Marcelo Gusmão Paraíso Cavalcanti

Three-dimensional computed tomography landmark measurement in craniofacial surgical planning: Experimental validation in vitro

PURPOSEnThis study evaluated the measurement accuracy of three-dimensional (3D) volumetric images from spiral computed tomography (CT) in vitro.nnnMATERIALS AND METHODSnThe study sample consisted of nine cadaver heads that were submitted to an impact force by a special device to promote blunt traumatic craniofacial fractures. The heads were subsequently scanned by a spiral CT scanner (Toshiba Xpress S/X). The archived CT data were transferred to networked computer workstations (Sun Microsystems with Cemax VIP version 1.4 software) to generate 3D volumetric images. The visualization software was used to make interactive linear measurements on the 3D images. Measurements were made on the images twice by two observers, based on conventional craniofacial anatomic landmarks. The soft tissues were subsequently removed, and the same measurements were repeated on the cadaver heads with an electromagnetic digitizer (3 Space, Polhemus, Colchester, VT).nnnRESULTSnThe results showed no statistically significant differences between the 3D-CT and the physical measurements, with P>.05 for all measurements. The mean difference between the image and real measurements was less than 2 mm in all instances.nnnCONCLUSIONSnIt is concluded that measurement of the skull and facial bone landmarks by 3D reconstruction is quantitatively accurate for surgical planning and treatment evaluation of craniofacial fractures.

Spiral CT image deblurring for cochlear implantation

Cochlear implantation is the standard treatment for profound hearing loss, Preimplantation and postimplantation spiral computed tomography (CT) is essential in several key clinical and research aspects. The maximum image resolution with commercial spiral CT scanners is insufficient to define clearly anatomical features and implant electrode positions in the inner ear, In this paper, the authors develop an expectation maximization (EM)-like iterative deblurring algorithm to achieve spiral CT image super-resolution for cochlear implantation, assuming a spatially invariant linear spiral CT system with a three-dimensional (3-D) separable Gaussian point spread function (PSF). The authors experimentally validate the 3-D Gaussian blurring model via phantom measurement and profile fitting. The imaging process is further expressed as convolution of an isotropic 3-D Gaussian PSF and a blurred underlying volumetric image. Under practical conditions, an oblique reconstructed section is approximated as convolution of an isotropic two dimensional (2-D) Gaussian PSF and the corresponding actual cross section. The spiral CT image deblurring algorithm is formulated with sieve and resolution kernels for suppressing noise and edge artifacts. A typical cochlear cross section is used for evaluation, demonstrating a resolution gain up to 30%-40% according to the correlation criterion. Physical phantoms, preimplantation and postimplantation patients are reconstructed into volumes of 0.1-mm cubic voxels. The patient images are digitally unwrapped along the central axis of the cochlea and the implanted electrode array respectively, then oblique sections orthogonal to the central axis formed. After deblurring, representation of structural features is substantially improved in all the cases.

2-D and 3-D reconstructions of spiral computed tomography in localization of the inferior alveolar canal for dental implants ☆ ☆☆ ★

OBJECTIVEnThe purpose of this study was to compare and validate the accuracy of measurements on 2-dimensional and 3-dimensional reconstructions from spiral computed tomography in localization of the inferior alveolar canal.nnnSTUDY DESIGNnFour edentulous human cadaver heads with intact mandibles were imaged in a spiral computed tomography scanner. The data were transferred to a networked computer workstation to generate 2-dimensional orthoradially reformatted and 3-dimensional volumetric images. Linear measurements of the images were made from the superior border of the inferior alveolar canal to the alveolar crest. The specimens were then dissected at corresponding locations, and physical measurements were made.nnnRESULTSnThere were no statistically significant differences between the 2-dimensional computed tomography measurements and the physical measurements or between the 3-dimensional computed tomography measurements and the physical measurements. However, we did find a statistically significant difference between the 2-dimensional and 3-dimensional computed tomography measurements.nnnCONCLUSIONSn2-dimensional and 3-dimensional computed tomography images allow accurate measurements for localization of the inferior alveolar canal.

Computed tomography imaging findings of simultaneous bifid mandibular condyle and temporomandibular joint ankylosis: case report

Bifid mandibular condyle is an uncommon entity described in the literature as having a controversial etiology. Despite the absence of clinical symptomatology, the radiologist must be aware and should have some knowledge of this abnormality, as well its implications regarding functional and morphological changes. TMJ ankylosis is a disabling disease with involvement of the mandibular condyle, articular fossa and base of the skull. The association of bifid condyle with temporomandibular joint ankylosis is rare and must be carefully evaluated. The purpose of this paper is to report a case of simultaneous bifid mandibular condyle and temporomandibular joint ankylosis and to describe its computed tomography imaging findings.

3D-CT imaging processing for qualitative and quantitative analysis of maxillofacial cysts and tumors

The objective of this study was to evaluate spiral-computed tomography (3D-CT) images of 20 patients presenting with cysts and tumors in the maxillofacial complex, in order to compare the surface and volume techniques of image rendering. The qualitative and quantitative appraisal indicated that the volume technique allowed a more precise and accurate observation than the surface method. On the average, the measurements obtained by means of the 3D volume-rendering technique were 6.28% higher than those obtained by means of the surface method. The sensitivity of the 3D surface technique was lower than that of the 3D volume technique for all conditions stipulated in the diagnosis and evaluation of lesions. We concluded that the 3D-CT volume rendering technique was more reproducible and sensitive than the 3D-CT surface method, in the diagnosis, treatment planning and evaluation of maxillofacial lesions, especially those with intra-osseous involvement.

