Comparison between two tomographic sections in the diagnosis of external root resorption

OBJECTIVES: To assess the accuracy of coronal and sagittal CT sections to detect cavities simulating root resorption. MATERIAL AND METHODS: 60 mandibular incisors were embedded in plaster bases, and cavities with 0.6, 1.2 or 1.8 mm in diameter and 0.3, 0.6 or 0.9 mm in depth (small, medium and large cavities) were drilled on the buccal surfaces with high-speed round burs with diameters of 0.6, 1.2 and 1.8 mm to simulate external inflammatory root resorption. Simulations in the cervical, middle and apical thirds of each tooth root were made randomly. The Dental Scan software was used to obtain 1-mm-thick axial images from direct scanning, which were reconstructed in the coronal and sagittal planes using 3D software (Syngo FastView). Each series was loaded into the software. Fourteen images of each tooth were reconstructed in the coronal plane and 14 in the sagittal plane. A total of 1,652 images were obtained for analysis. Series information, tooth number and the plane reconstructed were stored. The images generated were saved on a CD-ROM together with the visualization software (Syngo FastView). Images were analyzed by a previously calibrated blinded, radiologist. Cochran's Q test was conducted separately for each region analyzed followed by pair-wise comparison by the McNemar test (p=0.05). RESULTS: No statistically significant difference (p>0.05) was observed in the diagnosis of simulated resorption between the apical, middle, and coronal thirds. When the axial plane was assessed separately, diagnoses were statistically different (p<0.05) among the three root thirds. The apical third differed significantly (p<0.05) from the cervical and middle thirds. Diagnostic errors were more often observed in the apical third compared to the cervical and middle thirds. Mid-sized cavities revealed no statistically significant differences (p>0.05) between planes, irrespective of the third in which the resorptions were located. CONCLUSION: When tomographic sections are requested for the diagnosis of buccal or lingual external root resorption, sagittal sections afford the best image characterization of the resorption process.

Tomografia computadorizada da coluna lombar após artrodese com emprego de material metálico: avaliação da qualidade da imagem para diferentes algoritmos matemáticos / Lumbar spine computed tomography after arthrodesis with metal implant: a qualitative evaluation of images reconstructed with different mathematical algorithms

OBJETIVO: Selecionar os melhores algoritmos para o exame de coluna lombar na avaliação de artrodese com material metálico. MATERIAIS E MÉTODOS: Utilizou-se um equipamento de tomografia computadorizada de 16 fileiras de detectores. Imagens de dez pacientes foram reconstruídas com filtros 20, 40, 60 e 80 e realizadas reformatações em três dimensões e multiplanares com espessuras de 2 mm e 4 mm. Um total de 320 imagens foi avaliado por três experientes radiologistas, que deram notas de 1 a 5 (1 = não-aceitável; 2 = abaixo dos padrões; 3 = aceitável; 4 = acima da média; 5 = excelente). Além disso, foram realizadas medidas de ruído para correlação com o tipo de filtro utilizado. RESULTADOS: As médias do valor de ruído para reconstrução com 2 mm e filtros 20, 40, 60 e 80 foram de 24,7 ± 4,3; 35,5 ± 4,2; 106,0 ± 18,5 e 145,9 ± 26,9, respectivamente, e para 4 mm foram de 18,1 ± 2,4; 25,1 ± 4,6; 76,7 ± 17,2 e 106,6 ± 23,4. CONCLUSÃO: As imagens coloridas em três dimensões são mais bem visualizadas com filtro 20, entretanto, nas imagens em tons de cinza um filtro intermediário de 40 ou 60 pode ser útil para demonstrar os parafusos com maior detalhe. Para reconstruções multiplanares com espessura de 2 mm o filtro 40 é mais bem aceito, e para uma espessura de 4 mm um filtro 60 apresentou melhor qualidade.

OBJECTIVE: To select the best mathematical algorithms for lumbar spine imaging studies to assess arthrodesis with metal implant. MATERIALS E METHODS: The images acquisition was performed with a multidetector (16 rows) CT scanner, and 2 mm and 4 mm slice thickness. Images of ten patients were reconstructed with filters 20, 40, 60 and 80, employing multiplanar three-dimensional volume-rendering techniques. A total of 320 images were evaluated by three experienced radiologists who rated the images from 1 to 5 (1 = unacceptable; 2 = substandard; 3 = acceptable; 4 = above the average; 5 = excellent). Additionally, noise measurements were performed for correlation with the type of filter utilized. RESULTS: For 2 mm thickness and filters 20, 40, 60 e 80, mean noise measurements for images reconstruction were, respectively, 24.7 ± 4.3, 35.5 ± 4.2, 106.0 ± 18.5 and 145.9 ± 26.9, and for 4 mm and filters 20, 40, 60 and 80 were, respectively, 18.1 ± 2.4, 25.1 ± 4.6, 76.7 ± 17.2 and 106.6 ± 23.4. CONCLUSION: Three-dimensional color images could be better visualized with filter 20; however, in the case of gray-scale, filters 40 or 60 could be useful to demonstrate the arthrodesis pedicle screws in higher detail. For multiplanar reconstructions with 2 mm slice thickness, the filter 40 was the most appropriate, and for 4 mm, a filter 60 presented a better image quality.

Protocolo de testes de aceitação em equipamentos de imagem por ressonância magnética / Acceptance testing protocol for magnetic resonance imaging systems

OBJETIVO: Este trabalho tem como objetivo criar um protocolo de testes de aceitação para equipamentos de imagem por ressonância magnética e demonstrar como e quais tipos de dispositivos de teste podem ser usados para a coleta de dados. MATERIAIS E MÉTODOS: Para cada um dos 15 testes selecionados foram elaborados a definição, o procedimento, a forma de análise e o critério de aceitação. RESULTADOS: Através dos testes de aceitação descritos é possível verificar características técnicas que constam nas propostas de venda dos fabricantes, assim como estabelecer valores de referências para serem utilizados em posteriores testes de constância. CONCLUSÃO: Futuros programas de garantia da qualidade em imagem por ressonância magnética devem considerar testes semelhantes ou iguais aos descritos neste trabalho.