Associations between visceral obesity and renal impairment in health checkup participants: a retrospective cohort study.

BACKGROUND: Obesity is a risk factor for chronic kidney disease. Although body mass index (BMI) or waist circumference is indicators of obesity, actual measurements of visceral fat area (VFA) more accurately reflect the amount of visceral fat. We aimed to determine the most sensitive obesity indicator for predicting renal impairment among VFA, BMI, waist circumference, waist-to-height ratio, and visceral-to-subcutaneous fat ratio (VSR). METHODS: Subjects who underwent VFA measurements during health checkups in 2012 were included. Obesity was defined using a separate baseline value for each indicator [VFA (100 cm2), BMI (25 kg/m2), waist circumference (85 cm for men and 90 cm for women), waist-to-height ratio (0.5), VSR (0.4)]. Changes in estimated glomerular filtration rate (eGFRcr) and time to new-onset proteinuria were measured. The relationships between obesity indicators and eGFRcr were evaluated using a linear mixed-effects model. The relationships between obesity indicators and new-onset proteinuria were evaluated using Poisson regression analysis. RESULTS: Analysis was performed on 2753 subjects (mean age 50.3 years). The VFA ≥ 100 cm2 group exhibited a larger annual difference in eGFRcr compared to the < 100 cm2 group (- 0.24 mL/min/1.73 m2, P = 0.03). There was a statistically significant difference in the proteinuria incidence rate ratio, which was 1.54 times (95% confidence interval 1.01-2.35) in the VFA ≥ 100 cm2 group. Statistically significant correlations were not observed with any of the other obesity indicators. CONCLUSION: VFA is suggested to be the most sensitive obesity indicator for decline in kidney function and new-onset proteinuria.

Peripheral circulatory disorders in essential thrombocythemia.

A significant number of patients with essential thrombocythemia (ET) complain of symptoms including distal parts of the extremities (e.g., paresthesias or Raynaud's phenomenon). The aim of the present study was to examine peripheral circulation in the upper extremities of individuals with ET. The study included 45 ET patients and 30 control subjects. All participants were subjected to thermography, photoplethysmography, impedance plethysmography, and applanation tonometry pulse wave analysis. The patients with ET differed significantly from the control subjects in terms of 3rd finger skin temperature (mean 31.04 vs. 32.45°C), skin temperature gradient (mean 1.82 vs. 0.11°C), photoplethysmographic amplitude (median 0.25 vs. 0.74%), and pulse waveform in the radial artery (more frequent occurrence of type B waveform). Pulse wave parameters correlated with the skin temperature gradient. The study findings imply the altered regulation of peripheral circulation in ET, including a decreased flow and an increased resistance.

Physical activity classification using time-frequency signatures of motion artifacts in multi-channel electrical impedance plethysmographs.

Physical activities are known to introduce motion artifacts in electrical impedance plethysmographic (EIP) sensors. Existing literature considers motion artifacts as a nuisance and generally discards the artifact containing portion of the sensor output. This paper examines the notion of exploiting motion artifacts for detecting the underlying physical activities which give rise to the artifacts in question. In particular, we investigate whether the artifact pattern associated with a physical activity is unique; and does it vary from one human-subject to another? Data was recorded from 19 adult human-subjects while conducting 5 distinct, artifact inducing, activities. A set of novel features based on the time-frequency signatures of the sensor outputs are then constructed. Our analysis demonstrates that these features enable high accuracy detection of the underlying physical activity. Using an SVM classifier we are able to differentiate between 5 distinct physical activities (coughing, reaching, walking, eating and rolling-on-bed) with an average accuracy of 85.46%. Classification is performed solely using features designed specifically to capture the time-frequency signatures of different physical activities. This enables us to measure both respiratory and motion information using only one type of sensor. This is in contrast to conventional approaches to physical activity monitoring; which rely on additional hardware such as accelerometers to capture activity information.

Lymphedema following gynecological cancer: Results from a prospective, longitudinal cohort study on prevalence, incidence and risk factors.

