Sustracción Radiográfica Digital de la Estructura Dentaria Removida Durante el Acceso Endodóntico En Incisivos Mandibulares

RESUMEN: El objetivo de este estudio fue comparar la estructura dentaria removida utilizando dos técnicas de acceso endodóntico diferentes en incisivos mandibulares. Treinta y cinco incisivos mandibulares extraídos fueron pesados individualmente con una balanza de precisión. Después de las radiografías iniciales tomadas por vestibular y proximal, los dientes fueron codificados y asignados aleatoriamente a dos grupos: acceso convencional (n = 17) o acceso incisal (n = 18). Luego se volvieron a pesar los dientes y se repitieron las radiografías. Las radiografías digitales se cargaron a un editor de imágenes (Adobe Photoshop) para la sustracción digital de las imágenes por las incidencias VP y MD. Dos observadores independientes y calibrados realizaron las mediciones de las áreas sustraídas. La concordancia inter-observador fue casi perfecta; coeficiente de correlación intraclase igual a 0,94 y 0,98 para las incidencias MD y VP, respectivamente. La prueba de Mann-Whitney encontró diferencias estadísticamente significativas entre los tipos de acc esos en cuanto a la diferencia mediana de los pesos (p = 0,0073) y el área VL (p = 0.0023). También encontró una diferencia estadísticamente significativa entre los tipos de acceso en cuanto al área MD (Prueba t de Welch, p < 0,001). La diferencia de peso fue menor para el acceso incisal que para el acceso convencional. El acceso incisal removió menos tejido dentario que el acceso convencional.

ABSTRACT: The aim of this study was to compare the area of tooth structure removed during two different endodontic access techniques in lower incisors. Thirty-two extracted lower incisors were weighed individually on a precision scale. After initial digital radiographs were taken from buccal and proximal, the teeth were coded and randomly assigned to two different groups: conventional access and incisal access. Once this stage was completed, each tooth was weighed again and 2 postoperative radiographs was taken again, buccal and proximal. Using an image processing software and digital subtraction technique, 2 independent and calibrated evaluators measured difference in tooth structure after access procedures. Interobserver agreement was almost perfect: intraclass correlation coefficient equal to 0,94 and 0,98 for proximal and buccal incidences, respectively. The Mann-Whitney test found statistically significant differences between the types of accesses in terms of weight difference (p = 0.0073) and area VL (p = 0.0023). Additionally, a statistically significant difference between the types of access in the MD area (Welch's t test, p <0.005) was observed. The difference in weight was less for incisal access than for conventional access with a statistically significant difference, in terms of MD and VL area, incisal access and areas of smaller size than conventional access.

Video analysis and 3d detection simulation of jump shot precision for basketball players / Análise de vídeo e simulação de detecção 3d da precisão do arremesso de jogadores de basquete / Análisis de video y simulación tridimensional de la precisión de lanzamiento de los jugadores de baloncesto

ABSTRACT With the rapid development and application of computer technology, the application of computer science knowledge in basketball is also more and more extensive. Based on genetic algorithm and the background subtraction method, video analysis and 3D detection simulation model of shot jump action precision were constructed in this study. According to the genetic algorithm search method, jump shot precision was analyzed, and the problems encountered in the actual shooting process of basketball players were studied and solved. The results show that this study is necessary and feasible.

RESUMO Com o rápido desenvolvimento e aplicação da tecnologia da computação, a aplicação do conhecimento da ciência da computação no basquete também vem crescendo cada vez mais. Com base no algoritmo genético e no método da subtração de fundo, construiu-se um modelo de análise de vídeo e simulação de detecção 3D para a precisão de arremesso. De acordo com o método de busca do algoritmo genético, analisou-se a precisão do arremesso, e os problemas encontrados no processo de arremesso dos jogadores de basquete foram estudados e resolvidos. Os resultados mostram que este estudo é necessário e viável.

RESUMEN Con el rápido desarrollo y aplicación de la tecnología de la computación, la aplicación del conocimiento de la ciencia de la computación en el baloncesto también viene creciendo cada vez más. Basándose en el algoritmo genético y en el método de la sustracción de fondo, se construyó un modelo de análisis de video y simulación de detección 3D para la precisión de lanzamiento. De acuerdo con el método de búsqueda del algoritmo genético, se analizó la precisión del lanzamiento, y los problemas encontrados en el proceso de lanzamiento de los jugadores de baloncesto fueron estudiados y resueltos. Los resultados muestran que este estudio es necesario y viable.

Impact factors of motion artifacts in chest dual-energy X-ray radiography / 中国医学影像技术

Objective: To observe the predilection sites of motion artifacts on chest DR dual-energy subtraction images, and to analyze the impact factors. Methods: Dual-energy subtraction chest images of 128 cases were analyzed. The position of motion artifacts were observed, and the length and width were measured and compared, and the correlations of heart rate and motion artifacts at different sites were analyzed. Results: Among 128 cases of dual-energy subtraction chest images, 115 cases showed black-and-white striped motion artifacts, 87 (75.65%) at left ventricular segment, 82 (71.30%)at aortic arch segment, 60 (52.17%)at right cardiac margin, 42 (36.52%) at diaphragmatic margin, 30 (26.09%)at left atrial auricular pulmonary segment and 27 (23.48%) at superior vena cava. Statistical differences of the mean length and width of motion artifacts were found among left ventricular segment, aortic arch segment and right cardiac margin (F=4.59, 3.46, both P<0.05). Heart rate was positively correlated with motion artifacts at left ventricular segment and aortic arch segment (r=1.00, 0.99, both P<0.05). Conclusion: Cardiac pulsation and breathing exercises can cause occurrence of motion artifacts in chest DR dual-energy subtraction images, mostly located at left ventricular segment and aortic arch segment. The faster the heart rate, the more obvious the motion artifacts.

Significance of enhanced MRI in evaluating the prognosis of early Perthes disease / 中华骨科杂志

Objective@#To investigate the reproducibility of the femoral head perfusion index by enhanced MRI and the predictive value of the Herring lateral pillar classification after the progression of early stage of Perthes disease (X-ray modified Waldenström stage Ia, Ib, IIa) to stage IIb.@*Methods@#From October 2016 to November 2018, a total of 30 children with early stage of Perthes disease were enrolled, including 29 males and 1 female, aged 7.5±1.0 years (range 6.3 to 9.5 years). All patients were evolved by unilateral with left 24 cases and 6 cases on the right side. There were 1 case in stage Ia, 16 cases in stage Ib and 13 cases in stage IIa. At the initial evaluation, X-ray films and enhanced MRI were performed. Three observers measured the femoral head perfusion index on the enhanced MRI. The ratio of the pixels in the affected ossified nucleus perfusion area to the pixels in the contralateral femoral skull nucleus was recorded. A total of 30 cases were measured with repeated evaluation at intervals of 1 to 2 weeks. The second measurement was independent of the first measurement results. The average of the two measurements was regarded as the final measurement results. At 3 months follow-up, anteroposterior and Lauenstein frog-lateral radiographs were taken. The follow-up duration was end at the stage IIb progression. The Herring lateral pillar of the femoral head was determined on the X-ray films. The differences in the early MRI femoral head perfusion index were compared between the different lateral column types.@*Results@#The ICC values of the femoral head perfusion index between the three observers were 0.876. The ICC values measured by the 1/3 perfusion index of the lateral femoral head were 0.729. The ICC values of the femoral head perfusion index measured by the same observer at different times were 0.932. The ICC values measured by the 1/3 perfusion index of the lateral femoral head were 0.805. A total of 30 children were followed to stage IIb at 6.49±5.12 months (range 2.3 to 22.1 months). There were 13 cases of type A and type B and 17 cases of type C. The sputum perfusion index of type A and type B was 59.77%±17.12% (range 25%-85%), and that of group C was 13.47%±10.65% (range 2%-23%). The difference between groups was statistically significant (t=8.563, P=0.000). The 1/3 perfusion index of the lateral femoral head of the A and B groups was 75.62%±15.03% (range 50%-95%), while the C type was 22.24%±12.28% (range 5%-45%) with significant difference (t=10.621, P=0.000).@*Conclusion@#The measurement of femoral head perfusion index on enhanced MRI has almost perfect agreement between and within observers across multiple rounds of study. In children with early Perthes disease, enhanced MRI has predictive effect on the Herring lateral pillar classification after progression to stage IIb.

