title: A comparison of the thresholding strategies of micro-CT for periodontal bone loss: a pilot study.
abstract: OBJECTIVE
  Micro-CT provides three-dimensional details and has been widely used for biomedical assessments. This study aimed to determine the most appropriate threshold method for quantitatively assessing the dynamics of periodontal destruction.
  
  
  METHODS
  Inflammation was induced by submerging a silk ligature in the sulcus of the maxillary second molars of rats, and the animals were killed prior to ligature placement and after 7 and 21 days. The maxillae were examined for the bone resorptive activities by micro-CT, histology and tartrate-resistant acid phosphatase staining. The imaging threshold was determined by CT phantom, global and local algorithms. A bone fraction measurement from each threshold-determining technique was compared with histomorphometry. The reliability and reproducibility were examined by the intraclass correlation coefficient (ICC) and the coefficient of variation.
  
  
  RESULTS
  Significant reduction of inflammatory infiltration (p < 0.01) and active osteoclastic resorption (p < 0.05) from Day 7 to Day 21 were noted. High inter- and intraexaminer agreement were demonstrated in both histomorphometric and micro-CT assessments (ICC > 0.98). The algorithm-based technique demonstrated stronger correlation to histomorphometry than phantom-based thresholds, and the highest agreement was presented by the local algorithm (ICC > 0.96). This, however, was considerably computationally expensive.
  
  
  CONCLUSIONS
  The local threshold-determining algorithm is suggested for examining inflammation-induced bone loss. Further investigation will be aimed at enhancing computational efficiency.
authors: National University of Singapore, Singapore. dencpc@nus.edu.sg
authors: P-C
authors: PC
authors: Chang
authors: K
authors: K
authors: Liang
authors: J C
authors: JC
authors: Lim
authors: M-C
authors: MC
authors: Chung
authors: L-Y
authors: LY
authors: Chien
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D000465:Algorithms; D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging* / Q000473:pathology; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D003094:Collagen; D004396:Coloring Agents; D003238:Connective Tissue / Q000473:pathology; D004195:Disease Models, Animal; D005881:Gingiva / Q000473:pathology; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D007527:Isoenzymes / Q000032:analysis; D008297:Male; D008439:Maxillary Diseases / Q000000981:diagnostic imaging / Q000473:pathology; D008963:Molar / Q000000981:diagnostic imaging; D010010:Osteoclasts / Q000473:pathology; D010518:Periodontitis / Q000000981:diagnostic imaging / Q000473:pathology; D019047:Phantoms, Imaging; D010865:Pilot Projects; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D000071681:Tartrate-Resistant Acid Phosphatase; D013997:Time Factors; D019237:Tooth Cervix / Q000473:pathology; D055114:X-Ray Microtomography / Q000379:methods*
chemical_list: D015415:Biomarkers; D004396:Coloring Agents; D007527:Isoenzymes; D003094:Collagen; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase