The Effect of Slice Thickness on Contours of Brain Metastases for Stereotactic Radiosurgery

Thrower, Sara L.; Feghali, Karine A. Al; Luo, Dershan; Paddick, Ian; Hou, Ping; Briere, Tina Marie; Li, Jing; McAleer, Mary Frances; McGovern, Susan L.; Woodhouse, Kristina D.; Yeboa, Debra Nana; Brock, Kristy K.; Chung, Caroline

doi:10.1016/j.adro.2021.100708

Cited by 18 publications

(18 citation statements)

References 29 publications

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“…As an example, in a recent study, MR slice thickness selection was associated with the number of brain metastases identified, as well as the target volume contoured for SRS treatment planning. 45 In addition, the effect of further varying the volume of interest used for anatomybased MR/CT co-registration in the overall TLA was not explicitly investigated. Moreover, several brain metas-tases were excluded from the patient study of this work due to presence of necrotic cores or being adjacent to vessels (see selection criteria in Section 2.2.1).…”

Section: Discussionmentioning

confidence: 99%

Target localization accuracy in frame‐based stereotactic radiosurgery: Comparison between MR‐only and MR/CT co‐registration approaches

Pappas

Seimenis

Kouris

et al. 2022

J Applied Clin Med Phys

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In frame-based Gamma Knife (GK) stereotactic radiosurgery two treatment planning workflows are commonly employed; one based solely on magnetic resonance (MR) images and the other based on magnetic resonance/computed tomography (MR/CT) co-registered images. In both workflows, target localization accuracy (TLA) can be deteriorated due to MR-related geometric distortions and/or MR/CT co-registration uncertainties. In this study, the overall TLA following both clinical workflows is evaluated for cases of multiple brain metastases. Methods: A polymer gel-filled head phantom, having the Leksell stereotactic headframe attached, was CT-imaged and irradiated by a GK Perfexion unit. A total of 26 4-mm shots were delivered at 26 locations directly defined in the Leksell stereotactic space (LSS), inducing adequate contrast in corresponding T2weighted (T2w) MR images. Prescribed shot coordinates served as reference locations. An additional MR scan was acquired to implement the "mean image" distortion correction technique. The TLA for each workflow was assessed by comparing the radiation-induced target locations, identified in MR images, with corresponding reference locations.Using T1w MR and CT images of 15 patients (totaling 81 lesions), TLA in clinical cases was similarly assessed, considering MR-corrected data as reference.For the MR/CT workflow,both global and region of interest (ROI)-based MR/CT registration approaches were studied. Results: In phantom measurements, the MR-corrected workflow demonstrated unsurpassed TLA (median offset of 0.2 mm) which deteriorated for MR-only and MR/CT workflows (median offsets of 0.8 and 0.6 mm, respectively). In real-patient cases, the MR-only workflow resulted in offsets that exhibit a significant positive correlation with the distance from the MR isocenter, reaching 1.1 mm (median 0.6 mm). Comparable results were obtained for the MR/CTglobal workflow, although a maximum offset of 1.4 mm was detected. TLA was improved with the MR/CT-ROI workflow resulting in median/maximum offsets of 0.4 mm/1.1 mm.

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Section: Discussionmentioning

confidence: 99%

Target localization accuracy in frame‐based stereotactic radiosurgery: Comparison between MR‐only and MR/CT co‐registration approaches

Pappas

Seimenis

Kouris

et al. 2022

J Applied Clin Med Phys

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“…The QAp results revealed a slice thickness slightly away from the expected optimal value for both methods. This result can be very influential, especially in brain metastases for stereotactic radiosurgery ( 38 ), but can be compensated by a registration on a treatment planning CT ( 39 ). The SNR of the conventional method was significantly higher than that of the MAGIC ® method for low-contrast detectability.…”

Section: Discussionmentioning

confidence: 99%

Synthetic MRI for Radiotherapy Planning for Brain and Prostate Cancers: Phantom Validation and Patient Evaluation

