Quantitative Emphysema Measurement On Ultra-High-Resolution CT Scans

Abstract

Yanyan Xu,1,2 Tsuneo Yamashiro,1,3 Hiroshi Moriya,3 Shun Muramatsu,3 Sadayuki Murayama1 1Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Okinawa, Japan; 2Department of Radiology, China-Japan Friendship Hospital, Beijing, People’s Republic of China; 3Department of Radiology, Ohara General Hospital, Fukushima, JapanCorrespondence: Tsuneo YamashiroDepartment of Radiology, Graduate School of Medical Science, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, JapanTel [phone]Fax [phone]Email [email protected]: To evaluate the advantages of ultra-high-resolution computed tomography (U-HRCT) scans for the quantitative measurement of emphysematous lesions over conventional HRCT scans.Materials and methods: This study included 32 smokers under routine clinical care who underwent chest CT performed by a U-HRCT scanner. Chronic obstructive pulmonary disease (COPD) was diagnosed in 13 of the 32 participants. Scan data were reconstructed by 2 different protocols: i) U-HRCT mode with a 1024×1024 matrix and 0.25-mm slice thickness and ii) conventional HRCT mode with a 512×512 matrix and 0.5-mm slice thickness. On both types of scans, lesions of emphysema were quantitatively assessed as percentage of low attenuation volume (LAV%, <−950 Hounsfield units). LAV% values determined for scan data from the U-HRCT and conventional HRCT modes were compared by the Wilcoxon matched-pairs signed rank test. The association between LAV% and forced expiratory volume in 1 s per forced vital capacity (FEV1/FVC) was assessed by the Spearman rank correlation test.Results: Mean values for LAV% determined for the U-HRCT and conventional HRCT modes were 8.9 ± 8.8% and 7.3 ± 8.4%, respectively (P<0.0001). The correlation coefficients for LAV% and FEV1/FVC on the U-HRCT and conventional HRCT modes were 0.50 and 0.49, respectively (both P<0.01).Conclusion: Compared with conventional HRCT scans, U-HRCT scans reveal emphysematous lesions in greater detail, and provide slightly increased correlation with airflow limitation.Keywords: chronic obstructive pulmonary disease, computed tomography, emphysema, ultra-high-resolution CT, quantitative measurement

Keywords

• Chronic obstructive pulmonary disease
• Computed tomography
• Emphysema
• Ultra-high-resolution CT
• Quantitative measurement