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1.
Juhani Trmnen Osmo Tervonen Antero Koivula Juhani Junila Ilkka Suramo 《Journal of magnetic resonance imaging : JMRI》1996,6(5):805-811
The purpose of this study was to explore systematically the effect of the imaging parameters changeable by the user in spin-echo (SE) imaging sequences to minimize image distortion when imaging joint prostheses. A titanium alloy hip joint prosthesis was studied at 1.0 T. The SE imaging parameters were bandwidth/pixel (BW/p), TE, strength of encoding gradients (matrix size), echo train length (ETL), and direction of phase and frequency encoding. The effect of ETL in rapid acquisition relaxation enhanced (RARE) sequences was also evaluated with a turbo-SE sequence using a different ETL with the same TR and an effective TE. It is concluded that an optimized image quality can be achieved in SE imaging by using a high bandwidth/pixel value (at least 130 Hz/pixel), a high resolution matrix (256–512), sequences with multiple refocusing, and a frequency-encoding axis parallel to the long axis of the prosthesis. The degree of distortion is reduced with this optimized technique. 相似文献
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Role of overlapping genetic and environmental factors in the relationship between early adolescent conduct problems and substance use in young adulthood 下载免费PDF全文
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Juho-Antti Junno Markus Paananen Jaro Karppinen Tuija Tammelin Jaakko Niinimäki Eveliina Lammentausta Markku Niskanen Miika T. Nieminen Marjo-Riitta Järvelin Jani Takatalo Osmo Tervonen Juha Tuukkanen 《The spine journal》2013,13(2):184-189
Background contextReduced vertebral strength is a clear risk factor for vertebral fractures. Men and women with vertebral fractures often have reduced vertebral size and bone mineral density (BMD). Vertebral strength is controlled by both genetic and developmental factors. Malnutrition and low levels of physical activity are commonly considered to result in reduced bone size during growth. Several studies have also demonstrated the general relationship between BMD and physical activity in the appendicular skeleton.PurposeIn this study, we wanted to clarify the role of physical activity on vertebral bodies. Vertebral dimensions appear to generally be less pliant than long bones when lifetime changes occur. We wanted to explore the association between physical activity during late adolescence and vertebral strength parameters such as cross-sectional size and BMD.Study designThe association between physical activity and vertebral strength was explored by measuring vertebral strength parameters and defining the level of physical activity during adolescence.Patient sampleThe study population consisted of 6,928 males and females who, at 15 to 16 and 19 years of age, responded to a mailed questionnaire inquiring about their physical activity. A total of 558 individuals at the mean age of 21 years underwent magnetic resonance imaging (MRI) scans.MethodsWe measured the dimensions of the fourth lumbar vertebra from the MRI scans of the Northern Finland Birth Cohort 1986 and performed T2* relaxation time mapping, reflective of BMD. Vertebral strength was based on these two parameters. We analyzed the association of physical activity on vertebral strength using the analysis of variance.Results and conclusionsWe observed no association between the level of physical activity during late adolescence and vertebral strength at 21 years. 相似文献
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Päivi E. Korhonen Tellervo Seppälä Salme Järvenpää Hannu Kautiainen 《Quality of life research》2014,23(1):67-74
Purpose
Obesity is known to be associated with a range of chronic medical comorbidities, but little is known about the impact of overweight and obesity on health-related quality of life (HRQoL) in persons without chronic diseases. The aim of this study was to assess HRQoL, body mass index (BMI) and health behavior patterns in a community sample of subjects who had no long-lasting medical comorbiditiesMethods
We assessed HRQoL in 1,187 apparently healthy individuals (mean age 57 ± 7 years), of whom 24 % were classified as normal weight, 49 % as overweight, 20 % as obese and 7 % as very obese. Two different instruments of HRQoL were used: the generic Short-Form Health Survey (SF-36) questionnaire and the preference-based instrument EuroQol (EQ-5D).Results
All physical components of the SF-36 decreased linearly according to BMI categories in women. In men, only poorer physical functioning scale showed linearity with rising BMI. Scores on the mental components of the SF-36 did not differ by BMI categories in either gender. The EQ-5D index and EuroQol visual analogue scale scores decreased linearly with rising BMI only in women.Conclusions
In apparently healthy middle-aged subjects, physical HRQoL decreases with increasing level of BMI and more so in women than in men. Mental components of HRQoL do not differ between the categories of BMI in either gender. 相似文献8.
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Kurunlahti M Karppinen J Haapea M Niinimäki J Autio R Vanharanta H Suramo I Tervonen O 《Spine》2004,29(16):1804-8; discussion 1809
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Ahmed Abou‐Elseoud Tuomo Starck Jukka Remes Juha Nikkinen Osmo Tervonen Vesa Kiviniemi 《Human brain mapping》2010,31(8):1207-1216
Independent component analysis (ICA) of functional MRI data is sensitive to model order selection. There is a lack of knowledge about the effect of increasing model order on independent components' (ICs) characteristics of resting state networks (RSNs). Probabilistic group ICA (group PICA) of 55 healthy control subjects resting state data was repeated 100 times using ICASSO repeatability software and after clustering of components, centrotype components were used for further analysis. Visual signal sources (VSS), default mode network (DMN), primary somatosensory (S1), secondary somatosensory (S2), primary motor cortex (M1), striatum, and precuneus (preC) components were chosen as components of interest to be evaluated by varying group probabilistic independent component analysis (PICA) model order between 10 and 200. At model order 10, DMN and VSS components fuse several functionally separate sources that at higher model orders branch into multiple components. Both volume and mean z‐score of components of interest showed significant (P < 0.05) changes as a function of model order. In conclusion, model order has a significant effect on ICs characteristics. Our findings suggest that using model orders ≤20 provides a general picture of large scale brain networks. However, detection of some components (i.e., S1, S2, and striatum) requires higher model order estimation. Model orders 30–40 showed spatial overlapping of some IC sources. Model orders 70 ± 10 offer a more detailed evaluation of RSNs in a group PICA setting. Model orders > 100 showed a decrease in ICA repeatability, but added no significance to either volume or mean z‐score results. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc. 相似文献