Abstract
Objective: Compare 3D conformal volumetric analysis (3DCVA) versus traditional linear measurements on serial MRI imaging of vestibular schwannomas (VS) for determination and assessment of accurate tumor volume and growth rates.
Method: Retrospectively identified VS patients followed with serial 0.7-3.0 Tesla MRI were included. Maximal linear dimensions were obtained from gadolinium-contrasted T1 sequences from 3 serial MRI scans per RECIST guidelines. Volumetric analysis was performed with semiautomated 3DCVA. Annual tumor growth rate and percentage change were compared for linear and volumetric measurements.
Results: The average time span during which the serial MRI scans were obtained was 2.86 years in this initial retrospective analysis of 11 patients. The linear growth measurements averaged 0.5 mm/y, corresponding to a 6.4% average change per year. With 3DCVA the average tumor growth rate was 5mm3/y, corresponding to 3.7 mm/y growth in each dimension. There was an average increase in tumor volume of 29% per year with 3DCVA, compared with 6.4% with linear measurements. The difference in percentage change per year between methods was significant when compared with paired 2-tailed t-test (P = .036).
Conclusion: VS assume complex configurations. In this initial retrospective study, linear measurements may underestimate true tumor growth compared to 3D conformal volumetric analysis. 3DCVA may provide a more robust tool in assessing tumor volume, growth rate, and volume change for a more accurate reflection of tumor progression compared to linear measurements.
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