OBJECTIVE: Cancer-related lymphedema is a debilitating condition that adversely influences function, health and quality of life. The purpose of this study was to assess the prevalence, incidence, and risk factors of lower-limb lymphedema pre- through to 24months post-surgery for gynecological cancer. METHODS: A clinic-based sample of women (n=408) with gynecological cancer participated in a prospective, longitudinal study (2008-2011) using self-reported measures (swelling in one or both legs) and objectively measured lymphedema (bioimpedance spectroscopy) at baseline (pre-surgery), six weeks-three months, 6-12months, and 15-24months post-surgery. RESULTS: At pre-surgery, 15% of women self-reported lymphedema and 27% had measurable evidence of lymphedema. By 24months post-surgery, incidence of new self-reported or measured lymphedema was 45% and 37%, respectively. Three-quarters of these new cases presented by 12-months post-treatment. While lymphedema was transient for some women, 60% had persistent lymphedema. More extensive lymph node dissection, receipt of chemotherapy and radiation therapy, increasing body mass index, insufficient levels of physical activity, diagnosis of vulvar/vaginal cancer and presence of pre-treatment lymphedema were identified as potential risk factors (p<0.05). CONCLUSION: Findings support the need for integration of pre-surgical assessment, and prospective, post-treatment surveillance of lymphedema into gynecological cancer care. Future research exploring the role of maintaining healthy body weight, regular physical activity and education about early detection of lymphedema to improve gynecological cancer survivorship is warranted.

Clinical utility of a functional lumen imaging probe in management of dysphagia following head and neck cancer therapies.

Background and aims Chemoradiotherapy for head and neck cancer (HNC) with/without laryngectomy commonly causes dysphagia. Pharyngoesophageal junction (PEJ) stricturing is an important contributor. We aimed to validate a functional lumen imaging probe (the EndoFLIP system) as a tool for quantitating pretreatment PEJ distensibility and treatment-related changes in HNC survivors with dysphagia and to evaluate the diagnostic accuracy of EndoFLIP-derived distensibility in detecting PEJ strictures. Methods We studied 34 consecutive HNC survivors with long-term (> 12 months) dysphagia who underwent endoscopic dilation for suspected strictures. Twenty non-dysphagic patients undergoing routine endoscopy served as controls. PEJ distensibility was measured at endoscopy with the EndoFLIP system pre- and post-dilation. PEJ stricture was defined as the presence of a mucosal tear post-dilation. Results PEJ stricture was confirmed in 22/34 HNC patients (65 %). During distension up to 60 mmHg, the mean EndoFLIP-derived narrowest cross-sectional area (nCSA) in HNC patients with strictures, without strictures, and in controls were 58 mm2 (95 % confidence interval [CI] 22 to 118), 195 mm2 (95 %CI 129 to 334), and 227 mm2 (95 %CI 168 to 316), respectively. A cutoff of 114 mm2 for the nCSA at the PEJ had perfect diagnostic accuracy in detecting strictures (area under the receiver operating characteristic curve = 1). In patients with strictures, a single session of dilation increased the nCSA by 29 mm2 (95 %CI 20 to 37; P < 0.001). In patients with no strictures, dilation caused no change in the nCSA (mean difference 13 mm2 [95 %CI -4 to 30]; P = 0.13). Conclusions EndoFLIP is a highly accurate technique for the detection of PEJ strictures. EndoFLIP may complement conventional diagnostic tools in the detection of pharyngeal outflow obstruction.

Harmonic analysis of peripheral pulse for screening subjects at high risk of diabetes.

