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.