• Maxillofacial Plastic and Reconstructive Surgery
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• v.42
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• pp.17.1-17.11
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• 2020

Background: To evaluate the facial asymmetry, three-dimensional computed tomography (3D-CT) has been used widely. This study proposed a method to quantify facial asymmetry based on 3D-CT. Methods: The normal standard group consisted of twenty-five male subjects who had a balanced face and normal occlusion. Five anatomical landmarks were selected as reference points and ten anatomical landmarks were selected as measurement points to evaluate facial asymmetry. The formula of facial asymmetry index was designed by using the distances between the landmarks. The index value on a specific landmark indicated zero when the landmarks were located on the three-dimensional symmetric position. As the asymmetry of landmarks increased, the value of facial asymmetry index increased. For ten anatomical landmarks, the mean value of facial asymmetry index on each landmark was obtained in the normal standard group. Facial asymmetry index was applied to the patients who had undergone orthognathic surgery. Preoperative facial asymmetry and postoperative improvement were evaluated. Results: The reference facial asymmetry index on each landmark in the normal standard group was from 1.77 to 3.38. A polygonal chart was drawn to visualize the degree of asymmetry. In three patients who had undergone orthognathic surgery, it was checked that the method of facial asymmetry index showed the preoperative facial asymmetry and the postoperative improvement well. Conclusions: The current new facial asymmetry index could efficiently quantify the degree of facial asymmetry from 3D-CT. This method could be used as an evaluation standard for facial asymmetry analysis.

• Journal of Korean Neurosurgical Society
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• v.56 no.5
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• pp.400-404
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• 2014

Objective : Clip artifacts limit the visualization of intracranial structures in CT scans from patients after aneurysmal clipping with cobalt alloy clips. This study is to analyze the parameters influencing the degree of clip artifacts. Methods : Postoperative CT scans of 60 patients with straight cobalt alloy-clipped aneurysms were analyzed for the maximal diameter of white artifacts and the angle and number of streak artifacts in axial images, and the maximal diameter of artifacts in three-dimensional (3-D) volume-rendered images. The correlation coefficient (CC) was determined between each clip artifact type and the clip blade length and clip orientation to the CT scan (angle a, lateral clip inclination in axial images; angle b, clip gradient to scan plane in lateral scout images). Results : Angle b correlated negatively with white artifacts (r=-0.589, p<0.001) and positively with the angle (r=0.636, p<0.001) and number (r=0.505, p<0.001) of streak artifacts. Artifacts in 3-D images correlated with clip blade length (r=0.454, p=0.004). Multiple linear regression analysis revealed that angle b was the major parameter influencing white artifacts and the angle and number of streak artifacts in axial images (p<0.001), whereas clip blade length was a major factor in 3-D images (p=0.034). Conclusion : Use of a clip orientation perpendicular to the scan gantry angle decreased the amount of white artifacts and allowed better visualization of the clip site.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.8
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• pp.126-131
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• 2009

Acetabular dysplasia is a condition defined by inadequate development of an individual's acetabulum. Individual diversity of the symptoms in this disease needs safe and accurate preoperative planning. Technologies that utilize multidimensional image information are thus important. The assessment method by Janzen et al. was suggested a coefficient method in evaluation of acetabular dysplasia. In this study, we applied it, using a three-dimensional computed tomography (3D CT) on the koreans. 19 cases of the normal hips and 4 cases of the acetabular dysplasia were investigated to evaluate the proved method; 3D CT was used to define the geometric center of the femoral head and to measure center edge angles at $10^{\circ}$ rotational increments around the acetabular rim. Mean and standard deviation in CEAs (Center Edge Angle) of normal 19 hips at $10^{\circ}$ rotational increments from anterior to posterior rim were determined, and termed as a 'normal curve'. Then this normal values were compared with the CEA data measured from 4 cases of acetabular dysplasia patiens. Quantative comparison of the CEA values between the normal cases and dysplasia cases was successfully demonstrated, and thus, we claim that this simple CT method of assessing acetabular dysplasia can be well applicable to diagnosis, quantification and surgical planning for adult acetabular dysplasia patients.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.4
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• pp.307-311
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• 2007

