The functional capacity and quality of life of women with advanced breast cancer.

BACKGROUND: The rehabilitation needs of patients with metastatic breast cancer (MBC) are poorly studied. The primary aim of the study was to evaluate the functional capacity of women with MBC and quality of life (QoL). METHODS: The present study is an open, non-randomized, prospective cross-sectional observation study. The functional capacity of 128 MBC patients with ongoing cancer treatments, were studied in Helsinki University Hospital (HUS): Peak expiratory flow (PEF), dynamic and static balance, 6 minute walking distance (6MWD), 10 meter walking, sit-to-stand test, repeated squat, grip strength, shoulder movement, pain, and QoL by Beck's depression scale (BDI), health assessment questionnaire (HAQ), RAND SF-36 and EORTC QLQ-30 items. RESULTS: The walking capacity was compromised in half and the strength of the lower extremities in one-third of the patients. PEF was below the normal reference in 55 %, static balance in 62 % and dynamic balance in 73 % (≤60 year olds) and 81 % (≥61 year olds). The grip power was lowered in 44/30 % of the patients (right/left) and the shoulder movement was restricted in 30 %. Some disability in physical functioning experienced 55 % (HAQ) and 37 % felt depressive (BDI). The QoL (RAND SF-36) was poor especially in the field of physical, role and social functioning and bodily pain (<0.001). Pain, depression, and a poor 6MWD results independently determined the physical component of QoL (p < 0.001). CONCLUSIONS: The functional capacity of patients with MBC was significantly lowered. This, in association with distressing symptoms like pain and depression causes a vicious circle further leading to functional disabilities and impaired QoL.

Self-rated health in patients with rheumatoid arthritis is associated with health-related quality of life but not with clinical variables.

OBJECTIVES: Self-rated health (SRH) is a well-known overall health status measure used in the general population but it is rarely examined in a clinical setting. We assessed SRH-related factors in clinic-based patients with rheumatoid arthritis (RA). METHOD: The study included 123 consecutive outpatients treated in 1998-1999. Patient questionnaires, including a single SRH item, sociodemographics, the Health Assessment Questionnaire (HAQ) for functional ability, and the Nottingham Health Profile (NHP) for health-related quality of life (QoL), were collected at baseline. Comorbidities were measured by the Charlson Comorbidity Index (CCI) and data on the use of drugs and surgery for RA were verified from medical records and by querying patients. Factors associated with SRH were examined using regression models with the propensity score as the covariate. Mortality rates were collected up to 31 December 2014. Hazard ratios (HRs) were used to estimate SRH-associated mortality. RESULTS: In univariate analysis, poor SRH was associated with higher age and poorer patient-reported outcomes (PROs) but not with gender and clinical variables. After adjustment for the propensity score, the NHP dimensions for pain, energy, emotional reactions, and mobility remained significantly associated with SRH. The age- and sex-adjusted HR for death was 2.38 [95% confidence interval (CI) 1.13-5.04, p = 0.034] for the patients with poor vs. good SRH. The propensity score-adjusted HR for death was 1.69 (95% CI 0.74-3.86, p = 0.21). Conclusions  In patients with RA, SRH was associated with health-related QoL dimensions, reflecting patients' well-being rather than clinical factors. During the 16 years of follow-up, SRH had no independent association with mortality.

Effect of live and inactivated Lactobacillus rhamnosus GG on experimentally induced rhinovirus colds: randomised, double blind, placebo-controlled pilot trial.

