Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 30
Filter
1.
Rev Mal Respir ; 36(5): 625-632, 2019 May.
Article in French | MEDLINE | ID: mdl-31221484

ABSTRACT

Counseling and pharmacotherapy are smoking cessation interventions whose effectiveness has been widely demonstrated. Different pharmacologic treatment options exist with similar efficacy : notably nicotine replacement therapy, varenicline and bupropion. Providers can promote therapeutic adherence and the chances of successful quitting by involving patients in the choice of medication and incorporating their preferences in the decision process. The concept of shared decision-making is based on an exchange between doctor and patient in medical situations with several reasonable options. Decision aids support this approach by facilitating the transmission of information, communication and patient involvement. Despite opportunities for shared decision-making during the smoking cessation process, few decision aids are available. This article summarizes current knowledge in this field and its application to the process of smoking cessation. Shared decision making in smoking cessation is illustrated by a decision aid created to facilitate the choice between different smoking cessation medications.


Subject(s)
Choice Behavior/physiology , Decision Making, Shared , Patient Participation/methods , Smoking Cessation/methods , Bupropion/therapeutic use , Counseling , Humans , Nicotine/therapeutic use , Patient Participation/psychology , Patient Participation/statistics & numerical data , Patient Selection , Smoking Cessation/psychology , Tobacco Use Cessation Devices , Varenicline/therapeutic use
2.
BMC Health Serv Res ; 18(1): 779, 2018 Oct 16.
Article in English | MEDLINE | ID: mdl-30326886

ABSTRACT

BACKGROUND: We recently defined a global typology of primary care (PC) in Switzerland using a mixed inductive/deductive approach to construct latent, composite variables that summarize variance between practices. Now we explore associations between the primary variable that describes the comprehensiveness of services and patient-perceived access to PC in Switzerland. METHODS: Cross-sectional surveys were administered to physicians from the Swiss PC Active Monitoring (SPAM) network and their patients. The primary outcomes were patient responses to: "Was it easy to get the appointment?", "The opening hours are too restricted" and "In the past 12 months, did you postpone or abstain from a visit to this doctor or another GP when you needed one?" Multivariate, multilevel analyses with stepwise regression were used to assess associations between practice type (practices with a broader range of services have higher scores) and perceived access, controlling for patient characteristics. RESULTS: One hundred and ninety nine of 200 PC physicians in the network completed the questionnaire. Of 2628 patients approached after a physician visit, 1791 accepted (participation = 76%), with 9 patients at each practice. No association was observed between comprehensiveness of services and difficulty getting an appointment. When controlling for patient factors, there was a weak association between higher scores for comprehensiveness of services and patients reporting that the opening hours are too restricted (p = 0.05), though this was no longer significant after controlling for language area. Greater comprehensiveness of services was associated with fewer patients needing to postpone visits (OR 0.93, 95%CI 0.88-0.99, p = 0.03). CONCLUSIONS: Though fewer patients report needing to postpone visits at practices with more comprehensive offering of services, there is limited evidence of associations between patient-reported access and a global typology of Swiss primary care.


Subject(s)
Health Services Accessibility/statistics & numerical data , Primary Health Care/statistics & numerical data , Adult , Appointments and Schedules , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Multivariate Analysis , Surveys and Questionnaires , Switzerland , Time Factors
3.
New Microbes New Infect ; 11: 6-7, 2016 May.
Article in English | MEDLINE | ID: mdl-27006779

ABSTRACT

Zika virus is an emerging flavivirus that is following the path of dengue and chikungunya. The three Aedes-borne viruses cause simultaneous outbreaks with similar clinical manifestations which represents a diagnostic challenge in ill returning travellers. We report the first Zika virus infection case imported to Switzerland and present a diagnostic algorithm.

