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Article: Computer-Assisted Densitometric Image Analysis of Digital Subtraction Images: In Vivo Error of the Method and Effect of Thresholding

TitleComputer-Assisted Densitometric Image Analysis of Digital Subtraction Images: In Vivo Error of the Method and Effect of Thresholding
Authors
Issue Date1998
PublisherAmerican Academy of Periodontology. The Journal's web site is located at http://www.perio.org
Citation
Journal Of Periodontology, 1998, v. 69 n. 9, p. 967-974 How to Cite?
AbstractTHE AIM OF THE PRESENT STUDY was to assess the in vivo error of the method as well as the effect of thresholding when obtaining and evaluating standardized periapical radiographs for computer-assisted densitometric image analysis (CADIA). Twenty healthy volunteers participated in an experimental gingivitis study in which neither mechanical nor chemical plaque control was performed for 21 days. Two pairs of standardized periapical radiographs were taken at days O (baseline) and 21 (follow-up), one from a maxillary area (15 volunteers) and one from a mandibular molar/premolar area (17 volunteers). Each baseline radiograph was digitized and its image displayed on a monitor. The follow-up radiograph was then superimposed and digitized as well. After gray level correction, subtraction radiographic images were produced. The difference in gray level between the baseline and the follow-up image was calculated within each region of interest (ROI) at each picture point (pixel). In bone ROI, changes in density reflected the amount of change due to methodological errors plus the basic bone remodeling over 3 weeks. For gingival ROI, changes in density reflected the methodological error plus a possible change in soft tissue density during the experimental gingivitis. Within all of the ROI, some pixels indicated a change in gray level. A change in gray level was then thresholded; i.e., only changes >5 and then >10 gray levels were registered and used for calculation of the CADIA values. With a threshold of 5, 44/45 maxillary bone ROI and 60/66 mandibular bone ROI showed a change in density, while 41/45 maxillary gingiva ROI and 26/66 mandibular gingiva ROI indicated a change in density. With a threshold of 10, 16/45 maxillary bone ROI and 12/66 mandibular bone ROI indicated a change in density, while 13/45 maxillary gingiva ROI and 1/66 mandibular gingiva ROI indicated a change. The amounts of changes in density calculated in the various ROI were low even when applying no threshold, ranging from -0.279 to 0.621. Applying a threshold of 5, the CADIA values ranged from -0.234 to 0.727. With a threshold of 10, the changes in density ranged from -0.318 to 0.133. In vivo, CADIA of standardized radiographs indicated change in density due to methodological errors. Application of thresholds may avoid false-positive diagnoses. When applying CADIA in clinical research, the range of change to be expected due to methodological limitations as well as the threshold for true change should be evaluated. These thresholds may differ in various areas of the mouth, i.e., bone or gingival, maxillary/mandibular, anterior/ posterior ROI.
Persistent Identifierhttp://hdl.handle.net/10722/154035
ISSN
2015 Impact Factor: 2.844
2015 SCImago Journal Rankings: 1.070
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorBrägger, Uen_US
dc.contributor.authorBürgin, Wen_US
dc.contributor.authorFourmousis, Ien_US
dc.contributor.authorSchmid, Gen_US
dc.contributor.authorSchild, Uen_US
dc.contributor.authorLang, NPen_US
dc.date.accessioned2012-08-08T08:22:55Z-
dc.date.available2012-08-08T08:22:55Z-
dc.date.issued1998en_US
dc.identifier.citationJournal Of Periodontology, 1998, v. 69 n. 9, p. 967-974en_US
dc.identifier.issn0022-3492en_US
dc.identifier.urihttp://hdl.handle.net/10722/154035-
