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CT- and MRI-based gross target volume comparison in vestibular schwannomas
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Abstract
Aim
This 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).
Background
Multiple imaging in radiotherapy improves target localization.
Methods and materials
42 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.
Results
The 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 0.251[[ce:hsp sp="0.25"/]]cc to 27.27[[ce:hsp sp="0.25"/]]cc. The TV for CT, MRI T1 and T2 weighted were 5.15[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]5.2[[ce:hsp sp="0.25"/]]cc, 5.8[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]6.23[[ce:hsp sp="0.25"/]]cc, and 5.9[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]6.13[[ce:hsp sp="0.25"/]]cc, 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[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]18.3 and 66.68[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]20.3, respectively. The percentage of volume difference between CT and MRI (%VD: mean[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]SD for T1; 28.84[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]15.0, T2; 35.74[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]16.3) and volume error (%VE: T1; 18.77[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]10.1, T2; 23.17[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]13.93) were found to be significant, taking the CT volumes as the baseline.
Conclusions
MRI 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.
Abstract
Aim
This 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).
Background
Multiple imaging in radiotherapy improves target localization.
Methods and materials
42 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.
Results
The 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 0.251[[ce:hsp sp="0.25"/]]cc to 27.27[[ce:hsp sp="0.25"/]]cc. The TV for CT, MRI T1 and T2 weighted were 5.15[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]5.2[[ce:hsp sp="0.25"/]]cc, 5.8[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]6.23[[ce:hsp sp="0.25"/]]cc, and 5.9[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]6.13[[ce:hsp sp="0.25"/]]cc, 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[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]18.3 and 66.68[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]20.3, respectively. The percentage of volume difference between CT and MRI (%VD: mean[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]SD for T1; 28.84[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]15.0, T2; 35.74[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]16.3) and volume error (%VE: T1; 18.77[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]10.1, T2; 23.17[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]13.93) were found to be significant, taking the CT volumes as the baseline.
Conclusions
MRI 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.
Keywords
Vestibular schwannomas (VS); Computed tomography (CT); T1 weighted and T2 weighted; Magnetic resonance imaging (MRI)
About this articleTitle
CT- and MRI-based gross target volume comparison in vestibular schwannomas
Journal
Reports of Practical Oncology and Radiotherapy
Issue
Pages
201-208
Published online
2017-05-01
DOI
10.1016/j.rpor.2017.02.002
Bibliographic record
Rep Pract Oncol Radiother 2017;22(3):201-208.
Keywords
Vestibular schwannomas (VS)
Computed tomography (CT)
T1 weighted and T2 weighted
Magnetic resonance imaging (MRI)
Authors
Bhudevi Soubhagya Kulkarni
Harjot Bajwa
Mukka Chandrashekhar
Sunil Dutt Sharma
Rohith Singareddy
Dileep Gudipudi
Shabbir Ahmad
Alok Kumar
N.V.N. Madusudan Sresty
Alluri Krishnam Raju