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Pekka Niemi

Publications and source records attributed to Pekka Niemi.

9 recordsLinked to original sources
PubMed2006

Comparison of MRI and positron emission tomography for measuring myocardial perfusion reserve in healthy humans.

Myocardial perfusion reserve (MPR, defined as the ratio of the maximum myocardial blood flow (MBF) to the baseline) is an indicator of coronary artery disease and myocardial microvascular abnormalities. First-pass contrast-enhanced magnetic resonance imaging (CE-MRI) using gadolinium (Gd)-DTPA as a contrast agent (CA) has been used to assess MPR. Tracer kinetic models based on compartmental analysis of the CA uptake have been developed to provide quantitative measures of MBF by MRI. To study the accuracy of Gd-DTPA first-pass MRI and kinetic modeling for quantitative analysis of myocardial perfusion and MPR during dipyridamole infusion, we conducted a comparison with positron emission tomography (PET) in 18 healthy males (age = 40 +/- 14 years). Five planes were acquired at every second heartbeat with a 1.5T scanner using a saturation recovery turboFLASH sequence. A perfusion-related parameter, the unidirectional influx constant (Ki), was computed in three coronary artery territories. There was a significant correlation for both dipyridamole-induced flow (0.70, P = 0.001) and MPR (0.48, P = 0.04) between MRI and PET. However, we noticed that MRI provided lower MPR values compared to PET (2.5 +/- 1.0 vs. 4.3 +/- 1.8). We conclude that MRI supplemented with tracer kinetic modeling can be used to quantify myocardial perfusion.

Adult↗
PubMed2005

Connections between experience, beliefs, scientific knowledge, and self-evaluated expertise among investigators of child sexual abuse in Finland.

The purpose of this study was to investigate whether clinicians investigating child sexual abuse (CSA) rely more on scientific knowledge or on clinical experience when evaluating their own expertise. Another goal was to check what kind of pre-trial beliefs the clinicians had. The connections between these different factors were investigated. A questionnaire covering items concerning demographic data, experience, knowledge about CSA, self-evaluated expertise and beliefs about CSA was given to 126 social workers, 60 child psychiatrists and 134 psychologists. The results showed that the clinicians relied more on their clinical experience than on scientific knowledge when evaluating their expertise as investigators of CSA. Furthermore, social workers possessed stronger attitudes in favor of children than the other groups, while child psychiatrists had more negative attitudes towards the criminal justice system. Male participants had less strong beliefs than did the female participants. The findings indicate that the education of CSA investigators should focus more on theoretical knowledge and decision-making processes as well as the role of pre-trial beliefs.

Adult↗
PubMed2004

Inducing affective states with success-failure manipulations: a meta-analysis.

Meta-analytic techniques were used to assess whether successes and failures can be used experimentally to induce affective states. Data from 32 studies, with a total of 2,468 participants, were reviewed. Methods for producing success-failure experiences, as well as the resulting affective reactions, were analyzed. Effect sizes as a result of various methods of induction were calculated. The success-failure manipulation turned out to be capable of reliably inducing both positive and negative affective reactions. A framework for using success-failure manipulations in affect induction is presented. ((c) 2004 APA, all rights reserved)

Achievement↗
PubMed2003

Validity of a test of children's suggestibility for predicting responses to two interview situations differing in their degree of suggestiveness.

In the present study the relative contributions of internal and external sources of variation in children's suggestibility in interrogative situations were examined. One hundred and eleven children (48 4- to 5-year-olds and 63 7- to 8-year-olds) were administered a suggestibility test (BTSS) and the most suggestible (N=36) and the least suggestible (N=36) children were randomly assigned to either an interview condition containing several suggestive techniques or to one containing only suggestive questions. The effects of internal sources of variation in suggestibility were compared with the effects of the interview styles on the children's answers. The former did influence the children, but the external sources of variation in suggestibility had a stronger impact. Influences of cognitive, developmental factors could be found, but not when abuse-related questions were asked and high pressured interview methods were used. These findings indicate that individual assessment of suggestibility can be of some assistance when interviewing children, but diminishing suggestive influences in interrogations must be given priority.

Age Factors↗
PubMed2003

First-pass MR imaging in the assessment of perfusion impairment in patients with hypertrophic cardiomyopathy and the Asp175Asn mutation of the alpha-tropomyosin gene.

