CT- and MRI-based gross target volume comparison in vestibular schwannomas

Publication date: May–June 2017
Source:Reports of Practical Oncology & Radiotherapy, Volume 22, Issue 3
Author(s): Bhudevi Soubhagya N. Kulkarni, Harjot Bajwa, Mukka Chandrashekhar, Sunil Dutt Sharma, Rohith Singareddy, Dileep Gudipudi, Shabbir Ahmad, Alok Kumar, N.V.N. Madusudan Sresty, Alluri Krishnam Raju
AimThis study represents an enumeration and comparison of gross target volumes (GTV) as delineated independently on contrast-enhanced computed tomography (CT) and T1 and T2 weighted magnetic resonance imaging (MRI) in vestibular schwannomas (VS).BackgroundMultiple imaging in radiotherapy improves target localization.Methods and materials42 patients of VS were considered for this prospective study with one patient showing bilateral tumor. The GTV was delineated separately on CT and MRI. Difference in volumes were estimated individually for all the 43 lesions and similarity was studied between CT and T1 and T2 weighted MRI.ResultsThe male to female ratio for VS was found to be 1:1.3. The tumor was right sided in 34.9% and left sided in 65.1%. Tumor volumes (TV) on CT image sets were ranging from 0.251cc to 27.27cc. The TV for CT, MRI T1 and T2 weighted were 5.15±5.2cc, 5.8±6.23cc, and 5.9±6.13cc, respectively. Compared to MRI, CT underestimated the volumes. The mean dice coefficient between CT versus T1 and CT versus T2 was estimated to be 68.85±18.3 and 66.68±20.3, respectively. The percentage of volume difference between CT and MRI (%VD: mean±SD for T1; 28.84±15.0, T2; 35.74±16.3) and volume error (%VE: T1; 18.77±10.1, T2; 23.17±13.93) were found to be significant, taking the CT volumes as the baseline.ConclusionsMRI with multiple sequences should be incorporated for tumor volume delineation and they provide a clear boundary between the tumor and normal tissue with critical structures nearby.



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