Validity of three-dimensional computed tomography measurements for Le Fort I osteotomy.

The purpose of this study was to test the precision and accuracy of three-dimensional (3D) linear measurements for Le Fort I osteotomy, obtained from multi-slice computed tomography (MSCT) and cone beam computed tomography (CBCT) scans. The study population consisted of 11 dried skulls submitted to 64-row MSCT and CBCT scans. Three-dimensional reconstructed images (3D-CT) were generated, and linear measurements (n=11) based on anatomical structures and landmarks of interest for Le Fort I osteotomy were performed independently by two oral and maxillofacial radiologists, twice each, using Vitrea software; this allows true 3D measurement on 3D-CT images. The results demonstrated no statistically significant differences between the inter-examiner and intra-examiner analyses, and physical and true 3D linear measurements using MSCT and CBCT images. Regarding examiner accuracy, no statistically significant differences were found for the comparisons among the physical and the MSCT and the CBCT linear measurements by either examiner. For examiners 1 and 2, the analysis intra-examiner correlation coefficient ranged from 0.87 to 0.96 and 0.82 to 0.98, respectively, using MSCT, and from 0.84 to 0.98 and 0.80 to 0.98, respectively, using CBCT, indicating almost perfect agreement for all analyses performed. 3D linear measurements obtained from MSCT and CBCT images were considered precise and accurate for Le Fort I osteotomy and thus accurate and helpful for Le Fort I osteotomy planning.

Comparison of precision and accuracy of linear measurements performed by two different imaging software programs and obtained from 3D-CBCT images for Le Fort I osteotomy.

OBJECTIVE: The purpose of this study was to compare the precision and accuracy of linear measurements for Le Fort I osteotomy performed by two different imaging software programs and obtained from three-dimensional cone beam CT (3D-CBCT) images. METHODS: The study population consisted of 11 dried skulls submitted to CBCT, which generated 3D images. Linear measurements were based on craniometric anatomical landmarks pre-defined by the authors as specifically used for Le Fort I osteotomy and were identified by two radiologists twice each, independently, using Vitrea 3.8.1 (Vital Images Inc., Plymouth, MN) and open-source digital imaging communication in medicine viewer OsiriX 1.2 64-bit (Pixmeo, Geneva, Switzerland). Subsequently, a third examiner made physical measurements using a digital caliper (167 series; Mitutoyo Sul Americana Ltd, Suzano, SP, Brazil). RESULTS: The results demonstrated a statistically significant difference between OsiriX and the gold standard, especially in the pterygoid process (TPtg L = 0.019, LLpPtg R = 0.016 and LLpPtg L = 0.012). Vitrea showed no statistical difference in comparison with the gold standard, and showed a high level of accuracy in all the measurements performed. The major difference found was 0.42 mm (LLpPtg R). Interexaminer analysis ranged from 0.90 to 0.97 using Vitrea and from 0.8 to 0.97 using OsiriX. Intraexaminer correlation coefficient ranged from 0.90 to 0.98 and from 0.84 to 0.98 for Examiners 1 and 2, respectively, using Vitrea and from 0.93 to 0.99 for Examiner 1 and from 0.64 to 0.96 for Examiner 2 using OsiriX. CONCLUSION: Vitrea may be considered as precise and accurate, insofar as it was able to perform all the 3D linear measurements. On the other hand, linear measurements performed using OsiriX were not successful in producing accurate linear measurements for Le Fort I osteotomy.

Oral cleft volumetric assessment by 3D multislice computed tomographic images.

The aim of this study was to determine the quantitative assessment of bone volume defects using multislice computed tomography (CT), and to establish an image processing protocol that enables this analysis. Bone defects were created in nine dry skulls, to mimic oral clefts. All the defects were modelled with wax, following the contralateral shape of the alveolo-palatal region. The wax was used to obtain the real volume of the cleft (gold standard). The skulls (with and without wax) were submitted to multislice CT examination, and the images were processed in an independent workstation using volumetric software. All the images were analysed twice, by two examiners at different times, performing intra- and inter-examiner analyses. The results show that the protocol for image processing has high efficiency (P=0.995). Multislice CT showed excellent results, with high reliability in the study of bone defect volume (P=0.997). The intra- and inter-observer analysis showed no statistically significant differences. It was demonstrated that multislice CT is a reliable technique in the volumetric assessment of bone defects in the alveolar and palatal regions, and that this method was efficient for calculating the volume of the clefts.

