Factors associated with satisfaction with social roles and activities among people with systemic sclerosis: a Scleroderma Patient-centered Intervention Network (SPIN) cohort cross-sectional study.

OBJECTIVE: The objectives were to (1) compare satisfaction with social roles and activities in a large multinational systemic sclerosis (SSc) cohort to general population normative data and (2) identify sociodemographic, lifestyle and SSc disease factors associated with satisfaction with social roles and activities. METHODS: Participants in the Scleroderma Patient-centered Intervention Network Cohort completed the Patient Reported Outcomes Information System Version 2 satisfaction with social roles and activities domain questionnaire. Multivariable regression was used to assess associations with sociodemographic, lifestyle and disease factors. RESULTS: Among 2385 participants, mean satisfaction with social roles and activities T-score (48.1, SD=9.9) was slightly lower than the US general population (mean=50, SD=10). Factors independently associated with satisfaction were years of education (0.54 per SD, 95% CI 0.14 to 0.93); non-White race or ethnicity (-1.13, 95% CI -2.18 to -0.08); living in Canada (-1.33, 95% CI -2.40 to -0.26 (reference USA)) or the UK (-2.49, 95% CI -3.92 to -1.06); body mass index (-1.08 per SD, 95% CI -1.47 to -0.69); gastrointestinal involvement (-3.16, 95% CI -4.27 to -2.05); digital ulcers (-1.90, 95% CI -3.05 to -0.76); moderate (-1.62, 95% CI -2.78 to -0.45) or severe (-2.26, 95% CI -3.99 to -0.52) small joint contractures; interstitial lung disease (-1.11, 95% CI -1.97 to -0.25); pulmonary arterial hypertension (-2.69, 95% CI -4.08 to -1.30); rheumatoid arthritis (-2.51, 95% CI -4.28 to -0.73); and Sjogren's syndrome (-2.42, 95% CI -3.96 to -0.88). CONCLUSION: Mean satisfaction with social roles and activities is slightly lower in SSc than the general population and associated with multiple sociodemographic and disease factors.

Factors associated with physical function among people with systemic sclerosis: a SPIN cohort cross-sectional study.

OBJECTIVES: To compare physical function in systemic sclerosis (SSc, scleroderma) to general population normative data and identify associated factors. METHODS: Scleroderma Patient-centered Intervention Network Cohort participants completed the Physical Function domain of the Patient-Reported Outcomes Measurement Information System Version 2 upon enrolment. Multivariable linear regression was used to assess associations of sociodemographic, lifestyle, and disease-related variables. RESULTS: Among 2,385 participants, mean physical function T-score (43.7, SD = 8.9) was ∼2/3 of a standard deviation (SD) below the US general population (mean = 50, SD = 10). Factors associated in multivariable analysis included older age (-0.74 points per SD years, 95% CI -0.78 to -1.08), female sex (-1.35, -2.37 to -0.34), fewer years of education (-0.41 points per SD in years, -0.75 to -0.07), being single, divorced, or widowed (-0.76, -1.48 to -0.03), smoking (-3.14, -4.42 to -1.85), alcohol consumption (0.79 points per SD drinks per week, 0.45-1.14), BMI (-1.41 points per SD, -1.75 to -1.07), diffuse subtype (-1.43, -2.23 to -0.62), gastrointestinal involvement (-2.58, -3.53 to -1.62), digital ulcers (-1.96, -2.94 to -0.98), moderate (-1.94, -2.94 to -0.93) and severe (-1.76, -3.24 to -0.28) small joint contractures, moderate (-2.10, -3.44 to -0.76) and severe (-2.54, -4.64 to -0.44) large joint contractures, interstitial lung disease (-1.52, -2.27 to -0.77), pulmonary arterial hypertension (-3.72, -4.91 to -2.52), rheumatoid arthritis (-2.10, -3.64 to -0.56) and idiopathic inflammatory myositis (-2.10, -3.63 to -0.56). CONCLUSION: Physical function is impaired for many individuals with SSc and associated with multiple disease factors.

The association of resilience and positive mental health in systemic sclerosis: A Scleroderma Patient-centered Intervention Network (SPIN) cohort cross-sectional study.

