Search

Purpose: This study aimed to determine the changes in the cartilage contact pattern, contact area, and contact centroid between the humeral head and glenoid during abduction using magnetic resonance imaging (MRI) under static conditions in vivo. We hypothesized that as the glenohumeral abduction angle increases, the cartilage contact area increases and the contact pattern and contact centroid shift superiorly and anteriorly. Methods: The present study comprised 14 Japanese men with no history of shoulder injury or disorders. MRI was performed in the following four postures: neutral posture with arms at the side of the trunk and postures at 30°, 60°, and 120° of thoracohumeral abduction, which corresponded to 18.6° ± 5.7°, 27.8° ± 7.0°, and 66.8° ± 13.1° of glenohumeral abduction, respectively. The cartilage contact pattern was determined from the signal intensity profiles of MR images using image analysis software. Results: We observed that the contact area was independent of the thoracohumeral abduction angle. The contact area at 120° of thoracohumeral abduction was approximately 10% smaller than at other angles, although this difference was not statistically significant. The contact centroid was significantly shifted superiorly as the thoracohumeral abduction angle increased (p< 0.01), with a trend toward anterior movement. Conclusion: These results confirmed that the contact pattern and contact centroid shifted superiorly and anteriorly. We believe that determining the contact pattern and contact area of the glenohumeral joint is useful for detecting abnormal shoulder joint movements and can guide the diagnosis, treatment, and rehabilitation of patients with shoulder disorders.

Purpose: The tarsometatarsal (TMT) joints play crucial roles in walking and slow running. Some studies have treated the 1st to 5th TMT joints collectively as a single joint. However, few studies have examined each individual joint within the 1st to 5th TMT joints separately. This study sought to determine the rotation angles and axes of the 1st–5th TMT joints as each metatarsal head was dorsally displaced in vivo. Methods: CT imaging was conducted on 11 subjects under six conditions: a basic posture and isolated metatarsal movement postures in which one of the 1st to 5th metatarsals was dorsally displaced with a load of 55 N. The helical axis parameters (rotation angle and rotation axis) of the metatarsal were calculated by transitioning from the basic posture to each isolated metatarsal movement posture. Results: Multiple comparison testing on the dorsal rotation angles showed significant differences between all TMT joints, except between the 1st and 4th TMT joints and between the 1st and 5th TMT joints (p< 0.01). The 2nd TMT joint exhibited a significantly lower dorsal rotation angle than the other TMT joints. By transitioning from the 1st to the 5th TMT joints, the transversal plane rotation axis shifted from lateral-anterior to -posterior, while that of the sagittal plane shifted from anterior- to posterior-inferior. Conclusion: This study provided the rotation angles and axes of the 1st–5th TMT joints in vivo. The data provide a useful reference dataset for selecting diseased feet and developing new foot orthoses.

Although endovascular aortic repair (EVAR) has become the dominant therapeutic approach for abdominal aortic aneurysm (AAA), continued sac growth after EVAR remains a major concern and is still unpredictable. Since AAA formation is thought to arise from atherosclerotic vascular damage of the aortic wall, we hypothesize that the severity of atherosclerosis in the AAA wall may influence sac growth. Therefore, we investigated whether brachial-ankle pulse wave velocity (baPWV), a marker of atherosclerosis severity obtained by noninvasive automatic devices, can predict sac growth after EVAR.

Various structures in the body can undergo torsion, which requires emergent diagnosis to facilitate early surgical intervention to restore blood flow, and familiarity with the various imaging findings of torsion can aid in timely management.

After radiation therapy of the central nervous system, a variety of radiation-induced changes may be observed at imaging, and the radiologist should be familiar with the timeline of such changes and their imaging appearances to avoid pitfalls in image interpretation.

Diffusion tensor tractography (DTT) is not adequately reliable for prediction of facial and vestibulocochlear (VII–VIII) nerve locations, especially relative to a vestibular schwannoma (VS). Furthermore, it is often not possible to visualize normal VII–VIII nerves by DTT (visualization rates were 12.5–63.6 %). Therefore, DTT post-processing was optimized for normal VII–VIII nerve visualization with and without manual noise elimination. DTT examinations of ten patients were evaluated to assess the improvement in performance by modifying seed region of interest (ROI) and fractional anisotropy (FA) threshold. Seed ROI was placed at the porus of the internal auditory meatus, and FA threshold values were either fixed or variable for each patient. DTT visualization of cranial nerves VII–VIII was evaluated and the noise effect was measured. Cranial nerves VII–VIII were visualized in 90 % of patients without using manual noise elimination by modifying the seed ROI and FA threshold. The visualization rate with FA threshold of the upper limit in each patient (100 %) was significantly higher than that with FA threshold of 0.1 (75 %) ($$p=0.02$$ p=0.02 ). The incidence rate of noise with FA threshold of the upper limit (10 %) was not significantly different than the FA threshold of 0.1 (20 %) ($$p=0.66$$ p=0.66 ). Seed ROI modification and FA thresholding can improve the visualization of cranial nerve VII–VIII locations in DTT. This technique is promising for its potential to determine the relationship of cranial nerves VII–VIII to VS.

Brachial plexus injury (BPI) is a severe neurologic injury that causes functional impairment of the affected upper limb. Imaging studies play an essential role in differentiating between preganglionic and postganglionic injuries, a distinction that is crucial for optimal treatment planning. Findings at standard myelography, computed tomographic (CT) myelography, and conventional magnetic resonance (MR) imaging help determine the location and severity of injuries. MR imaging sometimes demonstrates signal intensity changes in the spinal cord, and enhancement of nerve roots and paraspinal muscles at MR imaging indicates the presence of root avulsion injuries. New techniques including MR myelography, diffusion-weighted neurography, and Bezier surface reformation can also be useful in the evaluation and management of BPI. MR myelography with state-of-the-art technology yields remarkably high-quality images, although it cannot replace CT myelography entirely. Diffusion-weighted neurography is a cutting-edge technique for visualizing postganglionic nerve roots. Bezier surface reformation allows the depiction of entire intradural nerve roots on a single image. CT myelography appears to be the preferred initial imaging modality, with standard myelography and contrast material–enhanced MR imaging being recommended as additional studies. Work-up will vary depending on the equipment used, the management policy of peripheral nerve surgeons, and, most important, the individual patient. © RSNA, 2006

Purpose: The aim of the study was to estimate the effect of distortion correction with correspondence to numbers of encoding directions to acquire diffusion tensor imaging (DTI) of improved quality. Materials and methods: Ten volunteers underwent DTI of the head using echo planar imaging with 6, 13, 27, and 55 encoding directions. Fractional anisotropy (FA) maps and apparent diffusion coefficient (ADC) maps were created before and after distortion correction. Regions of interest were placed in the corpus callosum on each map, and standard deviations of FA and ADC were calculated. FA maps were also evaluated visually by experienced neuroradiologists. Results: Dispersion of standard deviations tended to be reduced after distortion correction, with significant differences found in FA maps with 6 encoding directions, ADC maps with 6 directions, and ADC maps with 13 directions (P< 0.001, P< 0.005, and P< 0.05, respectively). Visual image quality was improved after distortion correction (P< 0.01 for all of the visual comparisons). Conclusion: Distortion correction is effective in providing DTI of enhanced quality, notwithstanding the number of encoding directions.