Male–female differences in forearm skin tissue dielectric constant

Tissue dielectric constant (TDC) measurements at 300 MHz via the coaxial line reflection method are useful to evaluate local skin tissue water and its change, but virtually all available data relate to measurements on women. Because TDC values in part depend on skin thickness, we hypothesized that differences in male–female skin may be associated with male–female differences in TDC. To test this hypothesis, we compared TDC values in volar forearm skin of 60 young adult volunteers (30 men, 25·0 ± 2·5 years, 30 women, 27·4 ± 6·6 years) in the seated position using a probe with an effective measurement depth of 1·5 mm. Results showed that TDC values (mean ± SD) for men were significantly greater than for women (33·2 ± 4·0 versus 29·4 ± 2·7, P<0·001) constituting an overall difference of about 13%. This finding suggests that when TDC measurements are used in research or clinical studies in which both men and women are included in a common study population, it would be prudent to consider this difference in both experimental design and data interpretation. This is especially true if absolute TDC values are of interest in contrast to changes in TDC values on the same subject subsequent to time passage or secondary to an intervention. Despite greater TDC values measured in men, calculations of the impact of a greater male skin thickness indicate that the greater TDC values of men may or may not reflect a greater relative local skin tissue water in men compared to women.     

Heat‐related changes in skin tissue dielectric constant (TDC)

The impact of 20 min of whole‐body heating (WBH) on the tissue dielectric constant (TDC) of forearm and hand skin was evaluated in 24 young adults. TDC was measured in triplicate at 300 MHz using an open‐ended transmission line method in which the effective measurement depth was about 2 mm. TDC measurements are an effective way to assess and track localized oedema and lymphoedema. The underlying hypothesis was that heat‐induced eccrine gland activation would increase TDC values via an increase in fluid within the TDC measurement volume. The goal was to test this concept and to determine the magnitude of the change when environmental temperatures were elevated to near 42°C and to estimate TDC recovery time. The practical aspect of this research is motivated by the fact that patients in whom such measurements are made may arrive at the clinic in various states of sweat gland activation. Thus, knowledge of the effect of such activation on measured TDC values permits better understanding of possible relationships between such activation and TDC values. Results showed that increasing environmental temperature from 23·3 ± 1·6 to 41·5 ± 1·3°C increased forearm and thenar eminence skin temperatures to 37·8 ± 0·5 and 37·9 ± 0·4°C, respectively. These changes were associated with increases in TDC at arm from 30·7 ± 4·6 to 36·3 ± 5·7 (18·2%) and at hand from 34·7 ± 4·9 to 45·1 ± 5·5 (30%). Based on calculated TDC recovery rates, it is concluded that temperature‐related TDC variability can be minimized using a wait time of at least 15 min after bandage removal prior to TDC measurements in affected limbs.     

Role of handedness on forearm skin tissue dielectric constant (TDC) in relation to detection of early‐stage breast cancer‐related lymphedema

skin tissue dielectric constant (TDC) measurements help assess local skin water to detect incipient early‐stage lymphedema subsequent to breast cancer treatment‐related lymphedema. However, presurgery measurements are not always obtained and assessments for evolving lymphedema are only made after surgery. Thus, subsequent TDC assessments may be biased in an unknown way dependent on a patient's handedness in relation to the at‐risk arm. We investigated this issue by comparing TDC values in dominant and non‐dominant volar forearms of 31 left‐handed women and 31 right‐handed women (age range 24–84 years). Body fat and water percentages were assessed by bioimpedance at 50 KHz. Results showed that TDC values of dominant versus non‐dominant arms did not significantly differ for left‐handers or for right‐handers. There was also no statistically significant difference in absolute TDC values between left‐ and right‐handers or a statistically significant difference in dominant‐to‐non‐dominant arm ratios between left‐ and right‐handers. For the composite data set (N = 62), TDC values for dominant and non‐dominant arms were, respectively, 30·0 ± 4·6 and 29·6 ± 4·2 and the dominant‐to‐non‐dominant arm TDC ratio for combined left‐ and right‐handers was 1·015 ± 0·075. These results suggest that handedness is not a major factor when assessing lymphedema status in women who have previously been treated for breast cancer but for whom pretreatment TDCvalues have not been obtained. Moreover, these results suggest that threshold ratios of incipient subclinical unilateral lymphedema based on interarm TDC ratios apply independent of a patient's handedness for the site and tissue depths herein measured.     

