Modeling Dynamic Contrast-Enhanced MRI Data with a Constrained Local AIF

Purpose

This study aims to develop a constrained local arterial input function (cL-AIF) to improve quantitative analysis of dynamic contrast-enhanced (DCE)-magnetic resonance imaging (MRI) data by accounting for the contrast-agent bolus amplitude error in the voxel-specific AIF.

Procedures

Bayesian probability theory-based parameter estimation and model selection were used to compare tracer kinetic modeling employing either the measured remote-AIF (R-AIF, i.e., the traditional approach) or an inferred cL-AIF against both in silico DCE-MRI data and clinical, cervical cancer DCE-MRI data.

Results

When the data model included the cL-AIF, tracer kinetic parameters were correctly estimated from in silico data under contrast-to-noise conditions typical of clinical DCE-MRI experiments. Considering the clinical cervical cancer data, Bayesian model selection was performed for all tumor voxels of the 16 patients (35,602 voxels in total). Among those voxels, a tracer kinetic model that employed the voxel-specific cL-AIF was preferred (i.e., had a higher posterior probability) in 80 % of the voxels compared to the direct use of a single R-AIF. Maps of spatial variation in voxel-specific AIF bolus amplitude and arrival time for heterogeneous tissues, such as cervical cancer, are accessible with the cL-AIF approach.

Conclusions

The cL-AIF method, which estimates unique local-AIF amplitude and arrival time for each voxel within the tissue of interest, provides better modeling of DCE-MRI data than the use of a single, measured R-AIF. The Bayesian-based data analysis described herein affords estimates of uncertainties for each model parameter, via posterior probability density functions, and voxel-wise comparison across methods/models, via model selection in data modeling.

     

Markers of Inflammation and Coagulation after Long-Term Exposure to Coarse Particulate Matter: A Cross-Sectional Analysis from the Multi-Ethnic Study of Atherosclerosis

Background

Toxicological research suggests that coarse particles (PM_10–2.5) are inflammatory, but responses are complex and may be best summarized by multiple inflammatory markers. Few human studies have investigated associations with PM_10–2.5 and, of those, none have explored long-term exposures. Here we examine long-term associations with inflammation and coagulation in the Multi-Ethnic Study of Atherosclerosis.

Methods

Participants included 3,295 adults (45–84 years of age) from three metropolitan areas. Site-specific spatial models were used to estimate 5-year concentrations of PM_10–2.5 mass and copper, zinc, phosphorus, silicon, and endotoxin found in PM_10–2.5. Outcomes included interleukin-6, C-reactive protein, fibrinogen, total homocysteine, D-dimer, factor VIII, plasmin–antiplasmin complex, and inflammation and coagulation scores. We used multivariable regression with multiply imputed data to estimate associations while controlling for potential confounders, including co-pollutants such as fine particulate matter.

Results

Some limited evidence was found of relationships between inflammation and coagulation and PM_10–2.5. Endotoxin was the PM_10–2.5 component most strongly associated with inflammation, with an interquartile range (IQR) increase (0.08 EU/m³) associated with 0.15 (95% CI: 0.01, 0.28; p = 0.03) and 0.08 (95% CI: –0.07, 0.23; p = 0.28) higher inflammation scores before and after control for city, respectively. Copper was the component with the strongest association with coagulation, with a 4-ng/m³ increase associated with 0.19 (95% CI: 0.08, 0.30; p = 0.0008) and 0.12 (95% CI: –0.05, 0.30; p = 0.16) unit higher coagulation scores before and after city adjustment, respectively.

Conclusions

Our cross-sectional analysis provided some evidence that long-term PM_10–2.5 exposure was associated with inflammation and coagulation, but associations were modest and depended on particle composition.

Citation

Adar SD, D’Souza J, Mendelsohn-Victor K, Jacobs DR Jr, Cushman M, Sheppard L, Thorne PS, Burke GL, Daviglus ML, Szpiro AA, Diez Roux AV, Kaufman JD, Larson TV. 2015. Markers of inflammation and coagulation after long-term exposure to coarse particulate matter: a cross-sectional analysis from the Multi-Ethnic Study of Atherosclerosis. Environ Health Perspect 123:541–548; http://dx.doi.org/10.1289/ehp.1308069     

Problems and hopes perceived by mothers,fathers and physicians of children receiving palliative care

Background

The quality of shared decision making for children with serious illness may depend on whether parents and physicians share similar perceptions of problems and hopes for the child.