4.
J Obstet Gynaecol ; 34(2): 198-9, 2014 Feb.
Article in English | MEDLINE | ID: mdl-24456452

ABSTRACT

We present a series of two cases complicated by uterine rupture following termination of pregnancy (TOP) in the 1st and 2nd trimesters using misoprostol in women with caesarean section scar. Current literature and practise have also been reviewed on ruptured uterus in women with caesarean section scar undergoing TOP using misoprostol; the diagnosis of adherent placenta in the 1st and 2nd trimesters in women with previous caesarean uterine scar; and likely implications of a ruptured uterus.


Subject(s)
Abortion, Induced/adverse effects , Cesarean Section/adverse effects , Cicatrix/complications , Uterine Rupture/etiology , Adult , Female , Humans , Pregnancy
5.
Euro Surveill ; 16(49): 20034, 2011 Dec 08.
Article in English | MEDLINE | ID: mdl-22172330

ABSTRACT

In October 2011 in Finland, two persons fell ill with symptoms compatible with botulism after having eaten conserved olives stuffed with almonds. One of these two died. Clostridium botulinum type B and its neurotoxin were detected in the implicated olives by PCR and mouse bioassay, respectively. The olives were traced back to an Italian manufacturer and withdrawn from the market. The public and other European countries were informed through media and Europe-wide notifications.


Subject(s)
Botulism/diagnosis , Clostridium botulinum , Food, Preserved/microbiology , Olea/microbiology , Adult , Aged , Animals , Botulism/etiology , Fatal Outcome , Finland , Food Contamination , Food, Preserved/adverse effects , Humans , Internationality , Mice , Olea/adverse effects
6.
BJOG ; 117(5): 565-74, 2010 Apr.
Article in English | MEDLINE | ID: mdl-20374595

ABSTRACT

OBJECTIVE: Pregnancy in women with pulmonary hypertension (PH) is reported to carry a maternal mortality rate of 30-56%. We report our experience of the management of pregnancies using a strategy of early introduction of targeted pulmonary vascular therapy and early planned delivery under regional anaesthesia. DESIGN: Retrospective observational study. SETTING: Specialist quaternary referral pulmonary vascular unit. POPULATION: Nine women with PH who chose to proceed with ten pregnancies. METHODS: A retrospective review of the management of all women who chose to continue with their pregnancy in our unit during 2002-2009. MAIN OUTCOME MEASURES: Maternal and fetal survival. RESULTS: All women commenced nebulised targeted therapy at 8-34 weeks of gestation. Four women required additional treatment or conversion to intravenous prostanoid therapy. All women were delivered between 26 and 37 weeks of gestation. Delivery was by planned caesarean section in nine cases. All women received regional anaesthesia and were monitored during the peripartum period in a critical care setting. There was no maternal mortality during pregnancy and all infants were free from congenital abnormalities. One woman died 4 weeks after delivery following patient-initiated discontinuation of therapy. All remaining women and infants were alive after a median of 3.2 years (range, 0.8-6.5 years) of follow-up. CONCLUSION: Although the risk of mortality in pregnant women with PH remains significant, we describe improved outcomes in fully counselled women who chose to continue with pregnancy and were managed with a tailored multiprofessional approach involving early introduction of targeted therapy, early planned delivery and regional anaesthetic techniques.


Subject(s)
Hypertension, Pulmonary/therapy , Pregnancy Complications, Cardiovascular/therapy , Prenatal Care/methods , Adult , Antihypertensive Agents/administration & dosage , Apgar Score , Birth Weight , Cardiac Catheterization , Cesarean Section , Female , Humans , Patient Care Team , Pregnancy , Pregnancy Outcome , Retrospective Studies , Treatment Outcome , Young Adult
7.
J Obstet Gynaecol ; 30(3): 253-6, 2010 Apr.
Article in English | MEDLINE | ID: mdl-20373925

