20 results on '"Schakel, Tim"'
Search Results
2. Improved delineation with diffusion weighted imaging for laryngeal and hypopharyngeal tumors validated with pathology
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Smits, Hilde J.G., Raaijmakers, Cornelis P.J., de Ridder, Mischa, Gouw, Zeno A.R., Doornaert, Patricia A.H., Pameijer, Frank A., Lodeweges, Joyce E., Ruiter, Lilian N., Kuijer, Koen M., Schakel, Tim, de Bree, Remco, Dankbaar, Jan W., Terhaard, Chris H.J., Breimer, Gerben E., Willems, Stefan M., and Philippens, Marielle E.P.
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- 2024
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3. Feasibility of cardiac-synchronized quantitative T1 and T2 mapping on a hybrid 1.5 Tesla magnetic resonance imaging and linear accelerator system
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Akdag, Osman, Mandija, Stefano, van Lier, Astrid L.H.M.W., Borman, Pim T.S., Schakel, Tim, Alberts, Eveline, van der Heide, Oscar, Hassink, Rutger J., Verhoeff, Joost J.C., Mohamed Hoesein, Firdaus A.A., Raaymakers, Bas W., and Fast, Martin F.
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- 2022
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4. Evaluation of diffusion weighted imaging for tumor delineation in head-and-neck radiotherapy by comparison with automatically segmented 18F-fluorodeoxyglucose positron emission tomography
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Schakel, Tim, Peltenburg, Boris, Dankbaar, Jan-Willem, Cardenas, Carlos E., Aristophanous, Michalis, Terhaard, Chris H.J., Hoogduin, Johannes M., and Philippens, Marielle E.P.
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- 2018
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5. Modality-specific target definition for laryngeal and hypopharyngeal cancer on FDG-PET, CT and MRI
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Ligtenberg, Hans, Jager, Elise Anne, Caldas-Magalhaes, Joana, Schakel, Tim, Pameijer, Frank A., Kasperts, Nicolien, Willems, Stefan M., Terhaard, Chris H.J., Raaijmakers, Cornelis P.J., and Philippens, Marielle E.P.
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- 2017
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6. Inter-observer agreement of MRI-based tumor delineation for preoperative radiotherapy boost in locally advanced rectal cancer
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Burbach, Johannes Peter Maarten, Kleijnen, Jean-Paul Johannes, Reerink, Onne, Seravalli, Enrica, Philippens, Marielle E.P., Schakel, Tim, van Asselen, Bram, Raaymakers, Bas W., van Vulpen, Marco, and Intven, Martijn
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- 2016
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7. Towards retrospective motion correction and reconstruction for clinical 3D brain MRI protocols with a reference contrast
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Gabrio Rizzuti, Schakel, Tim, Huttinga, Niek R F, Dankbaar, Jan Willem, Van Leeuwen, Tristan, and Sbrizzi, Alessandro
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Image and Video Processing (eess.IV) ,FOS: Electrical engineering, electronic engineering, information engineering ,Electrical Engineering and Systems Science - Image and Video Processing - Abstract
Motion artifacts often spoil the radiological interpretation of MR images, and in the most severe cases the scan needs be repeated, with additional costs for the provider. We discuss the application of a novel 3D retrospective rigid motion correction and reconstruction scheme for MRI, which leverages multiple scans contained in a MR session. Typically, in a multi-contrast MR session, motion does not equally affect all the scans, and some motion-free scans are generally available, so that we can exploit their anatomic similarity. The uncorrupted scan is used as a reference in a generalized rigid-motion registration problem to remove the motion artifacts affecting the corrupted scans. We discuss the potential of the proposed algorithm with a prospective in-vivo study and clinical 3D brain protocols. This framework can be easily incorporated into the existing clinical practice with no disruption to the conventional workflow.
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- 2023
8. Optimized flip angle schemes for the split acquisition of fast spin‐echo signals (SPLICE) sequence and application to diffusion‐weighted imaging.
