Reproducibility in contouring the neurovascular bundle for prostate cancer radiotherapy

Publication date: Available online 3 August 2017
Source:Practical Radiation Oncology
Author(s): Richard J. Cassidy, Sherif G. Nour, Tian Liu, Jeffrey M. Switchenko, Sibo Tian, Matthew J. Ferris, Robert H. Press, Jim Zhong, Mustafa Abugideiri, Peter J. Rossi, Ashesh B. Jani
PurposeEfforts to define the neurovascular bundle (NVB) for prostate radiation have varied. In this series, we sought to determine the reproducibility and reliability of contouring the classical posterolateral NVB on dedicated pelvic magnetic-resonance imaging (MRI).MethodsOne hundred and twenty total NVB structures were defined on ten 3-Tesla pelvic MRI's in patients with prostate cancer but without extraprostatic extension. One pelvic radiologist served as the expert in contouring the right and left NVB for each case. Five radiation oncologists, with varying levels of experience, contoured the right and left NVB on these same cases. The intraclass correlation coefficient (ICC) across each rater and the expert, Pearson's correlation coefficient (PCC) between each rater and the expert, and the Dice similarity coefficient (DSC) between each rater and the expert were calculated to evaluate contour agreement and overlap.ResultsThe overall ICC was 0.89 (95% CI: 0.81–0.95). The PCC for: rater 1 was 0.95 (95% CI: 0.86–0.98), rater 2 was 0.98 (95% CI: 0.95–0.99), rater 3 was 0.94 (95% CI: 0.86–0.98), rater 4 was 0.98 (95% CI: 0.95–0.99), and rater 5 was 0.84 (95% CI: 0.63–0.93). The mean DSC for: rater 1 was 0.72 (standard deviation: 0.07), rater 2 was 0.72 (standard deviation: 0.06), rater 3 was 0.73 (standard deviation: 0.09), rater 4 was 0.74 (standard deviation: 0.09), and rater 5 was 0.68 (standard deviation: 0.13). Overall, across all raters, the average DSC was 0.72 (standard deviation: 0.09).ConclusionsThe classic posterolateral NVB can be accurately and reliably be contoured on 3-T pelvic MRI's by radiation oncologists.



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