Single-slice Magnetic Resonance Imaging Research Articles

Adipose tissue fibrosis assessed by high resolution ex vivo MRI as a hallmark of tissue alteration in morbid obesity.

To determine whether magnetic resonance imaging (MRI) when used in an optimal ex vivo setting can help detecting and quantifying the 3D fibrosis fraction in human subcutaneous adipose tissue (SAT) samples, as compared to histology. This prospective observational study was approved by our institutional review board 3D MRI acquisitions were performed at 4.0 T (Bruker) on XX human SAT samples (around 1 cm3) collected from biopsy in morbidly obese patients. Such acquisitions included saturation-recovery T1 mapping (spatial resolution: 200 µm, acquisition time: ~16 minutes) and DIXON imaging (spatial resolution: 200 µm, acquisition time: ~20 minutes). After MRI, histological quantification of fibrosis was performed using picrosirius staining. T1 maps were clustered based on a k-means algorithm allowing quantification of fibrosis within the adipose tissue and percentage of fibrosis over the entire sample volume was calculated. Fat maps were computed from DIXON in-phase and out-of-phase images. The 3D MRI fibrosis percentage within the SAT samples were comprised between 6% and 15%. Excellent correlations and levels of agreement were observed between single slice MRI and histology (r=0.9, P=0.08) and between 3D MRI and histology in terms fibrosis percentages within SAT samples (r=0.9, P=0.01). High Field ex vivo MRI was able to quantify fibrosis in human SAT samples with high agreement with histology and moreover to provide 3D SAT fibrosis quantification avoiding histological sampling errors.

Does visceral adiposity have an effect on the survival outcomes of the patients with endometrial cancer?

Endometrial cancer is the most common cancer of the female reproductive tract in the developed countries. There are many risk factors defined for the development of endometrial cancer, including obesity. We aimed to evaluate the significance of adiposity on the survival outcomes of the patients with endometrial cancer. The patients diagnosed with endometrial cancer and underwent surgery between April 2009 and October 2017 were retrospectively reviewed. The visceral adipose tissue and subcutaneous adipose tissue volumes were measured at the level of umbilicus on single-slice magnetic resonance imaging. Visceral adiposity index was calculated. Patients were compared regarding their clinical, demographical, pathologic and survival characteristics. Patients divided into low visceral adiposity (≤0.265, group 1) and high visceral adiposity (>0.265, group 2). A total of 186 patients were included in this retrospective study. There was no significant difference in terms of the demographical, clinical and tumor characteristics of the patients, except age, menopausal status, subcutaneous adipose tissue and visceral adipose tissue. Although no significant difference in progression-free survival and disease-specific survival was noted between groups (P = 0.181), more patients in group 2 died because of endometrial cancer as statistically significant (P = 0.024). Disease-specific survival showed a significant difference between groups according to the log-rank test. Visceral adiposity tissue is a significant and reliable prognostic indicator for endometrial cancer prognosis. Women diagnosed with endometrial cancer should be informed about the deleterious effects of visceral adiposity on disease-specific survival.

Measuring body composition and regional fat mass accurately

Measuring body composition and regional fat mass accurately

Serum Triglyceride Levels Independently Contribute to the Estimation of Visceral Fat Amount Among Nondiabetic Obese Adults.