ABSTRACT

We compared the obstetric outcome of 1,922 teenage pregnant women with a control population of 10,550 women aged 20-39 years. The teenage women had a significantly higher normal vaginal delivery rate (65% vs 45%; RR 1.44, 95% CI: 1.38-1.49; p < 0.001) and a lower operative delivery rate compared with control women (elective caesarean section: 1.7% vs 4.9%, RR 0.347, 95% CI: 0.25-0.49, p < 0.001; emergency caesarean section: 13.3% vs 22.9%, RR 0.58, 95% CI: 0.51-0.65, p < 0.001; instrumental delivery: 19.3% vs 26.3%, RR 0.73, 95% CI: 0.66-0.81, p < 0.001). There was no difference in the pre-term delivery rate or in the stillbirth rate between the two groups. When stratified further, there was no difference in the pre-term delivery rate and low birth weight rate between teenage mothers aged 13-17 years and those aged 17-19 years. Teenage pregnant women have better obstetric performance in terms of mode of delivery without an increased risk of stillbirth or prematurity compared with older women.


Subject(s)
Pregnancy Outcome , Adolescent , Adult , Delivery, Obstetric/statistics & numerical data , Female , Humans , Incidence , Infant, Low Birth Weight , Infant, Newborn , Pregnancy , Pregnancy in Adolescence , Stillbirth/epidemiology , Young Adult
8.
Tech Coloproctol ; 13(4): 337-9, 2009 Dec.
Article in English | MEDLINE | ID: mdl-19603138

ABSTRACT

Malone antegrade continence enema (MACE) procedures are an effective treatment for both intractable faecal incontinence and constipation of neurogenic aetiology and have traditionally been used in a paediatric setting. MACE procedures are now being performed more commonly in adults suffering idiopathic chronic constipation where they are also effective. Increasing use in otherwise healthy adult females raises concerns about the durability of the appendiceal conduit should the patient become pregnant. We report the first case of successful pregnancy after a MACE procedure with an umbilical stoma and discuss the impact of the pregnancy on MACE function.


Subject(s)
Constipation/therapy , Enema/methods , Pregnancy Outcome , Surgical Stomas , Adult , Cesarean Section , Female , Humans , Pregnancy , Quality of Life , Therapeutic Irrigation/methods
9.
Neuropediatrics ; 39(3): 179-83, 2008 Jun.
Article in English | MEDLINE | ID: mdl-18991199

ABSTRACT

Alpers syndrome is a fatal disorder due to mutations in the POLG gene encoding the catalytic subunit of mitochondrial DNA polymerase gamma (Pol gamma) involved in mitochondrial DNA (mtDNA) replication. We describe a case of Alpers syndrome due to POLG mutations, with rapidly progressive course, a fatal outcome, and an essentially normal brain MRI in the early oligo-symptomatic phase. Our observation suggests that Alpers syndrome should be considered even in patients with an initially unremarkable brain MRI. The patient was found to harbor the p.Q497H, p.W748S and p.E1143G mutations in cis on one allele, and a fourth mutation, the p.G848S on the other allele. Although the individual mutations detected in the presented case have been previously reported, the specific genotype formed by the particular combination of these is novel.


Subject(s)
Brain/pathology , Diffuse Cerebral Sclerosis of Schilder/pathology , Magnetic Resonance Imaging , Brain/metabolism , DNA Polymerase gamma , DNA, Mitochondrial/genetics , DNA-Directed DNA Polymerase/genetics , Diffuse Cerebral Sclerosis of Schilder/genetics , Disease Progression , Female , Humans , Infant , Mutation
11.
J R Army Med Corps ; 152(1): 44-53, 2006 Mar.
Article in English | MEDLINE | ID: mdl-16749469

ABSTRACT

This article outlines some recent advances in both obstetrics and gynaecology. In obstetrics, the new screening tests for Down's syndrome and the introduction of computer analysis of the fetal ECG are discussed. Cervical screening and the role of human papilloma virus detection is examined and advances in the non-surgical management of menorrhaghia and improvements in the management of urinary stress incontinence are also reviewed.