The aim of this work was to investigate the usability of an experimental rhinovirus model in probiotic trials aiming to assess effectiveness in viral infections, and to provide preliminary data of live and inactivated probiotic Lactobacillus rhamnosus GG for larger-scale trials utilising the model. 59 subjects were randomised to receive 100 ml of fruit juice supplemented with 10(9) cfu of live or heat-inactivated (by spray-drying) L. rhamnosus GG or control juice daily for six weeks. After three weeks subjects were intranasally inoculated with experimental rhinovirus. Infection rate (at least one positive culture for challenge virus on five days following inoculation or at least four-fold rise in antibody response to challenge virus) was 14/19 in the group receiving live probiotic strain and 18/20 both in the group receiving heat-inactivated probiotic strain and in the control group (P=0.36). The occurrence and severity of cold symptoms on the five days following the inoculation was lowest in the group receiving live probiotic strain (P=0.45). This trial was the first one dedicated to the investigation of the effect of probiotics using the experimental rhinovirus model. The model showed potential for demonstration of efficacy of probiotics in controlled respiratory viral infections. Occurrence and severity of cold symptoms and number of subjects with rhinovirus infection was lowest in the group receiving live L. rhamnosus GG, but differences were not statistically significant. Further large-scale studies are needed to demonstrate the efficacy of L. rhamnosus GG in respiratory infections.

Patients with rheumatoid arthritis have better functional and working ability but poorer general health and higher comorbidity rates today than in the late 1990s.

OBJECTIVES: Better treatment strategies and therapeutic options have changed the treatment of rheumatoid arthritis (RA) during the past decade. Our objective was to examine clinical and patient-reported outcomes in patients with RA treated in 1998-99 and 2011-12. METHOD: The cross-sectional observational study included 303 consecutive outpatients (n = 103 in 1998-99 and n = 200 in 2011-12) from the same outpatient clinic. Patient questionnaires included patients' sociodemographics, the Health Assessment Questionnaire (HAQ) for functional ability, the Nottingham Health Profile (NHP) for health-related quality of life (HRQoL), self-reported general health (GH), and operations performed due to RA. A clinical examination was conducted for all patients. Comorbidities according to the Charlson Comorbidity Index (CCI), anti-rheumatic drugs and medications were recorded and the HAQ and NHP dimensions calculated. The results from these two patient cohorts were compared. RESULTS: The cohorts were comparable with regard to age, sex, and RA duration while the patients in the 2011-12 cohort were less often seropositive for rheumatoid factor (RF), had a better socioeconomic situation, better functional and working ability, and a decreased rate of RA surgery. The patients in 2011-12 had higher comorbidities and poorer GH while the HRQoL dimensions did not differ between the cohorts except for better mobility in 2011-12. Methotrexate (MTX) and combinations of conventional anti-rheumatic drugs were more frequently used in 2011-12. Biologicals were used only in 2011-12. CONCLUSIONS: According to our results, more active anti-rheumatic therapy coincides with better RA-related outcomes. However, the result was the opposite with regard to overall health and comorbidities. Is this a new challenge in the treatment RA?

Waist circumference based abdominal obesity may be helpful as a marker for unmet needs in patients with RA.

OBJECTIVES: To assess the impact of abdominal obesity (AO) on disease severity, cardiovascular risk factors, and patient-reported outcomes (PROs) in patients with rheumatoid arthritis (RA). METHOD: Two hundred and thirty consecutive outpatients were cross-sectionally assessed. Waist circumference (WC) with a cut-off point of ≥ 102 cm in men and ≥ 88 cm in women indicated AO. Clinical assessment included joint counts, radiographs of small joints, and laboratory tests. Comorbidities and medication were verified from the patients' database. Patient questionnaires included sociodemographics, pain intensity, global disease activity, the Beck Depression Inventory (BDI), the Health Assessment Questionnaire (HAQ), physical activity level, and the 36-item Short Form Health Survey (SF-36). Metabolic syndrome (MetS) was defined according to the criteria of National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III). The association of AO with the 28-joint count Disease Activity Score (DAS28) and mental (MCS) and physical component scores (PCS) of the SF-36 and the HAQ was assessed by using regression models with the propensity score as a covariate. RESULTS: The AO prevalence was 52% in the 200 eligible patients. In a univariate analysis, AO was associated with cardiovascular risk factors, low HAQ score, physical inactivity, disease activity parameters, impaired MCS, higher pain, and increased use of biological drugs and antidepressants. In a multivariable model, only poorer DAS28 (p = 0.018) and poorer HAQ score (p = 0.004) remained significantly associated with AO. CONCLUSIONS: AO is highly prevalent in patients with RA. In addition to cardiovascular risk factors, AO is associated with higher disease activity, higher disability, physical inactivity, more patients' perception of pain, and poorer mental health. Multifaceted promotion of lifestyle habits would be beneficial for improving AO-related health outcomes in patients with RA.