Determining the visceral fat amount is important in the risk stratification for the prevention of type 2 diabetes and obesity-related disorders. The area-based measurement of visceral fat area (VFA) via magnetic resonance imaging (MRI) is an accurate but expensive and time-consuming method for estimating visceral fat amount. The aim of our study was to identify a practical predictive parameter for visceral obesity in clinical settings.In this cross-sectional study, we recruited 51 nondiabetic obese (body mass index [BMI] ≥ 27 kg/m2) adults in Taiwan (21 men and 30 women, mean age 35.6 ± 9.2 years, mean BMI 33.3 ± 3.9 kg/m2). VFA was quantified by a single-slice MRI image. Anthropometric indices and biochemical parameters including fasting plasma glucose, serum level of alanine aminotransferase, and lipid profiles were measured. The associations between different variables and VFA were analyzed by linear regression analysis.Increases in BMI, waist circumference, serum levels of alanine aminotransferase and triglycerides (TGs), and decreased serum levels of high-density lipoprotein cholesterol were correlated with larger VFA. After adjustment for age, sex, and anthropometric indices, only serum TG level remained as an independent correlate of VFA. Besides demographic and anthropometric indices, adding TG level may explain a greater variance of VFA. In stepwise multivariate regression analysis, male sex, age, waist circumference, and serum TG level remained significant predictors of VFA. In a subgroup analysis among subjects with BMI ≥30 kg/m2, similar results were demonstrated and serum TG level remained as significant independent correlates of VFA in all of the predictive models.Among nondiabetic obese adults, serum TG level was positively associated with VFA. The combination of sex, age, anthropometric indices, and serum TG level may be used to estimate VFA in clinical settings.

Vitamin D Insufficiency Is Associated with Abdominal Obesity in Urban Asian Indians Without Diabetes in North India

We evaluated the associations of serum 25-hydroxyvitamin D [25(OH) D] levels with clinical, biochemical, and anthropometric profiles and total abdominal adipose tissue (TAAT), subcutaneous abdominal adipose tissue (SCAT), and intraabdominal adipose tissue (IAAT) depots in Asian Indians without diabetes residing in north India. In this cross-sectional study (n=137; 74 males and 63 females; 18-60 years of age), anthropometric (body mass index, waist and hip circumferences, and skinfold thickness at four sites) and biochemical (fasting plasma glucose, lipid profile, and fasting insulin levels) assessments were done. Measurement of percentage body fat was done by dual energy x-ray absorptiometry, and areas of TAAT, SCAT and IAAT were measured at the L2-L3 intervertebral level by single-slice magnetic resonance imaging. Levels of 25(OH) D were measured by radioimmunoassay. Correlation analysis was used to assess relationships among clinical, biochemical, and anthropometric profiles, areas of TAAT, SCAT, and IAAT, and 25(OH) D levels. The mean concentration of 25(OH) D was 40.5 ± 8.6 ng/mL. Overall, 6.6% had vitamin D deficiency (<10 ng/mL), 87.6% had insufficiency (<30 ng/mL), and 5.8% had a sufficient level (>30 ng/mL). Levels of 25(OH) D did not correlate with demographic, biochemical, and anthropometric profiles or with abdominal fat depots (TAAT, SCAT, and IAAT). In the correlation regression model, 25(OH) D was associated with TAAT in obese subjects. In obese urban Asian Indians without diabetes, higher values of total abdominal fat at the L2-L3 intervertebral level were associated with low 25(OH) D levels.

Young Women with Cold-Activated Brown Adipose Tissue Have Higher Bone Mineral Density and Lower Pref-1 than Women without Brown Adipose Tissue: A Study in Women with Anorexia Nervosa, Women Recovered from Anorexia Nervosa, and Normal-Weight Women

Anorexia nervosa (AN) is associated with depletion of body fat, loss of bone mineral density (BMD), and impaired thermogenesis. Brown adipose tissue (BAT) is lower in obese individuals and decreases during aging. Recent studies have suggested a link between BAT and bone metabolism. Our objective was to investigate the presence and quantity of BAT in patients with AN, recovered AN (AN-R), and normal-weight controls and to study the relationship between BAT and BMD and body composition and investigate hormonal predictors of BAT. This was a cross-sectional study at a clinical research center. Patients included 15 women: five with AN (mean age 30 ± 6.3 yr), five AN-R, and five healthy nonobese controls of comparable age. Cold-activated BAT was determined by fluorodeoxyglucose-positron emission tomography/computed tomography. BMD of total-body, spine, and hip, fat and lean mass was determined by dual-energy x-ray absorptiometry. Single-slice magnetic resonance imaging at L4 was done for abdominal fat compartments, and preadipocyte factor-1 (Pref-1), T₃, and T₄ were measured. Within the AN group, one of five; in the AN-R group, two of five; and in the healthy nonobese control group, four of five subjects were BAT positive. Subjects were divided into groups based on the presence (n = 7) or absence (n = 8) of BAT. Both groups were of comparable age and body mass index. Women with BAT had higher total-body BMD, higher T₃, and lower Pref-1 compared with women without BAT. There was a positive correlation between BAT and BMD that remained significant after controlling for disease status and body mass index. Young women with AN have low cold-activated BAT, which may be due to impaired BAT thermogenesis. Young women with BAT have higher BMD and lower Pref-1 compared with women without BAT, suggesting that BAT may be involved in the regulation of stem cell differentiation into the bone lineage at the expense of adipogenesis.