PURPOSE: To assess first-pass magnetic resonance (MR) imaging in the evaluation of perfusion impairment in a genetically homogeneous population of patients with hypertrophic cardiomyopathy (HCM) and the Asp175Asn mutation of the alpha-tropomyosin gene and to evaluate the association between hypertrophy and perfusion. MATERIALS AND METHODS: Rest-stress first-pass MR imaging with gadopentetate dimeglumine was performed in 17 patients with HCM and the Asp175Asn substitution in the alpha-tropomyosin gene and in five control subjects. Global and segmental first-pass reserve index (FPR) measurements were derived from signal intensity versus time curves. Left ventricular (LV) wall thickness and LV mass index were measured on cine MR images. The Mann-Whitney test was used to evaluate the difference in FPR between the patient group and the control group. The Spearman correlation was used to evaluate the association between LV hypertrophy and FPR. RESULTS: Global FPR was significantly lower in the patients with HCM than in the control subjects (1.12 +/- 0.35 vs 1.80 +/- 0.58, P =.015). In patients with HCM, maximal LV wall thickness and LV mass index correlated negatively with global FPR (r = -0.723, P =.001 and r = -0.598, P =.011, respectively). At the regional level, segmental FPR correlated inversely with LV wall thickness (r = -0.389; P <.001) in patients with HCM. CONCLUSION: First-pass MR imaging facilitates global and regional evaluation of perfusion impairment in patients with HCM. The severity of perfusion impairment is associated with the degree of LV hypertrophy.

Adenosine↗
PubMed2003

Motivational-emotional vulnerability and difficulties in learning to read and spell.

BACKGROUND: Although the relationship between motivation and learning problems has been studied in older children, little is known about how these factors interact during the first years of schooling or even earlier. AIMS: To compare the development of motivational-emotional profiles from preschool to grade 2 between groups classified as poor readers, good decoders and good readers in grade 2. To study the possibility that diverging motivational-emotional paths occur concomitantly with school experience. SAMPLE: A total of 127 children were followed longitudinally from preschool up to the second grade. In preschool, their mean age was 6 years 8 months. METHOD: Two different methods tapping motivational-emotional vulnerability were used. Firstly, researchers at preschool age and classroom teachers in grades 1 and 2 rated children's task, ego-defensive and social dependence orientations. Secondly, an experimental situation was arranged each year where children's play behaviour with LEGO bricks was observed in free play vs. in induced pressure situations, and their motivational orientations were scored. RESULTS: In preschool, the motivational-emotional profiles were almost the same among the three prospective reading-level groups, but in grades 1 and 2, classroom teachers rated poor readers as less task-oriented and more ego-defensive and socially dependent compared to good decoders and good readers. The ratings were corroborated by observational data on play behaviour in induced pressure situations. CONCLUSIONS: Early problems in learning to read and spell are related to motivational-emotional vulnerability in learning situations in the school context.

Affect↗
PubMed2003

Early words, multiword utterances and maternal reading strategies as predictors of mastering word inflections in Finnish.

This is the first study to report how children's language skills and mothers' book-reading strategies, measured at 2;0, predict mastery of word inflections at 3;0 and 5;0 in a sample of 66 Finnish children. Three theoretical models were tested on the longitudinal data using path analyses. The testing of the models suggests direct developmental continuity from producing words and multiword utterances on later inflectional growth, but indirect effects of maternal strategies on language outcomes. Moreover, mothers' complex expansions and questions are positively related, whereas labellings and corrections are negatively related, to children's concurrent and subsequent language skills. Finally, vocabulary size relates negatively to maternal attention regulation. When joint attention is easily built up in the dyad, mothers concentrate more on direct reading, which, together with the child's vocabulary, predicts mastery of inflections. In conclusion, the results can be viewed as support for a child-driven view on the future course of language acquisition.

Adult↗
PubMed2002

Electrophysiological findings in X-linked myopathy with excessive autophagy.

We report electrophysiological features and magnetic resonance imaging muscle findings in 4 patients and 1 female carrier of X-linked myopathy with excessive autophagy. Motor units were polyphasic with high mean amplitude and normal duration. The thigh muscles were most severely involved, but myotonic discharges were abundant in both clinically affected and unaffected muscles. Along with the clinicopathological features, these electrophysiological findings distinguish X-linked myopathy with excessive autophagy from other limb-girdle myopathies.

Adolescent↗