Power spectral density (PSD) of peripheral pulses in human has been investigated in the past for its clinical applications. Continuing the efforts, data acquired using Peripheral Pulse Analyser in research projects sponsored by Board of Research in Nuclear Sciences in 207 control subjects, 18 descendants of diabetic patients and 22 patients with systemic hypertension have been subjected to PSD analysis for its study of harmonics. Application software, named Pulse Harmonic Analyser specifically developed for this work, selected 131,072 samples from each data file, obtained PSD, derived 52 PHA parameters and saved them in an Excel sheet. Coefficient of variation in control data was reduced significantly by application of Central Limit Theorem, which enabled use of parametric methods for statistical analysis of the observations. Data in hypertensive patients have shown significant difference in comparison to that of controls in eight parameters at low values of α and ß. Data in offspring of diabetic patients also have shown significant difference in one parameter indicating its usefulness in screening subjects with genetic disposition of acquiring Type-II Diabetes. PHA analysis has also yielded sub-harmonic components, which are related to combined variability in the heart rate, pulse volume and pulse morphology and has a potential to become method of choice for real time variability monitoring.

Enhanced Local Disorder in a Clinically Elusive von Willebrand Factor Provokes High-Affinity Platelet Clumping.

Mutation of the cysteines forming the disulfide loop of the platelet GPIbα adhesive A1 domain of von Willebrand factor (VWF) causes quantitative VWF deficiencies in the blood and von Willebrand disease. We report two cases of transient severe thrombocytopenia induced by DDAVP treatment. Cys1272Trp and Cys1458Tyr mutations identified by genetic sequencing implicate an abnormal gain-of-function phenotype, evidenced by thrombocytopenia, which quickly relapses back to normal platelet counts and deficient plasma VWF. Using surface plasmon resonance, analytical rheology, and hydrogen-deuterium exchange mass spectrometry (HXMS), we decipher mechanisms of A1-GPIbα-mediated platelet adhesion and resolve dynamic secondary structure elements that regulate the binding pathway. Constrained by the disulfide, conformational selection between weak and tight binding states of A1 takes precedence and drives normal platelet adhesion to VWF. Less restrained through mutation, loss of the disulfide preferentially diverts binding through an induced-fit disease pathway enabling high-affinity GPIbα binding and firm platelet adhesion to a partially disordered A1 domain. HXMS reveals a dynamic asymmetry of flexible and ordered regions common to both variants, indicating that the partially disordered A1 lacking the disulfide retains native-like structural dynamics. Both binding mechanisms share common structural and thermodynamic properties, but the enhanced local disorder in the disease state perpetuates high-affinity platelet agglutination, characteristic of type 2B VWD, upon DDAVP-stimulated secretion of VWF leading to transient thrombocytopenia and a subsequent deficiency of plasma VWF, characteristic of type 2A VWD.

Mechanisms of Vasovagal Syncope in the Young: Reduced Systemic Vascular Resistance Versus Reduced Cardiac Output.

BACKGROUND: Syncope is a sudden transient loss of consciousness and postural tone caused by cerebral hypoperfusion. The most common form is vasovagal syncope (VVS). Presyncopal progressive early hypotension in older VVS patients is caused by reduced cardiac output (CO); younger patients have reduced systemic vascular resistance (SVR). Using a priori criteria for reduced CO (↓CO) and SVR (↓SVR), we studied 48 recurrent young fainters comparing subgroups of VVS with VVS-↓CO, VVS-↓SVR, and both VVS-↓CO&↓SVR. METHODS AND RESULTS: Subjects were studied supine and during 70-degrere upright tilt with a Finometer to continuously measure blood pressure, CO, and SVR and impedance plethysmography to estimate thoracic, splanchnic, pelvic, and calf blood volumes, blood flows, and vascular resistances and electrocardiogram to measure heart rate and rhythm. Central blood volume was decreased in all VVS compared to control. VVS-↓CO was associated with decreased splanchnic blood flow and increased splanchnic blood pooling compared to control. Seventy-five percent of VVS patients had reduced SVR, including 23% who also had reduced CO. Many VVS-↓SVR increased CO during tilt, with no difference in splanchnic pooling, caused by significant increases in splanchnic blood flow and reduced splanchnic resistance. VVS-↓CO&↓SVR patients had splanchnic pooling comparable to VVS-↓CO patients, but SVR comparable to VVS-↓SVR. Splanchnic vasodilation was reduced, compared to VVS-↓SVR, and venomotor properties were similar to control. Combined splanchnic pooling and reduced SVR produced the earliest faints among the VVS groups. CONCLUSIONS: Both ↓CO and ↓SVR occur in young VVS patients. ↓SVR is predominant in VVS and is caused by impaired splanchnic vasoconstriction.

