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Virtual airway endoscopy with cone beam computed tomography
OOOOE Volume 101, Number 1
Abstracts E9
Fig. 3. MSCT-image. Fig. 1. Preparation of specimen using formalized cadaver head.
Table II. Differences between radiographic and direct measurements Mean 6 SD [mm] Observer Protocol
W & H [mm]
U70u U90u H30s H60s CB
0.37 ÿ0.10 0.50 0.09 0.06
6 6 6 6 6
1.3 1.4 0.99 0.92 1.16
Computer W
0.59 0.01 0.52 0.12 ÿ0.07
6 6 6 6 6
W 1.66 1.20 1.09 1.11 1.49
ÿ0.25 ÿ0.35 0.74 ÿ0.16 0.22
6 6 6 6 6
1.62 1.61 1.76 1.53 1.61
REFERENCE 1. Maes F, Collignon A, Vandermeulen D, Marchal G, Suetens P. Multi-modality image registration by maximization of mutual information. IEEE TMI 1997;16:187-11.
VIRTUAL AIRWAY ENDOSCOPY WITH CONE BEAM COMPUTED TOMOGRAPHY. P. Mah,1 M. Noujeim,1 R. Langlais,1 and M. Mah,2 1University of Texas Health Science Center San Antonio, 2University of Southern California, Los Angeles.
Fig. 2. CBCT-image.
Table I. Acquisition protocols
mA(s) kV Filter Comp
Somatom VolumeZoom
Somatom Sensation
3D Accuitomo
90 mAs 120 U90u/U70u Siemens, DE
90 mAs 120 H60s/H30s Siemens, DE
4 mA 70 n.a. Morita, JP
Conclusion. For linear measurements, CBCT images seem to obtain the same level of accuracy as MSCT images. Considering the present pilot, the maximal deviation from the real anatomical situation is submillimeter for both CT image data sets. This study is part of IWT/GBOU/02195.
Background. Assessment of the airway is central to many disciplines of medicine and dentistry. Endoscopic methods are often impractical and prohibitive for a variety of reasons. An alternative to physical methods of airway assessment could be virtual endoscopy using 3-dimensional x-ray imaging (cone beam computed tomography). In many cases, the image data has already been obtained for another clinical indication. The software tools to perform virtual endoscopy have been developed and are currently available. Objectives. To demonstrate the ability to conduct virtual airway endoscopy on volumetric data obtained by Cone Beam Computed Tomography (CBCT). Methods and Materials. De-identified DICOM data (10 mA, 110 kVp) from a Hitachi CBCT device was imported into 3-D visualization software (V-Works, version 4.0; CyberMed Inc., USA). A visualization preset was customized to enhance the airway and volume sculpting was performed manually to remove peripheral data.
OOOOE January 2006
E10 Abstracts Threshold values were selected to increase the contrast of the airway. Semi-automatic segmentation was performed to create a surfaced model of the airway. Manual camera location and position were established to visualize the anatomy. Animation pathways were manually created to simulate video examination of the airway. Results. Virtual airway endoscopy was performed on CBCT DICOM data. The basic steps of image enhancement, volume sculpting, thresholding, segmentation and image reformatting were accomplished. Discussion. Volumetric examination and measurement could be used as an alternative or adjunct to mechanical methods of airway endoscopy. The process is relatively quick (;15 minutes) and could be used to evaluate airway anomalies in an efficient manner. This abstract provides the basic methodology for further studies in this area, in particular, correlation of the airway anatomy with specific clinical presentation of airway problems. CyberMed Inc USA for their assistance with the images.
