Clinical significance of visceral adiposity assessed by computed tomography: A Japanese perspective

Abdominal obesity, rather than total amount of fat, is linked to obesity-related disorders. Visceral adiposity is an important component of obesity-related disorders in Japanese individuals with a mild degree of adiposity compared with Western subjects. In 1983, our group reported techniques for body fat analysis using computed tomography (CT) and established the concept of visceral fat obesity in which intra-abdominal fat accumulation is an important factor in the development of obesity-related complications, such as diabetes, lipid disorders, hypertension and atherosclerosis. Our group also established ideal imaging conditions for determining abdominal fat area at the umbilical level CT scan. Visceral fat area (VFA) measured in a single slice at L4 level correlated significantly with the total abdominal visceral fat volume measured on multislice CT scan. In a large-scale study of a Japanese population, the mean number of obesity-related cardiovascular risk factors (hypertension, low high-density lipoprotein cholesterolemia and/or hypertriglyceridemia, and hyperglycemia) was greater than 1.0 at 100 cm² of VFA, irrespective of gender, age and body mass index. Our group also demonstrated that reduction of visceral fat accumulation subsequent to voluntary lifestyle modification, “Hokenshido”, correlated with a decrease in the number of obesity-related cardiovascular risk factors. It is important to select the most appropriate subjects from the general population (e.g., non-obese subjects with a cluster of risk factors for the metabolic syndrome) that are most suitable for body weight reduction, with the goal of preventing atherosclerotic cardiovascular diseases.     

16排CT检测糖尿病患者腹部脂肪的初步研究

目的 评价16排CT在糖尿病患者腹部脂肪检测中的作用.方法 用16排CT对糖尿病患者(糖尿病组,n=40例)和正常人群(对照组,n=40例)进行腹部脂肪扫描,应用16排CT测量研究对象脐上下2.5 cm腹部脂肪体积(VAA)、内脏脂肪(VVA)、腹壁脂肪(VSA)体积、内脏脂肪(VA)和腹壁脂肪(SA)面积,并计算出二者比值(内/壁比),比较2组间的差异.结果 糖尿病组VAA、VVA、VSA、VA、SA、VVA/VSA和VA/SA均明显高于对照组(P均<0.05).结论糖尿病患者存在腹部脂肪堆积.     

Measurement of visceral fat/subcutaneous fat ratio by 0.3 tesla MRI

PURPOSE: Visceral fat-type obesity is known to be closely related to hyperlipidemia and diabetes. The visceral fat area/subcutaneous fat area ratio is used for the diagnosis of visceral fat-type obesity. In this study, we measured the visceral and subcutaneous fat areas in the fat images obtained using 0.3 Tesla open-type MRI, and investigated their usefulness. MATERIALS AND METHODS: A short TR was set to shorten the acquisition time, and in-phase and out-of-phase images were acquired during holding of breath. The visceral and subcutaneous fat areas were automatically measured from the fat image using a workstation. The measurements were compared with the visceral and subcutaneous fat areas measured by CT as the gold standard. RESULTS: No major differences were observed in the fat areas measured by MRI and CT. This method was capable of imaging during holding of breath, and clearly imaged visceral and subcutaneous fat. CONCLUSION: CT is not free from the concern of radiation exposure, whereas MRI is free from radiation. For measurement of the visceral and subcutaneous fat areas, 0.3 Tesla MRI was useful.     

Visceral fat analysis at CT colonography

RATIONALE AND OBJECTIVES: Obesity is associated with increased risks for colorectal neoplasia. Few studies have examined quantitative body fat measurements as predictors of colorectal polyps. The objective is to determine whether visceral fat is associated with colorectal polyps at computed tomography (CT) colonography. MATERIALS AND METHODS: Case (n = 25) and control (n = 25) subjects with proven large (>1 cm) colorectal adenomas or normal colons respectively were randomly selected from among an established CT colonography research study cohort. Using supine CT colonography data, the body wall was traced at three levels: top of the right kidney, iliac crest, and superior acetabulum. Total area from the three slices and each slice area were determined within the visceral fat range (-170 to -45 Hounsfield units) and recorded within the selected region. Visceral fat measures were compared between patient groups with and without polyps. RESULTS: None of the single slice visceral fat area measures or summed measures predicted case or control status. The most informative visceral fat measure was obtained at the top of the right kidney with a maximum area under the received operator characteristic curve of 0.77 (0.05 SE). For a selected sensitivity of 75%, the maximum specificity for a large (>or=1 cm) polyp was 64%. CONCLUSION: In this pilot study, visceral fat measures at CT colonography were not significantly associated with the presence of large colorectal adenomas. However, odd ratios were elevated by a factor of 2. This suggests that a larger study may be justified.     