A dual-energy X-ray fluoroscopy method for image-guided lung radiotherapy / 中国医学影像技术

Objective: To investigate a dual-energy X-ray fluoroscopy imaging method to acquire a high-and low-energy X-ray image sequence within a breathing cycle, so as to obtain soft tissue image through an improved dual-energy image subtraction algorithm to improve tumor visibility for marker-less lung tumor tracking in image-guided radiotherapy. Methods: A dual-energy X-ray fluoroscopy imaging system with a C-arm rotating mechanical structure and a high-low energy fast switching mechanism was designed. A sequence of high-and low-energy X-ray image pairs of 9 or 10 breathing phase within a breathing cycle were acquired from 4 different projection directions. For a high-and low-energy image pair in the same phase, a soft tissue image was obtained by removing the skeleton through an optimized weighted logarithmic subtraction algorithm. The best soft tissue image was automatically determined by using CNR as the image quality evaluation parameter in the subtraction algorithm. Twenty patients with lung tumor were collected, and their data were analyzed to evaluate the improvement of tumor visibility in soft tissue subtraction images. Results: In the projection directions of 0°, 45°, 90° and 135°, 198, 196, 198 and 198 high and low energy image pairs were collected, respectively. The visibility images of tumor were 198, 38, 69 and 49 pairs, respectively. On soft tissue images after removing skeleton from high and low energy image pairs by automatic subtraction algorithm, the visibility images of tumors were 198, 108, 149 and 159, respectively. Conclusion: The above mentioned dual-energy X-ray fluoroscopy method can be used to acquire real-time high-and low-energy X-ray image sequences of respiratory cycle, therefore obtain soft tissue subtraction images and significantly improve the visibility of lung tumors.

The diagnostic value of enhanced MR subtracted venography in iliac vein stenosis / 实用放射学杂志

Objective To investigate the diagnostic value of enhanced MR subtracted venography (MRsV)in iliac vein stenosis. Methods 21 patients were recruited for unilateral venous circulation disorders,and they were all performed two kinds of MR venography,including time of flight (TOF)and MRsV.All raw data were reconstructed and maximum intensity proj ection (MIP)images were gained after post-processing in workstation.The image quality and diagnostic accuracy were evaluated by two experienced radiologists.All the results were analyzed,with P<0.05.Results 18 patients were enrolled in our study with good image quality,including 10 cases of unilateral iliac venous thrombosis,1 case of iliac venous stenosis infiltrated by tumor recurrence,3 cases of IVCS and 4 cases without iliac venous thrombosis.The sensitivity and specificity of MRsV-MIP were higher than TOF-MIP (100% vs 92.3%,100% vs 75%,respectively). There was significant difference in diagnostic accuracy between MRsV-MIP and TOF-MIP(χ2=4.827 2,P=0.028 0).Conclusion MRsV demonstrates better image quality and diagnostic performance than TOF in evaluation of iliac vein stenosis.MRsV has greater potential in providing the differential diagnosis evidence in venous stenosis.It could be established as an independent iliac venous imaging method.

Effectiveness of digital subtraction radiography in detecting artificially created osteophytes and erosions in the temporomandibular joint

PURPOSE: Erosions and osteophytes are radiographic characteristics that are found in different stages of temporomandibular joint (TMJ) osteoarthritis. This study assessed the effectiveness of digital subtraction radiography (DSR) in diagnosing simulated osteophytes and erosions in the TMJ. MATERIALS AND METHODS: Five intact, dry human skulls were used to assess the effectiveness of DSR in detecting osteophytes. Four cortical bone chips of varying thicknesses (0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm) were placed at the medial, central, and lateral aspects of the condyle anterior surface. Two defects of varying depth (1.0 mm and 1.5 mm) were created on the lateral, central, and medial poles of the condyles of 2 skulls to simulate erosions. Panoramic images of the condyles were acquired before and after artificially creating the changes. Digital subtraction was performed with Emago dental image archiving software. Five observers familiar with the interpretation of TMJ radiographs evaluated the images. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic accuracy of the imaging methods. RESULTS: The area under the ROC curve (Az) value for the overall diagnostic accuracy of DSR in detecting osteophytic changes was 0.931. The Az value for the overall diagnostic accuracy of panoramic imaging was 0.695. The accuracy of DSR in detecting erosive changes was 0.854 and 0.696 for panoramic imaging. DSR was remarkably more accurate than panoramic imaging in detecting simulated osteophytic and erosive changes. CONCLUSION: The accuracy of panoramic imaging in detecting degenerative changes was significantly lower than the accuracy of DSR (P<.05). DSR improved the accuracy of detection using panoramic images.