Clinical relevance is associated with allergen-specific wheal size in skin prick testing.

BACKGROUND: Within a large prospective study, the Global Asthma and Allergy European Network (GA(2) LEN) has collected skin prick test (SPT) data throughout Europe to make recommendations for SPT in clinical settings. OBJECTIVE: To improve clinical interpretation of SPT results for inhalant allergens by providing quantitative decision points. METHODS: The GA(2) LEN SPT study with 3068 valid data sets was used to investigate the relationship between SPT results and patient-reported clinical relevance for each of the 18 inhalant allergens as well as SPT wheal size and physician-diagnosed allergy (rhinitis, asthma, atopic dermatitis, food allergy). The effects of age, gender, and geographical area on SPT results were assessed. For each allergen, the wheal size in mm with an 80% positive predictive value (PPV) for being clinically relevant was calculated. RESULTS: Depending on the allergen, from 40% (blatella) to 87-89% (grass, mites) of the positive SPT reactions (wheal size ≥ 3 mm) were associated with patient-reported clinical symptoms when exposed to the respective allergen. The risk of allergic symptoms increased significantly with larger wheal sizes for 17 of the 18 allergens tested. Children with positive SPT reactions had a smaller risk of sensitizations being clinically relevant compared with adults. The 80% PPV varied from 3 to 10 mm depending on the allergen. CONCLUSION: These 'reading keys' for 18 inhalant allergens can help interpret SPT results with respect to their clinical significance. A SPT form with the standard allergens including mm decision points for each allergen is offered for clinical use.

Milk containing probiotic Lactobacillus rhamnosus GG and respiratory illness in children: a randomized, double-blind, placebo-controlled trial.

BACKGROUND/OBJECTIVES: To determine whether long-term daily consumption of milk containing probiotic Lactobacillus rhamnosus GG (GG) decreases respiratory illness in children. SUBJECTS/METHODS: A randomized, double-blind, placebo-controlled trial was conducted with 523 children aged 2-6 years attending day care centers in Finland. Subjects received either normal milk or the same milk with GG on three daily meals for 28 weeks. Daily recording of children' symptoms was done by parents. Primary outcome data from 501 subjects were available for analysis, and data from 128 subjects were analyzed as completed cases in terms of recovery of GG in fecal samples. RESULTS: Number of days with at least one respiratory symptom in all subjects was 5.03/month (95% confidence interval (CI): 4.92-5.15) in the GG group and 5.17/month (95% CI: 5.05-5.29) in the placebo group incidence rate ratio (IRR) 0.97; 95% CI: 0.94-1.00; P=0.098). In the completed cases, the figures were 4.71 days/month (95% CI: 4.52-4.90) in the GG group and 5.67 days/month (95% CI: 5.40-5.94) in the placebo group (IRR 0.83; 95% CI: 0.78-0.88; P<0.001). CONCLUSIONS: Consumption of GG reduced the occurrence of respiratory illness in children attending day care centers in the completed cases subgroup, but not in the total population. Thus, future clinical trials are warranted to clarify the association between fecal recovery of a probiotic and the symptom prevalence.

Effects of long-term intake of lactotripeptides on cardiovascular risk factors in hypertensive subjects.