Measuring visceral fat with water-selective suppression methods (SPIR, SPAIR) in patients with metabolic syndrome.

We attempted to measure the area and volume of visceral fat using magnetic resonance (MR) imaging to avoid radiation exposure. We used water suppression-spectral attenuation with inversion recovery (WS-SPAIR) as prepulses and conducted T(1) high-resolution isotropic volume examination (THRIVE). Image processing software can be used to estimate the area and volume of fat and separate the fat and water signals at a visually optimal threshold in the MR image, which requires contrast enhancement between intestinal contents and visceral fat. In 14 volunteers, we evaluated WS-SPAIR and water suppression-spectral presaturation with inversion recovery (WS-SPIR) with respect to the relationship between the flip angle of THRIVE and signal contrast. We used flip angles of 5 degrees, 10 degrees, and 20 degrees. The minimum threshold that allowed exclusion of intestinal contents from the masked region was determined for each technique. The volume and area of the masked region, which included subcutaneous fat, were measured at the umbilicus level. Both volume and area increased with a smaller flip angle. The masked region was larger with WS-SPIR-THRIVE (flip angle 5 degrees ). The size of the masked region was determined according to the minimum threshold that allowed exclusion of the intestinal contents from the masked region, expressing the contrast between the intestinal contents and fat in a relative manner. It was speculated that by separating the signals at the threshold, WS-SPIR-THRIVE (flip angle 5 degrees) was a more suitable technique for measuring the area and volume of visceral fat.     

Automated quantification of body fat distribution on volumetric computed tomography

OBJECTIVE: To develop a computerized method to automatically quantify visceral and subcutaneous fat distribution within the abdomen and pelvis on volumetric computed tomographic (CT) images. METHODS: Given the slices of interest, the algorithm automatically delineates a contour that separates the visceral fat from the subcutaneous fat on each slice. Explicitly, starting with extraction of the body perimeter, radii at a fixed angle increment are drawn from the perimeter to the center of the body. Along each radius, intensity profile is analyzed to determine the point on the subcutaneous fat layer that is closest to the body center (inner point). All inner points are then connected to form an inner contour, and a specific smoothing algorithm is subsequently applied to correct suboptimal results. Pixels having HU values between -190 and -30 are considered fat pixels. This procedure is repeated on each of the slices of interest. The visceral and subcutaneous fat volumes computed automatically were compared with those after the radiologist's adjustments. Ratios of volumetric visceral fat-to-total fat and visceral fat-to-subcutaneous fat were compared on average and with single-slice measurements obtained at L4 and L5 vertebral body levels. RESULTS: Subcutaneous and visceral fat were automatically segmented using this algorithm on 419 axial CT slices in 9 CT scans (patients) within the abdomen and pelvis. The overall average percentage difference between the automated segmentation and the segmentation edited by the radiologist were 1.54% for the visceral fat and 0.65% for the subcutaneous fat. CONCLUSIONS: Preliminary results have shown that total compartmental fat, including visceral and subcutaneous fat, can be automatically and accurately segmented on volumetric CT.     

Variation of mesorectal volume with abdominal fat volume in patients with rectal carcinoma: assessment with MRI

