Pulmonary nodules: Assessing the imaging biomarkers of malignancy in a "coffee-break".

Introduction: Although nodule volumetry is a recognized biomarker of malignancy in pulmonary nodules (PNs), caution is needed in its interpretation because of variables such as respiratory volume variation and inter-scan variability of up to 25%. CT Texture Analysis (CTTA) is a potential independent biomarker of malignancy but inter-scan variability and respiratory volume variation has not been assessed.

Methods: In this prospective cohort study, 40 patients (20 with an indeterminate PN and 20 with pulmonary metastases) underwent two LDCTs within a 60-min period (the "Coffee-break") with the aim of assessing the repeatability of CTTA and semi-automated volume measurements. Texture features were extracted from each automatic contoured region surrounding the PN. Patients were also randomized to two inspiratory control groups: normal breath hold, and controlled lung volume to study the influence of inspiratory control on these measurements.

Results: The mean difference in volume between the two scans was 6.3%,SD:29.9%. The textural features displayed 95% CI below ±17.8%, and were less variable than nodule volume (95%CI ± 28.9%). All features had high repeatability, calculated by the concordance correlation coefficient, (0.84 ≤ CCC ≤ 0.99). All measurements were more repeatable for the controlled lung volume group than the normal breath-hold group.

Conclusion: CTTA repeatability was comparable to automatic volumetric measurements, and appears to be improved using controlled volume breath holding.