Radiologist variability in assessing the position of the cavoatrial junction on chest radiographs

Objectives: To assess the variability in identifying the cavo-atrial junction (CAJ) on chest x-rays amongst radiologists. Methods: Twenty-three radiologists (13 consultants and 10 trainees) assessed 25 postero-anterior erect chest x-rays (including eight duplicates) and marked the positions of the CAJ. Differences in the CAJ position both within and between observers were evaluated and reported as limits of agreement, repeatability coefficients, intra-class correlation coefficients and displayed graphically with Bland- Altman plots. Results: The mean difference for within observer assessments was -0.2 cm (95% limits of agreement, -1.5 to +1.1 cm) and between observers was -0.3 cm (95% limits of agreement, -2.5 to +1.8 cm). Intra-observer repeatability coefficients (RC) were marginally lower for consultants when compared to trainees (1.1 versus 1.5). RCs between observers were comparable (2.1 versus 2.2) for for consultants and trainees, respectively. Conclusions: This study detected a large inter-observer variability of the CAJ position (up to 4.3 cm). This is a significant finding considering that the length of the SVC is reported to be approximately 7cm. We conclude that there is poor consensus regarding the CAJ position amongst radiologists. Advances in knowledge: No comparisons exist between radiologists in determining CAJ position from chest X-rays. This report provides evidence of the large observer variability amongst radiologists and adds to the discussion regarding the use of chest X-rays in validating catheter tip location systems