The purpose of this study was to assess the variability in the volume of the mesorectum in patients with rectal carcinoma. A retrospective review was made of pelvic MRI studies in 30 patients (mean age 64 years, range 34-88 years, 18M:12F) with histologically proven rectal carcinomas that were confined to the mesorectum. The outer low signal margin of the mesorectum was traced, over at least 10 consecutive 10 mm contiguous slices, until its disappearance. The visceral fascial compartment, body cross-sectional area and body mass index were measured, on a solitary slice, at the level of the L5/S1 disc. Linear regression was calculated for independent determinants of the mesorectal volume. Mean mesorectal volume in males was 227.5 cm3 (95%CI 191.6-263.4), and in females was 157.5 cm3 (95%CI 129.3-185.7). The difference in mesorectal volume between men and women was statistically significant (p<0.001). Mean visceral compartment area in males was 18.4 cm2 (95%CI 16.3-20.5) and in females was 14.6 cm2 (95%CI 12.8-16.4). Visceral compartment area correlated with mesorectal area and volume in females (p<0.05), and extremely well in males (p<0.005). Body cross-sectional area, body mass index and age did not correlate with mesorectal size. The correlation of visceral compartment area with mesorectal volume and mean area suggests that the mesorectum is determined in a similar way to other body fat compartments, with a similar anatomical variation. This significant variation in size and volume may have an important prognostic implication in patients with rectal carcinoma. This volume can be measured and reported on pre-operative MRI scanning and may be communicated to surgeons and radiotherapists.     

Automated quantitation of pericardiac fat from noncontrast CT

INTRODUCTION: Increased abdominal visceral fat has been shown to be a cardiovascular risk factor. Preliminary studies indicate that pericardiac fat (PF) may provide similar information. We aimed to develop new software (QFAT) for automatic quantitation of PF from noncontrast cardiac CT and compare PF measures to other cardiovascular risk factors. METHODS: QFAT accepts user-defined range of noncontrast transverse cardiac CT slices, automatically segments the heart, and determines PF volume (PFV) as contiguous pericardial fat voxels. PFV normalized to cardiac volume defines PF ratio (PFR). QFAT and manual processing (MAN) was performed in 105 patients (mean BMI, 27; range, 17-41) by 2 observers. RESULTS: Mean processing time was 20 +/- 4 seconds for QFAT, and 9 +/- 6 minutes for MAN. There was excellent agreement between QFAT and MAN for PFV (R = 0.98) and PFR (R = 0.98). MAN and QFAT interobserver variability were comparable. Interscan and interscanner variability for PFV and PFR were comparable to corresponding interobserver variability. PFV (R = 0.88, P < 0.0001) and PFR (R = 0.81, P < 0.0001) correlated strongly with abdominal visceral fat area, moderately with BMI (R = 0.58, P < 0.0001 and R = 0.48, P < 0.0001), and weakly with abdominal subcutaneous fat area (R = 0.33, P < 0.0001 and R = 0.32, P = 0.001). CONCLUSIONS: PFV and PFR can be accurately and automatically quantified from noncontrast CT acquired for coronary calcium screening and may provide complementary information regarding cardiovascular risk.     

Shark liver oil-induced lipoid pneumonia in pigs: correlation of thin-section CT and histopathologic findings.

PURPOSE: To evaluate sequential changes in thin-section computed tomographic (CT) findings after inducement of lipoid pneumonia and provide the histopathologic bases of these findings. MATERIALS AND METHODS: Shark liver oil was administered to 12 sites in seven pigs. Thin-section CT scans were obtained within 1 hour and at 1 week, 2 weeks, 4 weeks, 8 weeks, 12 weeks, and 16 weeks after oil administration. Scans were assessed for opacity, distribution, location at the lobular level, extent, and volume of the lesions. The CT number in consolidation areas also was measured. Findings at CT were correlated with those in the histopathologic specimens. RESULTS: Diffuse ground-glass opacity was noted on all immediately obtained scans. The opacity of the lesions was highest at 1 week; then it decreased gradually to an area of ground-glass opacity. The extent and volume of the lesions decreased at follow-up CT. Histopathologically, the lesions showed a lobular distribution sharply demarcated from the normal lungs. The lobules of decreased volume showed residual thickening of the alveolar walls with bronchiolectasis and mild collagen deposition of the interlobular septa. Pathologic examination of the low-attenuating consolidation area at CT revealed evidence of partial aeration. CONCLUSION: Thin-section CT findings of lipoid pneumonia include ground-glass opacity and airspace consolidation, followed by complete or incomplete resolution with volume loss and septal thickening. Low-attenuating consolidation at CT does not always indicate the presence of fat.     

Abdominal fat distribution on computed tomography predicts ureteric calculus fragmentation by shock wave lithotripsy

Objectives

To assess the effects of abdominal fat on shock wave lithotripsy (SWL). We used pre-SWL unenhanced computed tomography (CT) to evaluate the impact of abdominal fat distribution and calculus characteristics on the outcome of SWL.

