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PubMed2006

Health care utilization among Medicare-Medicaid dual eligibles: a count data analysis.

BACKGROUND: Medicare-Medicaid dual eligibles are the beneficiaries of both Medicare and Medicaid. Dual eligibles satisfy the eligibility conditions for Medicare benefit. Dual eligibles also qualify for Medicaid because they are aged, blind, or disabled and meet the income and asset requirements for receiving Supplement Security Income (SSI) assistance. The objective of this study is to explore the relationship between dual eligibility and health care utilization among Medicare beneficiaries. METHODS: The household component of the nationally representative Medical Expenditure Panel Survey (MEPS) 1996-2000 is used for the analysis. Total 8,262 Medicare beneficiaries are selected from the MEPS data. The Medicare beneficiary sample includes individuals who are covered by Medicare and do not have private health insurance during a given year. Zero-inflated negative binomial (ZINB) regression model is used to analyse the count data regarding health care utilization: office-based physician visits, hospital inpatient nights, agency-sponsored home health provider days, and total dental visits. RESULTS: Dual eligibility is positively correlated with the likelihood of using hospital inpatient care and agency-sponsored home health services and the frequency of agency-sponsored home health days. Frequency of dental visits is inversely associated with dual eligibility. With respect to racial differences, dually eligible Afro-Americans use more office-based physician and dental services than white duals. Asian duals use more home health services than white duals at the 5% statistical significance level. The dual eligibility programs seem particularly beneficial to Afro-American duals. CONCLUSION: Dual eligibility has varied impact on health care utilization across service types. More utilization of home healthcare among dual eligibles appears to be the result of delayed realization of their unmet healthcare needs under the traditional Medicare-only program rather than the result of overutilization in response to the expanded benefits of the dual eligibility program. The dual eligibility program is particularly beneficial to Asian and Afro-American duals in association with the provision of home healthcare and dental benefits.

Aged↗

PubMed1993

Localization of IBF as a D-2 dopamine receptor imaging agent in nonhuman primates.

Preliminary study of iodine-123 labeled IBF, (S)-5-iodo-7-N-[(1-ethyl-2-pyrrolidinyl)methyl] carboxamido-2, 3-dihydrobenzofuran, has demonstrated the potential of using this agent to evaluate the status of the CNS D-2 dopamine receptor in humans. To further characterize this ligand and evaluate single-photon emission tomography (SPET) quantitation, a detailed biodistribution study in monkeys (Macaca fascicularis) with 123I- and 125I-IBF was performed. The dual tracer was simultaneously injected for in vivo imaging, bio-distribution, and ex vivo autoradiography in the same monkey. After the injection, SPET data (10 min/frame x 15) were collected with a triple-head gamma camera. Dynamic imaging data indicated that IBF localized in basal ganglia (BG) with a half life of 90-120 min. Other regions, i.e., cerebellum (CB) and cortex (CX), showed very low uptake. At 2.2 h after the injection, the monkey was sacrificed. Organ distribution data indicated that, as expected, there was a significant uptake in basal ganglia (0.029% ID/g), and the BG/CB and BG/CX ratios were 17.8 and 14.2 respectively. Lower ratios were obtained from SPET image analysis (BG/CB = 3.5 at 2.5 h). The eye uptake was observed with SPET, but was only quantified on autoradiograms with significant uptake (0.017% ID/g). Autoradiography of the eye demonstrated that predominant uptake was localized in the ciliary body and the choroid. The selective retention and high BG/CB ratio of 123I-IBF make it a useful agent for in vivo D-2 dopamine receptor imaging with SPET.

Animals↗

PubMed2006

Prevention of ventricular desynchronization by permanent para-Hisian pacing after atrioventricular node ablation in chronic atrial fibrillation: a crossover, blinded, randomized study versus apical right ventricular pacing.