OBJECTIVE: A previous study using Scleroderma Patient-centered Intervention Network (SPIN) Cohort data identified five classes of people with systemic sclerosis (also known as scleroderma) based on patient-reported somatic (fatigue, pain, sleep) and mental health (anxiety, depression) symptoms and compared indicators of disease severity between classes. Across four classes ("low", "normal", "high", "very high"), there were progressively worse somatic and mental health outcomes and greater disease severity. The fifth ("high/low") class, however, was characterized by high disease severity, fatigue, pain, and sleep but low mental health symptoms. We evaluated resilience across classes and compared resilience between classes. METHODS: Cross-sectional study. SPIN Cohort participants completed the 10-item Connor-Davidson-Resilience Scale (CD-RISC) and PROMIS v2.0 domains between August 2022 and January 2023. We used latent profile modeling to identify five classes as in the previous study and multiple linear regression to compare resilience levels across classes, controlling for sociodemographic and disease variables. RESULTS: Mean CD-RISC score (N = 1054 participants) was 27.7 (standard deviation = 7.3). Resilience decreased progressively across "low" to "normal" to "high" to "very high" classes (mean 4.7 points per step). Based on multiple regression, the "high/low" class exhibited higher resilience scores than the "high" class (6.0 points, 95% confidence interval [CI] 4.9 to 7.1 points; standardized mean difference = 0.83, 95% CI 0.67 to 0.98). CONCLUSIONS: People with worse disease severity and patient-reported outcomes reported substantially lower resilience, except a class of people with high disease severity, fatigue, pain, and sleep disturbance but positive mental health and high resilience.

Researcher and patient experiences of co-presenting research to people living with systemic sclerosis at a patient conference: content analysis of interviews.

BACKGROUND: Patient engagement in research is important to ensure research questions address problems important to patients, that research is designed in a way that can effectively answer those questions, and that findings are applicable, relevant, and credible. Yet, patients are rarely involved in the dissemination stage of research. This study explored one way to engage patients in dissemination, through co-presenting research. METHODS: Semi-structured, one-on-one, audio-recorded interviews were conducted with researchers and patients who co-presented research at one patient conference (the 2022 Canadian National Scleroderma Conference) in Canada. A pragmatic orientation was adopted, and following verbatim transcription, data were analyzed using conventional content analysis. RESULTS: Of 8 researchers who were paired with 7 patients, 5 researchers (mean age = 28 years, SD = 3.6 years) and 5 patients (mean age = 45 years, SD = 14.2 years) participated. Researcher and patient perspectives about their experiences co-presenting and how to improve the experience were captured across 4 main categories: (1) Reasons for accepting the invitation to co-present; (2) Degree that co-presenting expectations were met; (3) The process of co-presenting; and (4) Lessons learned: recommendations for co-presenting. CONCLUSIONS: Findings from this study suggest that the co-presenting experience was a rewarding and enjoyable way to tailor research dissemination to patients. We identified a patient-centred approach and meaningful and prolonged patient engagement as essential elements underlying co-presenting success.

Involving patients throughout the entire research process is important to ensure research effectively addresses problems important to patients and that findings are applicable, relevant, and credible. Yet, patients are rarely involved in the dissemination of research. We explored one way to engage patients in dissemination, through co-presenting research. We conducted one-on-one interviews with 5 researchers and 5 patients who co-presented research at a patient conference in Canada. Both researchers and patients indicated that the co-presenting experience was rewarding and enjoyable and a useful way to tailor dissemination to patients. We found that a patient-centred approach and meaningful and prolonged patient engagement were essential elements underlying co-presenting success.

Moderators of Loneliness Trajectories in People with Systemic Sclerosis During the COVID-19 Pandemic: A SPIN COVID-19 Cohort Longitudinal Study.