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Rahbek, Sofie, Schakel, Tim, Mahmood, Faisal, Madsen, Kristoffer H., Philippens, Marielle E.P., and Hanson, Lars G.
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ECHO-planar imaging ,DIFFUSION magnetic resonance imaging ,STEREOTAXIC techniques ,MAGNETIC resonance imaging - Abstract
Purpose: The diffusion‐weighted SPLICE (split acquisition of fast spin‐echo signals) sequence employs split‐echo rapid acquisition with relaxation enhancement (RARE) readout to provide images almost free of geometric distortions. However, due to the varying T2$$ {}_2 $$‐weighting during k‐space traversal, SPLICE suffers from blurring. This work extends a method for controlling the spatial point spread function (PSF) while optimizing the signal‐to‐noise ratio (SNR) achieved by adjusting the flip angles in the refocusing pulse train of SPLICE. Methods: An algorithm based on extended phase graph (EPG) simulations optimizes the flip angles by maximizing SNR for a flexibly chosen predefined target PSF that describes the desired k‐space density weighting and spatial resolution. An optimized flip angle scheme and a corresponding post‐processing correction filter which together achieve the target PSF was tested by healthy subject brain imaging using a clinical 1.5 T scanner. Results: Brain images showed a clear and consistent improvement over those obtained with a standard constant flip angle scheme. SNR was increased and apparent diffusion coefficient estimates were more accurate. For a modified Hann k‐space weighting example, considerable benefits resulted from acquisition weighting by flip angle control. Conclusion: The presented flexible method for optimizing SPLICE flip angle schemes offers improved MR image quality of geometrically accurate diffusion‐weighted images that makes the sequence a strong candidate for radiotherapy planning or stereotactic surgery. [ABSTRACT FROM AUTHOR]
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- 2023
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9. Diffusion weighted MRI in head-and-neck cancer: Geometrical accuracy
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Schakel, Tim, Hoogduin, Johannes M., Terhaard, Chris H.J., and Philippens, Marielle E.P.
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- 2013
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10. Diffusion weighted MRI for tumor delineation in head and neck radiotherapy
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Schakel, Tim, Lagendijk, JJW, Terhaard, CHJ, Philippens, Marielle, Hoogduin, JM, and University Utrecht
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delineation ,diffusion ,head and neck cancer ,radiotherapy ,MRI - Abstract
In radiotherapy treatments of head and neck cancer, ionizing radiation is used to destroy malignant tumor tissue, while sparing the surrounding healthy tissue. For successful delivery of radiotherapy treatments, an accurate definition of the target is essential. This target is defined using threedimensional imaging techniques such as computed tomography (CT), positron emission tomography (PET) and magnetic resonance imaging (MRI). MRI can visualize, amongst others, local differences in the diffusion of water: diffusion weighted MRI (DW-MRI). Tumors have different diffusion characteristics than normal tissue. With DW-MRI these differences can be visualized and used in target volume delineation. In order to use DW-MRI in a radiotherapy setting, geometric accuracy is vital. The most common method to acquire DW-MRI, DW-EPI, is known for its sensitivity to geometric distortions, especially in areas with large magnetic field inhomogeneities. The geometric accuracy of DW-EPI was evaluated in patients with a retrospective analysis of magnetic field maps. It was found that severe geometric distortions are present when using DW-EPI in the head and neck region. Therefore, the use of an alternative acquisition method, DW-SPLICE, was proposed. This method is based on a turbo spin echo sequence, which is used for standard anatomical imaging and has comparable, high geometric accuracy. The method was implemented and demonstrated in patients. Using DW-SPLICE, diffusion weighted images with excellent geometric accuracy were acquired in head and neck cancer patients. Additionally, the DW-SPLICE technique was extended in order to improve fat suppression. Additional images were acquired in order to yield a dataset which was suitable for water fat separation. The results from the water fat separation were applied in order to provide a more robust and homogeneous fat suppression. The diffusion weighted images acquired with DW-SPLICE were used to generate target volume delineations. Using an intensity threshold, an initial volume was segmented on diffusion weighted images. Subsequently these were manually adjusted based on the diffusion coefficients. These delineations were compared with those based on PET. Pathology validation of PET delineations has shown these to be quite accurate. The (semi-)automatic target volume delineations on DW-SPLICE show good correspondence with target volume delineations based on PET, indicating that, for a large part, both techniques indicate the same target for treatment. Using surgical specimens, obtained after total laryngectomy, pathological validation of DW-MRI can be performed. Patients received an MRI exam with DW-MRI prior to surgery. The surgical specimen of the larynx was processed, resulting in a digitally reconstructed threedimensional volume which was matched to the imaging prior to surgery. The initial results from the first patient show that the target volume delineation based on DW-MRI has very good agreement with the tumor defined on pathology. When diffusion weighted images are acquired with good geometrical accuracy, these images can be a valuable addition for target volume delineation in head and neck radiotherapy.
