Thor Aspelund - Academia.edu (original) (raw)

Papers by Thor Aspelund

Introduction.—B-mode ultrasonography of the carotid arteries enables quantitative measurements of... more Introduction.—B-mode ultrasonography of the carotid arteries enables quantitative measurements of atherosclerotic plaque area and composition assessed as grayscale median (GSM). The purpose of this study was to set up a standardized ultrasound protocol to measure longitudinal changes in plaque area and composition and to determine the intra- and interobserver variability of the measurements in a longitudinal population based study, the Age Gene/Environment Susceptibility Reykjavik study.Method.—A total of 219 participants from the Age Gene/Environment Susceptibility Reykjavik study (76 ± 6 years old, 36% males) underwent 2-dimensional, B-mode ultrasound examination of the carotid arteries approximately 5 years apart for a longitudinal assessment of plaque area and composition. Standardized protocol was used to acquire comparable images from both visits. Ultrasound was performed bilaterally on the common carotid artery, internal carotid artery, and bifurcation. An image analysis prog...

European Psychiatry, 2013

Journal for Vascular Ultrasound

ABSTRACT Introduction.—B-mode ultrasonography of the carotid arteries enables quantitative measur... more ABSTRACT Introduction.—B-mode ultrasonography of the carotid arteries enables quantitative measurements of atherosclerotic plaque area and composition assessed as grayscale median (GSM). The purpose of this study was to set up a standardized ultrasound protocol to measure longitudinal changes in plaque area and composition and to determine the intra- and interobserver variability of the measurements in a longitudinal population based study, the Age Gene/Environment Susceptibility Reykjavik study.Method.—A total of 219 participants from the Age Gene/Environment Susceptibility Reykjavik study (76 ± 6 years old, 36% males) underwent 2-dimensional, B-mode ultrasound examination of the carotid arteries approximately 5 years apart for a longitudinal assessment of plaque area and composition. Standardized protocol was used to acquire comparable images from both visits. Ultrasound was performed bilaterally on the common carotid artery, internal carotid artery, and bifurcation. An image analysis program was modified and adapted for a longitudinal assessment of plaque area and plaque composition by GSM. Twenty-five subjects were selected from the group of 219 for intra- and interobserver variability assessment.Results.—Intraobserver variability for plaque area ranged from 12.10 to 18.63% and 0.89 to 0.96 for coefficient of variation and correlation (r), respectively, for plaque GSM ranged from 7.77 to 8.04% and 0.86 to 0.90. Interobserver variability for plaque area was 23.29% and 0.81 and 8.55% and 0.87 for plaque GSM.Conclusion.—The results from this study show that ultrasound can be used consistently for assessment of changes in plaque area and GSM over time. This can be achieved by proper training of ultrasound sonographers and by applying and following strict image acquisition and image analysis protocols.

The Journal of prosthetic dentistry, 2018

Gingival recession after soft tissue displacement for impression making in fixed prosthodontics m... more Gingival recession after soft tissue displacement for impression making in fixed prosthodontics may pose a problem for treatment success in the esthetic areas of the mouth. Knowledge about the soft tissue reaction of common gingival displacement methods is limited. The purpose of this clinical randomized controlled trial (RCT) was to evaluate changes in the marginal soft tissue height with 3 different gingival tissue displacement techniques for definitive impression making of natural teeth. A total of 67 individuals were randomized to 3 groups. In test group 1 (P; n=22), only aluminum chloride paste was used to displace the gingiva. In test group 2 (CP; n=23), a cord was inserted, and aluminum chloride paste was also used. In the control group (C; n=22), 2 cords were used to displace the gingiva (double-cord technique). Clinical measurements of the gingival position were made before treatment began and at 30 ±10 days after prosthesis delivery. Study casts were fabricated at differen...

Thorax, Jan 9, 2018

We investigated the association between interstitial lung abnormalities (ILA) and self-reported m... more We investigated the association between interstitial lung abnormalities (ILA) and self-reported measures of health and functional status in 5764 participants from the Age, Gene/Environment Susceptibility-Reykjavik study. The associations of ILA to activities of daily living (ADLs), general health status and physical activity were explored using logistic regression models. Participants with ILA were less likely to be independent in ADLs (OR 0.70; 95% CI 0.55 to 0.90) to have good or better self-reported health (OR 0.66; 95% CI 0.52 to 0.82) and to participate in physical activity (OR 0.72; CI 0.56 to 0.91). The results demonstrate ILA's association with worsening self-reported health and functional status.

