Brouwers, J.E.M.

Huiskes, H.W.J.

Rietbergen, van, B.

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Brouwers, JEM Julienne

Rietbergen, B Bert  van

Huiskes, HWJ Rik

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In-vivo micro-ct radiation does not affect bone structure in rats

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 In-vivo micro-ct radiation does not affect bone structure in ratsCitation for published version (APA):Brouwers, J. E. M., Rietbergen, van, B., & Huiskes, H. W. J. (2005). In-vivo micro-ct radiation does not affectbone structure in rats. Poster session presented at Mate Poster Award 2005 : 10th Annual Poster Contest.Document status and date:Published: 01/01/2005Document Version:Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can beimportant differences between the submitted version and the official published version of record. Peopleinterested in the research are advised to contact the author for the final version of the publication, or visit theDOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and pagenumbers.Link to publicationGeneral rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            • Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            • You may not further distribute the material or use it for any profit-making activity or commercial gain            • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, pleasefollow below link for the End User Agreement:www.tue.nl/taverneTake down policyIf you believe that this document breaches copyright please contact us at:openaccess@tue.nlproviding details and we will investigate your claim.Download date: 05. Oct. 2023/mhj12IntroductionRecently developed animal in vivo high-resolution micro-CTscanners offer the possibility to monitor longitudinal changes in bone micro­structure of small rodents. They do, however, impose a relatively high ionizing radiation dose, which may lead to tissue damage [1]. Our goal was to determine whether an intensive 8 weeks in-vivo scanning regime of the rat proximal tibia would lead tobone damage. MethodsNine female, 30 weeks-old Wistar rats were kept under normal conditions (approved by Animals Ethics Committee). Eight weekly in-vivo CT scans of the right proximal tibia were made using a Scanco vivaCT 40 scanner. During scanning the animals were anesthetized using isoflurane. The total scan length was 6 mm. A voxel resolution of 15 microns was used, resulting in a local CT dose index (CTDI) of 0.49 Gy(according to the manufacturer). Two weeks after the last weekly scan a final scan was made. The left tibia was only scanned on the first and last time point. Image processing included filtering and segmentation. From the metaphyseal bone the structuralparameters were determined. The right/left ratio for all parameters was determined for the first and the last scan. It was assumed that the effects of the radiation dose on the structural parameters would be negligible if the right/left ratio of a parameter after 9 weeks would not differ significantly from that at baseline. The animals were sacrificed after the last scan. The bone marrow was flushed out of the scanned part of both tibias and was tested for cell viability using trypan blue staining. Results Figure 2 shows a typical 3-D scan and segmented slice, obtained for the tibia in-vivo. Figure 3 shows the bone volume fraction for all rats longitudinally, missing line segments indicate excluded measurements due to movement artefacts.For the structural parameters, no significant difference was seen between the ratio right/left of the first and the last measurement (p>0.05) , except for the connectivity density.No significant difference was seen between the percentageand the absolute number of living cells of the left and right tibia (p>0.39, based on paired student t-test). DiscussionEight weekly scans resulted in no significant radiation bone damage with the exception of the connectivity density. This parameter, however, had shown to have a low reproducibility in a previous study. No significant difference was found between the percentage and number of viable cells of the right and left tibia, indicating neither long nor short term effects on cell viability, which is not unlikely considering the CTDI [2]. In conclusion: the results suggest that the scanning frequency used here could be applied when performing a long-term experiment. However, careful consideration should be made when determining the number of scans and the CTDI.References:[1] Waarsing 2003 Bone 34: 163-169[2] Dare 1997 J. Dent. Res. 1997: 658–664In-vivo micro-ct radiation does not affect bone structure in ratsJ.E.M. Brouwers, B. v. Rietbergen, R. HuiskesBiomechanics & Tissue Engineering, Bone and Orthopedic BiomechanicsFigure 4 Left: Bone volume fraction for all rats during 9 weeks. Right: Cell trypan blue staining shows mostly living (white) cellsFigure 2 Left: a typical 3-D reconstruction of a tibia and fibula in-vivo obtained from the CT-scanner. Right: A section through the CT-scan showing the individual trabeculae and remains of the growth plate.Figure 1 Rat in CT-scanner, leg is fixatedFigure 3 Scan from a rat at week 0 and 9. No differences can be seen indicating correct image registration and no radiation damagebone volume fraction for right tibia00.050.10.150.20.250.30.350 2 4 6 8 10weekrat 1 rat 2rat 3rat 4rat 5rat 6rat 7rat 8rat 9