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- 2018
11. Diffusion weighted MRI with minimal distortion in head-and-neck radiotherapy using a turbo spin echo acquisition method
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Schakel, Tim, Hoogduin, JM, Terhaard, Chris H J, and Philippens, Marielle E P
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image distortions ,head-and-neck cancer ,diffusion ,Journal Article ,mri ,radiotherapy - Abstract
PURPOSE: Diffusion weighted (DW) MRI, showing high contrast between tumor and background tissue, is a promising technique in radiotherapy for tumor delineation. However, its use for head-and-neck patients is hampered by poor geometric accuracy in conventional echo planar imaging (EPI) DW-MRI. An alternative turbo spin echo sequence, DW-SPLICE, is implemented and demonstrated in patients. METHODS: The DW-SPLICE sequence was implemented on a 3.0T system and evaluated in 10 patients. The patients were scanned in treatment position, using a customized head support and immobilization mask. Image distortions were quantified at the gross tumor volume (GTV) using field map analysis. The apparent diffusion coefficient (ADC) was evaluated using an ice water phantom. RESULTS: The DW images acquired by DW-SPLICE showed no image distortions. Field map analysis at the gross tumor volumes resulted in a median distortion of 0.2 mm for DW-SPLICE, whereas for the conventional method this was 7.2 mm. ADC values, measured using an ice water phantom were in accordance with literature values. CONCLUSIONS: The implementation of DW-SPLICE allows for diffusion weighted imaging of patients in treatment position with excellent geometrical accuracy. The images can be used to facilitate target volume delineation in RT treatment planning. This article is protected by copyright. All rights reserved.
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- 2017
12. Pushing functional MRI spatial and temporal resolution further: High‐density receive arrays combined with shot‐selective 2D CAIPIRINHA for 3D echo‐planar imaging at 7 T.
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Hendriks, Arjan D., D'Agata, Federico, Raimondo, Luisa, Schakel, Tim, Geerts, Liesbeth, Luijten, Peter R., Klomp, Dennis W.J., and Petridou, Natalia
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ECHO-planar imaging ,FUNCTIONAL magnetic resonance imaging ,THREE-dimensional imaging ,VISUAL cortex ,BRAIN anatomy - Abstract
To be able to examine dynamic and detailed brain functions, the spatial and temporal resolution of 7 T MRI needs to improve. In this study, it was investigated whether submillimeter multishot 3D EPI fMRI scans, acquired with high‐density receive arrays, can benefit from a 2D CAIPIRINHA sampling pattern, in terms of noise amplification (g‐factor), temporal SNR and fMRI sensitivity. High‐density receive arrays were combined with a shot‐selective 2D CAIPIRINHA implementation for multishot 3D EPI sequences at 7 T. In this implementation, in contrast to conventional inclusion of extra kz gradient blips, specific EPI shots are left out to create a CAIPIRINHA shift and reduction of scan time. First, the implementation of the CAIPIRINHA sequence was evaluated with a standard receive setup by acquiring submillimeter whole brain T2*‐weighted anatomy images. Second, the CAIPIRINHA sequence was combined with high‐density receive arrays to push the temporal resolution of submillimeter 3D EPI fMRI scans of the visual cortex. Results show that the shot‐selective 2D CAIPIRINHA sequence enables a reduction in scan time for 0.5 mm isotropic 3D EPI T2*‐weighted anatomy scans by a factor of 4 compared with earlier reports. The use of the 2D CAIPIRINHA implementation in combination with high‐density receive arrays, enhances the image quality of submillimeter 3D EPI scans of the visual cortex at high acceleration as compared to conventional SENSE. Both the g‐factor and temporal SNR improved, resulting in a method that is more sensitive to the fMRI signal. Using this method, it is possible to acquire submillimeter single volume 3D EPI scans of the visual cortex in a subsecond timeframe. Overall, high‐density receive arrays in combination with shot‐selective 2D CAIPIRINHA for 3D EPI scans prove to be valuable for reducing the scan time of submillimeter MRI acquisitions. [ABSTRACT FROM AUTHOR]
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- 2020
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13. Interobserver variation among pathologists for delineation of tumor on H&E-sections of laryngeal and hypopharyngeal carcinoma. How good is the gold standard?