BACKGROUND: Many individuals with systemic sclerosis (SSc) are at heightened risk for COVID-19 related morbidity and isolation due to interstitial lung disease, frailty, and immunosuppressant use. Minimal research has explored loneliness predictors in individuals with chronic illnesses during COVID-19. This study evaluated moderators of loneliness trajectories in individuals with SSc during COVID-19. METHODS: Longitudinal data were analyzed across 30 timepoints from April 2020 to May 2022 from 775 adults in the Scleroderma Patient-centered Intervention Network (SPIN) COVID-19 Cohort. Hierarchical linear modeling evaluated cross-level moderators of loneliness trajectories, including marital status, baseline number of household members, number of virtual or telephone one-on-one or virtual group conversations, number of hours spent enjoying in-person household conversations or activities, and satisfaction with quality of in-person household conversations (all in the past week). Level-1 moderation analyses assessed effects of conversation, activity, and satisfaction means and slopes over time. RESULTS: Baseline values were not statistically significant moderators of loneliness trajectories. Higher mean (averaged over time) virtual or telephone one-on-one and in-person household conversations, in-person household activity, and in-person household conversation satisfaction were associated with lower loneliness trajectories (ps < .05). The relationship between in-person household conversation satisfaction and loneliness trajectory was statistically significantly but minimally attenuated over time (p < .001). CONCLUSIONS: For people with SSc, higher mean conversation, activity, and satisfaction variables were associated with lower levels of loneliness during the pandemic, but changes in these social variables were generally not predictive of changes in loneliness.

Pulmonary Histoplasmosis in People Living with Human Immunodeficiency Virus in French Guiana: Clinical Epidemiology, Medical Imaging and Prognostic.

BACKGROUND: Histoplasmosis is mainly described as a disseminated disease in people living with HIV (PLHIV). Compared to historical descriptions in immunocompetent individuals, knowledge is lacking on the detailed clinical and radiological findings and outcomes of pulmonary histoplasmosis (PH). Overlooked or misdiagnosed with other AIDS-defining condition, prognostic of PLHIV may be at risk because of inappropriate care. METHODS: A retrospective multicentric study was conducted in PLHIV from French Guiana between January 1988 and October 2019. Proven PH were documented through mycological direct examination, culture, or histology. Patients with concomitant respiratory infections were excluded. RESULTS: Among 65 patients, sex ratio M:F was 2.4 with a median age of 39 years [IQR 25-75%: 34-44]. Median CD4 count was 24 cells/mm3 [11-71], with histoplasmosis as the AIDS-defining condition in 88% and concomitant AIDS-defining conditions in 29%. Clinical findings were fever (89%), cough (58%), dyspnea (35%), expectoration (14%), and hemoptysis (5%). Sixty-one X-rays and 24 CT-scans were performed. On X-rays, an interstitial lung disease was mainly found (77%). On CT-scans, a nodular pattern was predominant (83%): mostly miliary disease (63%), but also excavated nodules (35%). Consolidations were present in 46%, associated with miliary disease in 21%. Thoracic lymphadenopathies were found in 58%, mainly hilar and symmetric (33%). Despite antifungal treatment, case-fatality rate at one month was 22%. CONCLUSION: When faced with an interstitial lung disease on X-rays or a miliary pattern on CT-scans in advanced PLHIV, physicians in endemic areas, apart from tuberculosis or pneumocystosis, should include histoplasmosis as part of their differential diagnoses.

Differential Item Functioning on the Cochin Hand Function Scale Among People With Systemic Sclerosis by Language, Sex, and Disease Subtype: A Scleroderma Patient-Centered Intervention Network (SPIN) Cohort Study.

OBJECTIVE: To evaluate the degree that the Cochin Hand Function Scale (CHFS) generates scores that are comparable across language, sex, and disease subtype. METHODS: We included participants enrolled in the Scleroderma Patient-centered Intervention Network (SPIN) Cohort who completed the CHFS at their baseline assessment between April 2014 and September 2020. Confirmatory factor analysis (CFA) was used to test unidimensionality, and multiple indicator multiple cause (MIMIC) models were used for differential item functioning (DIF) analysis based on language, sex, and disease subtype. Both intraclass correlation coefficient (ICC) and Pearson's correlation were calculated using factor scores obtained from unadjusted and DIF-adjusted MIMIC models to evaluate agreement and correlation between scores. RESULTS: A total of 2,155 participants were included. CFA with covarying error terms supported a good fit of the model (χ2 [127] = 1,754.671; P < 0.001; Tucker-Lewis index = 0.985; comparative fit index = 0.987; root mean square error of approximation = 0.077). Nine items displayed statistically significant DIF for language of administration, 10 items for sex, and 10 items for disease subtype. However, the overall impact of DIF was negligible when comparing factor scores that did and did not account for DIF (ICC = 0.999; r = 0.999). CONCLUSION: The CHFS has score comparability in systemic sclerosis regardless of participants' language, sex, and disease subtype.