Methods

One hundred and eighty-five patients with a solitary ureteric calculus treated with SWL were retrospectively reviewed. Each patient underwent unenhanced CT within 1 month before SWL treatment. Treatment outcomes were evaluated 1 month later. Unenhanced CT parameters, including calculus surface area, Hounsfield unit (HU) density, abdominal fat area and skin to calculus distance (SSD) were analysed.

Results

One hundred and twenty-eight of the 185 patients were found to be calculus-free following treatment. HU density, total fat area, visceral fat area and SSD were identified as significant variables on multivariate logistic regression analysis. The receiver-operating characteristic analyses showed that total fat area, para/perirenal fat area and visceral fat area were sensitive predictors of SWL outcomes.

Conclusion

This study revealed that higher quantities of abdominal fat, especially visceral fat, are associated with a lower calculus-free rate following SWL treatment. Unenhanced CT is a convenient technique for diagnosing the presence of a calculus, assessing the intra-abdominal fat distribution and thereby helping to predict the outcome of SWL.

Key Points

? Unenhanced CT is now widely used to assess ureteric calculi. ? The same CT protocol can provide measurements of abdominal fat distribution. ? Ureteric calculi are usually treated by shock wave lithotripsy (SWL). ? Greater intra-abdominal fat stores are generally associated with poorer SWL results.     

间歇低氧暴露对高脂膳食大鼠胰岛素敏感性的影响

目的:探讨间歇低氧暴露对高脂膳食肥胖大鼠胰岛素抵抗的影响。方法:40只雄性SD大鼠随机分为普通膳食常氧组、普通膳食间歇低氧组、高脂膳食常氧组、高脂膳食间歇低氧组。普通膳食采用普通饲料,高脂膳食采用高脂饲料,间歇低氧暴露采用常压低氧方法,氧浓度控制在15.4%,每天10小时。干预6周后取材测试大鼠内脏脂肪总量、空腹血糖和胰岛素,并计算胰岛素敏感指数。结果:与普通膳食常氧组相比,高脂膳食常氧组大鼠Lee指数、内脏脂肪总量和血清胰岛素水平极显著增加而胰岛素敏感指数极显著下降(P<0.01),但普通膳食间歇低氧组大鼠Lee指数、内脏脂肪总量显著减少(P<0.05,P<0.01),胰岛素敏感指数显著升高(P<0.05);与高脂膳食常氧组比较,高脂膳食间歇低氧组大鼠Lee指数、内脏脂肪总量和胰岛素水平极显著下降(P<0.01),胰岛素敏感指数极显著提高(P<0.01)。相关性分析显示,内脏脂肪总量与胰岛素水平存在一定正相关,且胰岛素水平和胰岛素敏感指数存在高度负相关(P<0.01)。结论:体内脂肪总量增加可使血清胰岛素水平升高,胰岛素敏感性下降,而间歇低氧暴露可以减少高脂膳食大鼠体内脂肪含量,提高胰岛素敏感性,改善胰岛素抵抗。     

An assessment of abdominal fatty tissue distribution in obese children. A comparison between echography and computed tomography

PURPOSE: Computed tomography (CT) and, more recently, ultrasound (US), have proved excellent tools for quantifying adipose tissue distribution. Body fat distribution is an important factor in the treatment of obesity and its complications. We investigated the correlation between CT and US measurements in pediatric obesity. MATERIAL AND METHODS: Forty obese children and adolescents aged 4.1-14.8 years were submitted to CT and US. Intra-abdominal, subcutaneous and total body fat were calculated (in cm2), with the CT image analysis software. The rectus muscle-spine and rectus muscle-aorta distances, as indicative of visceral fat thickness, were measured on US images with(out) compression. The distance between skin-fat and fat-rectus muscle interfaces was measured as subcutaneous fat thickness. We also compared US-CT findings with other morphometric variables--i.e., patient's (ideal) body weight and skin fold measures. RESULTS: At US, the rectus muscle-aorta and rectus muscle-spine distances ranged 2.4-7.5 cm (mean: 4.47 cm) and 3.6-8.9 cm (mean: 5.79 cm), respectively. The skin-rectus muscle distance ranged 1.2-7.5 cm (mean: 3.14 cm). A statistically significant correlation was found between the CT measurement of visceral fat and the aorta-rectus muscle and rectus muscle-spine distances (r = 0.80 and 0.74, respectively). The US measurements of subcutaneous fat were correlated with CT subcutaneous fat area (r = 0.82). No correlation was found between overweight, as calculated by body mass index, and CT or US fat. CONCLUSION: Our findings indicate that US is as useful as CT in evaluating body fat distribution in pediatric obesity.     