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Jager, Elise Anne, Willems, Stefan M., Schakel, Tim, Kooij, Nina, Slootweg, Pieter J., Philippens, Marielle E P, Caldas Magalhaes, Joana, Terhaard, Chris H. J., and Raaijmakers, Cornelis P J
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Letter ,Oncology ,Radiology Nuclear Medicine and imaging ,Research Support, Non-U.S. Gov't ,Randomized Controlled Trial ,Hematology - Published
- 2016
14. Integrated Multimodal Imaging of Dynamic Bone-Tumor Alterations Associated with Metastatic Prostate Cancer
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Brisset, Jean-Christophe, Hoff, Benjamin A., Chenevert, Thomas L., Jacobson, Jon A., Boes, Jennifer L., Galban, Stefanie, Rehemtulla, Alnawaz, Johnson, Timothy D., Pienta, Kenneth J., Galban, Craig J., Meyer, Charles R., Schakel, Timothy, Nicolay, Klaas, Alva, Ajjai S., Hussain, Maha, Ross, Brian D., and Schakel, Tim
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Male ,Oncology ,BIOMARKER ,Pathology ,Osteolysis ,Bone density ,Bone disease ,FUNCTIONAL DIFFUSION MAP ,lcsh:Medicine ,PROGRESSION ,Docetaxel ,SDG 3 – Goede gezondheid en welzijn ,Multimodal Imaging ,030218 nuclear medicine & medical imaging ,Mice ,Prostate cancer ,0302 clinical medicine ,Bone Density ,Prostate ,PARAMETRIC RESPONSE MAP ,lcsh:Science ,Non-U.S. Gov't ,Multidisciplinary ,Diphosphonates ,Research Support, Non-U.S. Gov't ,Bone metastasis ,Clinical Trial ,Tumor Burden ,3. Good health ,THERAPY RESPONSE ,Treatment Outcome ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,ANDROGEN INDEPENDENCE ,Taxoids ,Research Article ,medicine.medical_specialty ,GLIOBLASTOMA ,Antineoplastic Agents ,Bone Neoplasms ,Research Support ,N.I.H ,03 medical and health sciences ,Breast cancer ,SDG 3 - Good Health and Well-being ,Research Support, N.I.H., Extramural ,DW-MRI ,Osteoclast ,Internal medicine ,medicine ,Journal Article ,Animals ,Humans ,BREAST-CANCER ,Osteoblasts ,business.industry ,lcsh:R ,Prostatic Neoplasms ,Extramural ,WEIGHTED MRI ,medicine.disease ,Disease Models, Animal ,Diffusion Magnetic Resonance Imaging ,lcsh:Q ,business - Abstract
Bone metastasis occurs for men with advanced prostate cancer which promotes osseous growth and destruction driven by alterations in osteoblast and osteoclast homeostasis. Patients can experience pain, spontaneous fractures and morbidity eroding overall quality of life. The complex and dynamic cellular interactions within the bone microenvironment limit current treatment options thus prostate to bone metastases remains incurable. This study uses voxel-based analysis of diffusion-weighted MRI and CT scans to simultaneously evaluate temporal changes in normal bone homeostasis along with prostate bone metatastsis to deliver an improved understanding of the spatiotemporal local microenvironment. Dynamic tumor-stromal interactions were assessed during treatment in mouse models along with a pilot prospective clinical trial with metastatic hormone sensitive and castration resistant prostate cancer patients with bone metastases. Longitudinal changes in tumor and bone imaging metrics during delivery of therapy were quantified. Studies revealed that voxel-based parametric response maps (PRM) of DW-MRI and CT scans could be used to quantify and spatially visualize dynamic changes during prostate tumor growth and in response to treatment thereby distinguishing patients with stable disease from those with progressive disease (p
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- 2015
15. Technical Note: Diffusion-weighted MRI with minimal distortion in head-and-neck radiotherapy using a turbo spin echo acquisition method.