et al. 2022

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PurposeWe aimed to evaluate the accuracy of T1 and T2 mappings derived from a multispectral pulse sequence (magnetic resonance image compilation, MAGiC®) on 1.5-T MRI and with conventional sequences [gradient echo with variable flip angle (GRE-VFA) and multi-echo spin echo (ME-SE)] compared to the reference values for the purpose of radiotherapy treatment planning.MethodsThe accuracy of T1 and T2 measurements was evaluated with 2 coils [head and neck unit (HNU) and BODY coils] on phantoms using descriptive statistics and Bland–Altman analysis. The reproducibility and repeatability of T1 and T2 measurements were performed on 15 sessions with the HNU coil. The T1 and T2 synthetic sequences obtained by both methods were evaluated according to quality assurance (QA) requirements for radiotherapy. T1 and T2in vivo measurements of the brain or prostate tissues of two groups of five subjects were also compared.ResultsThe phantom results showed good agreement (mean bias, 8.4%) between the two measurement methods for T1 values between 490 and 2,385 ms and T2 values between 25 and 400 ms. MAGiC® gave discordant results for T1 values below 220 ms (bias with the reference values, from 38% to 1,620%). T2 measurements were accurately estimated below 400 ms (mean bias, 8.5%) by both methods. The QA assessments are in agreement with the recommendations of imaging for contouring purposes for radiotherapy planning. On patient data of the brain and prostate, the measurements of T1 and T2 by the two quantitative MRI (qMRI) methods were comparable (max difference, <7%).ConclusionThis study shows that the accuracy, reproducibility, and repeatability of the multispectral pulse sequence (MAGiC®) were compatible with its use for radiotherapy treatment planning in a range of values corresponding to soft tissues. Even validated for brain imaging, MAGiC® could potentially be used for prostate qMRI.

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“…A CT with contiguous 0.6mm slices ( 14 ) was performed in a customized radiosurgery mask (Brainlab, Germany) and a 1.5 T T1-Gad MPR planning MRI scan were obtained on the same day. The CT and MRI were fused rigidly and then again with deformable registration to correct any distortion in the MRI.…”

Section: Methodsmentioning

confidence: 99%

Radiosurgery for Five to Fifteen Brain Metastases: A Single Centre Experience and a Review of the Literature

et al. 2022

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PurposeStereotactic radiosurgery (SRS) is now mainstream for patients with 1-4 brain metastases however the management of patients with 5 or more brain metastases remains controversial. Our aim was to evaluate the clinical outcomes of patients with 5 or more brain metastases and to compare with published series as a benchmarking exercise.MethodsPatients with 5 or more brain metastases treated with a single isocentre dynamic conformal arc technique on a radiosurgery linac were identified from the institutional database. Endpoints were local control, distant brain failure, leptomeningeal disease and overall survival. Dosimetric data were extracted from the radiosurgery plans. Series reporting outcomes following SRS for multiple brain metastases were identified by a literature search.Results36 patients, of whom 35 could be evaluated, received SRS for 5 or more brain metastases between February 2015 and October 2021. 25 patients had 5-9 brain metastases (group 1) and 10 patients had 10-15 brain metastases (group 2). The mean number of brain metastases in group 1 was 6.3 (5-9) and 12.3 (10-15) in group 2. The median cumulative irradiated volume was 4.6 cm3 (1.25-11.01) in group 1 and 7.2 cm3 (2.6-11.1) in group 2. Median follow-up was 12 months. At last follow-up, local control rates per BM were 100% and 99.8% as compared with a median of 87% at 1 year in published series. Distant brain failure was 36% and 50% at a median interval of 5.2 months and 7.4 months after SRS in groups 1 and 2 respectively and brain metastasis velocity at 1 year was similar in both groups (9.7 and 11). 8/25 patients received further SRS and 7/35 patients received whole brain radiotherapy. Median overall survival was 10 months in group 1 and 15.7 months in group 2, which compares well with the 7.5 months derived from the literature. There was one neurological death in group 2, leptomeningeal disease was rare (2/35) and there were no cases of radionecrosis.ConclusionWith careful patient selection, overall survival following SRS for multiple brain metastases is determined by the course of the extracranial disease. SRS is an efficacious and safe modality that can achieve intracranial disease control and should be offered to patients with 5 or more brain metastases and a constellation of good prognostic factors.

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The Effect of Slice Thickness on Contours of Brain Metastases for Stereotactic Radiosurgery

Cited by 18 publications

References 29 publications

Target localization accuracy in frame‐based stereotactic radiosurgery: Comparison between MR‐only and MR/CT co‐registration approaches

Target localization accuracy in frame‐based stereotactic radiosurgery: Comparison between MR‐only and MR/CT co‐registration approaches

Synthetic MRI for Radiotherapy Planning for Brain and Prostate Cancers: Phantom Validation and Patient Evaluation

Radiosurgery for Five to Fifteen Brain Metastases: A Single Centre Experience and a Review of the Literature

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