Validity, Reliability, and Differential Item Functioning of English and French Versions of the 10-Item Connor-Davidson Resilience Scale in Systemic Sclerosis: A Scleroderma Patient-Centered Intervention Network Cohort Study.

OBJECTIVE: Some individuals with systemic sclerosis (SSc) report positive mental health, despite severe disease manifestations, which may be associated with resilience, but no resilience measure has been validated in SSc. This study was undertaken to assess the validity, reliability, and differential item functioning (DIF) between English- and French-language versions of the 10-item Connor-Davidson Resilience Scale (CD-RISC-10) in SSc. METHODS: Eligible participants were enrolled in the Scleroderma Patient-centered Intervention Network Cohort and completed the CD-RISC-10 between August 2022 and January 2023. We used confirmatory factor analysis (CFA) to evaluate the CD-RISC-10 factor structure and conducted DIF analysis across languages with Multiple Indicators Multiple Causes models. We tested convergent validity with another measure of resilience and measures of self-esteem and depression and anxiety symptoms. We assessed internal consistency and test-retest reliability using Cronbach's alpha and intraclass correlation coefficient (ICC). RESULTS: A total of 962 participants were included in this analysis. CFA supported a single-factor structure (Tucker-Lewis index = 0.99, comparative fit index = 0.99, root mean square error of approximation = 0.08 [90% confidence interval (90% CI) 0.07, 0.09]). We found no meaningful DIF. Internal consistency was high (α = 0.93 [95% CI 0.92, 0.94]), and we found that correlations with other measures of psychological functioning were moderate to large (|r| = 0.57-0.78) and confirmed study hypotheses. The scale showed good 1-2-week test-retest reliability (ICC 0.80 [95% CI 0.75, 0.85]) in a subsample of 230 participants. CONCLUSION: The CD-RISC-10 is a valid and reliable measure of resilience in SSc, with score comparability across English and French versions.

Epidemiology of infection by pulmonary non-tuberculous mycobacteria in French Guiana 2008-2018.

INTRODUCTION: Unlike diseases caused by Mycobacterium tuberculosis, M. leprae and M. ulcerans, the epidemiology of pulmonary non-tuberculous mycobacteria (PNTM) has not received due attention in French Guiana. The main objective of the current study was to define the incidence of these PNTM infections: NTM pulmonary diseases (NTM-PD) and casual PNTM isolation (responsible of latent infection or simple colonization). The secondary objectives were to determine species diversity and geographic distribution of these atypical mycobacteria. METHODS: A retrospective observational study (2008-2018) of French Guiana patients with at least one PNTM positive respiratory sample in culture was conducted. Patients were then classified into two groups: casual PNTM isolation or pulmonary disease (NTM-PD), according to clinical, radiological and microbiological criteria defined by the American Thoracic Society / Infectious Disease Society of America (ATS / IDSA) in 2007. RESULTS: 178 patients were included, out of which 147 had casual PNTM isolation and 31 had NTM-PD. Estimated annual incidence rate of respiratory isolates was 6.17 / 100,000 inhabitants per year while that of NTM-PD was 1.07 / 100,000 inhabitants per year. Among the 178 patients, M. avium complex (MAC) was the most frequently isolated pathogen (38%), followed by M. fortuitum then M. abscessus (19% and 6% of cases respectively), the latter two mycobacteria being mainly found in the coastal center region. Concerning NTM-PD, two species were mainly involved: MAC (81%) and M. abscessus (16%). DISCUSSION/CONCLUSION: This is the first study on the epidemiology of PNTM infections in French Guiana. PNTM's incidence looks similar to other contries and metropolitan France and NTM-PD is mostly due to MAC and M.abscessus. Although French Guiana is the French territory with the highest tuberculosis incidence, NTM should not be overlooked.

Allergy to Mammalian Meat Linked to Alpha-Gal Syndrome Potentially After Tick Bite in the Amazon: A Case Series.

