An open-source musculoskeletal model of the lumbar spine and lower limbs: a validation for movements of the lumbar spine.

Musculoskeletal models of the lumbar spine have been developed with varying levels of detail for a wide range of clinical applications. Providing consistency is ensured throughout the modelling approach, these models can be combined with other computational models and be used in predictive modelling studies to investigate bone health deterioration and the associated fracture risk. To provide precise physiological loading conditions for such predictive modelling studies, a new full-body musculoskeletal model including a detailed and consistent representation of the lower limbs and the lumbar spine was developed. The model was assessed against in vivo measurements from the literature for a range of spine movements representative of daily living activities. Comparison between model estimations and electromyography recordings was also made for a range of lifting tasks. This new musculoskeletal model will provide a comprehensive physiological mechanical environment for future predictive finite element modelling studies on bone structural adaptation. It is freely available on https://simtk.org/projects/llsm/.

Is there a role for free breathing non-contrast steady-state free precession renal MRA imaging for assessing live donors? A preliminary study.

OBJECTIVE: Accurate pre-operative evaluation of renal vascular anatomy is essential for successful renal harvest in live donor transplantation. Non-contrast renal MR angiographic (MRA) techniques are potentially well suited to the screening of donors; however, their restricted imaging field of view (FOV) has previously been an important limitation. We sought to assess whether the addition of a large FOV balanced fast field echo (BFFE) steady-state free precession (SSFP) sequence to non-contrast SSFP MRA could overcome this problem. Comparison with contrast-enhanced MRA (CE MRA) and findings at surgery were performed. METHODS: 22 potential renal donors each underwent SSFP and CE MRA. 11 out of 22 potential donors subsequently underwent a donor nephrectomy. RESULTS: All images were diagnostic. Both SSFP MRA and CE MRA identified an equal number of arteries. Surgery confirmed two accessory renal arteries, both demonstrated with both imaging techniques. A third accessory vessel was identified with both techniques on a kidney contralateral to the donated organ. 6 out of 11 procured kidneys demonstrated early branch arteries at surgery, 5 out of 6 of which had been depicted on both SSFP and CE MRA. The median grading of image quality for main renal arteries was slightly better for CE MRA (p=0.048), but for accessory vessels it was better for SSFP MRA. CONCLUSION: This pilot study indicates that by combining free-breathing SSFP MRA with large-FOV bFFE images, an accurate depiction of renal vascular anatomy without the need for intravenous contrast administration can be obtained, as compared with surgical findings and CE MRA.

Changes in brain morphology in patients with obstructive sleep apnoea.

BACKGROUND: Obstructive sleep apnoea (OSA) is a common disease that leads to daytime sleepiness and cognitive impairment. Attempts to investigate changes in brain morphology that may underlie these impairments have led to conflicting conclusions. This study was undertaken to aim to resolve this confusion, and determine whether OSA is associated with changes in brain morphology in a large group of patients with OSA, using improved voxel-based morphometry analysis, an automated unbiased method of detecting local changes in brain structure. METHODS: 60 patients with OSA (mean apnoea hypopnoea index 55 (95% CI 48 to 62) events/h, 3 women) and 60 non-apnoeic controls (mean apnoea hypopnoea index 4 (95% CI 3 to 5) events/h, 5 women) were studied. Subjects were imaged using T1-weighted 3-D structural MRI (69 subjects at 1.5 T, 51 subjects at 3 T). Differences in grey matter were investigated in the two groups, controlling for age, sex, site and intracranial volume. Dedicated cerebellar analysis was performed on a subset of 108 scans using a spatially unbiased infratentorial template. RESULTS: Patients with OSA had a reduction in grey matter volume in the right middle temporal gyrus compared with non-apnoeic controls (p<0.05, corrected for topological false discovery rate across the entire brain). A reduction in grey matter was also seen within the cerebellum, maximal in the left lobe VIIIb close to XI, extending across the midline into the right lobe. CONCLUSION: These data show that OSA is associated with focal loss of grey matter that could contribute to cognitive decline. Specifically, lesions in the cerebellum may result in both motor dysfunction and working memory deficits, with downstream negative consequences on tasks such as driving.

Effectiveness and relevance of MR acceptance testing: results of an 8 year audit.

The effectiveness and relevance of independent acceptance testing was assessed by means of an audit of acceptance procedures for 17 MRI systems, with field strengths in the range 0.5-1.5 T, acquired over 8 years. Signal-to-noise ratio and geometric linearity were found to be the image quality parameters most likely to fall below acceptable or expected standards. These received confirmed successful corrective action in 69% of instances. Non-uniformity, ghosting and poor fat suppression were the next most common non-compliant parameters, but yielded less satisfactory outcomes. Spatial resolution was not found to be a sensitive parameter in determining acceptability. 49% of all non-compliant parameters received verifiable corrective attention. A schedule of actual acceptance criteria is presented and shown to be reasonable. Parameter failure rates were shown not to have improved with time. A safety audit of 11 of the installations revealed the most common failings to be inadequate suite layout and poor use of signs. The mean number of safety issues per installation identified as requiring attention was 5, from a questionnaire of 100 points. A number of anecdotal errors and omissions are reported. The data support the importance of an appropriate acceptance procedure for new clinical MRI equipment and for the involvement of a suitably qualified safety adviser on the project team from the outset.