Validation of Ultrasound Estimates of Visceral Fat in Black South African Adolescents

Accurate quantification of visceral adipose tissue (VAT) is needed to understand ethnic variations and their implications for metabolic disease risk. The use of reference methods such as computed tomography (CT) and magnetic resonance imaging (MRI) is limited in large epidemiological studies. Surrogate measures such as anthropometry and dual-energy X-ray absorptiometry (DXA) do not differentiate between VAT and subcutaneous abdominal adipose tissue (SCAT). Ultrasound provides a validated estimate of VAT and SCAT in white populations. This study aimed to validate the use of ultrasound-based assessment of VAT in black South African adolescents. One hundred healthy adolescents (boys = 48, girls = 52) aged 18-19 years participating in the birth to twenty cohort study had VAT and SCAT measured by single slice MRI at L4. These MRI "criterion measures" were related to ultrasound VAT and SCAT thickness, anthropometry (BMI, waist and hip circumferences), and DXA android region fat. Ultrasound VAT thickness showed the strongest correlations with MRI VAT (Spearman's correlation coefficients: r = 0.72 and r = 0.64; in boys and girls, respectively), and substantially improved the estimation of MRI VAT compared to anthropometry and DXA alone; in regression models the addition of ultrasound VAT thickness to models containing BMI, waist, and DXA android fat improved the explained variance in VAT from 39% to 60% in boys, and from 31% to 52% in girls. In conclusion, ultrasound substantially increased the precision of estimating VAT beyond anthropometry and DXA alone. Black South African adolescents have relatively little VAT compared to elderly whites, and we therefore provide new ultrasound-based prediction equations for VAT specific to this group.

Cutoffs of Abdominal Adipose Tissue Compartments as Measured by Magnetic Resonance Imaging for Detection of Cardiovascular Risk Factors in Apparently Healthy Adult Asian Indians in North India

We aimed to define cutoffs of abdominal adipose tissue depots [total abdominal adipose tissue (TAAT), intraabdominal adipose tissue (IAAT), and abdominal subcutaneous adipose tissue (SCAT)] in adult Asian Indians in North India. We carried out a cross-sectional study that included 100 healthy adult Asian Indians. Anthropometric measurement (waist circumference, body mass index), metabolic profile [oral glucose tolerance test (OGTT), lipid profile], and imaging (for quantification of area of abdominal adipose tissue components using single slice magnetic resonance imaging) were done. Odds ratios (ORs) for detecting presence of greater than one cardiovascular (CV) risk factor were computed using tertiles of adipose tissue compartments and cutoffs were generated using receiver operating characteristics curve analysis. The gender-specific cutoff limits for of TAAT, IAAT, and SCAT were 245.6 cm(2) (male) and 203.46 cm(2) (female), 135.3 cm(2) (male) and 75.73 cm(2) (female), and 110.74 cm(2) (male) and 134.02 cm(2) (female), respectively. For detection of CV risk factors, distinct gender differences were seen in ORs for SCAT [3.54 (95% confidence interval [CI], 1.10-11.46) and 6.6 (95% CI, 1.75-24.85) in males and females, respectively] but not for IAAT. The cutoffs of TAAT, IAAT, and SCAT generated for the first time in Asian Indians could be used for metabolic research, interethnic comparisons of adiposity and CV risk factors, and optimal selection of anthropometric parameters.