RELATIONSHIP OF MANDIBULAR BONE DENSITY AND CENTRAL BONE MINERAL DENSITY IN MEN. S. Mardini,1 P. Nummikoski,2 J. Bruder,3 D. McDavid,4 E. Paunovich,5 and T. Prihoda T,6 1Boston University Goldman School of Dental Medicine, 2,4University of Texas Health Science Center at San Antonio, 3,5South Texas Veterans Hospital, San Antonio. Background. Many attempts have been made to develop simple and inexpensive screening methods for detecting osteoporosis. Dental radiography techniques are both simple and relatively inexpensive when compared to medical imaging. There is an increasing interest in developing a technique using dental imaging for osteoporosis screening. Measuring bone density is a common method for determining risk for osteoporosis. The gold standard for measuring bone mineral density is DXA (dual x-ray absorptiometry) of the spine, hip and wrist. Previous studies have linked the mandible to osteoporosis. This leads to the question of how mandibular bone density and the density of central bone, such as the spine, are related. A pilot study was created to generate preliminary data on this relationship. Objectives. To determine if there is a correlation between mandibular bone mineral density and central bone density. Methods and Materials. Seventy male subjects ages 41-83 were recruited to take part in a clinical study of mandibular bone density. The University of Texas Institutional Review Board granted approval. These subjects were previously referred by their physicians for bone mineral density scans of the spine, hip and radius at the Osteoporosis Study Center. After consenting to take part in the study, one periapical x-ray was taken of the posterior mandible using a digital PSP system and a density reference wedge. Densities from the mandible were tested for correlation with DXA density results of the spine, hip and radius. Results. Significant positive correlations (r [ .05) were seen between the mandible and both the spine and hip. The radius and mandible did not show a significant correlation. Specific areas such as the apical bone and posterior mandible showed stronger correlations with the central bone than alveolar or anterior bone. Discussion. Bone in the apical and posterior regions of the mandible appear to be the most consistent for measuring bone mineral density. We would like to thank the Department of Dental Diagnostic Science at the University of Texas Health Science Center at San Antonio. Special thanks to the South Texas Veterans Hospital research clinic staff.
OPTIMAL GRAY SCALE OF DIGITAL RADIOGRAPH FOR DETERMINATION OF ENDODONTIC FILE POSITIONING. M.-S. Heo, D.-H. Han, W.-J. Yi, S.-S. Lee, and S.-C. Choi, Dept. of Oral and Maxillofacial Radiology and Dental Research Institute, College of Dentistry, Seoul National University, Seoul, Korea. Background. There were some reports in 1990s that 8 bit radiographic images were enough to diagnose on the dental lesions. Recently, over 10 bit digital radiographic image is recommended and most radiographic machines are developed at over 10 bit in medical field, however, most of dental radiographic images are acquired at 8 bit gray scale.1,2 Objectives. This study was performed to evaluate the optimal gray scale on observer performance for determination of endodontic file positioning. Methods and Materials. No. 08 K-file was placed into the canal of 88 extracted permanent premolars and positioned so that the tip was either (1) flush with the radiological root apex or (2) 1 mm short of the radiological root apex. The samples were imaged with both conventional using E-speed film and digital radiography technique. The direct digital radiographs were taken at both 8 bit and 12 bit images using CCD sensor (SUNI Corp. San Jose, Calif) and SDR software (MJRAD Inc., Seoul, Korea). 11 observers scored both films and digital images for the file tip positioning using the 5-point scale system for ROC analysis. All digital images were viewed on a highresolution monochrome TFT-LCD monitor (1536 3 2048 3 10 bit gray scale) and conventional radiographic images on the conventional viewbox. Results. The 12 bit images showed similar observer performance compared to conventional radiographic images, but the 8 bit images showed the lowest observer performance. Discussion. Although previously study showed that 8 bit image was enough to diagnose on the dental lesions, we thought that they were not always enough to be seen on the 8 bit image because some examples on this study showing subtle density changes was not enough to be seen. Therefore, we suggest that the dental digital radiographic images must be set at over 10 bit gray scale for the images showing the higher diagnostic accuracy. This work was supported by the grant from the Ministry of Commerce, Industry and Energy entitled ‘‘Development of Core-technology of medical devices for the elderly (#2004-00633)’’.
REFERENCES 1. Lehmann TM, Troeltsch E, Spitzer K. Image processing and enhancement provided by commercial dental software programs. Dentomaxillofac Radiol 2002;31:264-72. 2. Schaefer CM, Greene R, Hall DA, Lindemann SR, Llewellyn HJ, McCarthy KA, et al. Mediastinal abnormalities: detection with storage phosphor digital radiography. Radiology 1991;178:169-73.
DETECTION OF LONGITUDINAL ROOT FRACTURES USING LOCAL COMPUTED TOMOGRAPHY. M. A. Mora, and A. Mol, The University of North Carolina at Chapel Hill. Background. The detection of non-displaced longitudinal root fractures is a significant challenge in clinical practice. The twodimensional nature of conventional radiographs makes this modality not suitable for this purpose. The detection of root fractures requires a high-resolution 3D imaging technique. Local Computed Tomography (LCT) offers a novel opportunity to meet this requirement. LCT combines a limited field of view with a high resolution detector,
Abstracts E9
Fig. 3. MSCT-image. Fig. 1. Preparation of specimen using formalized cadaver head.
