Comparison of Computed Tomography– and Magnetic Resonance Imaging–based Clinical Target Volume Contours at Brachytherapy for Cervical Cancer
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
- Southeast Louisiana Radiation Oncology Group, Baton Rouge, Louisiana (United States)
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
- Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
- Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
Purpose: We prospectively compared computed tomography (CT)– and magnetic resonance imaging (MRI)–based high-risk clinical target volume (HR-CTV) contours at the time of brachytherapy for cervical cancer in an effort to identify patients who might benefit most from MRI-based planning. Methods and Materials: Thirty-seven patients who had undergone a pretreatment diagnostic MRI scan were included in the analysis. We delineated the HR-CTV on the brachytherapy CT and brachytherapy MRI scans independently for each patient. We then calculated the absolute volumes for each HR-CTV and the Dice coefficient of similarity (DC, a measure of spatial agreement) for the HR-CTV contours. We identified the clinical and tumor factors associated with (1) a discrepancy in volume between the CT HR-CTV and MRI HR-CTV contours; and (2) DC. The mean values were compared using 1-way analysis of variance or paired or unpaired t tests, as appropriate. Simple and multivariable linear regression analyses were used to model the effects of covariates on the outcomes. Results: Patients with International Federation of Gynecology and Obstetrics stage IB to IVA cervical cancer were treated with intracavitary brachytherapy using tandem and ovoid (n=33) or tandem and cylinder (n=4) applicators. The mean CT HR-CTV volume (44.1 cm{sup 3}) was larger than the mean MRI HR-CTV volume (35.1 cm{sup 3}; P<.0001, paired t test). On multivariable analysis, a higher body mass index (BMI) and tumor size ≥5 cm with parametrial invasion on the MRI scan at diagnosis were associated with an increased discrepancy in volume between the HR-CTV contours (P<.02 for both). In addition, the spatial agreement (as measured by DC) between the HR-CTV contours decreased with an increasing BMI (P=.013). Conclusions: We recommend MRI-based brachytherapy planning for patients with tumors >5 cm and parametrial invasion on MRI at diagnosis and for those with a high BMI.
- OSTI ID:
- 22645700
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 4 Vol. 96; ISSN IOBPD3; ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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