BACKGROUND/OBJECTIVES: Lactobacillus helveticus LBK-16H-fermented milk products containing tripeptides isoleucine-proline-proline and valine-proline-proline lower blood pressure in hypertensive subjects using office and home blood pressure registration. The present study was aimed to evaluate the effects of two doses of these lactotripeptides on 24-h ambulatory blood pressure and lipidomics profiles in mildly hypertensive subjects. SUBJECTS/METHODS: In a randomized, double-blind, placebo-controlled parallel group study, 89 mildly hypertensive subjects ingested, after a 1-month run-in period, a fermented milk drink with 5 mg per day of lactotripeptides during 3 months, and a milk drink with 50 mg per day of lactotripeptides for the following 3 months, or a placebo milk drink without lactotripeptides. Ambulatory blood pressure (24 h) was recorded at baseline and at the end of the intervention periods. Lipidomics profiles were characterized before and after the 6-month intervention. RESULTS: After the second intervention period (50 mg per day of lactotripeptides), systolic and diastolic 24-h blood pressures decreased significantly in the peptide, but not in the placebo group. However, the treatment effects -2.6 mm Hg (95% confidence interval (CI): -5.7 to 0.4) in systolic and -1.3 mm Hg (95% CI: -3.4 to 0.8) in diastolic blood pressure did not reach statistic significance. Ingestion of 5 mg per day of lactotripeptides for 3 months did not lower blood pressure. The peptide group was dominated by decrease in multiple phospholipids (PL). CONCLUSIONS: Ingestion of fermented milk with daily dose of 50 mg of lactotripeptides appears to lower elevated blood pressure slightly from the baseline, but not significantly compared with the placebo group and to induce significant decreases in multiple PL.

Effect of supervised and home exercise training on bone mineral density among breast cancer patients. A 12-month randomised controlled trial.

UNLABELLED: The ability of combined step aerobic- and circuit-training to prevent bone loss after breast cancer treatments was related to skeletal site and patients' menopausal status. Among premenopausal breast cancer survivors, a 12-month exercise intervention completely prevented bone loss at the femoral neck, whereas no exercise effect was seen at lumbar spine or at neither site in postmenopausal women. INTRODUCTION: The primary objective of this randomised clinical trial was to determine the preventive effect of supervised weight-bearing jumping exercises and circuit training on bone loss among breast cancer patients. METHODS: Of 573 breast cancer survivors aged 35-68 years randomly allocated into exercise or control group after adjuvant treatments, 498 (87%) were included in the final analysis. The 12-month exercise intervention comprised weekly supervised step aerobic- and circuit-exercises and similar home training. Bone mineral density (BMD) at lumbar spine and femoral neck were measured by dual-energy X-ray absorptiometry. Physical performance was assessed by 2-km walking and figure-8 running tests, and the amount of physical activity was estimated in metabolic equivalent-hours/week. RESULTS: In premenopausal women, bone loss at the femoral neck was prevented by exercise, the mean BMD changes being -0.2% among the trainees vs. -1.4% among the controls (p = 0.01). Lumbar bone loss could not be prevented (-1.9% vs. -2.2%). In postmenopausal women, no significant exercise-effect on BMD was found either at the lumbar spine (-1.6% vs. -2.1%) or femoral neck (-1.1% vs. -1.1%). CONCLUSIONS: This 12-month aerobic jumping and circuit training intervention completely prevented femoral neck bone loss in premenopausal breast cancer patients, whereas no effect on BMD was seen in postmenopausal women.

Anti-citrullinated peptide antibodies and the progression of radiographic joint erosions in patients with early rheumatoid arthritis treated with FIN-RACo combination and single disease-modifying antirheumatic drug strategies.

