MR-OPERA: A Multicenter/Multivendor Validation of Magnetic Resonance Imaging–Only Prostate Treatment Planning Using Synthetic Computed Tomography Images

Persson, Erik; Gustafsson, Christian Jamtheim; Nordström, Fredrik; Sohlin, Maja; Gunnlaugsson, Adalsteinn; Petruson, Karin; Rintelä, Niina; Hed, K.; Blomqvist, Lennart; Zackrisson, Björn; Nyholm, Tufve; Olsson, Lars; Siversson, Carl; Jönsson, Johan

doi:10.1016/j.ijrobp.2017.06.006

Cited by 82 publications

(79 citation statements)

References 31 publications

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“…In practice, manufacturer and scanner differences, magnetic field strength, image acquisition and coil differences will inevitably result in variations in MRI signals. Recently, Persson et al have studied prostate RTP dose calculation accuracy of atlas-based sCTs produced via cloud-based conversion system [24]. They presented a mean dose difference of 0.2 ± 0.4% in the target with 145 patients with four different MR scanners.…”

Section: Discussionmentioning

confidence: 99%

Intensity-based dual model method for generation of synthetic CT images from standard T2-weighted MR images – Generalized technique for four different MR scanners

Koivula

Kapanen

Seppälä

et al. 2017

Radiotherapy and Oncology

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Section: Discussionmentioning

confidence: 99%

Intensity-based dual model method for generation of synthetic CT images from standard T2-weighted MR images – Generalized technique for four different MR scanners

Koivula

Kapanen

Seppälä

et al. 2017

Radiotherapy and Oncology

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“…So far, many of the algorithms proposed in the literature and those implemented clinically have demonstrated promising performance and as such, they seem ready for use in clinical setting with acceptable errors . Aside from the brain, MRI‐guided radiation therapy for the prostate in the pelvic region has attracted much attention recently as some algorithms are becoming clinically available . Nevertheless, there is a lack of direct comparison across the state‐of‐the‐art methods and consensus on a scheme of evaluation reflecting the key performance parameters.…”

Section: Introductionmentioning

confidence: 99%

Comparative study of algorithms for synthetic CT generation from MRI: Consequences for MRI‐guided radiation planning in the pelvic region

et al. 2018

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Overall, machine learning and advanced atlas-based methods exhibited promising performance by achieving reliable organ segmentation and synthetic CT generation. DCNN appears to have slightly better performance by achieving accurate automated organ segmentation and relatively small dosimetric errors (followed closely by advanced atlas-based methods, which in some cases achieved similar performance). However, the DCNN approach showed higher vulnerability to anatomical variation, where a greater number of outliers was observed with this method. Considering the dosimetric results obtained from the evaluated methods, the challenge of electron density estimation from MR images can be resolved with a clinically tolerable error.

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“…[6][7][8][9][10] The dosimetric accuracy in high-quality sCTs for prostate cancer RTP is sufficient. 6,7,[11][12][13] The sCTs can also be used as reference images for image-guided RT. 14 Thus, the entire RTP workflow can be conducted with MRI only.…”

Section: Introductionmentioning

confidence: 99%

Registration free automatic identification of gold fiducial markers in MRI target delineation images for prostate radiotherapy

et al. 2017

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Purpose: The superior soft tissue contrast of magnetic resonance imaging (MRI) compared to computed tomography (CT) has urged the integration of MRI and elimination of CT in radiotherapy treatment (RT) for prostate. An intraprostatic gold fiducial marker (GFM) appears hyperintense on CT. On T2-weighted (T2w) MRI target delineation images, the GFM appear as a small signal void similar to calcifications and post biopsy fibrosis. It can therefore be difficult to identify the markers without CT. Detectability of GFMs can be improved using additional MR images, which are manually registered to target delineation images. This task requires manual labor, and is associated with interoperator differences and image registration errors. The aim of this work was to develop and evaluate an automatic method for identification of GFMs directly in the target delineation images without the need for image registration. Methods: T2w images, intended for target delineation, and multiecho gradient echo (MEGRE) images intended for GFM identification, were acquired for prostate cancer patients. Signal voids in the target delineation images were identified as GFM candidates. The GFM appeared as round, symmetric, signal void with increasing area for increasing echo time in the MEGRE images. These image features were exploited for automatic identification of GFMs in a MATLAB model using a patient training dataset (n = 20). The model was validated on an independent patient dataset (n = 40). The distances between the identified GFM in the target delineation images and the GFM in CT images were measured. A human observatory study was conducted to validate the use of MEGRE images. Results: The sensitivity, specificity, and accuracy of the automatic method and the observatory study was 84%, 74%, 81% and 98%, 94%, 97%, respectively. The mean absolute difference in the GFM distances for the automatic method and observatory study was 1.28 AE 1.25 mm and 1.14 AE 1.06 mm, respectively. Conclusions: Multiecho gradient echo images were shown to be a feasible and reliable way to perform GFM identification. For clinical practice, visual inspection of the results from the automatic method is needed at the current stage.

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MR-OPERA: A Multicenter/Multivendor Validation of Magnetic Resonance Imaging–Only Prostate Treatment Planning Using Synthetic Computed Tomography Images

Cited by 82 publications

References 31 publications

Intensity-based dual model method for generation of synthetic CT images from standard T2-weighted MR images – Generalized technique for four different MR scanners

Intensity-based dual model method for generation of synthetic CT images from standard T2-weighted MR images – Generalized technique for four different MR scanners

Comparative study of algorithms for synthetic CT generation from MRI: Consequences for MRI‐guided radiation planning in the pelvic region

Registration free automatic identification of gold fiducial markers in MRI target delineation images for prostate radiotherapy

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