OBJECTIVES: The aim of our study was to evaluate the feasibility, the safety, and hemodynamic improvements induced by permanent para-Hisian pacing in patients with chronic atrial fibrillation and narrow QRS who underwent atrioventricular (AV) node ablation. BACKGROUND: Right ventricular apical pacing, inducing asynchronous ventricular contraction, may impair cardiac function; permanent para-Hisian pacing could preserve interventricular synchrony and improve left ventricular function. METHODS: After AV node ablation, 16 patients were implanted with a dual-chamber pacemaker connected to a screw-in lead positioned in close proximity to the His bundle and to a right ventricular apical lead. Clinical and echocardiographic data were collected at baseline and after two randomized six-month periods (with para-Hisian and conventional pacing). RESULTS: During para-Hisian pacing, the interventricular electromechanical delay improved as well (34 +/- 18 ms) as during right apical pacing (47 +/- 19 ms), p < 0.05. Para-Hisian pacing allowed an improvement in New York Heart Association functional class (1.75 +/- 0.4 vs. 2.33 +/- 0.6 at baseline and 2.5 +/- 0.4 during apical pacing, p < 0.05 for both), in quality-of-life score (16.2 +/- 8.7 vs. 32.5 +/- 15.0 at baseline, p < 0.05), and in the 6-min walk test (431 +/- 73 m vs. 378 +/- 60 m at baseline and 360 +/- 71 m during apical pacing, p < 0.5 for both). Mitral and tricuspid regurgitation improved during para-Hisian pacing (1.22 +/- 0.8 and 1.46 +/- 0.5 index, respectively, vs. 1.68 +/- 0.6 [p < 0.05] and 1.62 +/- 0.7 [p = NS] index at baseline, respectively), with a slight worsening during apical pacing (1.93 +/- 1 and 1.93 +/- 0.7 index, respectively, p < 0.05 for both). CONCLUSIONS: Permanent para-Hisian pacing is feasible and safe. Compared with conventional right apical pacing, it allows an improvement in functional and hemodynamic parameters over long-term follow-up.

Aged↗

PubMed2005

Deficits in size-adjusted bone mass in children with Alagille syndrome.

OBJECTIVES: To describe bone status in children with Alagille syndrome (AGS) and healthy control children adjusted for age, gender and height (HT), and to identify dietary intake and AGS-related factors associated with bone status. METHODS: Prepubertal children with AGS and healthy controls comparable in age and ethnicity were evaluated. Subjects were > or =4 years of age, prepubertal and had whole body (WB) and/or lumbar spine (LS) dual energy X-ray absorptiometry (DXA) scans of acceptable quality. Anthropometric (weight, HT), diet and AGS-specific data (e.g., coefficient of fat absorption, labs, liver transplantation) were also collected. Bone area (BA), bone mineral content (BMC) and HT were log transformed for best fit. Bone data were analyzed unadjusted, adjusted for gender, age and HT, and as HT-specific z-scores. RESULTS: AGS and control groups were similar in age, pubertal status and ethnicity. Children with AGS were small-for-age, had decreased BA and BMC-for-age, and decreased WB BA and BMC-for-HT z-scores compared to healthy controls. Prevalence of low BMC-for-HT z-scores (< -2) among AGS subjects was 20% for the WB and 39% for the LS. Bone mineralization was positively related to fat absorption but not dietary intake. CONCLUSIONS: Children with AGS have deficits in bone size and bone mass relative to body size. Modifiable factors, such as treatment of malabsorption should be explored as an early focus of AGS care to prevent bone fragility.

Absorptiometry, Photon↗

PubMed1987

Radionuclide cardiac monitoring system using dual cadmium telluride (CdTe) detectors: specification and some clinical applications.

The construction, physical characteristics, software and some clinical applications of a computerized dual cadmium telluride (CdTe) detectors system for continuous cardiac monitoring are described. The detectors and collimators are small, light and convenient for attachment to the chest wall. Data can be collected at 0.05 s intervals and for up to 3 h. Clinical studies in 33 patients using a prototype system demonstrated reasonably good correlation with left ventricular ejection fractions determined by a scintillation camera-computer system (r = 0.928). The application of this system to continuous monitoring of left ventricular function during exercise or drug stimulations has been found to be clinically useful.