OBJECTIVES: To evaluate the impact of antibodies to cyclic citrullinated peptide (ACPAs) on radiographic progression in patients with early rheumatoid arthritis (RA) initially treated either with a combination of 3 disease-modifying antirheumatic drugs (DMARDs) or with a single DMARD. METHODS: This study included 129 patients with early active RA initially randomised to treatment either with a combination of methotrexate, sulfasalazine, hydroxychloroquine, and prednisolone (FIN-RACo) (n=69) or with a single DMARD (initially sulfalasalazine) with or without prednisolone (SINGLE) (n=60). After 2 years, the use of DMARDs and prednisolone became unrestricted. Radiographic progression in hands and feet was assessed at baseline and at 1, 2, 3, 4 and 5 years. ACPAs at baseline were determined with enzyme immunoassay. RESULTS: ACPAs were positive in 92 (71%) patients. ACPA-positive vs. negative patients were more frequently rheumatoid factor (RF) positive (83% vs. 22%, p<0.001) and had an erosive disease (54% vs. 22%, p<0.001) at baseline. The presence of ACPA was associated with radiographic progression in FIN-RACo group even when the impact of RF was controlled; the radiographic progression was remarkably slower in ACPA-negative than in ACPA-positive cases (RF adjusted change over time between groups p=0.034). In the SINGLE group, the radiographic changes progressed parallel in ACPA-negative and positive patients. CONCLUSIONS: Most ACPA-positive RA patients have joint erosions already at diagnosis. ACPA positivity in early RA was related to radiographic progression even in patients treated initially with the FIN-RACo regimen. The initial FIN-RACo therapy seems to slow down the progression of joint damage in ACPA-negative patients.

Quality of life and physical performance and activity of breast cancer patients after adjuvant treatments.

OBJECTIVE: The study aimed at investigating the quality of life (QoL) and physical performance and activity, and their interrelations, in Finnish female breast cancer patients shortly after adjuvant treatments. METHODS: A total of 537 disease-free breast cancer survivors aged 35-68 years were surveyed at the beginning of a one year randomized exercise intervention. The patients were interviewed using EORTC QLQ-C30, FACIT-F, RBDI, and WHQ (for vasomotor symptoms) questionnaires. Physical performance was tested by a 2 km walking test. Physical activity was measured by a questionnaire and a prospective two-week diary. Multivariate analysis was used to study the factors associated with QoL. RESULTS: About 26% of the patients were rated as depressed, 20.4% as fatigued, and 82% suffered from menopausal symptoms. The global QoL was lower than in general population (69.4 vs 74.7, p<0.001). About 62% of the walking test results were below the population average. Fatigue (p<0.001), depression (p<0.001), body mass index (p = 0.016) and comorbidity (p = 0.032) impaired, and physical activity (p = 0.003) improved QoL. Physical activity level correlated positively to physical performance (r = -0.274, p<0.0001). CONCLUSIONS: The QoL of the patients shortly after adjuvant treatments was impaired and the physical performance poor as compared to general population. In particular, depression and fatigue were related to impaired QoL. Physical performance and activity level were the only factors that correlated positively to QoL. Thus, physical exercise could be useful in rehabilitation of cancer survivors, especially for depressed and fatigued patients.

Hypertensive women with the metabolic syndrome are at risk of renal insufficiency more than men in general population.

The prevalence of renal insufficiency in hypertensive participants without comorbidities affecting renal function is unknown. The objective of this study was to assess the prevalence and predictors of renal insufficiency in general hypertensive population. We examined 994 hypertensive participants aged 45-70 years without previously diagnosed diabetes, cardiovascular disease or chronic kidney disease. Renal insufficiency was defined as estimated glomerular filtration rate <60 ml min(-1) per 1.73 m(2) by the Modification of Diet in Renal Disease formula. The metabolic syndrome was defined according to the International Diabetes Federation and the US National Cholesterol Education Program Third Adult Treatment Panel criteria. Glucose homoeostasis was assessed with an oral glucose tolerance test. The prevalence of renal insufficiency was 6.7% (95% confidence interval (CI) 5.3-8.5). In a multivariate model, the presence of renal insufficiency was predicted by female gender (odds ratio (OR) 3.57 (95% CI 1.90-6.72)), older age (OR 1.13 (95% CI 1.07-1.18)), use of diuretics (OR 2.13 (95% CI 1.19-3.82)) and metabolic syndrome (OR 2.79 (95% CI 1.34-5.79)). Newly diagnosed diabetes or prediabetes did not predict renal insufficiency. The prevalence of renal insufficiency was found to be lower than previously reported in hypertensive general population. Metabolic syndrome, but not newly diagnosed diabetes or prediabetes per se, was strongly associated with renal insufficiency especially in women. Renal insufficiency was also associated with the use of diuretics, but the clinical relevance of this finding needs to be clarified.

