title: Micro-CT vs. Whole Body Multirow Detector CT for Analysing Bone Regeneration in an Animal Model.
abstract: OBJECTIVE
  Compared with multirow detector CT (MDCT), specimen (ex vivo) micro-CT (μCT) has a significantly higher (~ 30 x) spatial resolution and is considered the gold standard for assessing bone above the cellular level. However, it is expensive and time-consuming, and when applied in vivo, the radiation dose accumulates considerably. The aim of this study was to examine whether the lower resolution of the widely used MDCT is sufficient to qualitatively and quantitatively evaluate bone regeneration in rats.
  
  
  METHODS
  Forty critical-size defects (5mm) were placed in the mandibular angle of rats and covered with coated bioactive titanium implants to promote bone healing. Five time points were selected (7, 14, 28, 56 and 112 days). μCT and MDCT were used to evaluate the defect region to determine the bone volume (BV), tissue mineral density (TMD) and bone mineral content (BMC).
  
  
  RESULTS
  MDCT constantly achieved higher BV values than μCT (10.73±7.84 mm3 vs. 6.62±4.96 mm3, p<0.0001) and consistently lower TMD values (547.68±163.83 mm3 vs. 876.18±121.21 mm3, p<0.0001). No relevant difference was obtained for BMC (6.48±5.71 mm3 vs. 6.15±5.21 mm3, p = 0.40). BV and BMC showed very strong correlations between both methods, whereas TMD was only moderately correlated (r = 0.87, r = 0.90, r = 0.68, p < 0.0001).
  
  
  CONCLUSIONS
  Due to partial volume effects, MDCT overestimated BV and underestimated TMD but accurately determined BMC, even in small volumes, compared with μCT. Therefore, if bone quantity is a sufficient end point, a considerable number of animals and costs can be saved, and compared with in vivo μCT, the required dose of radiation can be reduced.
authors.affiliation: Department of Oral- and Maxillofacial Surgery, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Bissinger
authors.affiliation: Department of Diagnostic and Interventional Radiology, Section of Neuroradiology, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany.
authors.forename: Jan S
authors.initials: JS
authors.lastname: Kirschke
authors.affiliation: Department of Oral- and Maxillofacial Surgery, Ludwig-Maximilians-University of Munich, Munich, Germany.
authors.forename: Florian Andreas
authors.initials: FA
authors.lastname: Probst
authors.affiliation: Scanco Medical AG, Brüttisellen, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Stauber
authors.affiliation: Department of Oral- and Maxillofacial Surgery, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany.
authors.forename: Klaus-Dietrich
authors.initials: KD
authors.lastname: Wolff
authors.affiliation: Institute of Medical Statistics and Epidemiology, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Haller
authors.affiliation: Department of Oral- and Maxillofacial Surgery, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany.
authors.forename: Carolin
authors.initials: C
authors.lastname: Götz
authors.affiliation: Institute of Molecular Immunology - Experimental Oncology, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Plank
authors.affiliation: Department of Oral- and Maxillofacial Surgery, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany.|Institute of Molecular Immunology - Experimental Oncology, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kolk
mesh_terms: D000818:Animals; D015519:Bone Density; D001861:Bone Regeneration / Q000502:physiology*; D001842:Bone and Bones / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D004195:Disease Models, Animal; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014057:Tomography, X-Ray Computed; D055114:X-Ray Microtomography