Table II. Differences between radiographic and direct measurements Mean 6 SD [mm] Observer Protocol
W & H [mm]
U70u U90u H30s H60s CB
0.37 ÿ0.10 0.50 0.09 0.06
6 6 6 6 6
1.3 1.4 0.99 0.92 1.16
Computer W
0.59 0.01 0.52 0.12 ÿ0.07
6 6 6 6 6
W 1.66 1.20 1.09 1.11 1.49
ÿ0.25 ÿ0.35 0.74 ÿ0.16 0.22
6 6 6 6 6
1.62 1.61 1.76 1.53 1.61
REFERENCE 1. Maes F, Collignon A, Vandermeulen D, Marchal G, Suetens P. Multi-modality image registration by maximization of mutual information. IEEE TMI 1997;16:187-11.
VIRTUAL AIRWAY ENDOSCOPY WITH CONE BEAM COMPUTED TOMOGRAPHY. P. Mah,1 M. Noujeim,1 R. Langlais,1 and M. Mah,2 1University of Texas Health Science Center San Antonio, 2University of Southern California, Los Angeles.
Fig. 2. CBCT-image.
Table I. Acquisition protocols
mA(s) kV Filter Comp
Somatom VolumeZoom
Somatom Sensation
3D Accuitomo
90 mAs 120 U90u/U70u Siemens, DE
90 mAs 120 H60s/H30s Siemens, DE
4 mA 70 n.a. Morita, JP
Conclusion. For linear measurements, CBCT images seem to obtain the same level of accuracy as MSCT images. Considering the present pilot, the maximal deviation from the real anatomical situation is submillimeter for both CT image data sets. This study is part of IWT/GBOU/02195.
Background. Assessment of the airway is central to many disciplines of medicine and dentistry. Endoscopic methods are often impractical and prohibitive for a variety of reasons. An alternative to physical methods of airway assessment could be virtual endoscopy using 3-dimensional x-ray imaging (cone beam computed tomography). In many cases, the image data has already been obtained for another clinical indication. The software tools to perform virtual endoscopy have been developed and are currently available. Objectives. To demonstrate the ability to conduct virtual airway endoscopy on volumetric data obtained by Cone Beam Computed Tomography (CBCT). Methods and Materials. De-identified DICOM data (10 mA, 110 kVp) from a Hitachi CBCT device was imported into 3-D visualization software (V-Works, version 4.0; CyberMed Inc., USA). A visualization preset was customized to enhance the airway and volume sculpting was performed manually to remove peripheral data.
OOOOE January 2006
E10 Abstracts Threshold values were selected to increase the contrast of the airway. Semi-automatic segmentation was performed to create a surfaced model of the airway. Manual camera location and position were established to visualize the anatomy. Animation pathways were manually created to simulate video examination of the airway. Results. Virtual airway endoscopy was performed on CBCT DICOM data. The basic steps of image enhancement, volume sculpting, thresholding, segmentation and image reformatting were accomplished. Discussion. Volumetric examination and measurement could be used as an alternative or adjunct to mechanical methods of airway endoscopy. The process is relatively quick (;15 minutes) and could be used to evaluate airway anomalies in an efficient manner. This abstract provides the basic methodology for further studies in this area, in particular, correlation of the airway anatomy with specific clinical presentation of airway problems. CyberMed Inc USA for their assistance with the images.