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Schakel, Tim, Hoogduin, Johannes M., Terhaard, Chris H.J., and Philippens, Marielle E.P.
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HEAD & neck cancer , *DIFFUSION magnetic resonance imaging , *RADIOTHERAPY , *ELECTRON spin echoes , *DIFFUSION coefficients - Abstract
Purpose Diffusion-weighted ( DW) MRI, showing high contrast between tumor and background tissue, is a promising technique in radiotherapy for tumor delineation. However, its use for head-and-neck patients is hampered by poor geometric accuracy in conventional echo planar imaging ( EPI) DW- MRI. An alternative turbo spin echo sequence, DW- SPLICE, is implemented and demonstrated in patients. Methods The DW- SPLICE sequence was implemented on a 3.0 T system and evaluated in 10 patients. The patients were scanned in treatment position, using a customized head support and immobilization mask. Image distortions were quantified at the gross tumor volume ( GTV) using field map analysis. The apparent diffusion coefficient ( ADC) was evaluated using an ice water phantom. Results The DW images acquired by DW- SPLICE showed no image distortions. Field map analysis at the gross tumor volumes resulted in a median distortion of 0.2 mm for DW- SPLICE, whereas for the conventional method this was 7.2 mm. ADC values, measured using an ice water phantom were in accordance with literature values. Conclusions The implementation of DW- SPLICE allows for diffusion-weighted imaging of patients in treatment position with excellent geometrical accuracy. The images can be used to facilitate target volume delineation in RT treatment planning. [ABSTRACT FROM AUTHOR]
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- 2017
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16. Validated guidelines for tumor delineation on magnetic resonance imaging for laryngeal and hypopharyngeal cancer.
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Jager, Elise Anne, Ligtenberg, Hans, Caldas-Magalhaes, Joana, Schakel, Tim, Philippens, Marielle E., Pameijer, Frank A., Kasperts, Nicolien, Willems, Stefan M., Terhaard, Christiaan H., and Raaijmakers, Cornelis P.