Investigation of clinical application for severe segmental calcification by subtraction technique of coronary artery CT angiography / 复旦学报（医学版）

Objective To investigate the feasibility of subtraction coronary computed tomography angiography (Sub-CCTA) for the diagnosis of coronary heart disease in the segment with severe calcification.Methods A retrospective analysis was performed on 27 patients who underwent clinically indicated digital subtraction angiography (DSA) and CCTA using a 320-detector row CT.Compared with the results of DSA,sensitivity,specificity,positive predictive value,negative predictive value and accuracy of Con-CCTA and Sub-CCTA were calculated.The clinical diagnostic accuracy of the two imaging methods was evaluated using the receiver operating characteristic (ROC) curve.The stenosis of coronary segments was divided into four grades (Ⅰ,Ⅱ,Ⅲ,Ⅳ).Kappa coefficient was used to measure agreement between two imaging methods.Image quality of 4-scale grade scoring method was used and t test was conducted.Results A total of 52 segments with severe calcification were evaluated.The scores of image quality in Con-CCTA and Sub-CCTA were 2.8 ± 0.5 and 3.4 ± 0.7,respectively.There was significant difference between them (t =5.9,P ＜ 0.05).Compared with the result of DSA as the golden standard,the Kappa coefficients were 0.55 and 0.81 respectively in Con-CCTA and Sub-CCTA for the quantitative evaluation of the severe calcified segments.The sensitivity,specificity,positive predictive value and negative predictive value and accuracy of Con-CCTA were 81.0％,63.1％,63.1％,81.1％ and 70.8 ％;and for Sub-CCTA they were 90.5 ％,85.2％,82.1 ％,92.0％ and 87.5 ％ respectively.Compared with Con-CCTA,the area under the ROC curve of Con-CCTA and Sub-CCTA were 0.84 (95％CI:0.70-0.93) and 0.96 (95％ CI:0.86-1.00),respectively,and the difference was statistically significant (P =0.03).Conclusions Sub-CCTA can improve the diagnostic accuracy of coronary artery stenosis in severe calcified segment.Application of subtraction technique in CCTA can reduce or even eliminate the artifacts caused by severe calcified plaque,and has a good clinical application prospect.

A posteriori registration and subtraction of periapical radiographs for the evaluation of external apical root resorption after orthodontic treatment

PURPOSE: This study employed a posteriori registration and subtraction of radiographic images to quantify the apical root resorption in maxillary permanent central incisors after orthodontic treatment, and assessed whether the external apical root resorption (EARR) was related to a range of parameters involved in the treatment. MATERIALS AND METHODS: A sample of 79 patients (mean age, 13.5±2.2 years) with no history of trauma or endodontic treatment of the maxillary permanent central incisors was selected. Periapical radiographs taken before and after orthodontic treatment were digitized and imported to the Regeemy software. Based on an analysis of the posttreatment radiographs, the length of the incisors was measured using Image J software. The mean EARR was described in pixels and relative root resorption (%). The patient's age and gender, tooth extraction, use of elastics, and treatment duration were evaluated to identify possible correlations with EARR. RESULTS: The mean EARR observed was 15.44±12.1 pixels (5.1% resorption). No differences in the mean EARR were observed according to patient characteristics (gender, age) or treatment parameters (use of elastics, treatment duration). The only parameter that influenced the mean EARR of a patient was the need for tooth extraction. CONCLUSION: A posteriori registration and subtraction of periapical radiographs was a suitable method to quantify EARR after orthodontic treatment, and the need for tooth extraction increased the extent of root resorption after orthodontic treatment.

Comparação de diferentes métodos de registro (a priori e a posteriori) na subtraçÆo radiográfica digital (SRD) para avaliação da produção de ruídos estruturais / Comparison of different recording methods (a priori and a posteriori) in the digital radiographic subtraction (DRS) to evaluate the production of structural noise

Objetivo: A Subtração Radiográfica Digital (SRD) é uma técnica utilizada para comparar duas radiografias de um mesmo objeto, realizadas em diferentes momentos, para demonstrar a existência de diferenças entre elas. Contudo, a reprodutibilidade da geometria de relação entre objeto, filme e fonte de raios X é indispensável para evitar a formação de ruídos estruturais. O objetivo deste trabalho foi comparar a aplicação de diferentes métodos de registros (a priori e a posteriori), em diferentes tempos de exposiçao (0,2 e 0,4 segundos), na produçÆo de ruído estrutural em imagens subtraídas. Método: dez mandíbulas foram radiografadas em duas situaçães: com uso de posicionadores convencionais sem registro e com registro a priori, sendo que ambos os métodos foram reproduzidos após 15 dias. O registro a posteriori foi realizado por meio do programa Regeemy© 0.2.43, e a subtraçÆo no programa Image Tool© 3.0. O ruído estrutural foi quantificado pelo programa Adobe Photoshop©7.0, que fornece valores de desvio padrÆo dos níveis de cinza na regiÆo de interesse (ROI). Esses valores foram submetidos à análise estatística ANOVA e teste Tukey a 5% de significância. Resultados: no tempo de exposiçÆo 0,4 s, os grupos obtiveram valores menores de desvio padrÆo em relaçÆo ao tempo de 0,2 s. Os grupos com registro a posteriori e a priori associados tiveram os menores valores de desvio padrÆo, seguidos pelos grupos com registro a posteriori. ConclusÆo: nas condiçães estudadas, o tempo de 0,4 s foi o mais adequado e a utilizaçÆo do registro a posteriori foi essencial na formaçÆo de imagens subtraídas com baixo ruído estrutural...