The Interrelationships between Abdominal Adiposity, Leptin and Bone Mineral Content in Overweight Latino Children

Background/Aims: The link between abdominal fat and bone mineral content (BMC), independent of weight, has not been extensively studied. In Latino children, the contributions of abdominal subcutaneous and visceral fat to BMC have not been examined. Research on the effect of leptin on BMC has also been inconclusive. Methods: The present study included 256 overweight Latino children (111 girls, 145 boys; mean BMI 28.2; age 11.1 ± 1.7 years) from Los Angeles, California. Subcutaneous abdominal adipose tissue (SAAT) and intra-abdominal adipose tissue (IAAT) were determined by single-slice magnetic resonance imaging. BMC was measured using dual-energy X-ray absorptiometry. Results: Independent of age, Tanner stage and weight, abdominal adipose tissue (SAAT + IAAT) was inversely correlated with BMC (r = –0.46, p < 0.0001; n = 256). In girls, there was an inverse correlation between SAAT and BMC (r = –0.38, p < 0.05), between IAAT and BMC (r = –0.32, p < 0.05) and between leptin and BMC (r = –0.39, p < 0.05). In boys, SAAT and BMC were inversely correlated (r = –0.26, p < 0.05), but the correlation between IAAT and BMC was not significant (p = 0.22). Leptin was also inversely correlated with BMC (r = –0.38, p < 0.05) in boys and contributed to the variances in BMC in both girls and boys. Conclusion: Total abdominal adipose fat and leptin are negatively associated with BMC in Latino children. The correlation between SAAT and BMC is stronger in girls than boys. IAAT and BMC are negatively associated in girls but not correlated in boys.

Predictive Equations for Body Fat and Abdominal Fat With DXA and MRI as Reference in Asian Indians

To develop accurate and reliable equations from simple anthropometric parameters that would predict percentage of total body fat (%BF), total abdominal fat (TAF), subcutaneous abdominal adipose tissue (SCAT), and intra-abdominal adipose tissue (IAAT) with a fair degree of accuracy. Anthropometry, %BF by dual-energy X-ray absorptiometry (DXA) in 171 healthy subjects (95 men and 76 women) and TAF, IAAT, and SCAT by single slice magnetic resonance imaging (MRI) at L3-4 intervertebral level in 100 healthy subjects were measured. Mean age and BMI were 32.2 years and 22.9 kg/m(2), respectively. Multiple regression analysis was used on the training data set (70%) to develop equations, by taking anthropometric and demographic variables as potential predictors. Predicted equations were applied on validation data set (30%). Multiple regression analysis revealed the best equation for predicting %BF to be: %BF = 42.42 + 0.003 x age (years) + 7.04 x gender (M = 1, F = 2) + 0.42 x triceps skinfold (mm) + 0.29 x waist circumference (cm) + 0.22 [corrected] x weight (kg) - 0.42 x height (cm) (R (2) = 86.4%). The most precise predictive equation for estimating IAAT was: IAAT (mm(2)) = -238.7 + 16.9 x age (years) + 934.18 x gender (M = 1, F = 2) + 578.09 x BMI (kg/m(2)) - 441.06 x hip circumference (cm) + 434.2 x waist circumference (cm) (R (2) = 52.1%). SCAT was best predicted by: SCAT (mm(2)) = -49,376.4 - 17.15 x age (years) + 1,016.5 x gender (M = 1, F = 2) +783.3 x BMI (kg/m(2)) + 466 x hip circumference (cm) (R (2) = 67.1). We present predictive equations to quantify body fat and abdominal adipose tissue sub-compartments in healthy Asian Indians. These equations could be used for clinical and research purposes.