Pericardial and visceral adipose tissues measured volumetrically with computed tomography are highly associated in type 2 diabetic families

RATIONALE AND OBJECTIVES: Pericardial and visceral adipose tissue volumes can provide new insight into the complex relation between obesity, adult-onset diabetes, and cardiovascular disease. We describe a new method for quantifying pericardial adipose tissue volumes with computed tomography (CT), and present its precision and relation to established measures of adiposity. METHODS: Eighty subjects randomly selected from a family study of sibling pairs concordant for type 2 diabetes and unaffected siblings, 69 with diabetes, had 2 cardiac CT scans with electrocardiographic gating and 1 abdominal scan as part of an examination designed to measure calcified atherosclerotic plaque. Pericardial adipose tissue and visceral adipose tissue were measured using a 3-dimensional analysis technique. Body mass index, waist circumference, waist-to-hip ratio, and percent fat by dual x-ray absorptiometry were measured during the same visit. RESULTS: Pericardial adipose tissue volumes measured independently and in a random order from the 2 sequential cardiac CT scans obtained during the same examination were highly correlated (Spearman R = 0.99; P < 0.0001). The mean +/- standard deviation (median) pericardial adipose tissue volume was 320.5 +/- 147.3 (281.7) mL. Pericardial adipose tissue was highly correlated with total abdominal visceral adipose tissue (R = 0.81; P < 0.0001). CONCLUSION: The significant association between pericardial and visceral adipose tissue volumes in this preliminary study suggests that pericardial, like visceral adipose tissue, may be an important predictor or risk factor for cardiovascular disease and other related illnesses and warrants further evaluation.     

Measurement of abdominal fat with T1-weighted MR images.

The cross-sectional area of visceral and subcutaneous fat in the abdomen was measured with T1-weighted spin-echo images acquired with a 1.5-T magnetic resonance (MR) imager. Four axial images centered on L-4 were acquired in each patient. Outline regions of interest (ROIs) were drawn manually for subcutaneous and visceral fat. The subcutaneous fat cross-sectional area was calculated from the ROIs drawn around the outer and inner margins of subcutaneous fat. Several adaptive processing methods were evaluated for measuring fat in the complex structure of the viscera. These methods were compared with an existing MR imaging measurement method for abdominal fat in 18 patients. The adaptive method that uses the valley between the fat and nonfat distributions in the average histogram curve was judged best for research evaluations because it reduces the effects of volume averaging while using a more natural division between fat and nonfat data. Another adaptive method that yielded comparable measurements was thought to be more suitable for clinical applications. Cross-sectional area measurements of abdominal fat were compared in 18 nonobese and 17 obese women to illustrate the utility of these measurements.     

Exophthalmos caused by excessive fat: CT volumetric analysis and differential diagnosis

CT has proven to be excellent in identifying orbital pathology responsible for proptosis. Occasionally, no discrete mass or extraocular muscle enlargement to explain the exophthalmos is found, only an appearance suggestive of an abnormal increase in orbital fat volume. Fifteen patients were studied with proptosis apparently resulting from increased orbital fat. Clinical follow-up revealed that four of them had Graves orbitopathy, unilateral in one; two had Cushing disease/syndrome; and nine were obese without endocrinopathy. The orbital volume and percentage orbital fat volume were measured by CT software analysis in these patients and in a control group of 16 patients without proptosis. Measurements of proptosis and thickness of the scalp fat pad at the inion level were also performed. Significantly greater values for orbital fat volume, percentage fat volume, and proptosis were found in the proptosis group compared with the control group. There was excellent correlation between proptosis and percentage fat volume, supporting the contention that increased orbital fat is responsible for the proptosis. The thickness of the scalp fat pad at the inion level was significantly greater in obese and Cushing patients than in control subjects, but the thickness was not significantly greater in Graves patients than in controls. Proptosis and inion fat were well correlated (r = 0.74) in the control and obese patients, which suggests a relation between general body fat and orbital fat volume.     

