Digital selenium radiography: anti-scatter grid for chest radiography in a clinical study.

The purpose of this study was to evaluate the diagnostic performance of an additional stationary anti-scatter grid in digital selenium radiography (DSR) compared with images acquired with only an air gap. Chest radiographs were obtained with DSR in 100 patients with and without an anti-scatter grid. Four observers scored 12 anatomical landmarks, catheters and wire cerclages for their visualization in both subsets of images. Statistical analysis was performed using a paired t-test. Anatomical landmarks, catheters and wire cerclages were statistically better visualized in regions of high attenuation when the images were performed with an anti-scatter grid. No statistically significant difference was noted for peripheral regions, nor for sex and weight of the patient between the two modalities. Therefore, an anti-scatter grid is not recommended for chest radiography as it increases the radiation exposure of patients without having a significant impact on visualization for all regions of the chest.

[Virtual cystoscopy with reduced tube current: an alternative to cystoscopy?]. / Virtuelle Zystoskopie mit reduziertem Röhrenstrom: Eine Alternative zur Zystoskopie?

PURPOSE: Virtual cystoscopy at different mAs settings in patients with tumors of the bladder in comparison with cystoscopy and axial CT. MATERIALS AND METHODS: The study included 28 patients with bladder tumors and 28 patients without tumors as control group. The bladder was distended with air and scanned at two different mAs settings (protocol 1 and 2). The radiation exposure was reduced by 82 % for protocol 2 in comparison with protocol 1. Three readers compared virtual cystoscopy with cystoscopy and axial CT as to tumor location and size. Sensitivity, specificity and accuracy were calculated. RESULTS: Of the 47 tumors seen at cystoscopy, all readers detected 45 tumors by virtual cystoscopy using protocol 1 and 44 tumors using protocol 2, with p > 0.05 in comparison with cystoscopy. Virtual cystoscopy showed higher sensitivity than axial CT (97.2 % vs. 86.5 % for protocol 1) and (96.5 % vs. 86.5 % for protocol 2) with the same specificity (100 %). The accuracy was 0.982 for protocol 1 and 0.978 for protocol 2. In comparison with virtual cystoscopy, axial CT shoved more often over- and underestimation of the tumor size. CONCLUSION: Virtual cystoscopy at reduced mAs setting is a modality suitable for the detection of polypoid tumors, but does not provide data of the mucosa and thus cannot replace cystoscopy yet.

Postural responses to changing task conditions in patients with cerebellar lesions.

OBJECTIVE: To investigate the role of the cerebellum in postural adaptation for changes to the stimulus type of support surface displacements (backward translations v "toes up" rotations). METHODS: A group of 13 patients with chronic, isolated lesions of the cerebellum and 15 control subjects were tested. Automatic postural responses of the medial gastrocnemius and anterior tibial muscles were recorded. The first paradigm consisted of 10 rotational perturbations followed by 10 backward translations of the platform, and 10 backward translations followed by 10 rotations. The second paradigm consisted of 18 rotations and two randomly interposed translational perturbations, and 18 translations with two rotations randomly interposed. RESULTS: When the type of perturbation changed from an expected translation to an unexpected rotation and vice versa both control subjects and cerebellar patients showed an immediate and significant change in the response amplitude of the medial gastrocnemius and at the same time an immediate and significant change in the response amplitude of the anterior tibial muscles. Neither controls nor cerebellar patients showed effects of prediction in surface displacements of unexpected types of perturbation. Both controls and cerebellar patients showed no gradual increase in the gastrocnemius response in subsequent trials of surface translations following a block of 10 surface rotations and no gradual increase in the response amplitude of the anterior tibial muscle in subsequent trials of surface rotations following a block of 10 surface translations. CONCLUSIONS: Despite postural hypermetria, the integrity of the cerebellum does not seem critical for adaptation of postural synergies to changing stimulus types of surface displacements. The present results support previous findings suggesting that the main role of the cerebellum in automatic postural responses may be gain control.