Objective

(i) Describe the problems and hopes reported by mothers, fathers and physicians of children receiving palliative care; (ii) examine the observed concordance between participants; (iii) examine parental perceived agreement; and (iv) examine whether parents who identified specific problems also specified corresponding hopes, or whether the problems were left ‘hopeless’.

Method

Seventy‐one parents and 43 physicians were asked to report problems and hopes and perceived agreement for 50 children receiving palliative care. Problems and hopes were classified into eight domains. Observed concordance was calculated between parents and between each parent and the physicians.

Results

The most common problem domains were physical body (88%), quality of life (74%) and medical knowledge (48%). The most common hope domains were quality of life (88%), suffering (76%) and physical body (39%). Overall parental dyads demonstrated a high percentage of concordance (82%) regarding reported problem domains and a lower percentage of concordance on hopes (65%). Concordance between parents and physicians regarding specific children was lower on problem (65–66%) and hope domains (59–63%). Respondents who identified problems regarding a child's quality of life or suffering were likely to also report corresponding hopes in these domains (93 and 82%, respectively).

Conclusion

Asking parents and physicians to talk about problems and hopes may provide a straightforward means to improve the quality of shared decision making for critically ill children.     

Coding sequence 1 and promoter single nucleotide polymorphisms in the CTLA-4 gene in Wegener's granulomatosis

OBJECTIVE: To analyze the association of Wegener's granulomatosis (WG) with 2 single nucleotide polymorphisms (SNP), a +49 A/G polymorphism in coding sequence (CDS) 1 and a C/T base exchange in the promoter region at position -318. METHODS: Restriction enzyme digestion of PCR amplified genomic DNA was used to analyze the CTLA-4 SNP in 32 patients with WG and 100-122 ethnically matched healthy controls. RESULTS: Patients were more often heterozygous for C/T in the promoter region (31% of the patients vs 14% of controls; p < 0.05). Homozygosity for C was less frequent in patients (69% of patients vs 86% of controls; p < 0.05). There was no association with the A/G SNP in CDS 1. There was a linkage disequilibrium between allele A of CDS 1 and the shortest allele, 86 bp, in the (AT)n of the 3' untranslated region in controls but not in patients. CONCLUSION: The CTLA-4 SNP in the promoter region at position -318 is associated with WG. The loss of linkage disequilibrium between allele A of CDS 1 and the short 86 bp in the (AT)n in patients indicates that the promoter SNP and the (AT)n polymorphism are independent genetic risk factors.     

The role of sex in health-related quality of life after cardiac surgery: a prospective study

BACKGROUND: To assess health-related quality of life (HRQOL) in patients after cardiac surgery with emphasis on sex differences. DESIGN AND METHODS: Between September 2004 and September 2005, 534 patients (413 males and 121 females) were consecutively included. HRQOL was measured by the short-form 36 (SF-36) before surgery with follow-up 6 and 12 months after surgery. RESULTS: Five hundred and twenty-one patients were alive after 12 months, 462 (89%) and 465 (89.4%) responded after 6 and 12 months, respectively. Female patients had less favorable scores than male patients on most subscales of the SF-36 both before and after surgery. Both male and female patients improved substantially after surgery, but female patients reported significantly less improvement on two of eight subscales of the SF-36; role emotional and bodily pain. CONCLUSION: The study demonstrates that there are sex differences concerning HRQOL both before and after cardiac surgery. A clear overall improvement in HRQOL over the first year after cardiac surgery, more specifically during the first 6 months for both sexes was found.     

