Comparison between 3D volumetric rendering and multiplanar slices on the reliability of linear measurements on CBCT images: an in vitro study

Abstract

Objective The purpose of this study was to determine the accuracy and reliability of two methods of measurements of linear distances (multiplanar 2D and tridimensional reconstruction 3D) obtained from cone-beam computed tomography (CBCT) with different voxel sizes.Material and Methods Ten dry human mandibles were scanned at voxel sizes of 0.2 and 0.4 mm. Craniometric anatomical landmarks were identified twice by two independent operators on the multiplanar reconstructed and on volume rendering images that were generated by the software Dolphin®. Subsequently, physical measurements were performed using a digital caliper. Analysis of variance (ANOVA), intraclass correlation coefficient (ICC) and Bland-Altman were used for evaluating accuracy and reliability (p<0.05).Results Excellent intraobserver reliability and good to high precision interobserver reliability values were found for linear measurements from CBCT 3D and multiplanar images. Measurements performed on multiplanar reconstructed images were more accurate than measurements in volume rendering compared with the gold standard. No statistically significant difference was found between voxel protocols, independently of the measurement method.Conclusions Linear measurements on multiplanar images of 0.2 and 0.4 voxel are reliable and accurate when compared with direct caliper measurements. Caution should be taken in the volume rendering measurements, because the measurements were reliable, but not accurate for all variables. An increased voxel resolution did not result in greater accuracy of mandible measurements and would potentially provide increased patient radiation exposure.

Method of visualisation influences accuracy of measurements in cone-beam computed tomography

“…The observed accuracies (in terms of mean, distribution and range of the average differences) are similar to the results portrayed in various other investigations for linear measurements performed with isosurface (Periago et al, 2008), direct volume rendering (Fernandes et al, 2014), MPR (Sun et al, 2011, Patcas et al, 2012, Patel et al, 2014 and maximum intensity projection (Markic et al, 2015), all demonstrating insufficient sub-millimetre accuracy for sub-millimetre voxel data.…”

“…Yet our results concur with the little prevailing evidence. Fernandes et al (2014) recently asserted comparable reproducibility for linear measurements on multiplanar images and volume rendering, but slightly superior accuracy for measurements taken on multiplanar sections. By comparing landmark identification on isosurface with a combination of MPR alongside the isosurface, a greater precision for the latter could be attested (Hassan et al, 2013).…”

Integração morfológica e modularidade em crânios das espécies do grupo Rhinella granulosa

“…The magnitudes of differences that we found for DIG and the micro-CT resolutions are similar to differences reported by other authors when comparing measurements taken with CT data and digital calipers (Richard et al 2014;Fernandes et al 2014), although the last authors did find a systematic bias in the CT data (all distances under-estimated). Yet, when comparing our results with other authors that measured the same specimens with a 3D digitizer (Polhemus 3Space) and CT (Corner et al 1992;Stull et al 2014), our error betweenmethods is much smaller (around five to ten times smaller).…”

“…When looking at the between-methods mean percentage error, the error in relation to the distances mean lengths, we can see that the cases around 10 % correspond to three small distances: 5 (frontoparietal bone), 13 (nasal bone) and 25 (parasphenoid bone), and just one longer distance: 16 (squamosal bone), which is composed of two landmarks detected with high deviations for DIG (landmarks 8 and 12). The magnitudes of differences that we found for DIG and the micro-CT resolutions are similar to differences reported by other authors when comparing measurements taken with CT data and digital calipers [18,21], although the last authors did find a systematic bias in the CT data (all distances under-estimated). Yet, when comparing our results with other authors that measured the same specimens with a 3D digitizer (Polhemus 3Space) and CT [15,19], our error betweenmethods is much smaller (around five to ten times smaller).…”

3D CBCT Evaluation of Condyle Position in Skeletal Class I & Class III Growing Subjects

“…15 The accuracy and reliability of Dolphin software for linear and angular measurements has been established by previous studies. 16 CBCT images are accurate and provide detailed images with good spatial resolution for assessing TMJ while the exposure is very low as compared to conventional CT.…”