Practical approach for estimation of subcutaneous and visceral adipose tissue

The first objective was to investigate the correlations between anthropometrical measurements and visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) in two cohorts differing in age using magnetic resonance imaging (MRI) as reference. A second objective was to investigate the potential usage of abdominal diameters in practical estimation of adipose tissue compartments using these cohorts. Measurements of body mass index, waist circumference, sagittal abdominal diameter (sagittal AD) and transverse abdominal diameter (transverse AD) were obtained from 336 volunteers of age 14-70 years. Manual measurements of VAT and SAT from single slice MRI at the L4-L5 level were used as reference. The abdominal diameters were measured from the MR images. Linear correlations between the anthropometrical measurements and the reference were studied. Sagittal AD showed the strongest correlation to VAT (r >or= 0 x 780, P<0 x 0001) and transverse AD was found to give information about the amount of SAT (r >or= 0 x 866, P<0 x 0001). The ellipse spanned by the sagittal AD and the transverse AD was strongly correlated to the total amount of adipose tissue (r >or= 0 x 962, P<0 x 0001). Strong correlations were found between sagittal and transverse abdominal diameters, assessed using MRI, and VAT and SAT, respectively. These results suggest the use of abdominal diameters in practical estimations of VAT and SAT depots.

Association of simple anthropometric measures of obesity with visceral fat and the metabolic syndrome in male Caucasian and Indo‐Asian subjects

The aims of this study were first, to investigate the relationship between simple anthropometric measures of obesity with visceral fat as assessed by a single slice magnetic resonance imaging (MRI)-scan in patients attending a hospital clinic. Second, to determine which anthropometric measure best relates to the adverse metabolic profile of the metabolic syndrome. Forty-one male subjects [body mass index (BMI): 30.2 + 5.8 kg/m(2), age: 50.3 + 13.6 years] were studied by MRI-scan to measure visceral fat at L4/L5 level and to investigate its relationship with simple anthropometric measures. Second, we studied 83 male subjects to determine which anthropometric measure best predicts the metabolic complications (using the ATPIII criteria) of obesity in the setting of a hospital clinic. Waist circumference was the best anthropometric measurement that correlated with MRI-visceral fat mass assessed at L4/L5 in 41 subjects who had an MRI scan (P = 0.0001, r(2) = 0.36, beta = 0.56) amongst variables which also included age, BMI, sagittal diameter, diabetes and ethnicity. Stepwise multiple regression analysis showed sagittal diameter (P = 0.001, r(2) = 0.4, beta = 0.406), age (P = 0.003, beta = 0.271) and waist circumference (P = 0.012, beta = 0.297) were the best predictors of the adverse metabolic profile of the metabolic syndrome in all 83 male subjects amongst BMI, waist-hip ratio (WHR), ethnicity and diabetes-related factors. Waist circumference is a simple anthropometric parameter that best correlates with single slice MRI-scan, but sagittal diameter (measured using abdominal calipers) better predicts the adverse metabolic profile of the metabolic syndrome. Although there is considerable variation in abdominal fat topography between ethnic groups, and also within populations, sagittal diameter assessment is a technique that is simple and best predicts the metabolic syndrome.

Influence of undersampling on magnetic resonance imaging measurements of intra-abdominal adipose tissue.

Single-slice magnetic resonance imaging (MRI) and computed tomography (CT) are finding increasing use as methods to estimate visceral fat content in human studies. To assess the validity of this approach, we have compared single- and multi-slice MRI methods for the measurement of intra-abdominal adipose tissue content. Multi-slice whole-body MR images and single-slices at the level of L2-L3 and L4-L5 were obtained from 59 healthy female volunteers chosen to cover a wide range of body size, and from 17 healthy female volunteers before and after a 6-month exercise intervention. Taking the group as a whole, significant correlation between multi-slice and single-slices was observed (L2-L3: r=0.56; P<0.01; L4-L5: r=0.76; P<0.01). However, the ranking of subjects according to their intra-abdominal fat content was significantly altered by the choice of MRI strategy, especially using L2-L3 methodology. Whole-body (-23.8+/-20.0%; P<0.01) and single-slice (L2-L3: -31.03+/-35.0%; P<0.01; L4-L5: -22.1+/-37.24%; p<0.05) MRI methods also detected a significant decrease in intra-abdominal fat following the exercise protocol, although the latter techniques gave rise to increased spreading of the data from the mean. These results suggest that the use of single-slice imaging techniques can lead to inconsistencies in the estimation of intra-abdominal fat content, which in turn can have significant effects on data interpretation. Single-slice MRI appears to be suitable for assessing changes in intra-abdominal fat content in interventional studies, especially in large cohort of subjects, where each subject can serve as its own control. However, for accurate determination of an individual's intra-abdominal fat content, and intersubject comparison, only multi-slice imaging will give precise results.

