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

• Published in: Journal of radiation research 2013-01, Vol.54 (1), p.135-139
• Main Authors: Subedi, Kalloo Sharma, Takahashi, Takeo, Yamano, Takafumi, Saitoh, Jun-ichi, Nishimura, Keiichiro, Suzuki, Yoshiyuki, Ohno, Tatsuya, Nakano, Takashi
• Format: Article
• Language: English
• Subjects: Aged; Brain; Brain Neoplasms - pathology; Brain Neoplasms - secondary; Brain Neoplasms - surgery; Brain tumors; Cancer metastasis; Comparative analysis; Contrast Media; Delineation; Dose-Response Relationship, Radiation; Female; Humans; Image contrast; Image Enhancement - methods; Imaging, Three-Dimensional - methods; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Male; Middle Aged; Optimization; Patients; Radiometry - methods; Radiosurgery - methods; Radiotherapy; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted - methods; Radiotherapy, Image-Guided - methods; Reproducibility of Results; Sensitivity and Specificity; Technology; Tumor Burden - radiation effects; Tumors
• ISSN: 0449-3060; 1349-9157
• DOI: 10.1093/jrr/rrs053

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 < 1ml volume and GTV-1 with > 1ml 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.