dc.description.abstractTHE AIM OF THE PRESENT STUDY was to assess the in vivo error of the method as well as the effect of thresholding when obtaining and evaluating standardized periapical radiographs for computer-assisted densitometric image analysis (CADIA). Twenty healthy volunteers participated in an experimental gingivitis study in which neither mechanical nor chemical plaque control was performed for 21 days. Two pairs of standardized periapical radiographs were taken at days O (baseline) and 21 (follow-up), one from a maxillary area (15 volunteers) and one from a mandibular molar/premolar area (17 volunteers). Each baseline radiograph was digitized and its image displayed on a monitor. The follow-up radiograph was then superimposed and digitized as well. After gray level correction, subtraction radiographic images were produced. The difference in gray level between the baseline and the follow-up image was calculated within each region of interest (ROI) at each picture point (pixel). In bone ROI, changes in density reflected the amount of change due to methodological errors plus the basic bone remodeling over 3 weeks. For gingival ROI, changes in density reflected the methodological error plus a possible change in soft tissue density during the experimental gingivitis. Within all of the ROI, some pixels indicated a change in gray level. A change in gray level was then thresholded; i.e., only changes >5 and then >10 gray levels were registered and used for calculation of the CADIA values. With a threshold of 5, 44/45 maxillary bone ROI and 60/66 mandibular bone ROI showed a change in density, while 41/45 maxillary gingiva ROI and 26/66 mandibular gingiva ROI indicated a change in density. With a threshold of 10, 16/45 maxillary bone ROI and 12/66 mandibular bone ROI indicated a change in density, while 13/45 maxillary gingiva ROI and 1/66 mandibular gingiva ROI indicated a change. The amounts of changes in density calculated in the various ROI were low even when applying no threshold, ranging from -0.279 to 0.621. Applying a threshold of 5, the CADIA values ranged from -0.234 to 0.727. With a threshold of 10, the changes in density ranged from -0.318 to 0.133. In vivo, CADIA of standardized radiographs indicated change in density due to methodological errors. Application of thresholds may avoid false-positive diagnoses. When applying CADIA in clinical research, the range of change to be expected due to methodological limitations as well as the threshold for true change should be evaluated. These thresholds may differ in various areas of the mouth, i.e., bone or gingival, maxillary/mandibular, anterior/ posterior ROI.en_US
dc.languageengen_US
dc.publisherAmerican Academy of Periodontology. The Journal's web site is located at http://www.perio.orgen_US
dc.relation.ispartofJournal of Periodontologyen_US
dc.subject.meshAbsorptiometry, Photonen_US
dc.subject.meshAdulten_US
dc.subject.meshAlveolar Process - Radiographyen_US
dc.subject.meshBicuspid - Radiographyen_US
dc.subject.meshBone Densityen_US
dc.subject.meshBone Remodelingen_US
dc.subject.meshCalibrationen_US
dc.subject.meshData Displayen_US
dc.subject.meshFalse Positive Reactionsen_US
dc.subject.meshFemaleen_US
dc.subject.meshFollow-Up Studiesen_US
dc.subject.meshGingiva - Radiographyen_US
dc.subject.meshGingivitis - Radiographyen_US
dc.subject.meshHumansen_US
dc.subject.meshImage Processing, Computer-Assisteden_US
dc.subject.meshMaleen_US
dc.subject.meshMandible - Radiographyen_US
dc.subject.meshMaxilla - Radiographyen_US
dc.subject.meshMolar - Radiographyen_US
dc.subject.meshPeriapical Tissue - Radiographyen_US
dc.subject.meshRadiographic Image Enhancementen_US
dc.subject.meshSubtraction Techniqueen_US
dc.titleComputer-Assisted Densitometric Image Analysis of Digital Subtraction Images: In Vivo Error of the Method and Effect of Thresholdingen_US
dc.typeArticleen_US
dc.identifier.emailLang, NP:nplang@hkucc.hku.hken_US
dc.identifier.authorityLang, NP=rp00031en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.pmid9776024-
dc.identifier.scopuseid_2-s2.0-0032160515en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0032160515&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume69en_US
dc.identifier.issue9en_US
dc.identifier.spage967en_US
dc.identifier.epage974en_US
dc.identifier.isiWOS:000076302600003-
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridBrägger, U=7005538598en_US
dc.identifier.scopusauthoridBürgin, W=7003413848en_US
dc.identifier.scopusauthoridFourmousis, I=6602718088en_US
dc.identifier.scopusauthoridSchmid, G=7202981533en_US
dc.identifier.scopusauthoridSchild, U=6602569290en_US
dc.identifier.scopusauthoridLang, NP=7201577367en_US

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