Evaluation of a new low-dose biplanar system to assess lower-limb alignment in 3D: a phantom study.
Skeletal Radiol
; 41(10): 1287-93, 2012 Sep.
Article
em En
| MEDLINE
| ID: mdl-22684406
ABSTRACT
OBJECTIVE:
Knee coronal alignment is routinely assessed on a full-length radiograph of the lower limbs. However, poor positioning of the knee during the procedure affects the accuracy of this kind of measurement, particularly in cases combining knee rotation and flexion. The purpose of this study was to assess the value of a three-dimensional assessment of the hip-knee-ankle (HKA) angle based on a biplanar radiographic system. MATERIALS ANDMETHODS:
A biplanar slot scanning system was used to take radiographs of three lower-limb synthetic models with similar frontal deviation (5° valgus) but different flexion angulations (0°, 9°, and 18°). Biplane acquisitions were done with lower-limb axial rotations ranging from 20° of internal rotation to 20° of external rotation on each of the lower limb models. Three independent observers performed standard 2D measurements of the HKA angle from each anteroposterior (AP) image and also modeled the lower limb in 3D for each biplane acquisition with dedicated software. The HKA angle was automatically calculated from the 3D models. The results of the 2D and 3D techniques were compared.RESULTS:
Axial rotation provoked 2D HKA measurement errors up to, respectively, 1.4°, 4.7°, and 6.8° for the lower extremities with 0°, 9°, and 18° flexion, while it never affected the 3D HKA measurement for more than 1.5°. Interobserver errors were 0.7° (SD = 0.5°) for the 2D measurements and 0.6° (SD = 0.4°) for the 3D measurements.CONCLUSIONS:
The 3D modeling allows for a more accurate evaluation of coronal alignment compared to 2D, eliminating bias due to wrong knee positioning.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Algoritmos
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Interpretação de Imagem Radiográfica Assistida por Computador
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Tomografia Computadorizada por Raios X
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Imagens de Fantasmas
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Imageamento Tridimensional
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Posicionamento do Paciente
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Perna (Membro)
Tipo de estudo:
Diagnostic_studies
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Prognostic_studies
Limite:
Humans
Idioma:
En
Ano de publicação:
2012
Tipo de documento:
Article