Adult↗

PubMed2007

Missed opportunities in patients with osteoporosis and distal radius fractures.

Low-energy wrist (distal radius) fractures are hallmarks of osteoporosis. Prompt diagnosis and treatment of osteoporosis reduce refracture rates. We retrospectively determined the type and frequency of osteoporosis-related interventions rendered to patients 50 years and older in the year after a wrist fragility fracture. In addition, we compared the rates of intervention between men and women. Data were collected from the computerized medical record of one military healthcare system. We identified 111 patients who sustained wrist fragility fractures between July and December 2002. Endocrinology referrals, dual-energy xray absorptiometry scans, and osteoporosis medication prescriptions in the year after their fracture were recorded. Overall, 28 patients (25%) were referred to endocrinology, 22 patients (20%) had a dual-energy xray absorptiometry scan, 33 patients (30%) were prescribed an approved medication for treatment of osteoporosis, and 52 patients (47%) were prescribed one of these medications and/or vitamin D and calcium. Sixty percent of patients received at least one intervention. All diagnostic and medical interventions were more likely ordered for women than men. Orthopaedic surgeons continue to miss opportunities to initiate diagnostic and therapeutic interventions for patients, especially men, presenting with fragility fractures.

Absorptiometry, Photon↗

PubMed1997

The impact of payor/provider type on health care use and expenditures among the frail elderly.

OBJECTIVES: This study examined whether health care expenditures and usage by the frail elderly differ under three payor/provider types: Medicare fee for service, Medicare health maintenance organization (HMO), and dual Medicare-Medicaid enrollment. METHODS: In-home interviews were conducted among 450 frail elderly patients of a San Diego, Calif, health care system. Cost and use data were collected from providers. RESULTS: Analyses revealed no difference in total expenditures between fee-for-service and HMO enrollees, but Medicare-Medicaid beneficiaries' expenditures were 46.8% higher than those for HMO enrollees and 52.2% higher than those for the fee-for-service group. Fee-for-service participants were less than half as likely as HMO enrollees to have two or more hospital admissions, but hospital usage rates between those two payor/provider groups did not differ. Not were there payor/provider differences in access to home health care, but HMO home health care users received significantly fewer services than the others. CONCLUSIONS: The care provided to these HMO beneficiaries resulted in a combination of restricted home health use and higher multiple hospitalizations. This raises compelling questions for future research. For the dually enrolled, stronger cost containment may be required.

Activities of Daily Living↗

PubMed2004

Field instrument for simultaneous large dynamic range measurement of atmospheric hydrogen sulfide, methanethiol, and sulfur dioxide.

We describe a membrane-based collection/analysis system that differentially monitors H2S and CH3SH, and to which a conductometric SO2 analyzer using the same collector was coupled. A diffusion scrubber (DS) comprised of a Nafion tube collects H2S selectively while a porous polytetrafluoroethylene (pPTFE) DS collects both H2S and CH3SH. Both gases are measured via their ability to react with fluorescein mercuric acetate (FMA) which results in decreased fluorescence. The limited dynamic range of a negative signal procedure was overcome by using dual DS units comprised of short and long scrubbers, placed serially in the liquid flow line. Different DS designs and membrane materials were investigated. H2S, CH3SH, and SO2 from a biogenic point source were continuously measured, and the H2S/CH3SH data compared well with a standard procedure involving Tedlar bag collection, preconcentration and thermal desorption from a Tenax trap, and measurement by gas chromatography/flame photometric detection. Walkaround portability of the instrument and very large dynamic range measurement of H2S and SO2 were demonstrated around the Mt. Aso volcano.

Air Pollutants↗

PubMed1990

Dual ion-channel regulation by cyclic GMP and cyclic GMP-dependent protein kinase.