Objective: The Digital Radiographic Subtraction (DRS) is a technique used for comparing two radiographs of the same subject taken at different moments to demonstrate the differences between them. However, reproducibility of the geometry of relation among object, film and x-ray source is mandatory to avoid structural noise formation. The aim of this study was to compare the application of different recording methods (a priori and a posteriori) at different exposure times (0.2 and 0.4 s) on the production of structural noises in subtracted images. Method: Radiographs of 10 mandibles were taken using conventional film holders without and with a priori record, and then both methods were reproduced 15 days later. The a posteriori record was made using the Regeemy© 0.2.43 software and the subtraction was performed with Image Tool© 3.0. Results: with the 0.4 s exposure time, the groups presented lower standard deviation values compared with the 0.2 s exposure. The groups with a posteriori and a priori records had the lowest standard deviation values, followed by the groups with a posteriori record. Conclusion: Under the tested conditions, the 0.4 s exposure time was more appropriate and the use of a posteriori record was essential to obtain subtracted images with low structural noise...

Comparação entre subtração radiográfica digital e radiografia digital direta na detecção de reabsorções radiculares / Comparison between radiographic digital subtraction and direct digital radiography in the detection of root resorption

A reabsorção severa da raiz diagnosticada tardiamente pode acarretar a perda dentária. Devido ao fato de a técnica de subtração radiográfica digital ser um importante recurso para detecção precoce de alterações minerais, este estudo propôs avaliar a eficiência no diagnóstico precoce da reabsorção radicular externa simulada nas regiões apical e lingual, pelas técnicas de subtração radiográfica digital e radiografia digital. Foram utilizados 14 dentes incisivos de mandíbulas humanas maceradas com reabsorções de diferentes dimensões, simuladas nas regiões apical e lingual, e radiografados com variação de ângulos de projeção. As radiografias foram subtraídas pelo programa Regeemy®, e para avaliação de desempenho dos métodos de diagnóstico, pares de radiografias periapicais e imagens subtraídas foram apresentadas a dois radiologistas. De acordo com os resultados, não foram observadas diferenças estatisticamente significantes entre os métodos na detecção de reabsorções linguais, independentemente do tamanho da lesão. Também não houve diversidade entre os métodos na detecção de reabsorções apicais, com exceção do examinador dois quanto às variações angular vertical e horizontal de 10º, utilizando o maior nível de desgaste, que apresentou a radiografia digital como método superior na avaliação em relação à subtração radiográfica. Também foi observado que o aumento do nível de desgaste permitiu melhor avaliação nas regiões de reabsorções apicais e linguais, e a menor variação dos ângulos verticais e horizontais nas detecções de reabsorções apicais e linguais permitiu uma melhor avaliação da imagem, principalmente no menor nível de desgaste.

The delay on diagnose severe root resorption can lead to tooth loss. Due to the fact that digital subtraction radiography is an important resource to detect initial mineral changes, this study aimed at evaluating the effectiveness of the digital subtraction radiography and digital radiography in early diagnosis of the simulated apical and lingual external root resorption. Fourteen human lower incisors, submitted to simulated apical and lingual resorption cavities of different sizes, imaged with different angle projection variations were included in this study. The images were subtracted by the Regeemy® program, and receiver operating characteristic analysis was used to evaluate the diagnostic performance for each imaging system, and the diagnostic accuracy of both diagnosis methods for detecting lesions was conducted by the assessment of the pairs of radiography (digital and subtracted) by two radiologists. According to the results, there were no statistically significant differences between the methods in detecting lingual resorption, independently of the lesion dimension. There was also no difference on the apical resorption detection, except by the viewer two as to 10º horizontal and vertical angles, who related that on the larger cavity, the digital radiography was more reliable than the subtraction radiography. It was also further noticed that the deeper the cavity size, the better the apical and lingual resorption detection; and the radiography taken of the apical and lingual resorption, with the smaller vertical and horizontal angles variation ensured a better assessment of the image, mainly on the shallower cavity size.

