title: Usefulness of double dose contrast-enhanced magnetic resonance imaging for clear delineation of gross tumor volume in stereotactic radiotherapy treatment planning of metastatic brain tumors: a dose comparison study.
abstract: The purpose of this study was to compare the size and clearness of gross tumor volumes (GTVs) of metastatic brain tumors on T1-weighted magnetic resonance images between a single dose contrast administration protocol and a double dose contrast administration protocol to determine the optimum dose of contrast-enhancement for clear delineation of GTV in stereotactic radiotherapy (SRT). A total of 28 small metastatic brain tumors were evaluated in 13 patients by intra-individual comparison of GTV measurements using single dose and double dose contrast-enhanced thin-slice (1-mm) magnetic resonance imaging (MRI). All patients had confirmed histological types of primary tumors and had undergone hypo-fractionated SRT for metastatic brain tumors. The mean tumor diameter with single dose and double dose contrast-enhancement was 12.0 ± 1.1 mm and 13.2 ± 1.1 mm respectively (P < 0.001). The mean incremental ratio (MIR) obtained by comparing mean tumor diameters was 11.2 ± 0.02 %. The mean volume of GTV-1 (single dose contrast-enhancement) and GTV-2 (double dose contrast-enhancement) was 1.38 ± 0.41 ml and 1.59 ± 0.45 ml respectively (P < 0.01). The MIR by comparing mean tumor volumes was 32.3 ± 0.4 %. The MIR of GTV-1 with < 1 ml volume and GTV-1 with > 1 ml volume was 41.8 ± 0.05 % and 12.4 ± 0.03 % respectively (P < 0.001). We conclude that double dose contrast-enhanced thin-slice MRI is a more useful technique than single dose contrast-enhanced thin-slice MRI, especially for clear delineation of GTVs of small metastatic brain tumors in treatment planning of highly precise SRT.
authors: Department of Radiation Oncology, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan. drksharma09@gmail.com
authors: Kalloo Sharma
authors: KS
authors: Subedi
authors: Takeo
authors: T
authors: Takahashi
authors: Takafumi
authors: T
authors: Yamano
authors: Jun-ichi
authors: J
authors: Saitoh
authors: Keiichiro
authors: K
authors: Nishimura
authors: Yoshiyuki
authors: Y
authors: Suzuki
authors: Tatsuya
authors: T
authors: Ohno
authors: Takashi
authors: T
authors: Nakano
mesh_terms: D000368:Aged; D001932:Brain Neoplasms / Q000473:pathology / Q000556:secondary* / Q000601:surgery*; D003287:Contrast Media; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011874:Radiometry / Q000379:methods; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D047368:Tumor Burden / Q000528:radiation effects
chemical_list: D003287:Contrast Media