Efficacy of bioelectrical impedance analysis during the perioperative period in children.

We evaluated the efficacy of bioelectrical impedance analysis (BIA) during the perioperative period by estimating the preoperative and postoperative body fluid status. After obtaining informed consent, we enrolled 100 children (3-12 years of age) scheduled for elective surgeries. All children had been fasted preoperatively. The children's body fluid status was estimated using a BIA machine (InBody S10; Biospace, Korea) in the ward on the afternoon before surgery (baseline), just before surgery and immediately after surgery. The total administered fluid volume during the fasting period, total administered fluid volume during the operation and fasting time were recorded. Continuous data are shown as mean ± standard deviation, and Pearson's correlation analysis was used to assess relationships between the preoperative fluid deficit and intracellular water (ICW)/extracellular water (ECW) changes. The mean fasting period was 13.3 h (range 5.8-19.7 h). A weak positive correlation was shown between the ICW and fluid deficit during the fasting period (Pearson correlation coefficient = 0.254; P = 0.010). A stronger positive correlation was shown between the ECW and fluid deficit during the fasting period (Pearson correlation coefficient = 0.359; P < 0.001). The baseline and postoperative ICW showed a strong positive correlation (Pearson correlation coefficient = 0.992, P < 0.001), as did the baseline and postoperative ECW (Pearson correlation coefficient = 0.990, P < 0.001). Also there was no dehydration and irritability on medical recording preoperatively. BIA may be an alternative method for estimating the perioperative fluid status in children and determining details of fluid administration.

Role of Intraluminal Esophageal Impedance Baseline in the Diagnosis of Esophagitis in Children.

Introduction Low values of esophageal impedance baseline (EIB) have been related to esophagitis. The aim of this study was to evaluate the diagnostic performance of EIB for erosive esophagitis (ErE) and histological esophagitis (HiE) in children studied for gastroesophageal reflux. Material and Methods Children who underwent esophageal multichannel intraluminal impedance-pH monitoring (MII-pH) and upper-endoscopy with esophageal biopsies were studied retrospectively. EIB values were obtained by MII-pH. ErE was assessed by endoscopy following the Hetzel-Dent classification; HiE was defined by basal zone hyperplasia, papillary lengthening, or inflammatory infiltration. EIB was compared between groups. Receiver operating characteristic (ROC) curves were obtained to calculate the global diagnostic performance of EIB and to find cut-off values for sensitivity and specificity. Logistic regression was used for age adjustment. Results Fifty-one patients were studied: 11 had ErE and 23 had HiE. EIB median values were 1,159 in ErE versus 2,583 in non-ErE (U = 80, p < 0.01). The adjusted ROC curve analysis for ErE was 0.85 (95% CI = 0.74-0.96); the EIB cut-off value = 2,379 determined sensitivity = 100% and specificity = 52.6% in children < 4 years old. and sensitivity = 100% and specificity = 63.2% in children > 4 years old. EIB median values were 1,666 in HiE versus 2,669 in non-HiE (U = 80, p < 0.01). The adjusted ROC curve analysis for HiE was 0.75 (95% CI = 0.59-0.90); the EIB cut-off value = 2,296 determined sensitivity = 71.2% and specificity = 83.1% in children < 4 years old, and sensitivity = 75.1% and specificity = 80.1% in children > 4 years old. Conclusion EIB provides statistically significant diagnostic performances for ErE and HiE. It could become a useful tool, especially to discriminate between ErE and non-ErE, avoiding other invasive tests.

Low testosterone levels are associated with endothelial dysfunction in oophorectomized early postmenopausal women.