Atrial natriuretic peptide, acting through its second messenger guanosine 3',5'-cyclic monophosphate (cGMP), suppresses Na+ absorption across the renal inner-medullary collecting duct and increases urinary Na+ excretion. Patch clamp studies show that cGMP reduces Na+ absorption by inhibiting an amiloride-sensitive cation channel in the apical membrane. We have now examined, using the patch clamp technique, the molecular mechanisms of cGMP inhibition. Cyclic GMP directly and specifically reduced the probability of a single channel being open (open probability, Po) by 39% (inhibition constant, Ki = 7.6 x 10(-7) M) by a phosphorylation-independent mechanism. Cyclic GMP also inhibited the channel by activating cGMP-dependent protein kinase (cGMP-kinase). Exogenous cGMP-kinase completely inhibited the channel by a phosphorylation-dependent mechanism. Activation of a pertussis toxin-sensitive G protein by GTP-gamma-S blocked cGMP-kinase inhibition of the channel. By contrast, cGMP-kinase inhibition of Po was completely reversed by GTP-gamma-S. Taken together with the results of a previous study showing that a G protein activates the cation channel, these data indicate that cGMP-kinase and a G protein sequentially regulate the cation channel. Our results show that atrial natriuretic peptide, acting through cGMP, inhibits Na+ absorption across the inner-medullary collecting duct by a dual mechanism, and that cGMP-kinase inhibits the channel by a pathway involving a G protein.

Amiloride↗

PubMed1998

Bone mineral density in French Canadian women.

This cross-sectional study investigated bone mineral density (BMD) at the lumbar spine (L2-4) and femoral neck in French Canadian women residing in the Quebec city area. Data collection was initiated in 1988 and completed in 1994. A total of 747 French Canadian Caucasian women (16-79 years of age) with no metabolic bone disease were evaluated. BMD measurements were obtained using dual-photon absorptiometry (DPA) or dual-energy X-ray absorptiometry (DXA). Anthropometric measures such as weight, height and body mass index (BMI) were recorded. Medical files provided information on demographic characteristics, hormonal profile and lifestyle habits. Results show a curvilinear trend of BMD with aging. Furthermore, the peak BMD at the lumbar spine (L2-4) was reached at 29 years followed by a stable phase until 35 years, after which BMD started to decrease. The pattern of bone evolution at the femoral neck was different, peak BMD being achieved earlier, at 21 years, while after age 26 years a significant decrease was already observed. Women older than 60 years showed the lowest BMD. Regression analysis showed that age, weight and height are determinants of BMD at the lumbar spine and explained 33.9% of inter-individual variation. At the femoral neck, 29.1% of variation was explained by age and height only. In conclusion, our data suggest that French Canadian women have a different pattern of bone loss at the femoral neck compared with the lumbar spine, according to their mean BMD values.

Adolescent↗

PubMed2000

Reduced bone mineral density in male rheumatoid arthritis patients: frequencies and associations with demographic and disease variables in ninety-four patients in the Oslo County Rheumatoid Arthritis Register.

OBJECTIVE: To examine reductions in bone mineral density (BMD) and factors associated with reduced BMD in 94 male rheumatoid arthritis (RA) registry patients ages 20-70 years. METHODS: Dual-energy x-ray absorptiometry was used to measure BMD in the anteroposterior lumbar spine at L2-LA, the femoral neck, and the total hip, and clinical data were collected. The patients were recruited from a validated county RA registry (completeness 85%) comprising 192 men ages 20-70 years. Age-specific BMD values were compared with a pooled healthy European/United States population. Bivariate and multivariate analyses were performed to determine demographic and disease-related associations with BMD and reduced bone mass (Z score of < or =1 SD below the mean value in controls). RESULTS: A statistically significant BMD reduction was found only for the oldest age group (60-70 years): 5.2% reduction in the femoral neck and 6.9% in the total hip. No BMD reduction was found at L2-L4. The proportions (95% confidence intervals) of RA patients with Z scores of < or =1 SD below control (16% expected) were 30.9% (21.6-40.2) for L2-L4, 30.8% (95% CI 21.3-40.3) for the femoral neck, and 33.0% (95% CI 23.3-42.7) for the total hip. Disease activity and severity measures were, in general, not associated with BMD or reduced bone mass. CONCLUSION: A 2-fold statistically significant increased frequency of patients with reduced bone mass (Z score of < or =1 SD below control; 16% expected) was found for both the spine and the hip. The only significant reduction in BMD by age group was for the hip in patients who were ages 60-70 years, with no reduction in L2-LA BMD. Multivariate analyses did not reveal consistent associations between reduced BMD and demographic or disease variables.