Influência dos simuladores de tecidos moles na densidade óssea e dentária por meio de duas análises radiográficas: subtração digital e intensidade de pixel / Influence of soft tissue materials in bone and tooth density through two radiographic analyses: digital subtraction and pixel intensity

Esse estudo teve como objetivo avaliar a influência dos simuladores de tecidos moles na imagem radiográfica digital, da região óssea e dental, pela subtração radiográfica e análise da intensidade de pixel. 30 mandíbulas humanas com 2 dentes posteriores foram selecionadas. Um dispositivo para o posicionamento do cilindro de raios X, mandíbula e sensor CCD eHD Visualix Gendex foi confeccionado. As mandíbulas foram posicionadas no dispositivo e 5 materiais simuladores de tecido mole (Acrílico, Cera, Água, Madeira e Tecido bovino) nas espessuras de 10mm, 15mm e 20mm foram posicionados anteriormente a mandíbula, em seqüência para a realização das tomadas radiográficas com 65 kV, 7mA, distância foco-sensor de 30 cm, e 0,08s. As imagens foram exportadas em 8 e 16 bits para análise. A subtração foi realizada com o programa X-Poseit usando a imagem sem material como referência da imagem com o material, em duas regiões, osso e estrutura dental. A área de ganho de densidade óssea e dental foi avaliada quanto à influência dos materiais e espessuras. A análise por intensidade de pixel foi realizada tanto no osso quanto na estrutura dental, numa área de 100x100pixels, com o programa ImageJ. Foi adotado o nível de significância de 0,05. Os resultados da subtração radiográfica digital e intensidade de pixel mostraram que tanto os simuladores testados influenciaram o ganho de densidade na região do osso. Entretanto, não foi encontrada diferenças entre os materiais e espessuras testados. Na região dental, tanto a analise por subtração quanto a por intensidade de pixel mostraram que os simuladores de tecido mole não influenciaram a densidade dessas regiões. A avaliação da profundidade de bit mostrou que não houve diferença entre os resultados. Podemos concluir que os simuladores de tecido mole influenciaram na densidade óssea e dental.

This study aimed to evaluate the effect of soft tissue simulators in digital radiographic image, of tooth and bone, by digital subtraction radiography and pixel intensity analysis. 30 human mandibles with two posterior teeth were selected. A device for positioning the cylinder X-ray, jaw and EHD Visualix Gendex CCD sensor was manufactured. The jaws were positioned on the device and 5 soft tissue simulators materials (acrylic, wax, water, wood, and bovine tissue) in thicknesses of 10mm, 15mm and 20mm, were positioned in front of the jaw line, in sequence to perform the X-ray expositions at 65 kV, 7mA, plate-focus distance of 30 cm and the exposure time of 0.08 s. The images were exported in 8 and 16 bit for analysis. The subtraction was performed with the X-Poseit image without using the image as a reference material with the material in two regions, bone and tooth structure. The gain area in bone and tooth density was assessed and the difference between material and thickness were evaluated. The pixel intensity analysis was performed both in bone and tooth structure in an area of 100x100pixels with ImageJ. Significance level of 0,05 was adopted. The results of digital subtraction radiography showed that both the material and the thickness tested didn’t influence the gain of density in bone. Pixel intensity analisys in bone region didn’t show these differences, except for lower density observed in the 14 image without material comparing with the materials tested. In the dental region, both subtraction and pixel intensity showed that soft tissue simulators influence the density of these regions. However there was no difference between the materials and thicknesses tested. The evaluation of the bit depth, showed no difference between the results. We can conclude that soft tissue materials influence bone and dental density.

Subtraction technique of 64-slice spiral CT angiography for intra- and extra-cranial artery imaging / 第二军医大学学报

