Virtual reality as a method of cognitive training of processing speed, working memory, and sustained attention in persons with acquired brain injury: a protocol for a randomized controlled trial.

BACKGROUND: Acquired brain injury (ABI) often leads to persisting somatic, cognitive, and social impairments. Cognitive impairments of processing speed, sustained attention, and working memory are frequently reported and may negatively affect activities of daily living and quality of life. Rehabilitation efforts aiming to retrain these cognitive functions have often consisted of computerized training programs. However, few studies have demonstrated effects that transfer beyond the trained tasks. There is a growing optimism regarding the potential usefulness of virtual reality (VR) in cognitive rehabilitation. The research literature is sparse, and existing studies are characterized by considerable methodological weaknesses. There is also a lack of knowledge about the acceptance and tolerability of VR as an intervention method for people with ABI. The present study aims to investigate whether playing a commercially available VR game is effective in training cognitive functions after ABI and to explore if the possible effects transfer into everyday functioning. METHODS: One hundred participants (18-65 years), with a verified ABI, impairments of processing speed/attention, and/or working memory, and a minimum of 12 months post injury will be recruited. Participants with severe aphasia, apraxia, visual neglect, epilepsy, and severe mental illness will be excluded. Participants will be randomized into two parallel groups: (1) an intervention group playing a commercial VR game taxing processing speed, working memory, and sustained attention; (2) an active control group receiving psychoeducation regarding compensatory strategies, and general cognitive training tasks such as crossword puzzles or sudoku. The intervention period is 5 weeks. The VR group will be asked to train at home for 30 min 5 days per week. Each participant will be assessed at baseline with neuropsychological tests and questionnaires, after the end of the intervention (5 weeks), and 16 weeks after baseline. After the end of the intervention period, focus group interviews will be conducted with 10 of the participants in the intervention group, in order to investigate acceptance and tolerability of VR as a training method. DISCUSSION: This study will contribute to improve understanding of how VR is tolerated and experienced by the ABI population. If proven effective, the study can contribute to new rehabilitation methods that persons with ABI can utilize in a home setting, after the post-acute rehabilitation has ended.

The potential of iodinated contrast reduction in dual-energy CT thoracic angiography; an evaluation of image quality.

INTRODUCTION: The purpose of this study was to compare a dual energy CT (DECT) protocol with 50% reduction of iodinated contrast to a single energy CT (SECT) protocol using standard contrast dose in imaging of the thoracic aorta. METHODS: DECT with a 50% reduction in iodinated contrast was compared with SECT. For DECT, monoenergetic images at 50, 55, 60, 65, 68, 70, and 74 keV were reconstructed with adaptive statistical iterative reconstruction (ASiR-V) of 50% and 80%. Objective image quality parameters included intravascular attenuation (HU), image noise (SD), contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR). Two independent radiologists subjectively assessed the image quality for the 55 and 68 keV DECT reconstructions and SECT on a five-point Likert scale. RESULTS: Across 14 patients, the intravascular attenuation at 50-55 keV was comparable to SECT (p > 0.05). The CNRs were significantly lower for DECT with ASIR-V 50% compared to SECT for all keV-values (p < 0.05 for all). For ASIR-V 80%, CNR was comparable to SECT at energies below 60 keV (p > 0.05). The subjective image quality was comparable between DECT and SECT independent of keV level. CONCLUSION: This study indicates that a 50% reduction in iodinated contrast may result in adequate image quality using DECT with monoenergetic reconstructions at lower energy levels for the imaging of the thoracic aorta. The best image quality was obtained for ASiR-V 80% image reconstructions at 55 keV. IMPLICATIONS OF PRACTICE: Dual energy CT with a reduction in iodinated contrast may result in adequate image quality in imaging of the thoracic aorta. However, increased radiation dose may limit the use to patients in which a reduction in fluid and iodinated contrast volume may outweigh this risk.

Reduction in dose from CT examinations of liver lesions with a new postprocessing filter: a ROC phantom study.

BACKGROUND: It is desirable to lower the dose from computed tomography (CT) examinations as much as possible without reducing diagnostic performance. Mathematical postprocessing filters are one tool to achieve dose reduction. PURPOSE: To evaluate the possibilities of reducing CT doses from liver examinations using a new postprocessing filter. MATERIAL AND METHODS: An anthropomorphic upper-abdomen phantom was used in receiver operating characteristic (ROC) studies of the detectability of liver lesions. A standard abdominal CT protocol was used. Only mA settings were changed; all other scan parameters were constant. The postprocessing filter used was SharpView CT, which provides context-controlled restoration of digital images using adaptive filters. Six readers were given a set of 10 images obtained at five different dose levels, each image with 32 predefined areas to be evaluated on a five-point scale. In total, 1920 areas were evaluated. At each dose level, the readers evaluated five images without enhancement and five images based on postprocessing filters. All images were randomized with respect to dose level. RESULTS: The postprocessing filter improved the diagnostic performance significantly compared to the unenhanced images at all dose levels. Radiation dose for abdominal CT examinations of liver lesions in the range 2-7 mm was reduced by 30% using postprocessing filters, while diagnostic performance of the examination was maintained or even improved. CONCLUSION: This study indicates great potential for lowering doses for CT examinations of liver lesions using the new postprocessing filter. The software must be fully tested clinically to reliably assess the benefits of this filtration.