Subject(s)
Down Syndrome/diagnosis , Fetal Monitoring , Menorrhagia/therapy , Sterilization, Tubal/methods , Urinary Incontinence, Stress/therapy , Uterine Cervical Neoplasms/diagnosis , Education, Medical, Continuing , Female , Humans , Hysteroscopy , Labor, Obstetric , Mass Screening , Pregnancy , Prenatal Diagnosis , Uterine Cervical Neoplasms/therapy , Uterine Cervical Neoplasms/virology
12.
Arch Dis Child ; 90(6): 574-8, 2005 Jun.
Article in English | MEDLINE | ID: mdl-15908619

ABSTRACT

AIMS AND METHODS: Thyroid function tests were initially carried out on 122 children with Down's syndrome aged 6-14 years and then repeated four to six years later in 103 adolescents (85% of the group of 122) when they were aged 10-20 years (median 14.4 years). At the second test two were hypothyroid and two with isolated raised thyroid stimulating hormone (IR-TSH) were receiving thyroxine. RESULTS: At the first test there were 98 (80%) euthyroid children: 83 were retested and four (5%) had IR-TSH. At the first test 24 had IR-TSH: 20 were retested and 14 (70%) had become normal. Seventeen with IR-TSH on initial testing had a thyrotrophin releasing hormone test within three months; TSH had become normal in eight (47%) of these children. There was no association between reported clinical symptoms and IR-TSH, but there were clear symptoms in one of the two with definite hypothyroidism. CONCLUSIONS: The likelihood ratio for a positive result on second testing when raised TSH and positive antibody status on first testing are combined is 20. This suggests initial testing results could be used as a basis to select a subgroup for further testing at say five yearly intervals unless new symptoms emerge in the interim. It also suggests that yearly screening (as recommended by the American Academy of Pediatrics, 2001) is probably not justified in the first 20 years of life.


Subject(s)
Down Syndrome/physiopathology , Hypothyroidism/diagnosis , Adolescent , Child , Down Syndrome/blood , Humans , Hypothyroidism/drug therapy , Longitudinal Studies , Mass Screening/methods , Prognosis , Thyroid Function Tests/methods , Thyrotropin/blood , Thyroxine/therapeutic use
13.
J Biomech Eng ; 125(1): 38-48, 2003 Feb.
Article in English | MEDLINE | ID: mdl-12661195

ABSTRACT

Extensive flow studies are conducted in two carotid bifurcation flow phantoms. These phantoms exactly replicate the lumen of the plaque excised intact from two patients with severe carotid atherosclerosis. The input flow into the phantom's common carotid artery is steady. Novel scanning techniques for flow visualization and particle image velocimetry are used. In addition, a novel boundary treatment technique is employed in velocimetry to extract first order accurate velocity gradients at walls. The data show that the flow fields are highly three-dimensional. Numerous separation and recirculation zones dominate the flow domain, except at the lowest Reynolds numbers. The separation regions are often so severe that highly directed internal jets form. At high Reynolds numbers, the flows become unsteady and chaotic, even though the input flow is steady. Flow fields have large regions of energetic flow and almost stagnant recirculation zones. These recirculation zones range in size from the full size of the arteries to zones within crevasses smaller than 1 mm. Velocity field and streamline patterns conform well to the lumen geometry. The streamlines are highly tortuous. Stagnation points correlate well with the topological features of the stenosis. Vorticity maps confirm the highly complex and three dimensional nature of the flow. Wall shear stresses at the stenoses are estimated to be on the order of 10 Pa. These studies conclusively show that the nature of the flow in the diseased bifurcation is primarily dictated by the lumen geometry.


Subject(s)
Arteriosclerosis/pathology , Arteriosclerosis/physiopathology , Carotid Artery Diseases/pathology , Carotid Artery Diseases/physiopathology , Models, Cardiovascular , Blood Flow Velocity , Carotid Arteries/pathology , Carotid Arteries/physiopathology , Computer Simulation , Hemorheology/instrumentation , Hemorheology/methods , Humans , Optics and Photonics/instrumentation , Phantoms, Imaging
14.
Aviat Space Environ Med ; 74(2): 145-52, 2003 Feb.
Article in English | MEDLINE | ID: mdl-12602446