Forearm skin tissue dielectric constant measured at 300 MHz: effect of changes in skin vascular volume and blood flow

Skin tissue dielectric constant (TDC) values measured via the open‐ended coaxial probe method are useful non‐invasive indices of local skin tissue water. However, the effect of skin blood flow (SBF) or skin blood volume (SBV) on TDC values is unknown. To determine the magnitude of such effects, we decreased forearm SBV via vertical arm raising for 5 min (test 1) and increased SBV by bicep cuff compression to 50 mmHg for 5 min (test 2) in 20 healthy supine subjects (10 men). TDC values were measured to a depth of 1·5 mm on anterior forearm, and SBF was measured with laser‐Doppler system simultaneously on forearm and finger. Results indicate that decreasing vascular volume (test 1) was associated with a small but statistically significant reduction in TDC (3·0 ± 4·3%, P = 0·003) and increasing vascular volume (test 2) was associated with a slight but statistically significant increase in TDC (3·5 ± 3·0%, P<0·001). SBF changes depended on test and measurement site. For forearm, test 1 significantly increased SBF (102·6 ± 156·2%, P<0·001) and test 2 significantly decreased it (39·5 ± 13·1%, P<0·001). In finger, SBF was significantly reduced by both tests: in test 1 by 55·3 ± 32·1%, P<0·001 and in test 2 by 53·3 ± 27·6%, P<0·001. We conclude that the small percentage changes in TDC values (3·0–3·5%) over the wide range of induced SBV and SBF changes suggest a minor effect on clinically determined TDC values because of SBV or SBF changes or differences when comparing TDC longitudinally over time or among individuals of different groups in a research setting.     

Local tissue water assessed by tissue dielectric constant: anatomical site and depth dependence in women prior to breast cancer treatment-related surgery

Assessing local tissue water using tissue dielectric constant (TDC) values is useful to evaluate oedema/lymphoedema features and their change. Knowledge of anatomical site and tissue depth dependence of TDC values could extend this method's utility. Our goal was to compare TDC values obtained at anatomically paired sites and to investigate their depth dependence. In 22 women (12 awaiting surgery for breast cancer and 10 cancer-free control subjects), four sites (mid-forearm, mid-biceps, axilla and lateral thorax) on both body sides were measured with a 2.5-mm sampling depth probe. Also, at forearm, four different probes with sampling depths of 0.5, 1.5, 2.5 and 5 mm were used. TDC values range between 1 for zero water to 78.5 for 100% water. Site comparisons showed TDC values (mean+/-SD) to be largest at axilla (36.4+/-8.9), least at biceps (21.6+/-3.5) and not different between forearm and thorax (24.3+/-4.0 versus 24.8+/-5.0). Group comparisons showed slightly greater values in patients at forearm and biceps (P<0.05) but no group difference at other sites. Dominant-non-dominant side comparisons showed no significant difference in paired-TDC values in either group at any site. Forearm TDC values decreased with increasing depth from 36.4+/-4.8 at 0.5 mm to a minimum of 21.4+/-3.9 at 5.0 mm, with a sharp decline between 1.5 and 2.5 mm. The composite findings suggest that TDC measurements have the necessary features for usefully assessing oedema/lymphoedema and its change on limbs and at body sites not routinely amenable to assessment by other techniques. The depth dependence feature provides additional flexibility to investigate oedematous or lymphoedematous conditions.     

Suitability of single tissue dielectric constant measurements to assess local tissue water in normal and lymphedematous skin

Previous reports described the use of average tissue dielectric constant (TDC) measurements to assess local tissue water and its change. Our goal was to determine if a single TDC measurement could be used in place of the average of multiple measurements. The comparison criteria used to test this was the extent to which single and averaged measurements yielded similar TDC values in both normal and lymphedematous tissue. Measurements were made in two groups of women; a control group (n = 20) and a group with unilateral arm lymphedema (n = 10). In the control group, TDC was measured to multiple depths (0·5–5·0 mm) on both ventral forearms and to a depth of 2·5 mm on the lateral thorax on both body sides. In the lymphedematous group, TDC was measured on both ventral forearms to a depth of 2·5 mm. Results showed that the 95% confidence interval for differences between single and averaged TDC values was less than ±1 TDC unit and that the limits of agreement between methods was less than ±2·5 TDC units (±6·5%) for each condition, site and depth measured. This finding suggests that where this level of agreement is acceptable suitable clinical assessments can be made using a single TDC measurement.     

