Dataset Information

Comparison of postoperative CT- and preoperative MRI-based breast tumor bed contours in prone position for radiotherapy after breast-conserving surgery.

ABSTRACT:

Objectives

To compare the target volume of tumor bed defined by postoperative computed tomography (post-CT) in prone position registered with or without preoperative magnetic resonance imaging (pre-MRI).

Methods

A total of 22 patients were included with early-stage breast invasive ductal cancer, who have undergone breast-conservative surgery and received the pre-MRI and post-CT in prone position. The MRI sequences (T1W, T2W, T2W-SPAIR, DWI, dyn-eTHRIVE, sdyn-eTHRIVE) were delineated and manually registered to CT, respectively. The clinical target volumes (CTVs) and planning target volumes (PTVs) were contoured on CT and different MRI sequences, respectively. Differences were measured in terms of consistence index (CI), dice coefficient (DC), geographical miss index (GMI), and normal tissue index (NTI).

Results

The differences of delineation volumes among CT and MRIs were significant, both in the CTVs (p?=?0.035) and PTVs (p??0.05) between the CI derived from the registration of CT and sdyn-eTHRIVE of CTV with the breast volume, the cavity visualization score (CVS) of CT, time interval from surgery to CT simulation, the maximum diameter of the intraoperative mass, and the number of titanium clips, respectively.

Conclusions

The CTVs and PTVs in MRI sequences were all smaller than those in CT. The pre-MRI, especially the sdyn-eTHRIVE, could be used to optimize the post-CT-based target delineation of breast cancer.

Key points

• Registered pre-MRI to post-CT in order to improve the accuracy of target volume delineation of breast cancer. • The CTVs and PTVs in MRI sequences were all smaller than those in CT. • The sdyn-eTHRIVE of pre-MRIs may be a better choice to improve the delineation of CT-based CTV and PTV.

SUBMITTER: Dong Y

PROVIDER: S-EPMC7755637 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Publications

Comparison of postoperative CT- and preoperative MRI-based breast tumor bed contours in prone position for radiotherapy after breast-conserving surgery.

Dong Yinping Y Liu Yang Y Chen Jinhu J Li Wanhu W Li Yongqing Y Zhao Qian Q Chen Yiru Y Huang Wei W

European radiology 20200801 1

<h4>Objectives</h4>To compare the target volume of tumor bed defined by postoperative computed tomography (post-CT) in prone position registered with or without preoperative magnetic resonance imaging (pre-MRI).<h4>Methods</h4>A total of 22 patients were included with early-stage breast invasive ductal cancer, who have undergone breast-conservative surgery and received the pre-MRI and post-CT in prone position. The MRI sequences (T1W, T2W, T2W-SPAIR, DWI, dyn-eTHRIVE, sdyn-eTHRIVE) were delineat ...[more]

PMID: 32740818

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Project description:BackgroundAccurate tumor bed delineation after breast-conserving surgery is important. However, consistency among observers on standard postoperative radiotherapy planning CT is low and volumes can be large due to seroma formation. A preoperative delineation of the tumor might be more consistent. Therefore, the purpose of this study was to determine the consistency of preoperative target volume delineation on CT and MRI for breast-conserving radiotherapy.MethodsTumors were delineated on preoperative contrast-enhanced (CE) CT and newly developed 3D CE-MR images, by four breast radiation oncologists. Clinical target volumes (CTVs) were created by addition of a 1.5 cm margin around the tumor, excluding skin and chest wall. Consistency in target volume delineation was expressed by the interobserver variability. Therefore, the conformity index (CI), center of mass distance (dCOM) and volumes were calculated. Tumor characteristics on CT and MRI were scored by an experienced breast radiologist.ResultsPreoperative tumor delineation resulted in a high interobserver agreement with a high median CI for the CTV, for both CT (0.80) and MRI (0.84). The tumor was missed on CT in 2/14 patients (14%). Leaving these 2 patients out of the analysis, CI was higher on MRI compared to CT for the GTV (p<0.001) while not for the CTV (CT (0.82) versus MRI (0.84), p=0.123). The dCOM did not differ between CT and MRI. The median CTV was 48 cm3 (range 28-137 cm3) on CT and 59 cm3 (range 30-153 cm3) on MRI (p<0.001). Tumor shapes and margins were rated as more irregular and spiculated on CE-MRI.ConclusionsThis study showed that preoperative target volume delineation resulted in small target volumes with a high consistency among observers. MRI appeared to be necessary for tumor detection and the visualization of irregularities and spiculations. Regarding the tumor delineation itself, no clinically relevant differences in interobserver variability were observed. These results will be used to study the potential for future MRI-guided and neoadjuvant radiotherapy.Trial registrationInternational Clinical Trials Registry Platform NTR3198.

Project description:PurposeSurgical clips are used as a target for postoperative breast radiotherapy, and displacement of surgical clips would result in inaccurate delivery of radiation. We investigated the displacement range of surgical clips in the breast during postoperative radiotherapy following breast-conserving surgery.MethodsA total of 178 patients who received breast-conserving surgery and postoperative radiation of 59.4 Gy in 33 fractions to the involved breast for 6.5 weeks were included. Surgical clips were used to mark the lumpectomy cavity during breast-conserving surgery. Patients undertook planning computed tomography (CT) scan for whole breast irradiation. Five weeks after beginning radiation, when the irradiation dose was 45 Gy, planning CT scan was performed again for a boost radiotherapy plan in all patients. The surgical clips were defined in both CT images and compared in lateromedial (X), anteroposterior (Y), superoinferior (Z), and three-dimensional directions.ResultsThe 90th percentile of displacement of surgical clips was 5.31 mm (range, 0.0-22.2 mm) in the lateromedial direction, 7.1 mm (range, 0.0-14.2 mm) in the anteroposterior direction, and 6.0 mm (range, 0.0-10.0 mm) in the superoinferior direction. The 90th percentile of three-dimensional displacement distance was 9.8 mm (range, 0.0-28.2 mm). On the multivariate analysis, seroma ≥15 mL was the only independent factor associated with the displacement of surgical clips. In patients with seroma ≥15 mL, the 90th percentile of displacement of surgical clips was 15.1 mm in the lateromedial direction, 12.7 mm in the anteroposterior direction, 10.0 mm in the superoinferior direction, and 21.8 mm in the three-dimensional distance.ConclusionA target volume expansion of 10 mm from surgical clips may be sufficient to compensate for the displacement of clips during postoperative radiotherapy after breast-conserving surgery. For patients who had a seroma, a replanning CT scan for a boost radiation should be considered to ensure exact postoperative radiotherapy in breast cancer.

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Dataset Information

Comparison of postoperative CT- and preoperative MRI-based breast tumor bed contours in prone position for radiotherapy after breast-conserving surgery.

Objectives

Methods

Results

Conclusions

Key points

Publications

Comparison of postoperative CT- and preoperative MRI-based breast tumor bed contours in prone position for radiotherapy after breast-conserving surgery.

Similar Datasets

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