Objective: To employ the subtraction technique of 64-slice spiral CT angiography for intra- and extra-cranial arteries imaging, so as to study the managing method and assess the clinical outcome. Methods: The pre-contrast and post-contrast images of 100 patients were obtained by 64-slice spiral CT angiography. A special head holder was used during the scanning to guarantee the accurate overlapping of the pre-contrast and post-contrast images. A reconstructed three-dimensional model of the pre-contrast bone dataset was subtracted from the post-contrast dataset to produce the subtracted images. (1) An experienced operator performed the conventional and subtraction reconstructions; the periods for image generation of both methods were recorded and compared. (2) The quality of the images were evaluated and graded (grade 1-5) by 2 experienced radiologists in a double-blinded manner. Results: (1) The new subtraction technique using 64-slice spiral CT angiography needed significantly less time than the conventional method did (11.01±1.89 min vs 14.30±2.25 min, P<0.01). (2)The correlation coefficient of the results of 2 radiologists was 0.87. The score of image quality by subtraction 64-slice spiral CT angiography was significantly higher than that by the conventional method (4.22±050 vs 2.93±0.36, P<0.05). Conclusion: Subtraction 64-slice spiral CT angiography is easy to use and time saving for intra- and extra-cranial artery imaging; it does not has the difficulty of separating artery from bone and is worth popularizing in clinic.

Preliminary application of cranial subtraction CT perfusion imaging / 中国介入影像与治疗学

Objective To investigate the possibility to obtain the cranial subtraction computed tomography perfusion imaging (sCTP) from the CTP examination, and to explore preliminary application value of sCTP. Methods Cerebral sCTP obtained from source imaging data of 11 patients (10 with stroke and 1 with brain tumor) were analyzed with subtraction software and perfusion 3 software at GE AW4.2 workstation. The parametric maps and region of interest (ROI) value of blood flow (BF), blood volume (BV), mean transit time (MTT) and/or permeability surface (PS) were generated from the CTP and sCTP imaging data respectively. Results ①The technical success rate of cranial sCTP created from CTP sources imaging data was 100%, and the post-processing time of sCTP was about from 1.0 to 2.5 h. The mappings and values of BF, BV, MTT and PS of ROI were all successfully obtained from sCTP and CTP imaging data. ②The cerebral mappings of BF, BV, MTT and PS obtained from sCTP were similar to those from CTP, which all depicted accurately the lesions and their microcirculation hemodynamics changes. ③Just like those from CTP, the values of BF, BV, MTT and PS of nidus obtained from sCTP were significantly different from those of the near and the contralateral corresponding cerebral tissues (P<0.025). Conclusion sCTP can be generated successfully with subtraction and perfusion imaging software. It is an alternative solution for functional diagnosis of stroke and brain neoplasms.

Subtraction computed tomographic perfusion imaging and observation of ischemic necrosis of femoral head on dog / 中国医学影像技术

Objective To investigate the technical protocols and feasibility of subtraction computed tomography perfusion imaging (sCTP) on observation of ischemic necrosis of femoral head (ANFH) on dog. Methods Sixteen laboratory canines underwent CT perfusion imaging (CTP) of femoral head before and after selective femoral circumflex artery embolization, and ANFH were observed. Then new sequence imaging data, created by sources imaging of CT perfusion scan using subtraction software, were analyzed at workstation (AW 4.2) with CT perfusion 3 analysis program, and data of sCTP were obtained. The parametric maps and indexes of capillary-level hemodynamics including blood volume (BV), blood flow (BF) and mean transit time (MTT) of CTP and sCTP were compared. Results ①The technical success rate of sCTP post-processing created from CTP sources imaging data was 100%. The values and mappings of BF, BV and MTT of region of interest (ROI) were all obtained from subtraction sequence images data. The post-processing time of sCTP was about 1-5 h. ② sCTP depicted ANFH well, though the values and mappings of BF, BV and MTT were different from those obtained with conventional bone CTP. Conclusion sCTP can be generated with subtraction and perfusion analysis program and techniques. It can be applied to bone CT perfusion imaging and early quantitative diagnosis of necrosis.

Simple Partial Status Epilepticus Localized by SPECT Subtraction in Chronic Cerebral Paragonimiasis / 대한간질학회지

A patient with chronic cerebral paragonimiasis began to have new motor seizures of the right face clonic contractions that occurred several hundred times a day resulting in the simple partial status epilepticus. The ictal EEG discharge started from the left frontal region and then spread to the left hemisphere. The ictal discharges were limited clearly to the left hemisphere. The brain MRI showed the multiple conglomerated round nodules with encephalomalacia in the left temporo-occipital lobes. Applying the ictal-interictal subtracted SPECT, we were able to localize the focal ictal hyperperfusion on the left precentral cortex adjacent to the lesions that correspond to the anatomical distribution of the left face motor area.