Aged↗

PubMed2004

Pharmacokinetics of indinavir and nelfinavir in treatment-naive, human immunodeficiency virus-infected subjects.

AIDS Clinical Trials Group protocol 388 was designed to compare a three-drug regimen (indinavir with dual nucleosides) to a four-drug regimen (indinavir plus nelfinavir or indinavir plus efavirenz with dual nucleosides). Blood samples from patients taking indinavir and nelfinavir were collected over 8 to 12 h following a specified dose and were analyzed with high-performance liquid chromatography. Pharmacokinetic data were derived by using noncompartmental analysis. Following administration of indinavir every 8 h in the absence of nelfinavir (n = 8), the median predose indinavir concentration (C(0)) was 369 ng/ml (range, <10 to 949 ng/ml; one subject had a concentration of <10 ng/ml), and the concentration 8 h after administration of the study dose was 159 ng/ml (range, 85 to 506 ng/ml). In the group receiving 1000 mg of indinavir every 12 h with nelfinavir (n = 10), the median indinavir C(0) was <10 ng/ml (range, <10 to 3740 ng/ml; six subjects had a value of <10 ng/ml), and the C(12 h) was 44 ng/ml (range, <10 to 4236 ng/ml; five subjects had a value of <10 ng/ml), while the subjects who received 1200 mg of indinavir every 12 h with nelfinavir (n = 7) had a C(0) of 146 ng/ml (range, 58 to 5215 ng/ml) and a C(12 h) of 95 ng/ml (range, 12 to 954 ng/ml). Indinavir clearance was significantly lower in the presence of nelfinavir (median [interquartile range], 34.1 liters/h [range, 22.6 to 45.8 liters/h] versus 47.9 liters/h [range, 42.7 to 70.3 liters/h]; P < 0.017). For subjects receiving 1,000 mg of indinavir every 12 h, the median C(0) value for nelfinavir (n = 9) was 1,779 ng/ml (range, <187.5 to 4579 ng/ml), and the C(12 h) was 1554 ng/ml (range, <187.5 to 5,540 ng/ml). Due to the unacceptable number of undetectable indinavir trough concentrations, 1200 mg of indinavir appears to be the preferred dose in a twice-daily regimen that includes nelfinavir.

Adult↗

PubMed2004

Membrane-associated and secreted genes in breast cancer.

The identification of membrane-associated and secreted genes that are differentially expressed is a useful step in defining new targets for the diagnosis and treatment of cancer. Extracting information on the subcellular localization of genes represented on DNA microarrays is difficult and is limited by the incomplete sequence and annotation that is available in existing databases. Here we combine a biochemical and bioinformatic approach to identify membrane-associated and secreted genes expressed in the MCF-7 breast cancer cell line. Our approach is based on the analysis of differential hybridization levels of RNAs that have been physically separated by virtue of their association with polysomes on the endoplasmic reticulum. This approach is specifically applicable to oligonucleotide microarrays such as Affymetrix, which use single-color hybridization instead of dual-color competitive hybridizations. Assignment to membrane-associated and secreted class membership is based on both the differential hybridization levels and an expression threshold, which are calculated empirically from data collected on a reference set of known cytoplasmic and membrane proteins. This method enabled the identification of 755 membrane-associated and secreted probe sets expressed in MCF-7 cells for which this annotation did not previously exist. The data were used to filter a previously reported expression dataset to identify membrane-associated and secreted genes which are associated with poor prognosis in breast cancer and represent potential targets for diagnosis and treatment. The approach reported here should provide a useful tool for the analysis of gene expression patterns, identifying membrane-associated or secreted genes with biological relevance that have the potential for clinical applications in diagnosis or treatment.