Echocardiography overestimates left ventricular mass

To compare measurement of left ventricular mass (LVM) by M-mode echocardiography and magnetic resonance imaging (MRI) in hypertensive subjects. A prospective study. Twenty-four untreated hypertensive patients [19 men and five women, aged 51 +/- 2 (mean +/- SEM) years, supine blood pressure 159/101 +/- 3/1 mmHg]. The Blood Pressure Unit, St Georges Hospital Medical School and Magnetic Resonance Unit, Royal Brompton National Heart and Lung Hospital, London. LVM estimated both by M-mode echocardiography and by MRI. Using three standard M-mode formulae, widely different values of LVM were obtained with echocardiography [American Society of Echocardiography (ASE) 319 +/- 21 g, Penn 273 +/- 19 g. Teichholz 191 +/- 11 g]. By MRI, the LVM was 232 +/- 11 g. The differences between MRI and echocardiography could not be explained in terms of the timing of measurements in the cardiac cycle. When single-slice MRI measurements at the appropriate level were applied to the ASE and Penn formulae, the LVM was again overestimated. Our study has shown major differences in LVM estimated using methods based on one-dimensional (echocardiography) compared with three-dimensional (MRI) data. These differences seem to be largely the result of the geometrical assumptions on which M-mode measurements are based. Our findings have important clinical implications for the assessment of the severity and response to treatment of left ventricular hypertrophy in hypertensive patients.

Evaluation of magnetic resonance imaging for determination of left ventricular ejection fraction and comparison with angiography

Left ventricular ejection fraction was measured by magnetic resonance imaging (MRI) and compared with standard monoplane left ventriculography in 46 patients with various cardiac diseases. Two different MRI strategies were used. In 28 patients (group 1), ejection fraction was determined using a single slice comparable with the right anterior oblique projection of the ventriculogram. Comparison of left ventricular ejection fraction yielded a poor correlation between single slice MRI (y) and ventriculography (x) (y = 28.7 + 0.47 x, r = 0.65). In 18 patients (group 2), a multiple contiguous slice MRI technique was used to allow ejection fraction and stroke volume determination by summing up the volumes of ventricular cavity intersections. Regression analysis showed a high correlation between multiple slice MRI (y) and ventriculography (x) (y = 7.2 + 0.88 x, r = 0.98). Also, correlation between MRI right (y) and left (x) ventricular stroke volumes was satisfactory, (y = −12.8 + 1.09 x, r = 0.83). It is concluded that the multiple slice imaging technique in MRI provides an accurate noninvasive means for quantification of left ventricular ejection fraction that can be extended to the determination of left ventricular volume.

Magnetic resonance imaging of the heart for determination of ejection fraction

In 28 patients with various cardiac diseases we compared ejection fractions obtained by magnetic resonance imaging in a single oblique slice with monoplane ventriculography in the right anterior oblique projection, the latter serving as the standard. Also, results were evaluated for clinical relevance and relation to image quality. The correlation between the two techniques was moderate ( r = 0.65). According to our standardized limits for clinical relevance, insufficiently correlating ejection fractions were obtained in 14 patients. In 8 of these patients this was attributed to poor endocardial edge detection. Edge detection problems were more frequently encountered by imaging with echo-time 20 msec than with echo-time 32 msec. Other causes for mismatching of the obtained ejection fractions are discussed. It is concluded that determination of ejection fraction by single slice magnetic resonance imaging should not be used for clinical application. Improvement can be expected by using a contiguous slicing technique, a longer echo-time in the spin-echo pulse sequence, or in due course by application of newly developed fast-imaging pulse sequences.