Interpretation of mandibular condyle fractures using 2D- and 3D-computed tomography

Computed tomography (CT) has been increasingly used in the examination of patients with craniofacial trauma. This technique is useful in the examination of the temporomandibular joint and allows the diagnosis of fractures of the mandibular condyle. Aiming to verify whether the three-dimensional reconstructed images from CT (3D-CT) produce more effective visual information than the two-dimensional (2D-CT) ones, we evaluated 2D-CT and 3D-CT examinations of 18 patients with mandibular condyle fractures. We observed that 2D-CT and 3D-CT reconstructed images produced similar information for the diagnosis of fractures of the mandibular condyle, although the 3D-CT allowed a better visualization of the position and displacement of bone fragments, as well as the comminution of fractures. These results, together with the possibility of refining and manipulating perspectives in 3D images, reinforce the importance of its use in the surgical planning and evaluation of treatment. We concluded that 3D-CT presented supplementary information for a more effective diagnosis of mandibular condyle fractures.

Osteochondroma of the temporomandibular joint: a case report

Osteochondroma of the mandibular condyle has been found in the oral and maxillofacial region rarely. This paper describes a case of osteochondroma of the mandibular condyle in a 20-year-old woman, who was referred to our service with facial asymmetry, prognathic deviation of chin, cross-bite to the contralateral side, changes in condylar morphology, limited mouth opening, and malocclusion. Computed tomography (CT) was performed for better evaluation to the pathological conditions on the temporomandibular joint. Based on the clinical examination, patient history, and complementary exams, the hypothesis of osteochondroma was established. Condylectomy was performed using a preauricular approach with total removal of the lesion. After 3 years of postoperative follow up and orthodontic therapy, the patient is symptom-free, and has normal mouth opening with no deviation in the opening pattern.

Radiologic interpretation of bone striae: An experimental study in vitro ☆ ☆☆ ★

OBJECTIVEnThe purpose of this study was to determine whether the mandibular alveolar striae patterns seen in radiographs represent trabecular bone.nnnSTUDY DESIGNnSegments of human cadaver mandible were obtained. Two identical radiographs were made of each segment initially, after removal of trabecular bone, after slight smoothing of the endosteal surface, and after aggressive smoothing of the endosteal surface. The radiographs were projected in random pairs for each sample. Six dentists judged whether a difference in the amount of trabecular bone could be detected.nnnRESULTSnChi-square test analysis revealed no significant difference in the amount of trabecular bone judged initially and after removal of trabecular bone. A significant difference appeared to exist on radiographs made initially and after slight smoothing. A significant difference was judged to exist on radiographs made after slight removal of the endosteal surface and after aggressive removal of the endosteal surface.nnnCONCLUSIONSnMandibular radiographic striae patterns, interpreted as arising from trabecular bone, actually result from bone patterns on the endosteal surface.

Effect of Cone-Beam Computed Tomography Field of View and Acquisition Frame on the Detection of Chemically Simulated Peri-Implant Bone Loss In Vitro

BACKGROUNDnThe aim of this study is to determine the influence of field of view (FOV) and number of acquisition projection images (frames) on the detection of chemically simulated peri-implant defects by cone-beam computed tomography (CBCT) using an in vitro bovine rib bone model.nnnMETHODSnEighty implants were placed in bovine ribs in which small and large bone defects were created using 70% perchloric acid. CBCT images were acquired at three acquisition protocols: protocol 1 (FOV 4 × 4 cm, 0.08-mm voxel size, 1,009 frames [high fidelity]; protocol 2 (same as protocol 1 except 512 frames [standard]); and protocol 3 (FOV 14 × 5 cm, 0.25-mm voxel size; high fidelity). Two oral and maxillofacial radiologists (OMRs) and two oral and maxillofacial surgeons (OMSs) rated the presence or absence of bone defects on a five-point scale. κ and area under the curve (AUC) were calculated and compared using analysis of variance with post hoc Tukey test at P ≤ 0.05.nnnRESULTSnIntra- and interobserver agreement for OMRs ranged from moderate to good and from slight to moderate for OMSs. For the detection of small lesions, protocol 1 (AUC 0.813 ± 0.045) provided higher detection rates than protocol 2 (AUC 0.703 ± 0.02) and protocol 3 (AUC 0.773 ± 0.55) [F(2,9) = 1.6377]. For larger defects, the trends were similar, with protocol 1 (AUC 0.852 ± 0.108) providing higher detection rates than protocol 2 (AUC 0.730 ± 0.045) and protocol 3 (AUC 0.783 ± 0.058) [F(2,9) = 1.9576].nnnCONCLUSIONnWithin the limits of this study, optimal detection of chemically simulated pericircumferential implant crestal bone defects is achieved at the least radiation detriment using the smallest FOV, the highest number of acquisition frames, and the smallest voxel.

CT-based analysis of malignant tumor volume and localization: a preliminary study

The purpose of this study was to correlate 3D-CT (3D computed tomography) volume measurements of malignant tumors with the response to treatment, and to observe bone invasion in these lesions applying a specific imaging protocol. We analyzed 17 individuals with maxillofacial malignant lesions who were submitted to spiral CT (2D-CT). The original data were transferred to an independent workstation using a 3D volume rendering package software, which was used by two examiners to obtain area and volume measurements of the lesions, independently, three times each, prior to and after treatment. The segmentation protocol was applied for the assessment of bone involvement. The difference between imaging and gold standard values was not considered significant (p > 0.05). Regarding bone invasion, three false-negatives were obtained using MPR-CT (multiplanar reconstruction) and no false-negatives were obtained using the 3D segmentation protocol. The use of 3D-CT may be a differential and important factor for expanding options regarding the localization, dimension, and clarification of lesion components.