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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.


Related in: MedlinePlus

Yellow rectangle representing the bone to be measured (left: μct, right: MDCT).Voxels that are filled to more than 50% are counted as bone (blue or red), while those that are filled to less than 50% are not counted (white). Because of the lower resolution of the larger voxels of the MDCT, it generates a higher BV than that of the real bone. In contrast, the μCt, with its high resolution and very small voxel size, generates a more precise volume.
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pone.0166540.g004: Yellow rectangle representing the bone to be measured (left: μct, right: MDCT).Voxels that are filled to more than 50% are counted as bone (blue or red), while those that are filled to less than 50% are not counted (white). Because of the lower resolution of the larger voxels of the MDCT, it generates a higher BV than that of the real bone. In contrast, the μCt, with its high resolution and very small voxel size, generates a more precise volume.

Mentions: MDCT significantly overestimated the BV values compared to μCT (10.73 mm3 ± 7.84 vs. 6.62 mm3 ± 4.96, mean of the differences = bias: + 4.11 mm3, p < 0.0001, Fig 3A, Table 2). In contrast, the MDCT data significantly underestimated the TMD values compared to μCT (547.68 mg HA/cm3 ± 163.83 vs. 876.18 mg HA/cm3 ± 121.21, bias: - 328.5 mg HA/cm3, p < 0.0001, Fig 3B, Table 2). Differences in the quality of resolution (Fig 2) between μCT (left column) and MDCT (right column) are clearly visible in a scheme explaining the influence of the different voxel sizes (Fig 4): voxels that were filled to more than 50% with mineralised tissue were counted as bone (blue = μCT, red = MDCT), whereas those that were filled to less than 50% with mineralised tissue were not counted (white). The yellow rectangle representing the bone to be measured (left: μCT, right: MDCT) was imaged much more precisely with μCT than with MDCT.


Micro-CT vs. Whole Body Multirow Detector CT for Analysing Bone Regeneration in an Animal Model
Yellow rectangle representing the bone to be measured (left: μct, right: MDCT).Voxels that are filled to more than 50% are counted as bone (blue or red), while those that are filled to less than 50% are not counted (white). Because of the lower resolution of the larger voxels of the MDCT, it generates a higher BV than that of the real bone. In contrast, the μCt, with its high resolution and very small voxel size, generates a more precise volume.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5120815&req=5

pone.0166540.g004: Yellow rectangle representing the bone to be measured (left: μct, right: MDCT).Voxels that are filled to more than 50% are counted as bone (blue or red), while those that are filled to less than 50% are not counted (white). Because of the lower resolution of the larger voxels of the MDCT, it generates a higher BV than that of the real bone. In contrast, the μCt, with its high resolution and very small voxel size, generates a more precise volume.
Mentions: MDCT significantly overestimated the BV values compared to μCT (10.73 mm3 ± 7.84 vs. 6.62 mm3 ± 4.96, mean of the differences = bias: + 4.11 mm3, p < 0.0001, Fig 3A, Table 2). In contrast, the MDCT data significantly underestimated the TMD values compared to μCT (547.68 mg HA/cm3 ± 163.83 vs. 876.18 mg HA/cm3 ± 121.21, bias: - 328.5 mg HA/cm3, p < 0.0001, Fig 3B, Table 2). Differences in the quality of resolution (Fig 2) between μCT (left column) and MDCT (right column) are clearly visible in a scheme explaining the influence of the different voxel sizes (Fig 4): voxels that were filled to more than 50% with mineralised tissue were counted as bone (blue = μCT, red = MDCT), whereas those that were filled to less than 50% with mineralised tissue were not counted (white). The yellow rectangle representing the bone to be measured (left: μCT, right: MDCT) was imaged much more precisely with μCT than with MDCT.

View Article: PubMed Central - PubMed

ABSTRACT

Objectives: Compared with multirow detector CT (MDCT), specimen (ex vivo) micro-CT (&mu;CT) 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). &mu;CT 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 &mu;CT (10.73&plusmn;7.84 mm3 vs. 6.62&plusmn;4.96 mm3, p&lt;0.0001) and consistently lower TMD values (547.68&plusmn;163.83 mm3 vs. 876.18&plusmn;121.21 mm3, p&lt;0.0001). No relevant difference was obtained for BMC (6.48&plusmn;5.71 mm3 vs. 6.15&plusmn;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 &lt; 0.0001).

Conclusions: Due to partial volume effects, MDCT overestimated BV and underestimated TMD but accurately determined BMC, even in small volumes, compared with &mu;CT. Therefore, if bone quantity is a sufficient end point, a considerable number of animals and costs can be saved, and compared with in vivo &mu;CT, the required dose of radiation can be reduced.

No MeSH data available.


Related in: MedlinePlus