Lesion measurement on a combined “all-in-one” window for chest CT: effect on intra- and interobserver variability

PURPOSE: A newly developed image processing technique fuses conventional windows into a single ‘All-In-One’ (AIO) window. This study aims to evaluate variability of CT measurement of lesions in thoracic oncology patients on this novel AIO-window. METHODS: Six radiologists with different levels of expertise measured 368 lesions of various size, origin and sharpness. All lesions were measured twice on the AIO-window and twice on the conventional window settings. Intraclass correlation coefficients and Bland-Altman plots were used to assess intra- and interobserver variability. RESULTS: Overall intra-observer agreement for lesion diameters on the AIO-window and conventional window settings was 0.986 (95% Confidence interval (CI): 0.983–0.989) and 0.991 (95% CI 0.989–0.993) respectively. For interobserver agreement this was 0.982 (95% CI 0.979–0.985) (AIO) and 0.979 (95% CI 0.957–0.982) (conventional). For both the AIO and conventional windows, intra- and interobserver agreement were dependent on size, sharpness and reader experience. Measurement variability decreased with increasing lesion size. Regarding sharpness, inter- and intra-observer agreement ranged from 0.986–0.989 (AIO) and 0.985–0.992 (conventional) for well-defined lesions and from 0.978–0.983 (AIO) and 0.974–0.991 (conventional) for ill-defined lesions. CONCLUSIONS: Lesion diameters were consistently smaller on the AIO-window compared to conventional window settings. Overall intra- and interobserver variability rates were similar for the AIO-window and conventional window settings. We conclude that the AIO-window offers a reliable and reproducible alternative for measurement of thoracic lesions.