The past decade has seen the emergence of a new type of food allergy occurring after ingestion of mammalian meat. This allergy is related to immunoglobulin (Ig)E specific for galactose-alpha-1,3 galactose (α-Gal). Originally described in the United States in 2009, other cases have subsequently been described in Australia and in Europe, but still very few in Latin America. The purpose of this study was to show the existence of this pathology in French Guiana and to describe the historical, clinical, and biological characteristics of these patients. Patients reporting an allergy to mammalian meat were included between September 2017 and August 2019. Eleven patients were included, nine of whom exhibited digestive symptoms; four, urticaria reactions; three, respiratory reactions; and five angioedema. The time between ingestion of red meat and reaction varied between 1.5 and 6 hours. The implicated meats were most often beef and pork. All patients had been regularly exposed to tick bites before the appearance of symptoms. All the samples (n = 7) were positive for anti-α-Gal anti-mammalian meats IgE. All the patients were Caucasian French expatriates. This study confirms the presence of this new entity in French Guiana and is the largest reported in Latin America. Our results do not clearly allow us to state that tick bites are the cause of this allergy, but all patients reported being exposed regularly to these arthropods.

Effects of non-pharmacological and non-surgical interventions on health outcomes in systemic sclerosis: protocol for a living systematic review.

INTRODUCTION: Systemic sclerosis (SSc; scleroderma) is a rare, chronic, autoimmune disease with a high level of burden, a significant impact on the ability to carry out daily activities, and a considerable negative impact on health-related quality of life. Non-pharmacological interventions could be provided to potentially improve mental and physical health outcomes. However, the effectiveness of non-pharmacological interventions on health and well-being among individuals with SSc has not been well established. The proposed living systematic review aims to identify and evaluate randomised controlled trial (RCT) evidence on the effectiveness of non-pharmacological and non-surgical interventions on mental and physical health outcomes and on the delivery of such services in SSc. METHODS AND ANALYSIS: Eligible studies will be RCTs that examine non-pharmacological and non-surgical interventions aimed at improving health outcomes among individuals with SSc or the delivery of services intended to improve healthcare or support of people with SSc (eg, support groups). All RCTs included in a previous systematic review that sought studies published between 1990 and March 2014 will be evaluated for inclusion. Additional trials will be sought from January 2014 onwards using a similar, augmented search strategy developed by a health sciences librarian. We will search the MEDLINE, Embase, CINAHL, PsycINFO, Cochrane Library and Web of Science databases and will not restrict by language. Two independent reviewers will determine the eligibility of identified RCTs and will extract data using a prespecified standardised form in DistillerSR. Meta-analyses will be considered if ≥2 eligible RCTs report similar non-pharmacological interventions and comparable health outcomes. We will conduct a qualitative synthesis for interventions that cannot be synthesised via meta-analysis. ETHICS AND DISSEMINATION: We will post initial and ongoing results via a website, publish results periodically via peer-reviewed journal publication, and present results at patient-oriented events. PROSPERO REGISTRATION NUMBER: CRD42020219914.

Design of a fast field-cycling magnetic resonance imaging system, characterization and methods for relaxation dispersion measurements around 1.5 T.

The dependence of the nuclear magnetic resonance relaxation rate on the magnetic field has been widely studied, in particular, in biomedical areas with the objectives to better understand the underlying microscopic mechanisms in tissues and provide biomarkers of diseases. By combining fast-field cycling (FFC) and magnetic resonance imaging (MRI), it is possible to provide localized relaxation dispersion measurements in heterogeneous systems with recent demonstrations in solutions, biological samples, human beings, and small animals. We report here the developments and performances of a device designed for small animal FFC-MRI comprising a resistive insert technology operating inside a 1.5 T MRI system. Specific measurement methods were developed to characterize the system efficiency, response time, homogeneity, stability, and compensation. By adding a non-linear element in the system and using a dual amplifier strategy, it is shown that large field offsets can be produced during relaxation periods while maintaining precise field control during detection periods. The measurement of longitudinal nuclear magnetic relaxation dispersion (NMRD) profiles in the range of 1.08 T-1.92 T is reported, essentially displaying a linear variation in this range for common MRI contrast agents. The slopes of both the longitudinal and transverse relaxation dispersion profiles at 1.5 T are measured and validated, extending the capabilities of previous approaches. The performances of a longitudinal relaxation dispersion mapping method are finally reported, opening the way to quantitative preclinical dispersion imaging studies at a high FFC-MRI field.

