Semi-Automatic Quantification of Subsolid Pulmonary Nodules: Comparison with Manual Measurements

Ernst Th Scholten,Hester A Gietema,Matthijs Oudkerk,Harry J De Koning,Saskia Van Amelsvoort-Van De Vorst,Rob J Van Klaveren,Pim A De Jong,Bram Van Ginneken,Mathias Prokop,Colin Jacobs,Rozemarijn Vliegenthart,Carlijn M Van Der Aalst,Bartjan De Hoop,Willem Th M Mali

doi:10.1371/journal.pone.0080249

Abstract

RationaleAccurate measurement of subsolid pulmonary nodules (SSN) is becoming increasingly important in the management of these nodules. SSNs were previously quantified with time-consuming manual measurements. The aim of the present study is to test the feasibility of semi-automatic SSNs measurements and to compare the results to the manual measurements.MethodsIn 33 lung cancer screening participants with 33 SSNs, the nodules were previously quantified by two observers manually. In the present study two observers quantified these nodules by using semi-automated nodule volumetry software. Nodules were quantified for effective diameter, volume and mass. The manual and semi-automatic measurements were compared using Bland-Altman plots and paired T tests. Observer agreement was calculated as an intraclass correlation coefficient. Data are presented as mean (SD).ResultsSemi-automated measurements were feasible in all 33 nodules. Nodule diameter, volume and mass were 11.2 (3.3) mm, 935 (691) ml and 379 (311) milligrams for observer 1 and 11.1 (3.7) mm, 986 (797) ml and 399 (344) milligrams for observer 2, respectively. Agreement between observers and within observer 1 for the semi-automatic measurements was good with an intraclass correlation coefficient >0.89. For observer 1 and observer 2, measured diameter was 8.8% and 10.3% larger (p<0.001), measured volume was 24.3% and 26.5% larger (p<0.001) and measured mass was 10.6% and 12.0% larger (p<0.001) with the semi-automatic program compared to the manual measurements.ConclusionSemi-automated measurement of the diameter, volume and mass of SSNs is feasible with good observer agreement. Semi-automated measurement makes quantification of mass and volume feasible in daily practice.

Highlights

Lung cancer screening with computed tomography (CT) has increased the awareness of a specific subtype of pulmonary nodules: the subsolid nodule (SSN)
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Subjects and nodule characteristics Thirty-three participants had a total of 33 SSNs at baseline according to NMS

Summary

Introduction

Lung cancer screening with computed tomography (CT) has increased the awareness of a specific subtype of pulmonary nodules: the subsolid nodule (SSN). A SSN is defined as a circumscribed area of increased lung attenuation with preservation of the bronchial and vascular margins and referred to as a ground glass opacity.[1] A SSN can be part-solid (part of the nodule completely obscures the underlying lung parenchyma) or pure nonsolid. Persistent SSNs have a high likelihood of malignancy. The ELCAP study [2] reported a malignancy rate of 34% for all nonsolid SSNs, 18% for pure ground glass lesions and 63% for part-solid SSNs. For part solid lesions even higher malignancy rates with numbers up to 75% are reported. For part solid lesions even higher malignancy rates with numbers up to 75% are reported. [3]

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