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.
Keywords: Computed tomography, Arthrodesis, Lumbar spine, Image quality
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