Measurement Variability of Persistent Pulmonary Subsolid Nodules on Same-Day Repeat CT: What Is the Threshold to Determine True Nodule Growth during Follow-Up?

• Published in: PloS one Vol. 11; no. 2; p. e0148853
• Main Authors: Kim, Hyungjin, Park, Chang Min, Song, Yong Sub, Sunwoo, Leonard, Choi, Ye Ra, Kim, Jung Im, Kim, Jae Hyun, Bae, Jae Seok, Lee, Jong Hyuk, Goo, Jin Mo
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 09.02.2016; Public Library of Science (PLoS)
• Subjects: Analysis; Automation; Biology and Life Sciences; Cancer; Care and treatment; CAT scans; Coefficient of variation; Computed tomography; Diagnosis; Female; Humans; Lung - diagnostic imaging; Lung - pathology; Lung cancer; Lung Neoplasms - classification; Lung Neoplasms - diagnosis; Lung Neoplasms - diagnostic imaging; Lung Neoplasms - pathology; Lung nodules; Male; Mathematical analysis; Measurement; Measurement methods; Medical diagnosis; Medical imaging; Medical research; Medicine; Medicine and Health Sciences; Middle Aged; Multiple Pulmonary Nodules - classification; Multiple Pulmonary Nodules - diagnosis; Multiple Pulmonary Nodules - diagnostic imaging; Multiple Pulmonary Nodules - pathology; Nodules; Observer Variation; Patients; People and Places; Physicians; Readers; Research and Analysis Methods; Statistics; Tomography, X-Ray Computed - psychology; Tumors; Variability; South Korea
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0148853

To assess the measurement variability of subsolid nodules (SSNs) in follow-up situations and to compare the degree of variability between measurement metrics. Two same-day repeat-CT scans of 69 patients (24 men and 45 women) with 69 SSNs were randomly assigned as initial or follow-up scans and were read by the same (situation 1) or different readers (situation 2). SSN size and solid portion size were measured in both situations. Measurement variability was calculated and coefficients of variation were used for comparisons. Measurement variability for the longest and average diameter of SSNs was ±1.3 mm (±13.0%) and ±1.3 mm (±14.4%) in situation 1, and ±2.2 mm (±21.0%) and ±2.1 mm (±21.3%) in situation 2, respectively. For solid portion, measurement variability on lung and mediastinal windows was ±1.2 mm (±27.1%) and ±0.8 mm (±24.0%) in situation 1, and ±3.7 mm (±61.0%) and ±1.5 mm (±47.3%) in situation 2, respectively. There were no significant differences in the degree of variability between the longest and average diameters and between the lung and mediastinal window settings (p>0.05). However, measurement variability significantly increased when the follow-up and initial CT readers were different (p<0.001). A cutoff of ±2.2 mm can be reliably used to determine true nodule growth on follow-up CT. Solid portion measurements were not reliable in evaluating SSNs' change when readers of initial and follow-up CT were different.