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Background:Validation of magnetic resonance imaging (MRI) and development of guidelines for the delineation of the gross tumor volume (GTV) is of utmost importance to benefit from the visibility of anatomical details on MR images and to achieve an accurate GTV delineation. In the ideal situation, the GTV delineation corresponds to the histopathologically determined ‘true tumor volume’. Consequently, we developed guidelines for GTV delineation of laryngeal and hypopharyngeal tumors on MRI and determined the accuracy of the resulting delineation of the tumor outline on histopathology as gold standard. Material and methods:Twenty-seven patients with T3 or T4 laryngeal/hypopharyngeal cancer underwent a MRI scan before laryngectomy. Hematoxylin and eosin sections were obtained from surgical specimens and tumor was delineated by one pathologist. GTV was delineated on MR images by three independent observers in two sessions. The first session (del1) was performed according to clinical practice. In the second session (del2) guidelines were used. The reconstructed specimen was registered to the MR images for comparison of the delineated GTVs to the tumor on histopathology. Volumes and overlap parameters were analyzed. A target margin needed to assure tumor coverage was determined. Results:The median GTVs (del1: 19.4 cm3, del2: 15.8 cm3) were larger than the tumor volume on pathology (10.5 cm3). Comparable target margins were needed for both delineation sessions to assure tumor coverage. By adding these margins to the GTVs, the target volumes for del1 (median: 81.3 cm3) were significantly larger than for del2 (median: 64.2 cm3) (p ≤ 0.0001) with similar tumor coverage. Conclusions:In clinical radiotherapy practice, the delineated GTV on MRI is twice as large as the tumor volume. Validated delineation guidelines lead to a significant decrease in the overestimation of the tumor volume. [ABSTRACT FROM PUBLISHER]
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- 2016
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17. The accuracy of target delineation in laryngeal and hypopharyngeal cancer.
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Caldas-Magalhaes, Joana, Kooij, Nina, Ligtenberg, Hans, Jager, Elise A., Schakel, Tim, Kasperts, Nicolien, Pameijer, Frank A., Terhaard, Chris H. J., Janssen, Luuk M., van Diest, Paul J., Philippens, Marielle E. P., and Raaijmakers, Cornelis P. J.
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COMPUTED tomography ,LARYNGECTOMY ,LARYNGEAL tumors ,RESEARCH methodology ,MICROSCOPY ,RESEARCH evaluation ,RESEARCH funding ,STAINS & staining (Microscopy) ,TISSUE culture ,WEIGHTS & measures ,HYPOPHARYNX ,PREDICTIVE tests ,INTER-observer reliability ,DESCRIPTIVE statistics ,TUMORS - Abstract
Background and purpose.To determine the spatial correspondence between the gross tumor volume (GTV) delineated on computer tomography (CT) and the actual tumor on histopathology. Material and methods.Sixteen patients with T3 or T4 laryngeal or hypopharyngeal cancer underwent a CT scan before total laryngectomy. The GTV was delineated on CT by three independent observers and by consensus between the three observers. After surgery, whole-mount hematoxylin-eosin stained (H&E) sections were obtained. One pathologist delineated the tumor in the H&E sections (tumorH&E). The reconstructed specimen was registered to the CT scan in order to compare the GTV to the tumorH&Ein three dimensions. The overlap between the GTV and the tumorH&Ewas calculated and the distance between the volumes was determined. Results.Tumor tissue was delineated in 203 of 516 H&E sections. For 14 patients a detailed analysis could be performed. The GTV volume was on average 1.7 times larger than the volume of the tumorH&E. The mean coverage of the tumorH&Eby the consensus GTV was 88%. tumorH&Etissue was found at 1.6 mm to 12.9 mm distance outside the GTV depending on observer and patient. Conclusions.GTVs delineated on CT for laryngeal and hypopharyngeal cancer were 1.7 times larger than the tumor. Complete coverage of the tumor by the GTV was, however, not obtained. [ABSTRACT FROM AUTHOR]
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- 2015
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18. MRI to quantify early radiation-induced changes in the salivary glands
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Houweling, Antonetta C., Schakel, Tim, van den Berg, Cornelis A.T., Philippens, Marielle E.P., Roesink, Judith M., Terhaard, Chris H.J., and Raaijmakers, Cornelis P.J.