A new paradigm for lung-conservative total liquid ventilation.

BACKGROUND: Total liquid ventilation (TLV) of the lungs could provide radically new benefits in critically ill patients requiring lung lavage or ultra-fast cooling after cardiac arrest. It consists in an initial filling of the lungs with perfluorocarbons and subsequent tidal ventilation using a dedicated liquid ventilator. Here, we propose a new paradigm for a lung-conservative TLV using pulmonary volumes of perfluorocarbons below functional residual capacity (FRC). METHODS AND FINDINGS: Using a dedicated technology, we showed that perfluorocarbon end-expiratory volumes could be maintained below expected FRC and lead to better respiratory recovery, preserved lung structure and accelerated evaporation of liquid residues as compared to complete lung filling in piglets. Such TLV below FRC prevented volutrauma through preservation of alveolar recruitment reserve. When used with temperature-controlled perfluorocarbons, this lung-conservative approach provided neuroprotective ultra-fast cooling in a model of hypoxic-ischemic encephalopathy. The scale-up and automating of the technology confirmed that incomplete initial lung filling during TLV was beneficial in human adult-sized pigs, despite larger size and maturity of the lungs. Our results were confirmed in aged non-human primates, confirming the safety of this lung-conservative approach. INTERPRETATION: This study demonstrated that TLV with an accurate control of perfluorocarbon volume below FRC could provide the full potential of TLV in an innovative and safe manner. This constitutes a new paradigm through the tidal liquid ventilation of incompletely filled lungs, which strongly differs from the previously known TLV approach, opening promising perspectives for a safer clinical translation. FUND: ANR (COOLIVENT), FRM (DBS20140930781), SATT IdfInnov (project 273).

Cross-relaxation parameters in cortical bone assessed with different MR sequences.

This study aimed to show evidence of MR cross-relaxation effects in cortical bone and to compare different MR sequences for the quantification of cross-relaxation parameters. Measurements were performed on bovine diaphysis samples with spectroscopic methods (inversion-recovery, off-resonance saturation) and with a variable flip angle (VFA) UTE imaging method on a 4.7 T laboratory-assembled scanner. Cross-relaxation parameter assessment was carried out via a two-pool model simulation with a matrix algebra approach. A proton signal amplitude of 28 Mol/L was observed (equivalent water fraction of 25%). It was attributed to collagen-bound water, with T2* values of ~ 0.3 ms, a "long-T2 " proton pool, in exchange with protons from the collagen macromolecules ( T2* of 10-20 µs). Magnetization transfer (MT) effects were detected with all sequences. The best precision of model parameters was obtained with off-resonance saturation; the fraction of collagen methylene protons was found in the range of 22-28% and the transverse relaxation time for collagen methylene protons was 11 µs (1% precision). The model parameters obtained were compatible with VFA-UTE results but could not be assessed with acceptable accuracy and precision using this method. In vivo MT quantification using off-resonance saturation with a single B1 amplitude and offset frequency may provide information about the relative amount of collagen per unit volume in cortical bone.

Quantitative Gd-DOTA-based aerosol deposition mapping in the lungs of asthmatic rats using 3D UTE-MRI.

Asthma is a chronic respiratory disease, commonly treated with inhaled therapy. Better understanding of the mechanisms of aerosol deposition is required to improve inhaled drug delivery. Three-dimensional ultrashort echo time (UTE) MRI acquisitions at 1.5 T were combined with spontaneous nose-only inhalation of aerosolized gadolinium (Gd) to map the aerosol deposition and to characterize signal enhancement in asthmatic rat lungs. The rats were sensitized to ovalbumin (OVA) to develop asthmatic models and challenged before imaging by nebulization of OVA to trigger asthmatic symptoms. The negative controls were not sensitized or challenged by nebulization of saline. The animal lungs were imaged before and after administration of Gd-based aerosol in freely breathing rats, by using a T1 -weighted 3D UTE sequence. A contrast-enhanced quantitative analysis was performed to assess regional concentration. OVA-sensitized rats had lower signal enhancement and lower deposited aerosol concentration. Their enhancement dynamics showed large inter-subject variability. The signal intensity was homogeneously enhanced for controls while OVA-sensitized rats showed heterogeneous enhancement. Contrast-enhanced 3D UTE was applied with aerosolized Gd to efficiently measure spatially resolved deposition in asthmatic lungs. The small administered dose (around 1 µmol/kg body weight) and the use of standard clinical MRI suggest a potential application for the exploration of asthma.