BACKGROUND: The actual consequences of low testosterone levels in women remain uncertain. OBJECTIVE: To assess endogenous testosterone influence on body composition, vascular and metabolic function in recent postmenopausal women. DESIGN: We studied 81 postmenopausal women under transdermal estradiol (E2) replacement therapy, 36 with bilateral oophorectomy (group O), and 45 controls (group C) through venous occlusion plethysmography, bioimpedance, DEXA, biochemical, hormonal, and inflammatory profile. RESULTS: Total testosterone level (TT) in group O was 11.0 (4.0-17.75) vs 23.0 (10.0-42.5) ng/dl in group C (P=0.001). Forearm blood flow, in ml/min/100  ml tissue, was lower in group O compared to group C at baseline (1.57 (1.05-2.47) vs 2.19 (1.59-2.66) P=0.036), following reactive hyperemia response (endothelium-dependent flow mediated dilatation, 3.44 (2.38-4.35) vs 4.3 (3.09-5.52), P=0.031) and following nitroglycerin (endothelium-independent dilation, 1.39 (0.99-1.7) vs 1.76 (1.15-2.0), P=0.025), with a positive correlation between TT and all parameters except for the reactive hyperemia response (r=0.233-0.312, P=0.036-0.004). The sVCAM1 levels were negatively correlated with TT (r=-0.320, P=0.005). E2 and other hormone levels, biochemical parameters and body composition did not differ between groups. Multiple linear regressions showed that the levels of TT, compared with other confounding variables, may explain the variation observed on endothelial parameters, with low explanatory power. CONCLUSION: The absence of ovarian testosterone production in recent postmenopausal oophorectomized women was associated with deleterious effects on endothelial function.

Treatment of physiotherapy-refractory secondary upper limb lymphedema with vascularized lymph node transfer: A case report with clinical and bioimpedance analysis correlation.

With radical treatment of cancer, lymphedema of limb has become a commonly faced adverse effect. The introduction of vascularized lymph node transfer (VLNT) has provided a possible treatment option for this troublesome condition. In this case report, we describe a 66-year-old lady who developed upper limb lymphedema after operation and radiotherapy for the cancer of her left breast. Her lymphedema did not improve despite wearing pressure garment and receiving six months of regular decongestive physiotherapy. VLNT was performed for this patient, the pre- and post-operative limb circumference and bioimpedance measurements were compared. After operation, the patient continued with her previous physiotherapy regimen. Complete resolution of pitting edema was demonstrated five months after VLNT. In addition, there was a marked improvement in both limb circumference and bioimpedance measurements. From this case report, VLNT appears to be a promising treatment option for secondary lymphedema. We suggest this case report can serve as a model for future studies.

The prevalence of gastro-esophageal reflux disease and esophageal dysmotility in Chinese patients with idiopathic pulmonary fibrosis.

BACKGROUND: The cause of idiopathic pulmonary fibrosis (IPF) remains unknown, yet gastro-esophageal reflux disease (GERD) is highly prevalent in this population. GERD prevalence was studied, and esophageal function tests (EFT) were assessed in Chinese IPF patients. METHODS: We prospectively studied 69 IPF patients who undertook both stationary High Resolution esophageal Manometry/Impedance (HRiM) and 24-hour esophageal Multi-Channel Intraluminal Impedance with pH Recordings (MII/pH). Patients were divided into GERD+ and GERD- groups according to pH results. Controls were HRiM treated healthy volunteers, and patients without IPF received HRiM and MII/pH diagnosed with GERD. RESULTS: 69 IPF patients, 62 healthy volunteers, and 88 IPF negative GERD patients were selected. GERD prevalence in IPF was 43/69 (62.3%), and 58.1% of patients presented with at least one typical symptom. Symptoms had a sensitivity of 58.1%, a specificity of 61.6%, a positive predictive value of 71.4% and a negative predictive of 47.1%. Compared with healthy volunteers, IPF patients had significantly decreased lower esophageal sphincter pressure (LESP), upper esophageal sphincter pressure (UESP) and complete bolus transit rate (CBTR). By contrast, IPF patients had increased total bolus transit time and prevalence of weak peristalsis. MII/pH showed that one third of IPF patients had abnormal distal and proximal reflux, especially non-acid reflux. Compared with GERD patients without IPF, GERD patients with IPF had significantly decreased CBTR and UESP with increased bolus exposure time. CONCLUSIONS: GERD prevalence in IPF was high, but symptoms alone were an unreliable predictor of reflux. IPF patients had lower LESP and UESP, impaired esophageal peristalsis and bolus clearance function with more proximal reflux events.