RELATIONSHIP OF MANDIBULAR BONE DENSITY AND CENTRAL BONE MINERAL DENSITY IN MEN. S. Mardini,1 P. Nummikoski,2 J. Bruder,3 D. McDavid,4 E. Paunovich,5 and T. Prihoda T,6 1Boston University Goldman School of Dental Medicine, 2,4University of Texas Health Science Center at San Antonio, 3,5South Texas Veterans Hospital, San Antonio. Background. Many attempts have been made to develop simple and inexpensive screening methods for detecting osteoporosis. Dental radiography techniques are both simple and relatively inexpensive when compared to medical imaging. There is an increasing interest in developing a technique using dental imaging for osteoporosis screening. Measuring bone density is a common method for determining risk for osteoporosis. The gold standard for measuring bone mineral density is DXA (dual x-ray absorptiometry) of the spine, hip and wrist. Previous studies have linked the mandible to osteoporosis. This leads to the question of how mandibular bone density and the density of central bone, such as the spine, are related. A pilot study was created to generate preliminary data on this relationship. Objectives. To determine if there is a correlation between mandibular bone mineral density and central bone density. Methods and Materials. Seventy male subjects ages 41-83 were recruited to take part in a clinical study of mandibular bone density. The University of Texas Institutional Review Board granted approval. These subjects were previously referred by their physicians for bone mineral density scans of the spine, hip and radius at the Osteoporosis Study Center. After consenting to take part in the study, one periapical x-ray was taken of the posterior mandible using a digital PSP system and a density reference wedge. Densities from the mandible were tested for correlation with DXA density results of the spine, hip and radius. Results. Significant positive correlations (r [ .05) were seen between the mandible and both the spine and hip. The radius and mandible did not show a significant correlation. Specific areas such as the apical bone and posterior mandible showed stronger correlations with the central bone than alveolar or anterior bone. Discussion. Bone in the apical and posterior regions of the mandible appear to be the most consistent for measuring bone mineral density. We would like to thank the Department of Dental Diagnostic Science at the University of Texas Health Science Center at San Antonio. Special thanks to the South Texas Veterans Hospital research clinic staff.
OPTIMAL GRAY SCALE OF DIGITAL RADIOGRAPH FOR DETERMINATION OF ENDODONTIC FILE POSITIONING. M.-S. Heo, D.-H. Han, W.-J. Yi, S.-S. Lee, and S.-C. Choi, Dept. of Oral and Maxillofacial Radiology and Dental Research Institute, College of Dentistry, Seoul National University, Seoul, Korea. Background. There were some reports in 1990s that 8 bit radiographic images were enough to diagnose on the dental lesions. Recently, over 10 bit digital radiographic image is recommended and most radiographic machines are developed at over 10 bit in medical field, however, most of dental radiographic images are acquired at 8 bit gray scale.1,2 Objectives. This study was performed to evaluate the optimal gray scale on observer performance for determination of endodontic file positioning. Methods and Materials. No. 08 K-file was placed into the canal of 88 extracted permanent premolars and positioned so that the tip was either (1) flush with the radiological root apex or (2) 1 mm short of the radiological root apex. The samples were imaged with both conventional using E-speed film and digital radiography technique. The direct digital radiographs were taken at both 8 bit and 12 bit images using CCD sensor (SUNI Corp. San Jose, Calif) and SDR software (MJRAD Inc., Seoul, Korea). 11 observers scored both films and digital images for the file tip positioning using the 5-point scale system for ROC analysis. All digital images were viewed on a highresolution monochrome TFT-LCD monitor (1536 3 2048 3 10 bit gray scale) and conventional radiographic images on the conventional viewbox. Results. The 12 bit images showed similar observer performance compared to conventional radiographic images, but the 8 bit images showed the lowest observer performance. Discussion. Although previously study showed that 8 bit image was enough to diagnose on the dental lesions, we thought that they were not always enough to be seen on the 8 bit image because some examples on this study showing subtle density changes was not enough to be seen. Therefore, we suggest that the dental digital radiographic images must be set at over 10 bit gray scale for the images showing the higher diagnostic accuracy. This work was supported by the grant from the Ministry of Commerce, Industry and Energy entitled ‘‘Development of Core-technology of medical devices for the elderly (#2004-00633)’’.
REFERENCES 1. Lehmann TM, Troeltsch E, Spitzer K. Image processing and enhancement provided by commercial dental software programs. Dentomaxillofac Radiol 2002;31:264-72. 2. Schaefer CM, Greene R, Hall DA, Lindemann SR, Llewellyn HJ, McCarthy KA, et al. Mediastinal abnormalities: detection with storage phosphor digital radiography. Radiology 1991;178:169-73.
DETECTION OF LONGITUDINAL ROOT FRACTURES USING LOCAL COMPUTED TOMOGRAPHY. M. A. Mora, and A. Mol, The University of North Carolina at Chapel Hill. Background. The detection of non-displaced longitudinal root fractures is a significant challenge in clinical practice. The twodimensional nature of conventional radiographs makes this modality not suitable for this purpose. The detection of root fractures requires a high-resolution 3D imaging technique. Local Computed Tomography (LCT) offers a novel opportunity to meet this requirement. LCT combines a limited field of view with a high resolution detector,