Aerosol deposition in the lungs of spontaneously breathing rats using Gd-DOTA-based contrast agents and ultra-short echo time MRI at 1.5 Tesla.

PURPOSE: Aerosol toxicology and drug delivery through the lungs, which depend on various parameters, require methods to quantify particle deposition. Intrapulmonary-administered MRI contrast agent combined with lung-specific imaging sequences has been proposed as a high performance technique for aerosol research. Here, aerosol deposition is assessed using ultra-short echo (UTE) sequences. METHODS: Before and after administration of Gd-DOTA-based aerosol delivered nose-only in free-breathing healthy rats, a T1 -weighted 3D UTE sequence was applied in a clinical 1.5 Tesla scanner. Administration lasted 14 min, and the experiment was performed on six rats. A contrast-enhanced quantitative analysis was done. RESULTS: Fifty percent signal enhancement was obtained in the lung parenchyma. Lung clearance of the contrast agent was evaluated to be 14% per h (corresponding to a characteristic clearance time of 3.6 h) and aerosol deposition was shown to be homogeneous throughout the lung in healthy rats. The total deposited dose was estimated to be 1.05 µmol/kg body weight, and the concentration precision was 0.02 mM. CONCLUSION: The UTE protocol with nebulized Gd-DOTA is replicable to significantly enhance the lung parenchyma and to map aerosol deposition. This functional strategy, applied in a clinical system with a clinical nebulization setup and a low inhaled dose, suggests a feasible translation to human.

AIDS-related Pneumocystis jirovecii genotypes in French Guiana.

The study described Pneumocystis jirovecii (P. jirovecii) multilocus typing in seven AIDS patients living in French Guiana (Cayenne Hospital) and seven immunosuppressed patients living in Brest, metropolitan France (Brest Hospital). Archival P. jirovecii specimens were examined at the dihydropteroate synthase (DHPS) locus using a PCR-RFLP technique, the internal transcribed spacer (ITS) 1 and ITS 2 and the mitochondrial large subunit rRNA (mtLSUrRNA) gene using PCR and sequencing. Analysis of typing results were combined with an analysis of the literature on P. jirovecii mtLSUrRNA types and ITS haplotypes. A wild DHPS type was identified in six Guianese patients and in seven patients from metropolitan France whereas a DHPS mutant was infected in the remaining Guianese patient. Typing of the two other loci pointed out a high diversity of ITS haplotypes and an average diversity of mtLSUrRNA types in French Guiana with a partial commonality of these haplotypes and types described in metropolitan France and around the world. Combining DHPS, ITS and mtLSU types, 12 different multilocus genotypes (MLGs) were identified, 4 MLGs in Guianese patients and 8 MLGs in Brest patients. MLG analysis allows to discriminate patients in 2 groups according to their geographical origin. Indeed, none of the MLGs identified in the Guianese patients were found in the Brest patients and none of the MLGs identified in the Brest patients were found in the Guianese patients. These results show that in French Guiana (i) PCP involving DHPS mutants occur, (ii) there is a diversity of ITS and mtLSUrRNA types and (iii) although partial type commonality in this territory and metropolitan France can be observed, MLG analysis suggests that P. jirovecii organisms from French Guiana may present specific characteristics.

DQF-MT MRI of connective tissues: application to tendon and muscle.

