Comparison of two - and three-dimensional filtering methods to improve image quality in multiplanar reconstruction of cone-beam computed tomography.
Sagawa M., Miyoseta Y., Hayakawa Y., Honda A.
Oral Radiology. 25(2)(pp 154-158), 2009. Date of Publication: December 2009.
AB Objectives Two- and three-dimensional (2D and 3D, respectively) filtering methods were examined to improve the accuracy of bone morphology depicted in dental conebeam computed tomography (CBCT) images. An attempt to improve multiplanar reconstruction (MPR) image quality was carried out by reducing the image noise. Methods CBCT examinations were performed with the following principal exposure parameters: I-mode, FOV 10 cm in diameter, 120 kV, 15 mA, 0.2 mm slice thickness, and exposure time of 10 s. 2D and 3D filtering procedures for averaging, median smoothing, and Gaussian smoothing were applied for improvement of MPR images. For comparison, 2D and 3D Laplacian sharpening for images preprocessed by Gaussian sharpening was also tested. Results MPR images at the midsagittal plane on the maxilla are presented. Three smoothing filters yielded improvements in slightly different ways. The Gaussian filter clearly showed moderate changes. Small but obvious differences were observed between 2D and 3D filtering. When we focused on the depiction of bone contours, the effects of these noise reduction filters seemed to be minimal in morphological bone depiction. The Laplacian filter was useful for sharpening and emphasized noise in the resulting images, in contrast to those processed by smoothing filters. copyright Japanese Society for Oral and Maxillofacial Radiology and Springer 2009.
Trifid mandibular condyle.
Sezgin O.S., Kayipmaz S.
Oral Radiology. 25(2)(pp 146-148), 2009. Date of Publication: December 2009.
AB Bifid and trifid condyles are rare disorders of the mandible. Their etiology and pathogenesis are unclear. They can be associated with temporomandibular joint disorders or can be diagnosed incidentally on routine radiographic examination. This article presents a case of trifidism of the right mandibular condylar head of a 31-year-old woman with a history of childhood trauma to the head and neck. The patient was asymptomatic. The abnormal formation of the condyle was diagnosed incidentally on a panoramic radiograph and was evaluated using cone-beam computed tomography. copyright Japanese Society for Oral and Maxillofacial Radiology and Springer 2009.
The effect of voxel size on image reconstruction in cone-beam computed tomography.
Tanimoto H., Arai Y.
Oral Radiology. 25(2)(pp 149-153), 2009. Date of Publication: December 2009.
AB Objectives This study evaluated the effects of changing the voxel size on the resolution and noise of cone-beam computed tomography (CBCT) reconstruction images. Methods The voxel sizes used for reconstruction were 160, 80, and 40 lm using prototype software for the Accuitomo F8 (J. Morita, Kyoto, Japan). The resolution was measured using a modulation transfer function (MTF), and CBCT images of a 1-mm-thick, 10-mm-diameter aluminum pipe set slightly inclined from the vertical were taken with a field of view of 8 cm. To measure the noise, a tomographic image of an 8-cm-diameter water phantom was taken and reconstructed at the three voxel sizes. The standard deviation (SD) of the noise was then determined. Results The MTF at 2 lp/mm was 0.05, 0.12, and 0.12 for voxel sizes of 160, 80, and 40 lm, respectively, and the SD of the noise was 10.0, 13.8, and 17.1% for the same respective voxel sizes. Conclusions The limit of resolution was determined to be the 80-mum voxel size. When the voxels were smaller, the noise increased. copyright Japanese Society for Oral and Maxillofacial Radiology and Springer 2009.
Fronto-orbital sphenoethmoidal fibrous dysplasia.
Orhan K., Icen M., Paksoy C.S., Arslan A., Oztas B.
Oral Radiology. 25(2)(pp 135-141), 2009. Date of Publication: December 2009.
AB Cranial fibrous dysplasias (FDs) are rare and comprise less than 1% of all primary bone lesions. They may produce cosmetic deformities, peripheral compressive cranial neuropathies, and compressive central neurologic manifestations. We describe an unusual presentation of a fronto-orbital sphenoethmoidal FD in a 32-year-old woman with conventional radiographic, CBCT, and MRI findings. In the head and neck examination, an asymmetry was noticed on the left side, without evidence of adenopathy, paresthesia, or motor nerve deficiency. Panoramic radiographs showed a radiopaque expanded bone in the region of the posterior maxillary sinus and orbita. Computed tomography with three-dimensional reconstruction demonstrated an expanding lesion of the cranial bones, involving the ethmoid and periorbital bone, producing a ground-glass appearance. After the radiologic examination, the patient was referred for surgery with a diagnosis of cranial FD and underwent a cranioplasty. The CT and MRI features were typical for FD, but physicians and dental professionals should be aware of this diagnosis, even if no symptom is apparent and the patient came in only for a routine dental examination. Maxillofacial radiologists should also consider that the signal intensity on both T1- and T2-weighted images and the degree of contrast enhancement on T1-weighted images depend on the amount and degree of bony trabeculae, cellularity, collagen, and cystic and hemorrhagic changes. copyright Japanese Society for Oral and Maxillofacial Radiology and Springer 2009.
Simple technique to achieve a natural position of the head for cone beam computed tomography.
Damstra J., Fourie Z., Ren Y.
British Journal of Oral and Maxillofacial Surgery. 48(3)(pp 236-238), 2010. Date of Publication: April 2010.
AB We developed a modified laser level technique to record the natural position of the head in all three planes of space. This is a simple method for use with three-dimensional images and may be valuable in routine craniofacial assessment. copyright 2009 The British Association of Oral and Maxillofacial Surgeons.