 In-vivo micro-ct radiation does not affect bone structure in ratsCitation for published version (APA):Brouwers, J. E. M., Rietbergen, van, B., & Huiskes, H. W. J. (2005). In-vivo micro-ct radiation does not affectbone structure in rats. Poster session presented at Mate Poster Award 2005 : 10th Annual Poster Contest.Document status and date:Published: 01/01/2005Document Version:Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can beimportant differences between the submitted version and the official published version of record. Peopleinterested in the research are advised to contact the author for the final version of the publication, or visit theDOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and pagenumbers.Link to publicationGeneral rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            • Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            • You may not further distribute the material or use it for any profit-making activity or commercial gain            • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, pleasefollow below link for the End User Agreement:www.tue.nl/taverneTake down policyIf you believe that this document breaches copyright please contact us at:openaccess@tue.nlproviding details and we will investigate your claim.Download date: 04. Oct. 2023/mhj12IntroductionRecently developed animal in vivo high-resolution micro-CTscanners offer the possibility to monitor longitudinal changes in bone micro­structure of small rodents. They do, however, impose a relatively high ionizing radiation dose, which may lead to tissue damage [1]. Our goal was to determine whether an intensive 8 weeks in-vivo scanning regime of the rat proximal tibia would lead tobone damage. MethodsNine female, 30 weeks-old Wistar rats were kept under normal conditions (approved by Animals Ethics Committee). Eight weekly in-vivo CT scans of the right proximal tibia were made using a Scanco vivaCT 40 scanner. During scanning the animals were anesthetized using isoflurane. The total scan length was 6 mm. A voxel resolution of 15 microns was used, resulting in a local CT dose index (CTDI) of 0.49 Gy(according to the manufacturer). Two weeks after the last weekly scan a final scan was made. The left tibia was only scanned on the first and last time point. Image processing included filtering and segmentation. From the metaphyseal bone the structuralparameters were determined. The right/left ratio for all parameters was determined for the first and the last scan. It was assumed that the effects of the radiation dose on the structural parameters would be negligible if the right/left ratio of a parameter after 9 weeks would not differ significantly from that at baseline. The animals were sacrificed after the last scan. The bone marrow was flushed out of the scanned part of both tibias and was tested for cell viability using trypan blue staining. Results Figure 2 shows a typical 3-D scan and segmented slice, obtained for the tibia in-vivo. Figure 3 shows the bone volume fraction for all rats longitudinally, missing line segments indicate excluded measurements due to movement artefacts.For the structural parameters, no significant difference was seen between the ratio right/left of the first and the last measurement (p>0.05) , except for the connectivity density.No significant difference was seen between the percentageand the absolute number of living cells of the left and right tibia (p>0.39, based on paired student t-test). DiscussionEight weekly scans resulted in no significant radiation bone damage with the exception of the connectivity density. This parameter, however, had shown to have a low reproducibility in a previous study. No significant difference was found between the percentage and number of viable cells of the right and left tibia, indicating neither long nor short term effects on cell viability, which is not unlikely considering the CTDI [2]. In conclusion: the results suggest that the scanning frequency used here could be applied when performing a long-term experiment. However, careful consideration should be made when determining the number of scans and the CTDI.References:[1] Waarsing 2003 Bone 34: 163-169[2] Dare 1997 J. Dent. Res. 1997: 658–664In-vivo micro-ct radiation does not affect bone structure in ratsJ.E.M. Brouwers, B. v. Rietbergen, R. HuiskesBiomechanics & Tissue Engineering, Bone and Orthopedic BiomechanicsFigure 4 Left: Bone volume fraction for all rats during 9 weeks. Right: Cell trypan blue staining shows mostly living (white) cellsFigure 2 Left: a typical 3-D reconstruction of a tibia and fibula in-vivo obtained from the CT-scanner. Right: A section through the CT-scan showing the individual trabeculae and remains of the growth plate.Figure 1 Rat in CT-scanner, leg is fixatedFigure 3 Scan from a rat at week 0 and 9. No differences can be seen indicating correct image registration and no radiation damagebone volume fraction for right tibia00.050.10.150.20.250.30.350 2 4 6 8 10weekrat 1 rat 2rat 3rat 4rat 5rat 6rat 7rat 8rat 9

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In-vivo micro-ct radiation does not affect bone structure in rats

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