Purpose: The aim of this study was simply assessing linear measurements in the lateral and medial approach, respectively, for bone harvesting using anatomic and three-dimensional(3D) computed tomographic(CT) analyses on a dried cadaveric proximal tibia. In addition, the availability of the three-dimensional computed tomographic(3D-CT) analysis was also estimated. Materials and methods: Ten dried proximal tibia were obtained from five Korean cadavers. Four the reference points, the SM(superior-medial), IM(inferior-medial), SL(superior-lateral), and IL(inferior-lateral) were marked around the tibial tuberosity. The PM(posterior-medial) and PL(posterior-lateral) points were randomly marked at points farthest from the lateral and medial reference points, respectively, in the posterior border of the superior articular surface of both condyles. All measurements were obtained on the dried proximal tibia. After computed tomography had been performed, the three dimensional images were reconstructed using V works $4.0^{TM}$(Cybermed Inc., Seoul, Korea), and the length between the reference points were measured three dimensionally using the method described above. The error between the mean actual and mean 3D-CT measurements was calculated in order to determine the availability of the three dimensional computed tomographic analysis. Results: The length between the reference points was greatest at the IL-PM, which averaged $65.39mm{\pm}10.35$. This was followed by the SL-PM with $63.24mm{\pm}8.10$, the IM-PL with $58.09mm{\pm}10.02$, and the SM-PL with $51.99mm{\pm}9.06$. The differences between the IL-PM and SM-PL were 13.4 mm. The mean values were 55.04 mm in the medial approach and 64.32 mm in the lateral approach, and the differences between medial and lateral were 9.28 mm. The error between the mean actual and mean 3D-CT measurements was 0.31% and the standard deviation was 0.28%. Conclusion: The anatomical and three dimensional computed tomographic analysis indicates that there was only a 9.28 mm linear difference between the lateral and medial approach. This is consistent with previous studies, which showed that there was little difference between the two approaches in terms of the bone volume. In addition, the error(0.31%) and the standard deviation(0.28%) were considered low, demonstrating high accuracy of 3D-CT. Therefore it can be used in preoperative treatment planning.

• The Journal of the Korean dental association
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• v.48 no.10
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• pp.724-728
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• 2010

Accurate analysis of facial asymmetry prior to any orthognathic or orthodontic treatment plan is essential in ensuring good treatment result. Dental CBCT (Cone-beam Computed Tomography) provides as actual three-dimensional measurements of distance and angle without any radiographic magnification as medical CT provides, while its field of view is limited to the oral and maxillofacial area. CBCT is a useful tool for the diagnosis of facial asymmetry. The coordinates of facial landmarks are obtained from the 3D reconstruction software which enables the establishment of perpendicular planes and the identification of the landmarks. Then, the bilateral discrepancies of the landmarks are obtained as spherical polar coordinates which can show the amount of asymmetry and its direction. A method of 3D analysis of facial asymmetry using CBCT is introduced in this report.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.91-98
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• 2006

Supernumerary teeth are teeth which result from the continued budding of the enamel organ of the preceding tooth or from excessive proliferation of cells. They are most often found in the maxillary anterior region. And they can be responsible for a variey of irregularities in the primary and transitional dentition. There are two morphological types of supernumerary teeth, supplemental and rudimentary. Supplemental teeth have normal shape and size. In contrast, rudimental teeth have abnormal shape and smaller size. Supplemental supernumerary teeth are most common in permanent lateral incisor area. Its extraction must be decided more carefully with differential diagnosis between normal teeth, because it has normal shape and size. We reports 3 cases of the normal incisor shaped teeth in the maxillary anterior region. In all cases, we used the 3D Dental-CT as well as the conventional plain film such as periapical, occlusal, and panoramic radiograph. Consequently, 3B Dental-CT was valualble to figure out the exact position and morphology of supernumerary teeth, to do more conservative surgery and to reduce surgery stress and time.

• Imaging Science in Dentistry
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• v.46 no.1
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• pp.33-38
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• 2016

Purpose: Facial asymmetry has been measured by the severity of deviation of the menton (Me) on posteroanterior (PA) cephalograms and three-dimensional (3D) computed tomography (CT). This study aimed to compare PA cephalograms and 3D CT regarding the severity of Me deviation and the direction of the Me. Materials and Methods: PA cephalograms and 3D CT images of 35 patients who underwent orthognathic surgery (19 males and 16 females, with an average age of $22.1{\pm}3.3years$) were retrospectively reviewed in this study. By measuring the distance and direction of the Me from the midfacial reference line and the midsagittal plane in the cephalograms and 3D CT, respectively, the x-coordinates ($x_1$ and $x_2$) of the Me were obtained in each image. The difference between the x-coordinates was calculated and statistical analysis was performed to compare the severity of Me deviation and the direction of the Me in the two imaging modalities. Results: A statistically significant difference in the severity of Me deviation was found between the two imaging modalities (${\Delta}x=2.45{\pm}2.03mm$, p<0.05) using the one-sample t-test. Statistically significant agreement was observed in the presence of deviation (k=0.64, p<0.05) and in the severity of Me deviation (k=0.27, p<0.05). A difference in the direction of the Me was detected in three patients (8.6%). The severity of the Me deviation was found to vary according to the imaging modality in 16 patients (45.7%). Conclusion: The measurement of Me deviation may be different between PA cephalograms and 3D CT in some patients.