Lung Volume Reduction in Emphysema Improves Chest Wall Asynchrony.

BACKGROUND: Lung volume reduction (LVR) techniques improve lung function in selected patients with emphysema, but the impact of LVR procedures on the asynchronous movement of different chest wall compartments, which is a feature of emphysema, is not known. METHODS: We used optoelectronic plethysmography to assess the effect of surgical and bronchoscopic LVR on chest wall asynchrony. Twenty-six patients were assessed before and 3 months after LVR (surgical [n = 9] or bronchoscopic [n = 7]) or a sham/unsuccessful bronchoscopic treatment (control subjects, n = 10). Chest wall volumes were divided into six compartments (left and right of each of pulmonary ribcage [Vrc,p], abdominal ribcage [Vrc,a], and abdomen [Vab]) and phase shift angles (θ) calculated for the asynchrony between Vrc,p and Vrc,a (θRC), and between Vrc,a and Vab (θDIA). RESULTS: Participants had an FEV1 of 34.6 ± 18% predicted and a residual volume of 217.8 ± 46.0% predicted with significant chest wall asynchrony during quiet breathing at baseline (θRC, 31.3° ± 38.4°; and θDIA, -38.7° ± 36.3°). Between-group difference in the change in θRC and θDIA during quiet breathing following treatment was 44.3° (95% CI, -78 to -10.6; P = .003) and 34.5° (95% CI, 1.4 to 67.5; P = .007) toward 0° (representing perfect synchrony), respectively, favoring the LVR group. Changes in θRC and θDIA were statistically significant on the treated but not the untreated sides. CONCLUSIONS: Successful LVR significantly reduces chest wall asynchrony in patients with emphysema.

Estimation of body composition depends on applied device in patients undergoing major abdominal surgery.

BACKGROUND: Bioelectrical impedance analysis (BIA) is a method used to estimate body compartments such as fat-free mass (FFM) and fat mass (FM). Two BIA devices, a single-frequency BIA (SF-BIA) device and a bioimpedance spectroscopy (BIS) approach, were compared to evaluate their reliability and to study whether their estimations resulted in similar classifications of body composition. MATERIALS AND METHODS: In a prospective observational study, body composition was estimated by SF-BIA and BIS in 123 adult patients scheduled for major abdominal surgery. Measurement agreement for the continuous variables FFM and FM were analyzed by using the intraclass correlation coefficient (ICC), the mean differences, and their limits of agreement. Measurement differences were also visualized by Bland-Altman plots. For the dichotomized FFM index (FFMI) and FM index (FMI), interobserver agreement was calculated using Cohen κ statistics; the McNemar test was performed to compare the paired proportions. RESULTS: Agreement for the continuous variables was almost perfect for FM (.86; 95% confidence interval [CI], .80-.90) and substantial for FFM (.78; 95% CI, .70-.84). For the dichotomous variables, the agreement was substantial for FMI (.67; 95% CI, .51-.83) and slight for FFMI (.19; 95% CI, .01-.37). BIS classified a larger proportion having a low FFMI and a high FMI. CONCLUSION: There were good ICCs between SF-BIA and BIS for FFM and FM. However, the mean differences were substantial, whereas the classification of body composition based on FFMI and FMI was influenced by the device. Therefore, BIA devices are not interchangeable.

Prospective surveillance of breast cancer-related lymphoedema in the first-year post-surgery: feasibility and comparison of screening measures.

