TOWARD AN IDEAL PERFORMANCE OF CIRCLES ON POMMEL HORSE —CENTRIFUGAL FORCE AND MASS-CENTRE VELOCITY—

To advance mechanical understanding of circles on pommel horse, we analysed the centrifugal force and the kinematics of whole-body mass centre during circles performed by five high-scored and five low-scored gymnasts. Three-dimensional kinematic and kinetic data were recorded using a motion capture system and force plates set under a no-leg pommel horse. The results showed that the high-scored gymnasts kept a greater mass-centre velocity and centrifugal force during the single-hand support phases than the low-scored gymnasts. It also seemed to be a reasonable interpretation, however, that the double-hand support phases were more complicated and difficult from a mechanical standpoint. Even the high-scored gymnasts who participated in this study might have room for further improvement especially in the double-hand support phases

Comparing 2-dimensional versus 3-dimensional MR myelography for cerebrospinal fluid leak detection

Purpose: We compared cerebrospinal fluid (CSF) leak conspicuity and image quality as visualized using 3D versus 2D magnetic resonance (MR) myelography in patients with spinal CSF leaks. Methods: Eighteen patients underwent spinal MR imaging at 3 Tesla. Three board-certified radiologists independently evaluated CSF leak conspicuity and image quality on a 4-point scale; the latter assessed by scoring fat suppression, venous visualization, and severity of CSF flow artifacts. Additionally, the evaluators ranked the overall performances of 2D versus 3D MR myelography upon completing side-by-side comparisons of CSF leak conspicuity. Inter-reader agreement was determined using the Gwet’s AC1. Results: The quality of 3D MR myelography images was significantly better than that of 2D MR myelography with respect to CSF leak conspicuity (mean scores: 3.3 vs. 1.9, p < 0.0001) and severity of CSF flow artifacts on the axial view (mean scores: 1.0 vs. 2.5, p = 0.0001). Inter-reader agreement was moderate to almost perfect for 2D MR myelography (AC1 = 0.55–1.00), and almost perfect for 3D MR myelography (AC1 = 0.85–1.00). Moreover, 3D MR myelography was judged to be superior to 2D acquisition in 78 %, 83 %, and 83 % of the samples per readers 1, 2 and 3, respectively; the inter-reader agreement was almost perfect (AC1: reader 1 vs. 2; 0.98, reader 2 vs. 3; 0.96, reader 3 vs. 1; 0.98). Conclusion: CSF leaks are more conspicuous when using 3D MR myelography than when using its 2D counterpart; therefore, the former is more reliable for identifying such leaks

＜Symposium IV＞Oligomeric Aβ is the sole culprit molecule to cause Alzheimer's disease?

Alzheimer's disease (AD) is the major and common disease usually for aged people to show progressive neurodegenerative disorder with the dementia. Amyloid-beta （also β-protein and referred here to as Aβ） is a wellestablished seminal peptide in AD that is produced from the amyloid precursor protein （APP） by consecutive digestions with β-secretase of BACE and gamma-secretase of the presenilin complex. Abnormal cerebral accumulation of Aβ such as insoluble fi brils in senile plaques and cerebral amyloid angiopathy （CAA） are observed as a neuropathological hallmark of AD. In contrast to such insoluble fi brillary Aβ, a soluble oligomeric complex is discussed as ADDLs, Aβ oligomer, low-n oligomer Aβ, Aβ*56 or so. Despite their diff erent names, it is proposed as the current hypothesis that oligomeric Aβ is the direct molecule to cause synaptic toxicity and cognitive dysfunction in the early stages of AD. We identifi ed a novel APP mutation （E693delta; referred to as the Osaka mutation） in a pedigree with probable AD resulting in a variant Aβ lacking glutamate at position 22. Based on theoretical prediction and in vitro studies on synthetic mutant Aβ peptides, the mutated Aβ peptide showed a unique aggregation property of enhanced oligomerization but no fi brillization. This was further confi rmed by PiB-PET analysis on the proband patient. Collectively together, we conclude that the Osaka mutation is the fi rst human evidence for the hypothesis that oligomeric Aβ is involved in AD

Bone marrow lesions: A systematic diagnostic approach

Bone marrow lesions on magnetic resonance (MR) imaging are common and may be seen with various pathologies. The authors outline a systematic diagnostic approach with proposed categorization of various etiologies of bone marrow lesions. Utilization of typical imaging features on conventional MR imaging techniques and other problem-solving techniques, such as chemical shift imaging and diffusion-weighted imaging (DWI), to achieve accurate final diagnosis has been highlighted