials and MethodsThis study was approved by the institutional review board. A U-HRCT scanner prototype with 0.25 mm x 4 rows and operating at 120 mAs was used. The C-HRCT images were obtained using a 0.5 mm x 16 or 0.5 mm x 64 detector-row CT scanner operating at 150 mAs. Images from both scanners were reconstructed at 0.1-mm intervals; the slice thickness was 0.25 mm for the U-HRCT scanner and 0.5 mm for the C-HRCT scanners. For both scanners, the display field of view was 80 mm. The image noise of each scanner was evaluated using a phantom. U-HRCT and C-HRCT images of 53 images selected from 37 lung nodules were then observed and graded using a 5-point score by 10 board-certified thoracic radiologists. The images were presented to the observers randomly and in a blinded manner.ResultsThe image noise for U-HRCT (100.87 ± 0.51 Hounsfield units [HU]) was greater than that for C-HRCT (40.41 ± 0.52 HU; P < .0001). The image quality of U-HRCT was graded as superior to that of C-HRCT (P < .0001) for all of the following parameters that were examined: margins of subsolid and solid nodules, edges of solid components and pulmonary vessels in subsolid nodules, air bronchograms, pleural indentations, margins of pulmonary vessels, edges of bronchi, and interlobar fissures.ConclusionDespite a larger image noise, the prototype U-HRCT scanner had a significantly better image quality than the C-HRCT scanners.

Highlights

High-resolution computed tomography (HRCT) of the lungs was first described in 1982; Todo et al reported that HRCT improved the visualization of the fine structures of the lungs, such as the peripheral pulmonary vessels, terminal bronchioles, and interlobular septa [1]
To obtain more detailed images of solitary pulmonary nodules, we have developed a prototype ultra-high-resolution CT (U-HRCT) scanner
U-HRCT was capable of depicting a 0.12-mm slit, whereas conventional HRCT (C-HRCT) was incapable of depicting even a 0.3-mm slit (Fig 4)

Summary

Introduction

High-resolution computed tomography (HRCT) of the lungs was first described in 1982; Todo et al reported that HRCT improved the visualization of the fine structures of the lungs, such as the peripheral pulmonary vessels, terminal bronchioles, and interlobular septa [1]. HRCT of the lung has played an important role in the diagnosis of solitary pulmonary nodules [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]. Multislice CT and low-dose CT lung cancer screening have been used to detect numerous small indeterminate pulmonary nodules. To obtain more detailed images of solitary pulmonary nodules, we have developed a prototype ultra-high-resolution CT (U-HRCT) scanner. The purpose of this study was to evaluate the image noise and image quality of a prototype U-HRCT scanner, compared with those of C-HRCT scanners

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Conclusion