Volumetric evaluation of upper extremities in 250 healthy persons

BACKGROUND AND PURPOSE: Upper extremity oedema frequently occurs as a complication of several diseases. The aim of this study was to establish normative data for upper extremity volumes with a modified water displacement method. These data were used to develop predictive formulas helpful in detecting abnormal swelling. SUBJECTS AND METHODS: Upper extremities of 250 healthy subjects (138 men and 112 women) were measured by water displacement. RESULTS: A mean difference of 3.0% (3.2%) between right and left arm (forearm) was found. Intra-class correlation coefficients were 0.99 for intra-rater and inter-rater reliabilities. Coefficient of variation was 0.23%. To predict the premorbid volume of an oedematous arm, prediction formulas were constructed. DISCUSSION AND CONCLUSION: Water displacement as used in this study is a highly reliable technique for volume measurement of upper extremities. This technique was applied to gather normative data for upper extremity volumes. We suggest that this technique can be used in daily clinical practice for the evaluation of upper extremity oedema or atrophy caused by various diseases as well as for volume monitoring. Prediction formulas can be used to define abnormal swelling.     

男性乳腺癌超声影像特征分析

目的 总结分析男性乳腺癌的超声特征,分析脂肪层厚度与乳腺癌发生的关系.方法 对患乳腺癌的男性患者进行详细超声检查,检查部位包括双乳、腺体周围淋巴引流区及胸壁(范围为双侧腋中线间锁骨上区至肋弓),记录其声像特征,测量乳腺癌患者的胸壁及脂肪层厚度并与正常体质量[(身高cm- 100)×0.9为标准体质量(kg),正负10％为正常体质量]健康体检者进行对比.结果 ①男性乳腺癌超声影像特征多见:边缘毛刺、内部回声不均、钙化、后方声衰、彩色多普勒血流丰富等.②肿块最大径、血流分级与淋巴结转移有关,肿块越大、血流分级越高,转移癌的发生率越高.肿块的边界、内部回声、有无钙化及后方声衰淋巴结转移者与无淋巴结转移者差异无统计学意义(P＞0.05).③乳腺癌组的胸壁及胸壁脂肪层厚度与健康对照组不同,胸壁厚度分别为(1.37±0.12)cm vs(1.31±0.08)cm(P＜0.05),胸壁脂肪层厚度为(0.89±0.09) cmvs (0.86±0.06) cm(P＜0.05).结论 男性乳腺癌超声特征典型,发生淋巴结转移较早,乳腺癌发生与脂肪密切相关,有必要进一步总结乳腺癌发生概率与脂肪层厚度的关系,为男性乳腺癌的发生提供预警和风险评估.     

脂肪组织提取液促进大鼠皮肤生长的实验研究

目的　观察脂肪组织提取液对大鼠皮肤体外培养生长的影响。方法　将 2 m m× 2 mm大小的新生大鼠皮肤接种到 2 4孔培养板内 ,分别加入含有体积分数为 10 %脂肪组织提取液 (提取液组 )或体积分数为10 %磷酸盐缓冲液 (PBS组 )的胎牛血清 Dulbecco改良 Eagle培养基培养 6 d,测量皮肤培养后的面积。结果　两组皮肤培养后均有生长 ,脂肪组织提取液组皮肤培养后面积为 (8.4 3± 1.4 0 ) mm2 ,而 PBS组为 (4.18±1.11) mm2 ,脂肪组织提取液组皮肤培养后面积约是 PBS组的 2倍 ,两组间差异有显著性 (P<0 .0 5 )。结论　脂肪组织提取液对皮肤生长有促进作用 ,其机制可能是脂肪组织提取液内含有促细胞增殖的某些生长因子和其他有利于细胞生存的物质。     

