The aim of this study was to analyze the imaging accuracy of cone beam computed tomography (CBCT) data sets compared with multislice spiral computed tomography (MSCT) data sets in determining the exact mesiodistal width of unerupted porcine tooth germs and to compare the radiologically obtained results of width measurements with the actual mesiodistal dimension of the tooth germs. In MSCT and CBCT data sets, the largest diameter of 24 tooth germs was determined with the aid of the mesial and distal contact points. The reference method used was mesiodistal width measurement using sliding callipers after the tooth germs had been osteotomized. Accuracy and precision were ascertained with difference plots and a one-way model II analysis of variance with random effects. Analysis of accuracy revealed marked differences between the measuring methods in the difference plot: slightly higher mean values were measured by MSCT and markedly lower values by CBCT than by the reference method (calliper); the mean deviation was significantly greater for CBCT. The width of the confidence interval in the comparison of CBCT versus clinical measurements is more than 4 times higher than in the comparison of MSCT versus clinical values. Precision analysis found that repeatability was twice as high with CBCT as with clinical measurement, whereas MSCT and clinical measurement differed only slightly. The mesiodistal width of displaced teeth can be determined by MSCT but also by CBCT. MSCT is superior to CBCT in determining tooth width; the difference was statistically significant (P = 0.05).

All selected landmarks offer suitably high levels of intra- and interserial precision for the three-dimensional (3D) metric assessment of facial soft-tissue parameters. No difference between (bi)lateral and facial midline landmarks was noted.

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Given our findings of acceptable agreement between 3D scanning and 2D lateral photography, in combination with almost perfect internal agreement between different 3D view modes, it appears useful to adapt Schwarz's method of facial profile assessment for clinical use in 3D virtual environments.

HistoryA 12-year-old castrated male domestic shorthair cat was evaluated for a history of decreased appetite and activity of 1 month' s duration. Vomiting or diarrhea had not been observed by the owner. On physical examination, the cat was quiet, alert, and responsive. On palpation, a mass that was approximately 8 cm in diameter was detected in the cranioventral aspect of the abdomen. No additional abnormalities were noted.A CBC revealed a high WBC count of 23.7 X 10 3 cells/µL (reference range, 3.5 X 10 3 to 16 X 10 3 cells/µL), and serum biochemical analysis revealed a mildly high alanine transaminase activity of 390 U/L (reference range, 10 to 100 U/L). Remaining laboratory values were within reference ranges. No abnormalities were detected on thoracic radiographs. Abdominal radiographs were obtained (Figure 1). Determine whether additional imaging studies are required, or make your diagnosis from Figure 1-then turn the page →