ABSTRACT

BACKGROUND: Sedation and functional impairments are side effects associated with the use of first-generation antihistamines that preclude their use in aviation. Selected second-generation antihistamines do not have such side effects and have been proposed for use in aircrew. METHODS: Forty-two healthy naval aviation personnel served as subjects in this double-blind, randomized, placebo-controlled crossover study. Subjective drowsiness, cognitive performance, and vigilance were measured under three conditions: 180 mg fexofenadine (F), 50 mg diphenhydramine (D) as a positive control, or placebo (P). RESULTS: Subjects receiving F vs. D tended to have a faster mean hit reaction time (adjusted mean difference +/- SE, -10.5 +/- 6.8 ms, p = 0.127). Subjects performed faster and better with F vs. D on measures of omission errors and commission errors (p < 0.05). Variable symbol digit coding delayed recall accuracy was better for F vs. D (p = 0.023), and approached significance for shifting attention and divided attention tasks (p = 0.062 and p = 0.057, respectively). Subjects reported significantly more drowsiness (p < 0.005) with D than F. CONCLUSIONS: Diphenhydramine administration resulted in significant psychomotor decrements compared with fexofenadine, while the effects of fexofenadine were similar to placebo. These results provide additional support for the safe use of fexofenadine by aviation personnel.


Subject(s)
Aerospace Medicine , Cognition/drug effects , Diphenhydramine/pharmacology , Histamine H1 Antagonists/pharmacology , Terfenadine/analogs & derivatives , Terfenadine/pharmacology , Administration, Oral , Adult , Attention/drug effects , Cross-Over Studies , Diphenhydramine/administration & dosage , Double-Blind Method , Female , Histamine H1 Antagonists/administration & dosage , Humans , Male , Placebos , Reaction Time , Sleep Stages/drug effects , Terfenadine/administration & dosage
15.
Aviat Space Environ Med ; 72(9): 805-12, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11565814

ABSTRACT

BACKGROUND: As evidence has accumulated for the role of HMG-CoA reductase inhibitors in the primary prevention of coronary artery disease, younger individuals with no other co-morbid conditions will be increasingly exposed to these agents. Some HMG-CoA reductase inhibitors have been reported to cause impairment of daytime cognitive processes that have the potential to directly impact the ability of pilots and other aircrew to perform. These studies suggested that there might be cognitive effects of these medications that would argue against their routine use in populations whose activities required high, sustained levels of cognitive performance. The objective of this study is to establish the effects of pravastatin and lovastatin on aircrew daytime cognitive function using tests that are correlated with actual cockpit tasks and inflight performance. METHODS: Military aircrew with hypercholesterolemia were enrolled in the study and assigned to lovastatin, pravastatin or placebo groups. Baseline cognitive and vigilance testing was performed with computerized test instruments. Following a 4-wk treatment period, subjects were retested on both cognitive and vigilance tasks. RESULTS: Laboratory studies confirmed that both medications were effective in lowering cholesterol. No major treatment-related side effects were encountered. Cognitive performance was not affected by either active treatment, and was not different from that of the placebo group. CONCLUSIONS: The tested medications did not have significant effects on performance as measured by two computerized performance tests. The data suggest that neither medication has significant effects on flight-related performance.


Subject(s)
Anticholesteremic Agents/pharmacology , Cognition/drug effects , Lovastatin/pharmacology , Military Personnel , Pravastatin/pharmacology , Psychomotor Performance/drug effects , Adult , Anticholesteremic Agents/therapeutic use , Double-Blind Method , Humans , Hypercholesterolemia/drug therapy , Lovastatin/therapeutic use , Male , Middle Aged , Military Personnel/psychology , Neuropsychological Tests , Pravastatin/therapeutic use
16.
Osteoporos Int ; 8(1): 16-24, 1998.
Article in English | MEDLINE | ID: mdl-9692073