Comparison of two methods to assess the tissue/blood partition coefficient for xenon in subcutaneous adipose tissue in man

Summary. A new method to calculate the tissue/blood partition coefficient (Λ) for xenon in studies on the subcutaneous adipose tissue blood flow was compared with a previously reported method based on local skinfold thickness (Λ_LSt). The former method included needle biopsies from the abdominal and femoral subcutaneous adipose tissue, and the mean fat cell diameter was measured (Λ_ECT)- The extracellular tissue fraction in subcutaneous tissue was then estimated from a diagram. The tissue lipid content was approximated to equal the relative intracellular volume and Ostwald's solubility coefficients for ¹³³Xe, based on the distribution of xenon in lipid, albumin and 0.9% saline were applied. Estimated Λ-values based on needle biopsies from the abdominal site were: 8.6±0.1 versus 9.9±0.4 ml g^-1 (meanæ) (P<0.05) and from the femoral site: 9.1±0.1 versus 9.6±0.2 in lean (n=10) and obese subjects (n=10), respectively. The corresponding Λ-values obtained from skinfold measurements were: 6.2±0.5 versus 11.0±0.4 (P<0.001) and 6.9±03 versus 11.4±0.4 (P<0.001) in lean and obese subjects, respectively. Pooled Λ_LsT-values correlated positively with estimated adipose tissue blood flow (ATBF) (r: 0.34, P<0.05, n=40) whereas no such correlation was found for Λ_ECT-values. In conclusion, a new method is presented which may allow an accurate determination of, and which may lead to reliable data on, subcutaneous ATBF in both lean and obese subjects. Comparative studies indicate that the widely used Λ-value of 10.0 in subcutaneous adipose tissue may be used as a rough estimate for subcutaneous blood flow studies in these patient groups.     

Quantifying the effect of hand preference on upper limb bone mineral and soft tissue composition in young and elderly women by dual-energy X-ray absorptiometry

Summary. The purpose of this study was to quantify the effect that hand preference has on upper limb bone mineral and soft tissue composition in healthy young and elderly women. Bone mineral content (BMC) in grams, bone mineral density (BMD) in g cm^-2, fat-free soft tissue (FFST) in grams, fat tissue (g), and percent fat were determined by dual-energy X-ray absorptiometry (DXA) for dominant and non-dominant upper limbs as well as total body fat (%) in 25 young (26–6 ± 4–3 years, mean ± SD) and 35 elderly women (68–4 ± 2–9 years). For both groups, the dominant upper limb had a greater BMC (P<0–001), BMD (young, P<0001; elderly, P<0–05), and FFST mass (P<0–001), and a lower percent fat (young, P<0–01; elderly, P<0–05) than the non-dominant limb; however, there was no difference between limbs for total fat mass. BMC, BMD, and FFST in the dominant limb of young women were 7–1%, 1–8%, and 5–1% greater than the non-dominant limb, while for older women the differences were 5–3%, 10%, and 4–2%. Relative fat of the dominant limb was 3–0% and 1 -3% less than the non-dominant limb for young and older women, respectively. Age did not affect the percent bone mineral or soft tissue difference. A higher bone mineral and FFST mass in the dominant limb is expected due to the greater activity demands placed upon these tissues. However, a larger bone and FFST mass increases the total mass of the dominant limb, resulting in a dilution of the fat tissue mass and hence a reduced fat percent for the limb. This study indicates that hand preference affects the tissue composition of the upper limb in both young and elderly women, resulting in an increased bone mineral and FFST mass with no change in absolute fat mass. Hand preference should be taken into account when upper limb bone mineral and/or soft tissue composition is assessed.     

Assessment of local tissue water in the arms and trunk of breast cancer survivors with and without upper extremity lymphoedema