PURPOSE: To examine the feasibility of a breast cancer-related lymphoedema (BCRL) screening programme. Additionally, to investigate the efficacy of bioimpedance analysis (BIA) compared to circumferential measurements (CM) in detecting BCRL. METHODS: This was a 12-month prospective feasibility study. Participants were recruited from two diagnostic breast clinics and consented to be screened for BCRL. Pre-surgical assessments were conducted, and participants were followed up at quarterly intervals. BIA and CM measurements were conducted at all time points. An L-Dex score of >10 or a 10-U increase from baseline or a ≥5 % increase in proximal, distal or total percentage volume difference (PVD) from baseline was indicative of BCRL. Information was collected on subjective symptoms, potential risk factors, demographics and medical data. Feasibility was based on uptake and retention. RESULTS: One hundred twenty-six participants were recruited with an attrition rate of 16.2 %. Participants' mean age was 59 years with the majority having stage I (63.9 %), infiltrating ductal carcinoma (87.4 %). 31.6 % were identified as having BCRL, 90.3 % detected by CM and 35.5 % by BIA (p = ≤0.0001). We found no significant correlation between BIA and CM. Participants identified as having BCRL had a higher BMI, a recent injury to their 'at-risk' arm and more lymph nodes excised (p = <0.05). These findings were not evident across all time points. A large percentage of participants had transient BCRL when assessed by a lymphoedema physiotherapist. CONCLUSIONS: BCRL screening is acceptable and valued by breast cancer survivors. Work needs to continue to establish the most effective screening tool and the natural behaviour of BCRL within the first-year post-surgery.

Assessment of body composition by dual-energy X-ray absorptiometry, bioimpedance analysis and anthropometrics in children: the Physical Activity and Nutrition in Children study.

OBJECTIVE AND METHODS: We compared InBody720 segmental multifrequency bioimpedance analysis (SMF-BIA) with Lunar Prodigy Advance dual-energy X-ray absorptiometry (DXA) in assessment of body composition among 178 predominantly prepubertal children. Segmental agreement analysis of body compartments was carried out, and inter-relationships of anthropometric and other measures of body composition were defined. Moreover, the relations of different reference criteria for excess body fat were evaluated. RESULTS: The prevalence of excess body fat varies greatly according to the used criteria. Intraclass and Pearson's correlations between SMF-BIA and DXA were >0·92 in total body and >0·74 in regional measures. SMF-BIA underestimated percentage body fat (%BF) and fat mass (FM), and overestimated lean mass (LM) and percentage LM with significant offset trend bias. Higher adiposity increased offsets, and overall agreement was poorer in girls. On average, %BF offsets (girls/boys) and limits of agreement (LA) were 3·9/1·6% [(-)1·4-9·2%/(-)3·4-6·7%]. Interestingly percentage offsets of fat content (%BF: 18·9/10·1%, FM: 18·8/11·1%) showed no significant bias trends indicating that the corresponding absolute methodological offset depends on the amount of fat content. The smallest percentage offset was found with LM: 4·3/0·1%, referring offset (LA) of 0·88/0·03 kg (±2·05/±1·71 kg). Correspondingly, segmental LM had poorer agreement than total body LM. All anthropometrics except for the waist-to-hip ratio showed strong correlations (r = 0·76-0·95) with abdominal and total body fat. CONCLUSION: Segmental multifrequency bioimpedance analysis is precise enough for total-LM analysis and had also sufficient trueness for total body composition analysis to be used in epidemiological purposes. There is need to generate scientifically and clinically relevant criteria and reference values for excess body fat.

Feasibility of electric property tomography of pelvic tumors at 3T.