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MAGNETIC resonance imaging of cancer , *CANCER radiotherapy , *SALIVARY glands , *PHARYNGEAL cancer , *CONTRAST-enhanced magnetic resonance imaging , *DRUG dosage , *SUBMANDIBULAR gland - Abstract
Abstract: Purpose: We investigated radiation-induced changes in the salivary glands, 6weeks after RT, using MRI. Materials and methods: Eighteen oropharyngeal cancer patients were treated with salivary gland sparing IMRT. All patients received a 3T MRI exam before and 6weeks after the end of RT, including a T1-weighted (T1w), a T2-weighted (T2w), and a dynamic contrast-enhanced (DCE) MRI. For both time points separately, the parotid and submandibular glands were delineated on the MR images. Differences in median signal intensity and signal variation within the glands were tested for significance. Correlations were studied between the MR changes and the planned RT dose. Results: The volume of the glands reduced significantly by 25%. The T1w signal decreased by 10% and the T2w signal increased by 23%. The k ep value decreased, while the v e increased. A correlation of the changes in T2w signal with the mean dose was found in both glands. Conclusions: Overall radiation-induced changes and volume loss were observed in the parotid and submandibular gland using MR. The observed differences indicated an increased water content such as found in oedema. The overall changes could be related to the mean dose, with a slightly greater impact in the high dose area. [Copyright &y& Elsevier]
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- 2011
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19. Target Volume Delineation Using Diffusion-weighted Imaging for MR-guided Radiotherapy: A Case Series of Laryngeal Cancer Validated by Pathology.
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Ligtenberg H, Schakel T, Dankbaar JW, Ruiter LN, Peltenburg B, Willems SM, Kasperts N, Terhaard CHJ, Raaijmakers CPJ, and Philippens MEP
- Abstract
In radiotherapy treatment planning, tumor delineation based on diffusion-weighted imaging (DWI) by magnetic resonance imaging (MRI) is a promising technique. MR-only-based target definition becomes important with the recent development of MRI integrated radiotherapy treatment modalities. In this case series, DWI-based gross tumor volume (GTV) was validated using pathology and compared with a clinical GTV based on computed tomography (CT) imaging and MRI. This case series includes three patients with a laryngeal tumor. Prior to total laryngectomy (TLE), imaging was performed on CT and MRI, including a DWI scan. After TLE, the surgical specimen was processed and cut into 3-mm thick slices. The tumor was delineated on hematoxylin-eosin (HE) stained sections by a pathologist (tumor
HE ). This pathological imaging, including the tumorHE delineation, was three-dimensionally reconstructed and registered to the imaging. The GTV was delineated by a radiation oncologist based on CT and MR imaging (GTVclinical ) and semi-automatically delineated based on DWI (GTVDWI ). The microscopic tumor extent outside the GTVDWI contour was 3.0 mm, 2.7 mm, and 11.3 mm for cases I, II, and III, respectively. The microscopic tumor extent outside the GTVclinical was 7.5 mm, 2.1 mm, and 1.5 mm for cases I, II, and III, respectively. The tumor, on histology, was covered by the GTVs for 80%, 74%, and 31% (GTVDWI ) and 73%, 72%, and 89% (GTVclinical ) for the three subsequent cases, respectively. The GTVDWI resembled the tumorHE more than the GTVclinical in case I and case II. In case III, GTVDWI missed the caudal part of the tumor that was included in the clinical delineation due to a lack of contrast and the heterogeneous signal intensity of the tumor in DWI. In this case series, we showed the potential of DWI for MR-guided radiotherapy treatment if a clear contrast is visible. DWI-based GTV delineation might be a fast alternative to manual delineation, which could speed up the on-table target definition using an MRI-linac system. A larger case series is needed to verify these results., Competing Interests: The authors have declared that no competing interests exist.- Published
- 2018
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20. Interobserver variation among pathologists for delineation of tumor on H&E-sections of laryngeal and hypopharyngeal carcinoma. How good is the gold standard?
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Jager EA, Willems SM, Schakel T, Kooij N, Slootweg PJ, Philippens ME, Caldas-Magalhaes J, Terhaard CH, and Raaijmakers CP
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- Eosine Yellowish-(YS) chemistry, Hematoxylin chemistry, Humans, Image Processing, Computer-Assisted methods, Neoplasm Staging, Prognosis, Carcinoma, Squamous Cell diagnosis, Hypopharyngeal Neoplasms diagnosis, Laryngeal Neoplasms diagnosis, Observer Variation, Staining and Labeling methods
- Published
- 2016
- Full Text
- View/download PDF
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