A comparative study on the accuracy of digital subtraction radiography according to the aquisition methods of reconstructed images / 대한구강악안면방사선학회지

PURPOSE: To compare the accuracy of digital subtraction images acquired by two different methods different in positioning four reference points for geometrical standardization. MATERIALS AND METHODS: A total of 36 digital radiographic images of 6 volunteers were taken at the areas of the incisor, premolar, and molar of both the maxilla and mandible using the Digora system. Each image was moved 4 mm vertically and horizontally. Four oral and maxillofacial radiologists performed digital subtraction radiography between the paired images before and after movement using Emago (Oral Diagnostic Systems, Amsterdam, The Netherlands) and Sunny (Biomedisys Co., Seoul, Korea). The standard deviation of the internal gray value in Region of Interest (ROI) was statistically analyzed between the two programs using the paired t-test. RESULTS: The standard deviation of pixel gray values from the digital subtraction images using the Sunny program were lower than that of the Emago program (p<0.05). All observers showed significant differences between each other when the Sunny program was used (p<0.05), but one observer showed a significantly higher score than other observers when they used Emago (p<0.05). The standard deviations of premolar area from both Sunny and Emago programs were significantly higher than those of anterior and molar regions (p<0.05). CONCLUSION: The subtracted images using the Sunny program were more accurate and sensitive than those taken using the Emago program.

Digital contrast subtraction radiography for proximal caries diagnosis / 대한구강악안면방사선학회지

PURPOSE: To determine whether subtraction images utilizing contrast media can improve the diagnostic performance of proximal caries diagnosis compared to conventional periapical radiographic images. MATERIALS AND METHODS: Thirty-six teeth with 57 proximal surfaces were radiographied using a size #2 RVG-ui sensor (Trophy Radiology, Marne-la-Vallee, France). The teeth immersed in water-soluble contrast media and subtraction images were taken. Each tooth was then sectioned for histologic examination. The digital radiographic images and subtraction images were examined and interpreted by three dentists for proximal caries. The results of the proximal caries diagnosis were then verified with the results of the histologic examination. RESULTS: The proximal caries sensitivity using digital subtraction radiography was significantly higher than simply examining a single digital radiograph. The sensitivity of the proximal dentinal carious lesion when analyzed with the subtraction radiograph and the radiograph together was higher than with the subtraction radiograph or the radiograph alone. CONCLUSION: The use of subtraction radiography with contrast media may be useful for detecting proximal dentinal carious lesions.

Digital contrast subtraction radiography for proximal caries diagnosis / 대한구강악안면방사선학회지

PURPOSE: To determine whether subtraction images utilizing contrast media can improve the diagnostic performance of proximal caries diagnosis compared to conventional periapical radiographic images. MATERIALS AND METHODS: Thirty-six teeth with 57 proximal surfaces were radiographied using a size #2 RVG-ui sensor (Trophy Radiology, Marne-la-Vallee, France). The teeth immersed in water-soluble contrast media and subtraction images were taken. Each tooth was then sectioned for histologic examination. The digital radiographic images and subtraction images were examined and interpreted by three dentists for proximal caries. The results of the proximal caries diagnosis were then verified with the results of the histologic examination. RESULTS: The proximal caries sensitivity using digital subtraction radiography was significantly higher than simply examining a single digital radiograph. The sensitivity of the proximal dentinal carious lesion when analyzed with the subtraction radiograph and the radiograph together was higher than with the subtraction radiograph or the radiograph alone. CONCLUSION: The use of subtraction radiography with contrast media may be useful for detecting proximal dentinal carious lesions.

A comparison of subtracted images from dental subtraction programs / 대한구강악안면방사선학회지

PURPOSE: To compare the standard deviation of gray levels on digital subtracted images obtained by different dental subtraction programs. MATERIALS AND METHODS: Paired periapical films were taken at the lower premolar and molar areas of the phantoms involving human mandible. The bite registration group used Rinn XCP equipment and bite registration material, based on polyvinyl siloxane, for standardization. The no bite registration group used only Rinn XCP equipment. The periapical film images were digitized at 1200 dpi resolution and 256 gray levels by a flat bed scanner with transparency unit. Dental digital subtraction programs used for this study were Subtractor (Biomedisys Co., Korea) and Emago (Oral Diagnostic Systems, The Netherlands). To measure the similarities between the subtracted images, the standard deviations of the gray levels were obtained using a histogram of subtracted images, which were then analyzed statistically. RESULTS: Subtracted images obtained by using the Emago program without manual selection of corresponding points showed the lowest standard deviation of gray levels (p<0.01). And the standard deviation of gray levels was lower in subtracted images in the group of a bite registration than in the group of no use of bite registration (p<0.01). CONCLUSION: Digital radiographic subtraction without manual selection of reference points was found to be a convenient and superior method.