PURPOSE: Investigation of the validity of the "transceive phase assumption" for Electric Property Tomography of pelvic tumors at 3T. The acquired electric conductivities of pelvic tumors are beneficial for improved specific absorption rate determination in hyperthermia treatment planning. METHODS: Electromagnetic simulations and magnetic resonance imaging measurements of a pelvic-sized phantom and the human pelvis of a volunteer and a cervix cancer patient. RESULTS: The reconstructed conductivity values of the phantom tumor model are in good quantitative agreement (mean deviation: 1-10%) with the probe measurements. Furthermore, the average reconstructed conductivity of a pelvic tumor model was in close agreement with the input conductivity (0.86 S/m vs. 0.90 S/m). The reconstructed tumor conductivity of the presented patient (cervical carcinoma, Stage: IVA) was 1.16 ± 0.40 S/m. CONCLUSION: This study demonstrates the feasibility of electric property tomography to measure quantitatively the conductivity of centrally located tumors in a pelvic-sized phantom and human pelvis with a standard magnetic resonance (MR) system and MR sequences. A good quantitative agreement was found between the reconstructed σ-values and probe measurements for a wide range of σ-values and for off-axis located spherical compartment. As most pelvic tumors are located in the central region of the pelvis, these results can be exploited in hyperthermia treatment planning systems.

The evaluation of a non-invasive respiratory volume monitor in surgical patients undergoing elective surgery with general anesthesia.

Continuous respiratory assessment is especially important during post-operative care following extubation. Respiratory depression and subsequent adverse outcomes can arise due to opioid administration and/or residual anesthetics. A non-invasive respiratory volume monitor (RVM) has been developed that provides continuous, real-time, measurements of minute ventilation (MV), tidal volume (TV), and respiratory rate (RR) via a standardized set of thoracic electrodes. Previous work demonstrated accuracy of the RVM versus standard spirometry and its utility in demonstrating response to opioids in postoperative patients. This study evaluated the correlation between RVM measurements of MV, TV and RR to ventilator measurements during general anesthesia (GA). Continuous digital RVM and ventilator traces, as well as RVM measurements of MV, TV and RR, were analyzed from ten patients (mean 62.6±7.4 years; body mass index 28.6±5.2 kg/m2) undergoing surgery with GA. RVM data were compared to ventilator data and bias, precision and accuracy were calculated. The average MV difference between the RVM and ventilator was -0.10 L/min (bias: -1.3%, precision: 6.6%, accuracy: 9.0%. The average TV difference was 40 mL (bias: 0.4%, precision: 7.3%, accuracy: 9.1%). The average RR difference was -0.22 breaths/minute (bias: -1.8%, precision: 3.7% accuracy: 4.1%). Correlations between the RVM traces and the ventilator were compared at various points with correlations>0.90 throughout. Pairing the close correlation to ventilator measurements in intubated patients demonstrated by this study with previously described accuracy compared to spirometry in non-intubated patients, the RVM can be considered to have the capability to provide continuity of ventilation monitoring post-extubation This supports the use of real-time continuous RVM measurements to drive post-operative and post-extubation protocols, initiate therapeutic interventions and improve patient safety.

Initial study on in vivo conductivity mapping of breast cancer using MRI.

PURPOSE: To develop and apply a method to measure in vivo electrical conductivity values using magnetic resonance imaging (MRI) in subjects with breast cancer. MATERIALS AND METHODS: A recently developed technique named MREPT (MR electrical properties tomography) together with a novel coil combination process was used to quantify the conductivity values. The overall technique was validated using a phantom study. In addition, 90 subjects were imaged (50 subjects with previously biopsy-confirmed breast tumor and 40 normal subjects), which was approved by our institutional review board (IRB). A routine clinical protocol, specifically a T2 -weighted FSE (fast spin echo) imaging data, was used for reconstruction of conductivity. RESULTS: By employing the coil combination, the relative error in the conductivity map was reduced from ~70% to 10%. The average conductivity values in breast cancers regions (0.89 ± 0.33S/m) was higher compared to parenchymal tissue (0.43 S/m, P < 0.0001) and fat (0.07 S/m, P < 0.00005) regions. Malignant cases (0.89 S/m, n = 30) showed increased conductivity compared to benign cases (0.56 S/m, n = 5) (P < 0.05). In addition, invasive cancers (0.96 S/m) showed higher mean conductivity compared to in situ cancers (0.57 S/m) (P < 0.0005). CONCLUSION: This study shows that conductivity mapping of breast cancers is feasible using a noninvasive in vivo MREPT technique combined with a coil combination process. The method may provide a tool in the MR diagnosis of breast cancer.