Assessment of linear measurements of bone for implant sites in the presence of metallic artefacts using cone beam computed tomography and multislice computed tomography.

The objective was to evaluate the influence of dental metallic artefacts on implant sites using multislice and cone-beam computed tomography techniques. Ten dried human mandibles were scanned twice by each technique, with and without dental metallic artefacts. Metallic restorations were placed at the top of the alveolar ridge adjacent to the mental foramen region for the second scanning. Linear measurements (thickness and height) for each cross-section were performed by a single examiner using computer software. All mandibles were analysed at both the right and the left mental foramen regions. For the multislice technique, dental metallic artefact produced an increase of 5% in bone thickness and a reduction of 6% in bone height; no significant differences (p>0.05) were detected when comparing measurements performed with and without metallic artefacts. With respect to the cone-beam technique, dental metallic artefact produced an increase of 6% in bone thickness and a reduction of 0.68% in bone height. No significant differences (p>0.05) were observed when comparing measurements performed with and without metallic artefacts. The presence of dental metallic artefacts did not alter the linear measurements obtained with both techniques, although its presence made the location of the alveolar bone crest more difficult.

Radiographic assessment of Gardner's syndrome.

The detection of osteomas in the maxillofacial region may be the initial clinical finding in Gardner's syndrome (GS). The most common location of osteomas is in the skull, but the lesion can also occur in the jaws. We present a case of a 47 year old male patient with GS who was referred for radiological evaluation. Extraoral examination revealed an epidermoid cyst and the patient had a history of intestinal polyps. A panoramic radiograph demonstrated numerous osteomas and diffuse sclerosis of the mandible, and compound odontomas with impacted teeth. CT scan allowed the localization and extension of the osteomas, and showed other sites in the maxillofacial region as well. CT images also revealed a different behaviour of osteoma, invading the mandibular canal.

Validity of single- and multislice CT for assessment of mandibular condyle lesions.

OBJECTIVES: The purpose of this study was to evaluate and to compare the validity of the different CT image protocols (single- and multislice CT) in the analysis of simulated mandibular condyle lesions. METHODS: Simulated lesions were created in 15 dry mandibles using a dental round burr. The mandibles were then submitted to a single slice CT, and the same specimens were subsequently submitted to a multislice CT. The analysis was performed by two previously calibrated examiners in four protocols: (1) single slice-axial, (2) multislice-axial, (3) single slice-axial/multiplanar reconstructed (MPR) and (4) multislice-axial/MPR. The examiners evaluated the absence or presence of bony destruction and their localization in each protocol, considering also some bony erosion caused by its reabsorption. Statistical analysis was carried out using validity and chi(2) tests to compare the protocols. RESULTS: Protocol 1 presented the lowest validity values (62.7%). The validity of Protocols 2 and 3 was 66.2% and 72.7%, respectively. The highest value of validity was 93.1% and corresponded to Protocol 4. CONCLUSIONS: All CT-imaging protocols were considered accurate for mandibular condyle lesions assessment. The association of axial with MPR images using multislice CT demonstrated highest accuracy. A new imaging protocol was established for diagnosis of these lesions.

Craniofacial measurements based on 3D-CT volume rendering: implications for clinical applications.

OBJECTIVES: This study was designed to determine the precision and accuracy of anthropometric measurements using three-dimensional computed tomography (3D-CT) volume rendering by computer systems for craniofacial clinical applications, and to compare the craniometric landmarks using bone and soft tissue protocols. METHODS: The study population consisted of 13 cadaver heads that were examined with spiral CT. The archived CT data were transferred to a workstation, and 3D-CT volume rendered images were generated using computer graphics tools. Linear measurements (n = 10), based upon conventional craniometric anatomical landmarks (n = 08), were identified in 2D-CT and in 3D-CT images by two radiologists twice each independently, and then performed by 3D-CT imaging using a computer graphics systems using bone and soft tissue protocols. In total, 520 imaging measurements were made. The soft tissues were subsequently removed from the cadaver heads and the measurements were repeated using an electromagnetic 3 Space trade mark digitizer. RESULTS: The results demonstrated no statistically significant difference between interobserver and intraobserver measurements or between imaging and physical measurements in both 3D-CT protocols. The standard error was found to be between 0.45% and 1.44% for all the measurements in both protocols, indicating a high level of precision. Furthermore, there was no statistically significant difference between imaging and physical measurements (P > 0.01). The error between the mean actual and mean 3D-based linear measurements was 0.83% for bone and 1.78% for soft tissue measurements, demonstrating high accuracy of both 3D-CT protocols. CONCLUSIONS: 3D-CT volume rendering images using craniometric measurements can be used for anthropological studies involving craniofacial applications.