• Journal of Magnetics
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• v.20 no.1
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• pp.40-46
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• 2015

This study investigated the accuracy of magnetic resonance angiography (MRA) and computed tomography angiography (CTA) in terms of reflecting the actual vascular length. Three-dimensional time of flight (3D TOF) MRA, 3D contrast-enhanced (CE) MRA, volume-rendering after CTA and maximum intensity projection were investigated using a flow model phantom with a diameter of 2.11 mm and area of $0.26cm^2$. 1.5 and 3.0 Tesla devices were used for 3D TOF MRA and 3D CE MRA. CTA was investigated using 16 and 64 channel CT scanners, and the images were transmitted and reconstructed by volume-rendering and maximum intensity projection, followed by conduit length measurement as described above. The smallest 3D TOF MRA measure was $2.51{\pm}0.12mm$ with a flow velocity of 40 cm/s using the 3.0 Tesla apparatus, and $2.57{\pm}0.07mm$ with a velocity of 71.5 cm/s using the 1.5 Tesla apparatus; both images were magnified from the actual measurement of 2.11 mm. The measurement with the 16 channel CT scanner was smaller ($3.83{\pm}0.37mm$) than the reconstructed image on maximum intensity projection. The images from CTA from examination apparatus and reconstruction technique were all larger than the actual measurement.

• Journal of Korean Neurosurgical Society
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• v.39 no.6
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• pp.427-431
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• 2006

Objective : The purpose of this study is to assess the usefulness of three-dimensional computed tomography angiography [3D-CTA] as a postoperative follow-up examination after intracranial aneurysms have been clipped. Methods : Between January 2002 and June 2005, 522 consecutive patients received treatment for intracranial aneurysms. A retrospective analysis of 310 patients with postoperative 3D-CTAs was performed to evaluate aneurysmal remnants and de novo aneurysms. This study was conducted in 271 patients with at least immediate and 6-month routine 3D-CT As for postoperative clipped aneurysm and 39 patients with 3D-CTAs for clipped aneurysm before 2002 when there was no 3D-CTA in our hospital. Results : Eight patients had abnormal CT angiographic findings. Aneurysm remnants were revealed in 4 patients and de novo aneurysms were discovered in 5 patients. Two patients were found at the postoperative 6-month 3D-CTA performed routinely. In 1 patient, the aneurysm was demonstrated on the way to the examination of syncope. In 2 patients, the author recommended 3D-CTA although there was no symptom because the patients had visited our institute long time ago [5.1, 4.5 years]. Of the 8 patients, 2 remnants and 1 de novo aneurysm were treated by endovascular treatment. Three de novo aneurysms at the middle cerebral artery and 1 pericallosal artery aneurysm were treated by direct clipping because these aneurysms were not suitable for the endovascular treatment in point of anatomical configuration. One patient with both remnant and de novo aneurysm was treated conservatively. Conclusion : 3D-CTA is an available, non-invasive diagnostic tool for the postoperative follow-up examination of aneurysmal state in patients after clipping.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.11
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• pp.4717-4721
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• 2014

Background: Dosimetric comparison of two dimensional (2D) radiography and three-dimensional computed tomography (3D-CT) based dose distributions with high-dose-rate (HDR) intracavitry radiotherapy (ICRT) for carcinoma cervix, in terms of target coverage and doses to bladder and rectum. Materials and Methods: Sixty four sessions of HDR ICRT were performed in 22 patients. External beam radiotherapy to pelvis at a dose of 50 Gray in 27 fractions followed by HDR ICRT, 21 Grays to point A in 3 sessions, one week apart was planned. All patients underwent 2D-orthogonal and 3D-CT simulation for each session. Treatment plans were generated using 2D-orthogonal images and dose prescription was made at point A. 3D plans were generated using 3D-CT images after delineating target volume and organs at risk. Comparative evaluation of 2D and 3D treatment planning was made for each session in terms of target coverage (dose received by 90%, 95% and 100% of the target volume: D90, D95 and D100 respectively) and doses to bladder and rectum: ICRU-38 bladder and rectum point dose in 2D planning and dose to 0.1cc, 1cc, 2cc, 5cc, and 10cc of bladder and rectum in 3D planning. Results: Mean doses received by 100% and 90% of the target volume were $4.24{\pm}0.63$ and $4.9{\pm}0.56$ Gy respectively. Doses received by 0.1cc, 1cc and 2cc volume of bladder were $2.88{\pm}0.72$, $2.5{\pm}0.65$ and $2.2{\pm}0.57$ times more than the ICRU bladder reference point. Similarly, doses received by 0.1cc, 1cc and 2cc of rectum were $1.80{\pm}0.5$, $1.48{\pm}0.41$ and $1.35{\pm}0.37$ times higher than ICRU rectal reference point. Conclusions: Dosimetric comparative evaluation of 2D and 3D CT based treatment planning for the same brachytherapy session demonstrates underestimation of OAR doses and overestimation of target coverage in 2D treatment planning.