CT and MRI anatomy of the lumbar spine.

Lumbosacral spine examinations represent approximately 30% of CT and MRI procedures. Aim of this article is to pinpoint the anatomy of lumbosacral spine whose knowledge is basic for understanding and interpreting CT and MR images.

[Digital film viewer versus conventional view boxes in the identification of bone and joint disorders]. / Diafanoscopio digitale vs tradizionale nell'identificazione delle malattie osteo-articolari.

PURPOSE: To compare the diagnostic accuracy of a digital film viewer (Smartlight 2000 Plus) versus a conventional view box for the identification of bone and joint disorders. MATERIAL AND METHODS: In order to evaluate the qualitative and quantitative differences of digital and conventional film viewers, 100 plain films of patients with bone and joint disorders taken in an emergency room January through May 1998 were reviewed utilizing both types of view boxes. Three radiologists expert of bone and joint disorders, independently compared the films, filled a form about the qualitative and quantitative analysis of the lesions depicted for each patient, and reported a few notes on the technical quality of the plain films in terms of exposure. The results were compared using the chi-square test (p < 0.005). RESULTS: Data analysis showed that the digital film viewer permitted a quicker reading of the film while decreasing the perception threshold for elementary lesions and ocular fatigue. All the radiographs read with the digital film viewer were considered technically adequate: the film quality was considered good in 10 cases and sufficient in 2. Two of the same radiographs read with the conventional view box were considered of good quality, nine were considered sufficient and one was considered insufficient due to overexposure. There were six cases of agreement and six of disagreement for the diagnosis: four were due to overexposure of the radiograph and two to better conspicuity provided by the digital film viewer. DISCUSSION: Correct image illumination is the first element a radiologist evaluates when reading a radiograph. A conventional view box may, when it is not properly maintained or when the radiograph is overexposed, decrease the radiologist's visual capacity. This increases the time required to read the radiograph and, therefore, physical and ocular fatigue, which in turn increases the risk of missing or misevaluating a lesion. A digital film viewer emits light with a variable intensity which is proportional to the optical density of the film. This increases the visual capacity of the radiologist and the lesion contrast, while reducing the factors which affect the radiograph reading. CONCLUSIONS: The use of a digital film viewer increased the visual capacity of the radiologist and eliminated the negative elements which complicated the radiograph reading and permitted the use of radiographs that would otherwise have been considered of poor quality due to overexposure. This, combined with the experience of the radiologist, decreased of the risk of missing or misevaluating a lesion.