OBJECT: The sequence combining DQF (double quantum filtering) with magnetisation transfer (DQF-MT) was tested as an alternative to the DQF sequence for characterising tendon and muscle by MR imaging. MATERIALS AND METHODS: DQF-MT images of tendon-muscle phantoms were obtained at 4.7 T using ultra-short time to echo (UTE) methods in order to alleviate the loss of SNR due to the short T2 of the tissues. Two different sampling schemes of the k-space, Cartesian or radial, were employed. In vivo images of the human ankle on a clinical 1.5 T scanner are also presented. Parameters providing optimal tendon signal as well as optimal contrast between this tissue and muscle were determined. RESULTS: Two sets of parameters resulting in different contrasts between the tissues were found. For the first set (short creation time τ = 10 µs and magnetisation exchange time t LM = 100 ms), DQF-MT signals in muscle and tendon were detected, with that of the tendon being the larger one. For the second set (long creation time τ = 750 µs and magnetisation exchange time 10 µs < t LM < 100 ms), the DQF-MT signal was detected only in the tendon, and the decay of the double quantum coherence was slower than that observed for the first one, which allowed us to acquire DQF-MT MR images on a clinical 1.5 T MR scanner with minimal software interventions. In favourable conditions, the DQF-MT signal in the tendon could represent up to 10 % of the single-quantum signal. CONCLUSION: Dipolar interaction within macromolecules such as collagen and myosin is at the origin of the DQF-MT signal observed in the first parameter set. This should enable the detection of muscle fibrosis.

Mechanical properties of glenoid cancellous bone.

BACKGROUND: Loosening of the glenoid component in total shoulder arthroplasty is the main late complication of this procedure; it may be assumed that it is highly dependent on the quality of the glenoid cancellous bone. Very little is known about the mechanical properties of this cancellous bone. The aim of this study was to determine these properties (Young's modulus and strength) as well as bone density in different parts of the glenoid cancellous bone to assess their variations. METHODS: Eleven scapulas were obtained from six fresh-frozen, unembalmed human cadavers. Eighty-two cubic cancellous bone specimens were extracted and tested using a uniaxial compression test; then the specimens were defatted and correlations with bone density were determined. FINDINGS: The study showed significant differences in the mechanical properties with anatomic location and directions of loading. Young's modulus and strength were found to be significantly higher at the posterior part of the glenoid with the weakest properties at the antero-inferior part. Cancellous bone was found to be anisotropic with higher mechanical properties in the latero-medial direction perpendicular to the articular surface of the glenoid. The apparent density was on average equal to 0.29 g/cm(3) with the higher values at the posterior and superior part of the glenoid. Good correlation between apparent density and elastic modulus was found only in the sagittal planes but not in the coronal and axial plane. INTERPRETATION: The mechanical properties determined in this study showed the anisotropy of the glenoid cancellous bone; values of these properties could provide input data for finite element method analyses in shoulder prosthesis designs.

Inhomogeneity of rat vertebrae trabecular architecture by high-field 3D mu-magnetic resonance imaging and variable threshold image segmentation.

PURPOSE: To analyze the 3D microarchitecture of rat lumbar vertebrae by micro-magnetic resonance imaging (micro-MRI). MATERIALS AND METHODS: micro-MR images (20 x 20 x 20 microm(3) apparent voxel size) were acquired with a three-dimensional spin-echo pulse sequence on four lumbar vertebrae of two rats. Apparent microarchitectural parameters like trabecular bone fraction (BV/TV), specific bone surface (BS/TV), mean intercept length (MIL), and Euler number per unit volume (Euler density, E(V)) were calculated using a novel semiquantitative variable threshold segmentation technique. The threshold value T was obtained as a point of minimum or maximum of the function E(V) = E(V)(T). RESULTS: Quantitative 3D analysis of micro-MRI images revealed a higher connectivity in the peripheral regions (E(V) = -570 +/- 70 mm(-3)) than in the central regions (E(V) = -130 +/- 50 mm(-3)) of the analyzed rat lumbar vertebrae. Smaller intertrabecular cavities and larger bone volume fractions were observed in peripheral regions as compared to central ones (MIL = 0.18 +/- 0.01 mm and 0.26 +/- 0.01 mm; BV/TV = 34 +/- 3% and 29 +/- 3%, respectively). The quantitative 3D study of MIL showed a structural anisotropy of the trabeculae along the longitudinal axis seen on the images. The inhomogeneity of the bone architecture was validated by micro-computed tomography (micro-CT) images at the same spatial resolution. CONCLUSION: 3D high-field micro-MRI is a suitable technique for the assessment of bone quality in experimental animal models.