$Research paper thumbnail of Sex differences in the spatial distribution of bone in relation to incident hip fracture: Findings from the AGES-Reykjavik study$

Bone, Jan 16, 2018

In this case-cohort study, we used data-driven computational anatomy approaches to assess within ... more In this case-cohort study, we used data-driven computational anatomy approaches to assess within and between sex spatial differences in proximal femoral bone characteristics in relation to incident hip fracture. One hundred male and 234 female incident hip fracture cases, and 1047 randomly selected noncase subcohort participants (562 female) were chosen from the population-based AGES-Reykjavik study (mean age of 77 years). The baseline -i.e. before hip fracture- hip quantitative computed tomography scans of these subjects were analyzed using voxel-based morphometry, tensor-based morphometry, and surface-based statistical parametric mapping to assess the spatial distribution of volumetric bone mineral density (vBMD), internal structure, and cortical bone properties (thickness, vBMD and trabecular vBMD adjacent to the endosteal surface) of the proximal femur, respectively, in relation to incident hip fracture. Results showed that in both men and women: 1) the superior aspect of the fe...

PloS one, 2018

Recent studies indicate that lifestyle factors in early life affect breast cancer risk. We theref... more Recent studies indicate that lifestyle factors in early life affect breast cancer risk. We therefore explored the association of high consumption of meat, milk, and whole grain products in adolescence and midlife, on breast cancer risk. We used data from the population based AGES-Reykjavik cohort (2002-2006), where 3,326 women with a mean age of 77 years (SD 6.0) participated. For food items and principal component derived dietary patterns we used Cox proportional models to calculate multivariate hazard ratios (HR) with 95% confidence intervals (95% CI). During a mean follow-up of 8.8 years, 97 women were diagnosed with breast cancer. For both adolescence and midlife, daily consumption of rye bread was positively associated with breast cancer (HR 1.7, 95% CI 1.1-2.6 and HR 1.8, 95% CI 1.1-2.9, respectively). In contrast, persistent high consumption of oatmeal was negatively associated with breast cancer (0.4, 95% CI 0.2-0.9). No association was found for other food items or dietary ...

International journal of cancer, Jan 15, 2018

Metabolic syndrome is associated with several cancers, but evidence for aggressive prostate cance... more Metabolic syndrome is associated with several cancers, but evidence for aggressive prostate cancer is sparse. We prospectively investigated the influence of metabolic syndrome and its components on risk of total prostate cancer and measures of aggressive disease in a cohort of Icelandic men. Men in the Reykjavik Study (n = 9,097, enrolled 1967-1987) were followed for incident (n = 1,084 total; n = 378 advanced; n = 148 high-grade) and fatal (n = 340) prostate cancer until 2014. Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for (1) measured metabolic factors at cohort entry (body mass index (BMI), blood pressure, triglycerides, fasting blood glucose) and (2) a metabolic syndrome score (range 0-4) combining the risk factors: BMI ≥30 kg/m ; systolic blood pressure (SBP) ≥130 or diastolic blood pressure (DBP) ≥85 mm Hg or taking antihypertensives; triglycerides ≥150 mg/dl; fasting blood glucose ≥100 mg/dl or self-reported type 2 diabetes. Hyp...

Bone, 2018

This study aimed to explore the relationships of several indicators of cigarette smoking habits (... more This study aimed to explore the relationships of several indicators of cigarette smoking habits (smoking status, pack-years, age at smoking initiation and smoking cessation) with quantitative computed tomographic (QCT)-derived proximal femur bone measures (trabecular vBMD, integral vBMD and the ratio of cortical to total tissue volume (cvol/ivol)) and with subsequent change in these measures over the next five years. A total of 2673 older adults (55.9% women), aged 66-92 years at baseline from the Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study, who had two QCT scans of the hip were studied. In multivariable linear regression models, compared to never-smokers, current smokers had lower cvol/ivol at baseline and former-smokers had poorer measures on all outcomes (lower trabecular vBMD, integral vBMD and cvol/ivol), even when adjusted for several potential confounders. Further, among former smokers, those with higher pack-years had worse bone outcomes and those with longer...

Clinical oral implants research, Jan 11, 2018

There is limited knowledge regarding the strength of zirconia abutments with internal and externa... more There is limited knowledge regarding the strength of zirconia abutments with internal and external implant abutment connections and zirconia abutments supported by a titanium resin base (Variobase, Straumann) for narrow diameter implants. To compare the fracture strength of narrow diameter abutments with different types of implant abutment connections after chewing simulation. Hundred and twenty identical customized abutments with different materials and implant abutment connections were fabricated for five groups: 1-piece zirconia abutment with internal connection (T1, Cares-abutment-Straumann BL-NC implant, Straumann Switzerland), 1-piece zirconia abutment with external hex connection (T2, Procera abutment-Branemark NP implant, Nobel Biocare, Sweden), 2-piece zirconia abutments with metallic insert for internal connection (T3, Procera abutment-Replace NP implant, Nobel Biocare), 2-piece zirconia abutment on titanium resin base (T4, LavaPlus abutment-VarioBase-Straumann BL-NC impla...

