Comparsion of magnetic resonance spectroscopic imaging and CT scan for clinical target volume definition in radiation therapy treatment planning of glioblastoma multiforme

One of the most important aspects in radiotherapy is target definition. Since routine methods of imaging (CT and MRI) are inadequate for treatment of glioblastoma multiforme (GBM), magnetic resonance spectroscopy (MRSI) as a functional imaging modality has recently been taken into consideration for target definition. In this study we tried to use MRSI in addition to CT and MRI in order to identify clinical target volume (CTV). The aim of the present study was to compare the clinical target volumes based on anatomical imaging (CT-MRI) and anatomical-biochemical imaging (CT-MRI-MRS). In this study, we used images of 16 GBM cancer cases. MRS and MRI images were fused with CT images. Then, treatment planning was preformed for each patient in two combined methods (CT+MRI and CT+MRS planning). CTVsCT+MRS were significantly larger than CTVCT+MRI (Pvalue<0.05). no other considerable changes in other important factors of treatment planning were found. Application of MRSI for target volume identification of GBM may lead to an increase in volume in comparison to CT planning alone; thereby, it is recommended to apply MRSI images for the purpose of target determination of radiotherapy because of its advantages.