Given the paucity of information on local tissue water (LTW) in the upper extremity and trunk of women after breast cancer surgery, the purpose of this study was to compare tissue dielectric constant (TDC) values between the affected and unaffected sides of breast cancer survivors with and without upper extremity lymphoedema (LE). Differences in LTW were assessed using the TDC method for three sites in the upper limbs, three sites in the lateral thorax and two sites on the back. Additional measures included demographic and clinical characteristics, arm circumference and bioimpedance analysis. For the 112 survivors without LE, no differences in TDC values were found between the affected and unaffected sides for the first dorsal web space, ventral forearm and upper arm, and upper and lower back. Compared to the unaffected side, TDC values were significantly higher on the affected side for the upper, mid and lower lateral thorax. For the 78 survivors with LE, compared to the unaffected side, TDC was significantly higher on the affected side for all of the sites evaluated except the hand web space. Our findings support the use of the TDC method to detect differences in upper extremity and truncal oedema in survivors with LE following breast cancer treatment. Measurement of LTW may provide a useful method to determine truncal as well as extremity LE. The ability to detect early signs of truncal oedema may lead to pre‐emptive interventions in breast cancer survivors.     

Age-related changes in diastolic atrioventricular annular velocity: Studies using pulsed Doppler tissue imaging

Age-related changes in the diastolic velocity of the mitral and tricuspid annuli were studied in 67 healthy subjects aged 15 to 79 years. Ventricular inflow velocities were recorded by pulsed Doppler echocardiography with sample volumes at the mitral and tricuspid orifices in the apical four-chamber view, and peak early (E) and late (A) diastolic velocities were measured. Atrioventricular annular velocities were recorded by Doppler tissue imaging with sample volume set on the lateral portion of each annulus in the same view, and peak early (Ea) and late (Aa) diastolic velocities were determined. E and Ea correlated inversely with age, while A and Aa correlated directly with age in both ventricles. E/A and Ea/Aa ratios correlated inversely with age in both ventricles. Coefficients of correlation of these variables with age were higher for annular velocity than for inflow velocity. The E/A ratio at the tricuspid orifice was higher than that at the mitral orifice in all decades. An E/A ratio of less than 1 was observed at the mitral orifice in the sixth decade, but at the tricuspid orifice in the seventh decade. The Ea/Aa ratio at the tricuspid annulus was lower than that at the mitral annulus in all decades. The Ea/Aa ratio was less than 1 at the mitral annulus in the fifth decade and at the tricuspid annulus in the fourth decade. Diastolic function of both ventricles thus deteriorates with age, and diastolic annular velocity reflects ventricular diastolic function more accurately than ventricular inflow velocity.     

Rectal foreign body in adult male: Unusual case report and literature review

The majority of rectal foreign bodies inserted by adults are for self‐gratification. As a result, they will probably be smooth, rounded, tubular, or egg‐shaped to make insertion and extraction easier. Herein, we describe a 50‐year‐old man who inserts a water bottle into a region 10 mm from the anorectal junction.     

纹理分析技术评估冠状动脉粥样硬化患者冠周脂肪组织的变化

目的  应用纹理分析技术初步评估冠状动脉粥样硬化患者冠周脂肪组织学的改变。方法  选取解放军总医院海南医院220例行冠状动脉CT血管成像的患者, 其中正常组110例, 病变组(包含钙化、非钙化及混合斑块)110例, 分别对其在冠状动脉三支主干近端(右冠状动脉、左冠前降支、回旋支)多平面重建图像上选取显示靶斑块周围脂肪组织较清晰层面进行纹理特征分析, 选取角二阶矩、对比度、自相关、逆差距、熵5个纹理特征参数, 采用Mann-Whitney U检验各组之间的纹理特征差异。结果  正常组与病变组的5个纹理特征参数的差异均有统计学意义(P_角二阶矩 < 0.001, P_对比度 < 0.001, P_自相关 < 0.001, P_逆差距 < 0.001, P_熵 < 0.001), 两组间冠周脂肪组织纹理特征存在差异, 各纹理参数均具有较好的诊断价值。ROC曲线证实5个纹理特征的曲线下面积均大于0.8, 具有较高的诊断价值。结论  正常组与病变组的冠状动脉周围脂肪组织的纹理特征不同, 纹理特征分析技术可基于冠状动脉CT血管成像检查, 初步评估冠状动脉粥样硬化患者的冠周脂肪组织学改变。     

Bioelectrical Impedance Assay (BIA) of Total Body Composition in Alcohol-Induced Migraine Patients. Preliminary Report.