Volumetric and linear assessment of maxillary sinuses using computed tomography.

The purpose of this work was to compare linear and volumetric measurements of maxillary sinus (with and without lesion), using 3D (gold standard) and multiplanar reconstructions (MRP) by computed tomography in order to establish the precision and accuracy of these methods, determining which one would allow more effective assessments for this site. Linear measurements were performed in the maxillary sinus of 50 patients and compared with MPR and 3D images. We also analyzed the area and volume of this anatomic structure. Inter- and intra-observer average percentage errors for linear measurements were lower than 4%, the samples with lesion presenting higher values. The average error of accuracy was 4.94% for sinuses with lesion, and 7.41% for those without. We could verify that the antero-posterior and right-left measurements in axial view showed smaller figures of error when compared to sagittal and coronal reconstructions, respectively. The largest diameters observed for the sinuses had, in average, 39.6 mm in the antero-posterior direction, 28.35 mm in the right-left direction, and 36.3 mm in the supero-inferior. For the volume and area assessment, the values of error ranged lower than 9%, the highest values corresponding to the samples with lesion. The precision of measurements was inferior for maxillary sinus with lesion when compared with those without lesion. Measurements performed in the axial view were more precise than those performed in MPR images, and the coronal view measurements were considered to be more precise than the sagittal measurements.

Clinical-embryological and radiological correlations of oculo-auriculo-vertebral spectrum using 3D-CT.

OBJECTIVES: The purpose of this paper is to present a variety of imaging findings of oculo-auriculo-vertebral spectrum (Goldenhar syndrome) using three-dimensional reconstructed images from computed tomography (3D-CT), associating clinical and embryological patterns of the syndrome. METHODS: The study population consisted of 10 patients with oculo-auriculo-vertebral spectrum with clinically identified hemifacial microsomia. The patients were examined using spiral CT, and abnormal imaging features were grouped under facial, ear and temporal bone, vertebral, and skull base anomalies. The original CT data were transferred to a networked computer workstation with a computer graphics system to generate 3D-CT volume rendered images of the skull and vertebra. Two observers analysed the bone and muscular setting protocols to assess the relationship between bone and muscular structures. RESULTS: Asymmetric underdevelopment was a characteristic pattern of this syndrome resulting from hypoplasia of the mandibular ramus and condyle, the zygomatic, sphenoid and auricular conduct bones, and the temporal and masseter muscles. The syndrome was associated with local atrophy seen on 3D-CT images using specific bone and muscles protocols in all cases. CONCLUSIONS: Understanding the aetiology, embryology and wide imaging spectrum of this syndrome is essential to make a correct diagnosis, for treatment planning, and for evaluation when associated with a 3D-CT computer graphics system.

3D volume rendering using multislice CT for dental implants.

OBJECTIVES: To determine the precision and accuracy of three-dimensional (3D) volume rendering spiral multislice computed tomography (CT)-based linear measurements of the mental foramen for dental implants, in vitro, and their precision, in vivo. METHODS: Five cadaver heads were imaged by multislice spiral CT (Toshiba Aquilion) with 0.5 mm thick axial slices (0.5 mm/0.5 s of table feed) at 0.5 mm interval reconstructions. The image data sets were transferred to a networked computer workstation. Using computer graphics the data were analysed with a 3D volume rendering technique using Vitrea software. Two oral and maxillofacial radiologists, independently, made electronic linear measurements from the superior border of the mental foramen to the crest of the alveolar process. The soft tissues were removed and physical measurements made using a 3 Space (Polhemus, Colchester, VT, USA) electromagnetic digitizer with a personal computer running Windows 98. The same linear measurements of 15 patients using the same imaging methodology were performed and the precision was analysed. RESULTS: The findings showed no statistically significant inter- or intra-observer differences in vitro and in vivo, or between imaging and physical measurements in vitro (P>0.05). CONCLUSIONS: 3D multislice spiral CT imaging allows highly accurate measurements for dental implant placement in proximity to the mental foramen. Computer graphics software, using volume rendering is suitable for implant planning.