$Research paper thumbnail of Testing the mechanostat theory: the relationship between CT bone and muscle variables in mid-thigh in elderly men and women and association with incident lower limb fractures$

Frontiers in Endocrinology

Osteoarthritis and Cartilage

PLOS ONE

Background Type 2 diabetes and prediabetes are established risk factors for atherosclerosis. The ... more Background Type 2 diabetes and prediabetes are established risk factors for atherosclerosis. The aim of this study was to evaluate the atherosclerotic plaque burden in the carotid arteries of patients with acute coronary syndrome according to their glycemic status. Methods Patients with acute coronary syndrome and no previous history of type 2 diabetes were consecutively included in the study. Glucose metabolism was evaluated with fasting glucose in plasma, HbA1c and a standard two-hour oral glucose tolerance test. Atherosclerotic plaque in the carotid arteries was evaluated with a standardized ultrasound examination where total plaque area was measured and patients classified as having no plaque or a significant plaque formation. Results A total of 245 acute coronary syndrome patients (male 78%, 64 years (SD: 10.9)) were included. The proportion diagnosed with normal glucose metabolism, prediabetes and type 2 diabetes was 28.6%, 64.1% and 7.3%, respectively. A significant atherosclerotic plaque was found in 48.5%, 66.9% and 72.2% of patients with normal glucose metabolism, prediabetes and type 2 diabetes, respectively. An incremental increase in total plaque area was found from normal glucose metabolism to prediabetes (25.5%) and from normal glucose metabolism to type 2 diabetes (35.9%) (p = 0.04). When adjusted for conventional cardiovascular risk factors the OR of having significant atherosclerotic plaque in the carotid arteries was 2.17 (95% CI 1.15-4.15) for patients with newly diagnosed dysglycemia compared to patients with normal glucose metabolism. When additionally adjusted for the 2-hour plasma glucose after glucose loading (2hPG) the OR attenuated to 1.77 (95% CI 0.83-3.84).

EP Europace

Atrial fibrillation (AF) has been associated with cognitive impairment. Additionally, brain volum... more Atrial fibrillation (AF) has been associated with cognitive impairment. Additionally, brain volume may be reduced in individuals with AF. Potential causes may include cerebral micro-embolism or reduced stroke volume due to the beat-to-beat variation in AF. The aims of this study were to measure cerebral blood flow and estimate whole brain perfusion in elderly individuals with and without AF.

Stroke

B rain infarcts are common findings on magnetic resonance (MR) images in older adults and have be... more B rain infarcts are common findings on magnetic resonance (MR) images in older adults and have been associated with cognitive decline and dementia. Their prevalence has been well documented in several population-based studies. 1-4 Imaging studies generally agree that the prevalence of brain infarcts increases steeply with increasing age, and it is >20% in the 70 to 79 age group and 35% in those older than 85. 4,5 Most studies with data on prevalence of brain infarcts show no sex disparity in infarct risk. 5 Information on the incidence of brain infarcts from population-based longitudinal studies is, however, scarce. Previous studies suggest that cerebrovascular abnormalities contribute to cognitive decline and the development of vascular dementia and Alzheimer's disease. 6,7 There is, however, limited information from imaging studies on whether this differs by brain region. The assessment of brain infarcts by region or type is important because the cause and clinical implications of cerebellar, cortical, and subcortical infarcts may differ. A distal branch middle cerebral artery occlusion resulting in a cortical stroke usually results from an embolus from either the heart, aortic arch, or carotid artery, whereas a small infarct in the subcortical white matter is usually because of a blockage of small penetrating artery (lacunar infarct). The most common causes of cerebellar infarcts are, however, thought to be atherosclerosis, cardiac embolism, and migraine. 8,9 Background and Purpose-The differentiation of brain infarcts by region is important because their cause and clinical implications may differ. Information on the incidence of these lesions and association with cognition and dementia from longitudinal population studies is scarce. We investigated the incidence of infarcts in cortical, subcortical, cerebellar, and overall brain regions and how prevalent and incident infarcts associate with cognitive change and incident dementia. Methods-Participants (n=2612, 41% men, mean age 74.6±4.8) underwent brain magnetic resonance imaging for the assessment of infarcts and cognitive testing at baseline and on average 5.2 years later. Incident dementia was assessed according to the international guidelines. Results-Twenty-one percent of the study participants developed new infarcts. The risk of incident infarcts in men was higher than the risk in women (1.8; 95% confidence interval, 1.5-2.3). Persons with both incident and prevalent infarcts showed steeper cognitive decline and had almost double relative risk of incident dementia (1.7; 95% confidence interval, 1.3-2.2) compared with those without infarcts. Persons with new subcortical infarcts had the highest risk of incident dementia compared with those without infarcts (2.6; 95% confidence interval, 1.9-3.4). Conclusions-Men are at greater risk of developing incident brain infarcts than women. Persons with incident brain infarcts decline faster in cognition and have an increased risk of dementia compared with those free of infarcts. Incident subcortical infarcts contribute more than cortical and cerebellar infarcts to incident dementia which may indicate that infarcts of small vessel disease origin contribute more to the development of dementia than infarcts of embolic origin in larger vessels.