"Whole body composition" was investigated in 30 people subject to alcohol-induced migraine. The control group was 30 people matched for age, sex, height and weight, who were not subject to migraine and who consumed moderate amounts of alcohol. The following were evaluated: anthropometric data, alcohol intake in grams per day, total body water, fat-free mass, fat mass, and body mass index (kg/m2). Two methods of measurement were used: skin fold thickness evaluation, and bioelectric impedance assay (BIA). BIA is a non-invasive method based on the principle that lean tissues conduct a low frequency alternating current of electricity better than do fatty tissues. Body mass index was increased in the alcohol-induced migraine patients (p less than 0.04), as was fat mass, (p less than 0.03) as evaluated by skin fold measurements. Bioelectric impedance assay demonstrated a slight total body water increase in alcohol-induced migraine patients (p less than 0.07). Possibly, if this total body water increase was reflected at the neuronal level, the bioelectric properties of the migrainous brain may be altered, thus creating a hypothetical link with the phenomenon of spreading depression.     

Relative fat mass assessment estimates changes in adiposity among female older adults with obesity after a 12-month exercise and diet intervention

Background/objectives/introductionIt is imperative to accurately estimate whole body fat percentage (%fat) to understand the deleterious nature of excess adiposity on cardiometabolic disease risk. Cost and accessibility often preclude the use of advanced imaging methods like dual-energy X-ray absorptiometry (DXA) and magnetic resonance imaging (MRI). Relative fat mass (RFM) is an emerging estimator of whole body %fat based on waist circumference, height, and biological sex. The purpose of this ancillary study was to examine the relationship between RFM and gold-standard measures of adiposity among community-dwelling older adults with obesity and to evaluate if changes in RFM reflect changes in %fat following a 12-month lifestyle intervention (clinicaltrials.gov #{"type":"clinical-trial","attrs":{"text":"NCT00955903","term_id":"NCT00955903"}}NCT00955903).Patients/materials and methodsParticipants (N = 163, 37.4% male, 70.3 ± 4.7 years) were randomized to the exercise only group, exercise + nutrient-dense weight maintenance group, or exercise + nutrient-dense energy restriction of 500 kcal/d group. Total and regional adiposity assessed by DXA and MRI, as well as anthropometrics, were evaluated at baseline and 12 months.ResultsRFM was significantly positively correlated with DXA whole body %fat and DXA trunk %fat at baseline. Equivalence testing revealed that RFM was considered equivalent to DXA whole body %fat for females only. Additionally, from baseline to 12 months, a significant reduction in RFM was observed among female participants in the exercise + energy restriction group only. Changes in RFM were significantly correlated with changes in DXA whole body %fat, DXA trunk fat, and total abdominal fat tissue determined by MRI.ConclusionResults support the use of RFM as an estimate of whole body %fat where advanced imaging techniques are not feasible. Furthermore, results suggest that this index is sensitive to changes in fat mass over 12 months in female older adults with obesity.

KEY MESSAGES

• Relative fat mass (RFM), an emerging estimator of whole body %fat based on waist circumference, height, and biological sex, was intentionally developed to be a simple estimate of adiposity that overcomes limitations of measures like body mass index.
• In the current study, results from correlations and agreement analyses support the use of RFM to estimate whole-body fat percentage in a community-dwelling older adult population with obesity when advanced methods, namely dual-energy X-ray absorptiometry, are not feasible.
• Significant reductions in RFM were also observed over a 12-month period that was significantly correlated with changes in whole body fat percentage; thus, supporting the sensitivity of RFM to lifestyle changes.

     

Age-related changes of water and fat content in muscles estimated by magnetic resonance (MR) imagine

The pixel values in fat/water suppression magnetic resonance (MR) images were measured for the thigh muscles of 18 healthy volunteers to investigate age-related changes in muscle water and fat content. Prior to the human studies the reproducibility of the data was confirmed using phantoms. The standard deviations (SDs) of the pixel values for one of the phantoms examined five times were found to be within a relatively narrow range. Both the pixel values in the fat suppression images (PV1) and the pixel values in the water suppression images (PV2) of all muscles tended to be higher in the oldest group. The results indicate that the water and fat content of skeletal muscles is higher in aged persons. Moreover, the PV1 in the non-dominant limbs was found to be increased in the extensor muscles of the knee joints, while the PV2 in the non-dominant limbs did not show a significant difference, except for the rectus femoris.