Clinical trial: multispecies probiotic supplementation alleviates the symptoms of irritable bowel syndrome and stabilizes intestinal microbiota.

BACKGROUND: Irritable bowel syndrome is the most common diagnosis in gastroenterology. Trials suggest certain probiotics to be beneficial. AIM: To investigate the effects of multispecies probiotic supplementation (Lactobacillus rhamnosus GG, L. rhamnosus Lc705, Propionibacterium freudenreichii ssp. shermanii JS and Bifidobacterium animalis ssp. lactis Bb12) on abdominal symptoms, quality of life, intestinal microbiota and inflammatory markers in irritable bowel syndrome. METHODS: Eighty-six irritable bowel syndrome patients (Rome II criteria) participated in this randomized, placebo-controlled 5-month intervention. Patients were randomized to receive daily either multispecies probiotic supplementation or placebo. Irritable bowel syndrome symptoms, quality of life, microarray-based intestinal microbiota stability (n = 20), serum cytokines and sensitive C-reactive protein were monitored. RESULTS: The composite irritable bowel syndrome score had at 5 months decreased 14 points (95% CI: -19 to -9) from baseline with the multispecies probiotic vs. three points (95% CI: -8 to 1) with placebo (P = 0.0083). Especially, distension and abdominal pain were affected. A stabilization of the microbiota was observed, as the microbiota similarity index increased with the probiotic supplementation (1.9 +/- 3.1), while it decreased with placebo (-2.9 +/- 1.7). No differences were seen in C-reactive protein. CONCLUSIONS: This multispecies probiotic seems to be an effective and safe option to alleviate symptoms of irritable bowel syndrome, and to stabilize the intestinal microbiota.

A probiotic, Lactobacillus fermentum ME-3, has antioxidative capacity in soft cheese spreads with different fats.

Our aim was to develop a prototype of a functional spread cheese containing both a specific probiotic and n-3 fatty acids and to analyze the viability of the probiotic and stability of n-3 fatty acids during 4 wk of shelf life. Lactobacillus fermentum ME-3 (Lf ME-3) isolated from a healthy Estonian child has been shown to have probiotic and antioxidative properties in several recent studies. In the current study this promising bacterial strain was combined with vegetable oils rich in nutritionally important alpha-linolenic acid and with unflavored cheese to obtain soft cheese spreads with different fat contents. Lactobacillus fermentum ME-3 survived well in all cheeses although the viable count did not increase during 4 wk of storage. The fatty acid composition of cheese triacylglycerols remained stable, whereas the profile of volatile compounds changed: hexanal and pentanal disappeared and the proportion of some alcohols increased. The changes in the profile of volatile compounds show the reductive power of Lf ME-3. A functional spread cheese containing n-3 fatty acids can be prepared with the probiotic Lactobacillus fermentum ME-3 strain leading to a reduced need for chemical anti-oxidants.

Effects of a physical exercise intervention on subjective physical well-being, psychosocial functioning and general well-being among office workers: a cluster randomized-controlled cross-over design.

The purpose of the study was to examine the effects of a workplace physical exercise intervention on subjective physical well-being, psychosocial functioning and general well-being. The study was a cluster randomized-controlled trial with the department (n=4) as the unit of randomization. The subjects (n=90) were office workers [mean age 45.7 (SD 8.5) years]. Psychosocial functioning and well-being variables were measured by descriptive visual rating scales. The cross-over design consisted of one 15-week intervention period of light resistance training and guidance and another 15-week period of no training and no guidance. The statistical analysis was based on linear mixed models. The active component of the intervention, light resistance training, resulted in a slight, but statistically significant, increase in subjective physical well-being (P=0.015). At the average training time of 5 min/working day (25 min/week) the average increase during the 15-week period was 4 units (95% confidence interval (CI) 1-7) and 5% (95% CI 1-9). The physical exercise intervention had no effect on somatic symptoms, anxiety, self-confidence, mood, mental stress at work, working atmosphere, life satisfaction or meaning of life. Daily light resistance training, conducted during the working day, had a positive direction on subjective physical well-being among office workers.