Comparative evaluation of FGF-2-, VEGF-A-, and VEGF-C-induced angiogenesis, lymphangiogenesis, vascular fenestrations, and permeability

Several endothelial growth factors induce both blood and lymphatic angiogenesis. However, a systematic comparative study of the impact of these factors on vascular morphology and function has been lacking. In this study, we report a quantitative analysis of the structure and macromolecular permeability of FGF-2-, VEGF-A-, and VEGF-C-induced blood and lymphatic vessels. Our results show that VEGF-A stimulated formation of disorganized, nascent vasculatures as a result of fusion of blood capillaries into premature plexuses with only a few lymphatic vessels. Ultrastructural analysis revealed that VEGF-A-induced blood vessels contained high numbers of endothelial fenestrations that mediated high permeability to ferritin, whereas the FGF-2-induced blood vessels lacked vascular fenestrations and showed only little leakage of ferritin. VEGF-C induced approximately equal amounts of blood and lymphatic capillaries with endothelial fenestrations present only on blood capillaries, mediating a medium level of ferritin leakage into the perivascular space. No endothelial fenestrations were found in FGF-2-, VEGF-A-, or VEGF-C-induced lymphatic vessels. These findings highlight the structural and functional differences between blood and lymphatic vessels induced by FGF-2, VEGF-A, and VEGF-C. Such information is important to consider in development of novel therapeutic strategies using these angiogenic factors.     

Modulation of anti-idiotypic immune response by immunization with the autologous M-component protein in multiple myeloma patients

Multiple myeloma is characterized by a proliferation of clonal B lymphocytes and plasma cells. The idiotypic structure of clonal immunoglobulin (Ig) expressed on the tumour B-cell surface can be regarded as a tumour-specific antigen and, as such, a potential target for anti-idiotypic T and B cells in an immune regulation of the tumour-cell clone. Active immunization using the autologous monoclonal Ig as a 'vaccine' was shown to induce tumour-specific immunity in murine B-cell tumours and in human B-cell lymphoma. With the aim to induce or amplify an anti-idiotypic response in multiple myeloma, five stage I–III patients were repeatedly immunized with the autologous monoclonal IgG. Induction of idiotype-specific cellular immunity was analysed in vitro by an enzyme-linked immunospot assay (interferon-γ and interleukin-4 secreting cells). B cells secreting anti-idiotypic IgM antibodies were also analysed. An anti-idiotypic T-cell response was amplified 1.9–5-fold in three of the five patients during immunization. The number of B cells secreting anti-idiotypic antibodies also increased in these three patients. In two of the patients induction of idiotype-specific immunity was associated with a gradual decrease of blood CD19⁺ B cells. The induced T-cell response was eliminated during repeated immunization. Further studies are warranted to optimize the immunization schedule in order to achieve a long-lasting T-cell immunity against idiotypic determinants on the tumour clone. A role for immunity in controlling the tumour clone remains to be established.     

Double versus single autotransplantation in multiple myeloma; a single center experience of 100 patients

One hundred patients with newly diagnosed multiple myeloma (MM) were treated with high-dose chemotherapy followed by single or double autologous stem cell transplantation (ASCT). Up-front treatment with a double ASCT tended to prolong progression-free and overall survival.     

Origins of serum semicarbazide-sensitive amine oxidase

Semicarbazide-sensitive amine oxidases (SSAO) are enzymes that are capable of deaminating primary amines to produce aldehyde, ammonia, and hydrogen peroxide. This activity has been associated with vascular adhesion protein-1 (VAP-1) and is found in the serum, endothelium, adipose, and smooth muscle of mammals. Circulating SSAO activity is increased in congestive heart failure, diabetes, and inflammatory liver diseases. To investigate the origin of circulating SSAO activity, two transgenic mouse models were created with full-length human VAP-1 (hVAP-1) expressed on either endothelial (mTIEhVAP-1) or adipose tissues (aP2hVAP-1), with tie-1 and adipocyte P2 promoters, respectively. Under normal conditions a circulating form of hVAP-1 was found at high levels in the serum of mice with endothelium-specific expression and at low levels in the serum of mice with adipose specific expression. The level of circulating hVAP-1 in the transgenic mice varied with gender, transgene zygosity, diabetes, and fasting. Serum SSAO activity was absent from VAP-1 knockout mice and endothelial cell-specific expression of human VAP-1 restored SSAO activity to the serum of VAP-1 knockout mice. Together, these experiments show that in the mouse VAP-1 is the only source of serum SSAO, that under physiological conditions vascular endothelial cells can be a major source of circulating VAP-1 protein and SSAO, and that serum VAP-1 can originate from both endothelial cells and adipocytes during experimental diabetes. An increased endothelial cell capacity for lymphocyte binding and altered expression of redox-sensitive proteins was also associated with the mTIEhVAP-1 transgene.