Breast Neoplasms↗

PubMed2005

Role of fibrinogen-like protein 2 prothrombinase/fibroleukin in experimental and human allograft rejection.

Immune coagulation is a major contributor to the pathogenesis of xenograft rejection, viral-induced hepatocellular injury and cytokine-induced fetal loss syndrome. In this study, we investigated the contribution of the novel gene product, fibrinogen-like protein 2 (fgl2) prothrombinase, in mediating immune injury in experimental and human acute allograft rejection. Using a mouse heterotopic cardiac transplant model, mouse fgl2(mfgl2)/fibroleukin mRNA transcripts and protein were highly expressed in macrophages, CD4- and CD8-positive T lymphocytes, and endothelial cells in rejecting cardiac allografts in association with deposits of fibrin. Although mfgl2-deficient mice rejected allografts at similar rates to littermate controls, survival of grafts from mfgl2-deficient mice were prolonged and deposition of intravascular fibrin was diminished. Treatment of wild-type mice with a neutralizing anti-fgl2 Ab ameliorated histological evidence for allorejection and intravascular fibrin deposition, and resulted in an increase in graft survival. To address further the relevance of fgl2 in acute allograft rejection, we examined kidney biopsies from patients who had undergone renal transplantation. Human fgl2 mRNA transcripts and protein were markedly expressed mainly in renal tubule cells, infiltrating lymphoid cells including macrophages, CD8(+) T cells, mature B cells (plasma cells), and endothelial cells. Dual staining showed fibrin deposition was localized mainly to blood vessels, in the glomerulus and interstitium and the lumen of tubules, and occurred in association with human fgl2 expression. These data collectively suggest that fgl2 accounts for the fibrin deposition seen in both experimental and human allograft rejection and provide a rationale for targeting fgl2 as adjunctive therapy to treat allograft rejection.

Adult↗

PubMed2005

Assessing the utility of atypical antipsychotic medication in adults with mild mental retardation and comorbid psychiatric disorders.

OBJECTIVE: Research on psychiatric outcomes among individuals dually diagnosed with mild mental retardation and co-occurring mental illness who are treated with antipsychotic medication is markedly limited due to difficulties encountered in (1) making valid and reliable psychiatric diagnoses and (2) accurately rating and following psychiatric symptom change over time in this specialty population. METHOD: To address these issues, DSM-IV psychiatric diagnoses were made by an experienced dual-diagnosis clinician, and the Aberrant Behavior Checklist (ABC) and the Global Assessment of Functioning were used to assess behavioral and psychiatric features in a psychiatric partial hospital setting. Data were collected by chart review from 72 patients admitted consecutively from January 1998 to December 1999. Assessments were compared at admission and discharge in this retrospective study for 3 treatment groups that were defined by antipsychotic medication status at discharge: no antipsychotic (N = 15), atypical antipsychotic only (N = 41), and mixed atypical/typical antipsychotics or typical anti-psychotic only (N = 16). RESULTS: Improvement on the ABC social withdrawal subscale was greater for atypical anti-psychotic medication-treated, dually diagnosed patients than for those who received other treatment regimens. In addition, a dose-response relationship was observed for this subscale and atypical antipsychotic medication dose. CONCLUSION: For certain psychotic patients with mild mental retardation, the atypical antipsychotics may be an appropriate and effective treatment modality.