Asthma exacerbations in children immediately following stressful life events: a Cox's hierarchical regression.

BACKGROUND: A recent prospective study of children with asthma employing a within subject, over time analysis using dynamic logistic regression showed that severely negative life events significantly increased the risk of an acute exacerbation during the subsequent 6 week period. The timing of the maximum risk depended on the degree of chronic psychosocial stress also present. A hierarchical Cox regression analysis was undertaken to examine whether there were any immediate effects of negative life events in children without a background of high chronic stress. METHODS: Sixty children with verified chronic asthma were followed prospectively for 18 months with continuous monitoring of asthma by daily symptom diaries and peak flow measurements, accompanied by repeated interview assessments of life events. The key outcome measures were asthma exacerbations and severely negative life events. RESULTS: An immediate effect evident within the first 2 days following a severely negative life event increased the risk of a new asthma attack by a factor of 4.69, 95% confidence interval 2.33 to 9.44 (p<0.001) [corrected] In the period 3-10 days after a severe event there was no increased risk of an asthma attack (p = 0.5). In addition to the immediate effect, an increased risk of 1.81 (95% confidence interval 1.24 to 2.65) [corrected] was found 5-7 weeks after a severe event (p = 0.002). This is consistent with earlier findings. There was a statistically significant variation due to unobserved factors in the incidence of asthma attacks between the children. CONCLUSION: The use of statistical methods capable of investigating short time lags showed that stressful life events significantly increase the risk of a new asthma attack immediately after the event; a more delayed increase in risk was also evident 5-7 weeks later.

Statistical inversion for medical x-ray tomography with few radiographs: I. General theory.

In x-ray tomography, the structure of a three-dimensional body is reconstructed from a collection of projection images of the body. Medical CT imaging does this using an extensive set of projections from all around the body. However, in many practical imaging situations only a small number of truncated projections are available from a limited angle of view. Three-dimensional imaging using such data is complicated for two reasons: (i) typically, sparse projection data do not contain sufficient information to completely describe the 3D body, and (ii) traditional CT reconstruction algorithms, such as filtered backprojection, do not work well when applied to few irregularly spaced projections. Concerning (i), existing results about the information content of sparse projection data are reviewed and discussed. Concerning (ii), it is shown how Bayesian inversion methods can be used to incorporate a priori information into the reconstruction method, leading to improved image quality over traditional methods. Based on the discussion, a low-dose three-dimensional x-ray imaging modality is described.

Statistical inversion for medical x-ray tomography with few radiographs: II. Application to dental radiology.

Diagnostic and operational tasks in dental radiology often require three-dimensional information that is difficult or impossible to see in a projection image. A CT-scan provides the dentist with comprehensive three-dimensional data. However, often CT-scan is impractical and, instead, only a few projection radiographs with sparsely distributed projection directions are available. Statistical (Bayesian) inversion is well-suited approach for reconstruction from such incomplete data. In statistical inversion, a priori information is used to compensate for the incomplete information of the data. The inverse problem is recast in the form of statistical inference from the posterior probability distribution that is based on statistical models of the projection data and the a priori information of the tissue. In this paper, a statistical model for three-dimensional imaging of dentomaxillofacial structures is proposed. Optimization and MCMC algorithms are implemented for the computation of posterior statistics. Results are given with in vitro projection data that were taken with a commercial intraoral x-ray sensor. Examples include limited-angle tomography and full-angle tomography with sparse projection data. Reconstructions with traditional tomographic reconstruction methods are given as reference for the assessment of the estimates that are based on the statistical model.