ABSTRACT

The purpose of this study was to quantify the heterogeneity in the trabecular bone structure in the calcaneus. Magnetic resonance (MR) images of the calcaneus were obtained in the sagittal plane at an in-plane resolution of 195 microns and a slice thickness of 1000 microns in 12 young normal subjects. Regions of interest (ROI) were selected to cover the calcaneus using a grid of square boxes (10 mm per side). A thresholding technique based on the regional intensity histogram was used to segment the images into trabecular bone and marrow phases and to calculate measures such as apparent trabecular bone area fraction, apparent trabecular spacing, apparent trabecular thickness and apparent trabecular number. Bone mineral density (BMD) of the calcaneus was assessed using dual-energy X-ray absorptiometry (DXA). Histological sections of three calcanei were also analyzed using transmission light illumination, and the results used to calibrate our computational software. For a relatively narrow inter-subject variation in posterior BMD, a significant inter-subject variation was seen in MRI-derived structural parameters. Furthermore, the spatial heterogeneity of the structural parameters in the posterior region was as high as 40%. Thus, the posterior tuberosity of the calcaneus, a typical site for BMD and single-point ultrasound assessments, can demonstrate significant regional variation in trabecular bone structure.


Subject(s)
Calcaneus/anatomy & histology , Magnetic Resonance Imaging , Absorptiometry, Photon , Adult , Bone Density , Calcaneus/physiology , Female , Humans , Male , Middle Aged
17.
Eur J Paediatr Neurol ; 2(1): 33-9, 1998.
Article in English | MEDLINE | ID: mdl-10726844

ABSTRACT

We measured free choline in cerebrospinal fluid (CSF) of 78 patients with movement disorders of paediatric onset and various controls as a putative index of central phospholipid metabolism. Most of the disorders studied were myoclonic disorders, such as progressive myoclonus epilepsy, the opsoclonus-myoclonus syndrome, and essential myoclonus, but other movement disorders, interictal seizure disorders, and different neurological and nonneurological disorders were also included. There were no significant differences in CSF choline concentrations in myoclonic disorders or other movement disorders compared with controls. The CSF choline levels were lowest in children with seizure disorders including progressive myoclonus epilepsy. In progressive myoclonus epilepsy, the CSF choline values resembled other epileptic disorders rather than other myoclonic disorders. When all the data were analysed collectively, no significant relation of CSF choline was found to patient age, gender, aliquot of CSF measured, or the length of time the sample was stored at -70 degrees C. Separate analyses of data from children and adults showed a trend toward a biphasic relation between patient age and CSF choline which could be pursued in developmental studies of normal subjects. Reduced CSF choline may indicate increased choline incorporation into brain phospholipids, disturbances of choline metabolism, decreased choline release, or non-neural factors.


Subject(s)
Choline/cerebrospinal fluid , Movement Disorders/cerebrospinal fluid , Acetylcholine/cerebrospinal fluid , Adrenocorticotropic Hormone/therapeutic use , Adult , Child , Child, Preschool , Chromatography, High Pressure Liquid/methods , Disease Progression , Epilepsies, Myoclonic/cerebrospinal fluid , Epilepsies, Myoclonic/complications , Female , Humans , Male , Movement Disorders/complications , Movement Disorders/drug therapy , Phospholipids/metabolism
18.
Calcif Tissue Int ; 60(2): 139-47, 1997 Feb.
Article in English | MEDLINE | ID: mdl-9056161

ABSTRACT

A high-resolution magnetic resonance imaging (MRI) protocol, together with specialized image processing techniques, was applied to the quantitative measurement of age-related changes in calcaneal trabecular structure. The reproducibility of the technique was assessed and the annual rates of change for several trabecular structure parameters were measured. The MR-derived trabecular parameters were compared with calcaneal bone mineral density (BMD), measured by dual X-ray absorptiometry (DXA) in the same subjects. Sagittal MR images were acquired at 1.5 T in 23 healthy women (mean age: 49.3 +/- 16.6 [SD]), using a three-dimensional gradient echo sequence. Image analysis procedures included internal gray-scale calibration, bone and marrow segmentation, and run-length methods. Three trabecular structure parameters, apparent bone volume (ABV/TV), intercept thickness (I.Th), and intercept separation (I.Sp) were calculated from the MR images. The short- and long-term precision errors (mean %CV) of these measured parameters were in the ranges 1-2% and 3-6%, respectively. Linear regression of the trabecular structure parameters vs. age showed significant correlation: ABV/TV (r2 = 33.7%, P < 0.0037), I.Th (r2 = 26.6%, P < 0.0118), I.Sp (r2 = 28.9%, P < 0.0081). These trends with age were also expressed as annual rates of change: ABV/TV (-0.52%/year), I.Th (-0.33%/year), and I.Sp (0.59%/year). Linear regression analysis also showed significant correlation between the MR-derived trabecular structure parameters and calcaneal BMD values. Although a larger group of subjects is needed to better define the age-related changes in trabecular structure parameters and their relation to BMD, these preliminary results demonstrate that high-resolution MRI may potentially be useful for the quantitative assessment of trabecular structure.


