Limits...
Micro-CT vs. Whole Body Multirow Detector CT for Analysing Bone Regeneration in an Animal Model

View Article: PubMed Central - PubMed

ABSTRACT

Objectives: 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.

No MeSH data available.


2D coronal (A—D) and sagittal (E—H) μCT (left column) and MDCT (right column) images (A, B, E and F) and corresponding colour-coded illustrations (C, D, G and H) of the CSD region.The newly formed woven bone is shown in dark (blue), and the original cortical bone is shown in bright (white). Within the former cylindrical defect of 5 mm (VOI), the ROI is illustrated.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5120815&req=5

pone.0166540.g002: 2D coronal (A—D) and sagittal (E—H) μCT (left column) and MDCT (right column) images (A, B, E and F) and corresponding colour-coded illustrations (C, D, G and H) of the CSD region.The newly formed woven bone is shown in dark (blue), and the original cortical bone is shown in bright (white). Within the former cylindrical defect of 5 mm (VOI), the ROI is illustrated.

Mentions: A standard circle with a diameter of 5 mm corresponding to the defect was manually drawn and served as the ROI (Fig 1E). A VOI (height, approximately 2.42 mm; diameter, 5 mm), which corresponded to the maximum medial-lateral width of the defect depending on the amount of bone regeneration, was determined from the 2D images (Figs 1E and 2 left column). A constrained 3D Gaussian filter was used to partially suppress the noise in the volumes. A global threshold was determined visually by two independent examiners (based on slice-wise 2D comparisons between the grey scale and segmented image of all samples and the associated histograms) [5, 7, 21]. All samples were binarised using the same parameters for sigma (1.2), support (2), and threshold (353.5 mg HA/cm3) [22]. All image processing steps were conducted automatically using Image Processing Language (IPL, Scanco Medical, Bruttisellen, Switzerland) on an Alpha-based open VMS workstation (DS20E, Hewlett Packard, Inc.) [22, 23].


Micro-CT vs. Whole Body Multirow Detector CT for Analysing Bone Regeneration in an Animal Model
2D coronal (A—D) and sagittal (E—H) μCT (left column) and MDCT (right column) images (A, B, E and F) and corresponding colour-coded illustrations (C, D, G and H) of the CSD region.The newly formed woven bone is shown in dark (blue), and the original cortical bone is shown in bright (white). Within the former cylindrical defect of 5 mm (VOI), the ROI is illustrated.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120815&req=5

pone.0166540.g002: 2D coronal (A—D) and sagittal (E—H) μCT (left column) and MDCT (right column) images (A, B, E and F) and corresponding colour-coded illustrations (C, D, G and H) of the CSD region.The newly formed woven bone is shown in dark (blue), and the original cortical bone is shown in bright (white). Within the former cylindrical defect of 5 mm (VOI), the ROI is illustrated.
Mentions: A standard circle with a diameter of 5 mm corresponding to the defect was manually drawn and served as the ROI (Fig 1E). A VOI (height, approximately 2.42 mm; diameter, 5 mm), which corresponded to the maximum medial-lateral width of the defect depending on the amount of bone regeneration, was determined from the 2D images (Figs 1E and 2 left column). A constrained 3D Gaussian filter was used to partially suppress the noise in the volumes. A global threshold was determined visually by two independent examiners (based on slice-wise 2D comparisons between the grey scale and segmented image of all samples and the associated histograms) [5, 7, 21]. All samples were binarised using the same parameters for sigma (1.2), support (2), and threshold (353.5 mg HA/cm3) [22]. All image processing steps were conducted automatically using Image Processing Language (IPL, Scanco Medical, Bruttisellen, Switzerland) on an Alpha-based open VMS workstation (DS20E, Hewlett Packard, Inc.) [22, 23].

View Article: PubMed Central - PubMed

ABSTRACT

Objectives: 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.

No MeSH data available.