Adult↗

PubMed2003

Cognitive-behavioural therapy and motivational intervention for schizophrenia and substance misuse. 18-month outcomes of a randomised controlled trial.

BACKGROUND: Comorbid substance misuse in people with schizophrenia is associated with poor clinical and social outcomes. There are few studies of psychological treatments for this population and little long-term follow-up of their benefits. AIMS: To investigate symptom, substance use, functioning and health economy outcomes for patients with schizophrenia and their carers 18 months after a cognitive-behavioural treatment (CBT) programme. METHOD: Patients with dual diagnosis from a randomised controlled trial of motivational intervention, individual CBT and family intervention were assessed on multiple outcomes at 18-month follow-up. Carers were assessed on symptom, functioning and needs over 12 months. Health economy data were collected over 18 months. RESULTS: There were significant improvements in patient functioning compared with routine care over 18 months. No significant differences between treatment groups were found in carer or cost outcomes. CONCLUSIONS: The treatment programme was superior to routine care on outcomes relating to illness and service use, and the cost was comparable to the control treatment.

Caregivers↗

PubMed2000

Bone mineral density, osteopenia, and osteoporosis in the rhesus macaques of Cayo Santiago.

This cross-sectional study investigates metabolic bone disease and the relationship between age and bone mineral density (BMD) in males and females of a large, well-documented skeletal population of free-ranging rhesus monkeys (Macaca mulatta), from the Caribbean Primate Research Center Museum collection from Cayo Santiago, Puerto Rico. The sample consists of 254 individuals aged 1.0-20+ years. The data consist of measurements of bone mineral content and bone mineral density, obtained from dual-energy X-ray absorptiometry (DEXA), of the last lumbar vertebra from each monkey. The pattern of BMD differs between male and female rhesus macaques. Females exhibit an initial increase in BMD with age, with peak bone density occurring around age 9.5 years, and remaining constant until 17.2 years, after which there is a steady decline in BMD. Males acquire bone mass at a faster rate, and attain a higher peak BMD at an earlier age than do females, at around 7 years of age, and BMD remains relatively constant between ages 7-18.5 years. After age 7 there is no apparent effect of age on BMD in the males of this sample; males older than 18.5 years were excluded due to the presence of vertebral osteophytosis, which interferes with DEXA. The combined frequency of osteopenia and osteoporosis in this population is 12.4%. BMD values of monkeys with vertebral wedge fractures are generally higher than those of virtually all of the nonfractured osteopenic/osteoporotic individuals, thus supporting the view that BMD as measured by DEXA is a useful but imperfect predictor of fracture risk, and that low BMD may not always precede fractures in vertebral bones. Other factors such as bone quality (i.e., trabecular connectivity) should also be considered. The skeletal integrity of a vertebra may be compromised by the loss of key trabeculae, resulting in structural failure, but the spine may still show a BMD value within normal limits, or within the range of osteopenia.

Absorptiometry, Photon↗

PubMed1995

Right ventricular volume estimation with an ellipsoidal shell model and two-plane magnetic resonance imaging.

In patients with congenital and other heart disease, measurement of right ventricular (RV) volumes would be as useful as left ventricular (LV) volume measurement has been for diseases of the LV. Model-based techniques have had limited success. Simpson's rule (multislice) techniques require lengthy data collection and reduction. We investigated a technique for volume estimation with a new but simple geometric model. A retrospective patient study compared RV volumes from model-based calculations with dual-plane cine magnetic resonance (MR) imaging and multislice calculations with biplane cineangiography. Linear regression showed high correlation (r = 0.98, standard error of the estimate = 11.8 ml) between the two techniques, with a slope near unity. Comparison of calculated right and left stroke volumes also showed an excellent correlation (r = 0.93, standard error of the estimate = 10.4 ml) and a slope near unity. It is concluded that the ellipsoidal shell model can be used to estimate RV volume reliably and practically with dual-plane MR imaging.

Adolescent↗