Subject(s)
Absorptiometry, Photon , Calcaneus/diagnostic imaging , Magnetic Resonance Imaging , Adult , Age Factors , Aged , Calibration , Female , Humans , Male , Middle Aged
19.
J Magn Reson Imaging ; 6(3): 549-59, 1996.
Article in English | MEDLINE | ID: mdl-8724422

ABSTRACT

MR measurements of transverse relaxation time, T2*, in trabecular bone may provide both structural and density-related information for assessment of bone mineral status in osteoporosis. Using submillimeter scale glass phantoms as simplified models of trabecular bone, we have made a quantitative investigation of the dependence of T2* decay on modeled trabecular microstructure and MR image resolution. The experimental MR data are in excellent agreement with predictions from a computer simulation. Decreasing the modeled trabecular bone volume fraction, sigma, decreases the decay rate, as expected. However, if trabecular width and spacing are both increased without changing sigma, the decay rate is unchanged. The measured decay curves closely follow the predicted dependence on trabecular orientation. The decay rates are independent of image resolution, provided that the pixel dimensions are larger than the intertrabecular spacing. For smaller pixel sizes, the decay rate decreases with decreasing pixel size.


Subject(s)
Bone Density/physiology , Magnetic Resonance Imaging/instrumentation , Osteoporosis/diagnosis , Phantoms, Imaging , Bone and Bones/pathology , Computer Simulation , Computer Systems , Contrast Media , Fourier Analysis , Humans , Image Enhancement
20.
Acad Radiol ; 3(4): 336-43, 1996 Apr.
Article in English | MEDLINE | ID: mdl-8796684

ABSTRACT

RATIONALE AND OBJECTIVES: Marrow transverse relaxation time (T2*) in magnetic resonance (MR) imaging may be related to the density and structure of the surrounding trabecular network. We investigated regional variations of T2* in the human calcaneus and compared the findings with bone mineral density (BMD), as measured by dual X-ray absorpiometry (DXA). Short- and long-term precisions were evaluated first to determine whether MR imaging would be useful for the clinical assessment of disease status and progression in osteoporosis. METHODS: Gradient-recalled echo MR images of the calcaneus were acquired at 1.5 T from six volunteers. Measurements of T2* were compared with BMD and (for one volunteer) conventional radiography. RESULTS: T2* values showed significant regional variation; they typically were shortest in the superior region of the calcaneus. There was a linear correlation between MR and DXA measurements (r = .66 for 1/T2* versus BMD). Differences in T2* attributable to variations in analysis region-of-interest placement were not significant for five of the six volunteers. Sagittal MR images had short- and long-term precision errors of 4.2% and 3.3%, respectively. For DXA, the precision was 1.3% (coefficient of variation). CONCLUSION: MR imaging may be useful for trabecular bone assessment in the calcaneus. However, given the large regional variations in bone density and structure, the choice of an ROI is likely to play a major role in the accuracy, precision, and overall clinical efficacy of T2* measurements.


Subject(s)
Absorptiometry, Photon , Bone Marrow/anatomy & histology , Calcaneus/anatomy & histology , Calcaneus/diagnostic imaging , Magnetic Resonance Imaging , Adult , Bone Density , Female , Humans , Male , Reference Values
SELECTION OF CITATIONS
SEARCH DETAIL
...