Intercenter agreement of brain atrophy measurement in multiple sclerosis patients using manually-edited SIENA and SIENAX.
Jasperse B., Valsasina P., Neacsu V., Knol DL., De Stefano N., Enzinger C., Smith SM., Ropele S., Korteweg T., Giorgio A., Anderson V., Polman CH., Filippi M., Miller DH., Rovaris M., Barkhof F., Vrenken H., Magnetic Imaging in Multiple Sclerosis (MAGNIMS) study group None.
PURPOSE: To investigate intercenter agreement of brain volume (change) measurement in multiple sclerosis (MS) using structural image evaluation using normalization of atrophy (SIENA) and the cross-sectional version of SIENA (SIENAX) with additional manual editing to correct for inadequate brain extraction. MATERIALS AND METHODS: Baseline and follow-up T1-weighted MR images of 20 MS patients were dispatched to five centers. Each center performed fully-automated and manually-edited analyses for SIENAX, yielding normalized brain volume (NBV), and SIENA, yielding percentage brain volume change (PBVC). Intercenter agreement was assessed with the concordance correlation coefficient (CCC). RESULTS: Intercenter agreement was perfect for fully automated NBV and PBVC (both CCC = 1.0), and remained substantial upon manual editing (CCC = 0.94 for NBV, CCC = 0.95 for PBVC). Mean NBV values for each center decreased significantly after manual editing (overall mean NBV = 1605.3 cm(3) vs. 1651.1 cm(3) without manual editing; t = -4.58, P < 0.001). Total variance in PBVC decreased significantly by a factor of 1.8 after manual editing (sigma(2) = 2.82 before, and sigma(2) = 1.54 after manual editing, P < 0.05). CONCLUSION: Substantial intercenter agreement was found for manually-edited SIENAX and SIENA, suggesting that measurements from multiple centers may be pooled. Manual editing reduces overestimation of NBV, and is likely to increase statistical power for PBVC.