肥胖合并2型糖尿病患者胃旁路手术后相关指标的变化

 目的 探讨肥胖合并2型糖尿病患者腹腔镜胃旁路手术(LRYGB)后相关指标的变化。方法 回顾性分析2011-03至2012-02在原武警总医院普外科接受LRYGB的52例肥胖合并2型糖尿病患者的临床资料,分别在术前、术后3、6、12个月,采用人体成分分析仪检测全身脂肪总量和非脂肪总量变化,通过日本东芝公司80排螺旋CT+美国明维思公司校准体模和定量CT(QCT)分析软件,记录腹部总体脂肪体积(TAFV)、腹部内脏脂肪总体积(TVFV)和腹部皮下脂肪总体积(TSFV)的变化;同时测定相应时间点血清瘦素、脂联素(APN)及糖脂代谢指标,部分指标随访5年。结果 (1)术后12个月糖尿病达标率为86.5%,肥胖症治愈率为67.3%,术后各时间点空腹胰岛素(Fins)和HOMA-IR数值呈逐渐下降趋势,仅在术后12个月和术后5年明显下降,差异有统计学意义(P＜0.05)。与术前相比,在术后12个月三酰甘油(TG)、胆固醇(CH)下降明显,差异均有统计学意义(P＜0.05),术后5年TG略有升高,但与术前差异仍有统计学意义(P＜0.05)。(2)与术前相比,术后6、12个月和2年瘦素下降明显,差异均有统计学意义(P＜0.05);术后APN在术后3个月略有下降,然后呈逐渐升高趋势,在术后12个月和2年APN数值显著升高,差异均有统计学意义(P＜0.05)。(3)术后各时间点体重和BMI均呈下降趋势,术后5年下降明显,与术前比较,差异有统计学意义(P＜0.05)。术后非脂肪总量有下降趋势,但仅在术后5年时变化明显。与术前相比,术后6个月TVFV显著下降,术后12个月TSFV显著下降,术后5年TSFV和TVFV均显著下降,差异有统计学意义(P＜0.05)。结论 LRYGB术后腹部内脏脂肪较皮下脂肪减少更为显著,伴血清瘦素降低和APN增高。     

Comparison of 3 T MRI and CT for the measurement of visceral and subcutaneous adipose tissue in humans

Objective CT is considered the gold standard imaging modality for measurement of visceral adipose tissue area. However, as CT imaging exposes subjects to ionising radiation, a comparable imaging technique without this exposure is desirable, such as MRI. Therefore, we compared the agreement of measures of visceral adipose tissue and subcutaneous adipose tissue area from single-slice images obtained at the umbilicus using a 3 T MRI scanner with single-slice images obtained via CT scan. Methods 64 images were obtained from 27 subjects who underwent MRI and CT scanning on the same day, after 10-12 hours of fasting. Visceral and subcutaneous adipose tissue depots were manually separated and quantified using a multimodality image-processing software program. Results We found good agreement between CT and MRI for the measurement of both visceral adipose tissue and subcutaneous adipose tissue. Bland-Altman difference analysis demonstrated a mean bias of -2.9% (as a portion of total abdominal area) for visceral adipose tissue and +0.4% for subcutaneous adipose tissue, as measured by MRI compared with CT. Conclusion MRI is a safe, accurate and precise imaging modality for measuring both visceral and subcutaneous adipose tissue, making it a favourable alternative to CT for quantification of these adipose depots.     

The mesorectum: morphometric assessment with magnetic resonance imaging

The purpose of the present study was to assess the size and configuration of the perirectal fatty tissues using magnetic resonance imaging, including the volume occupied by the rectum itself, and to establish a simple method by which such analysis could be derived. Included in the study were 25 consecutive patients without any large pelvic tumor (diameter of potential pelvic tumor less than 3 cm in any plane) referred for high-resolution pelvic MR imaging. The volume and cross-sectional parameters based on the amount of mesorectum to different sides of the rectum, and the total area occupied, including the rectum, were retrospectively measured using a transaxial three-dimensional T1-weighted gradient–echo sequence. The mesorectum, including the rectum within, occupied an axial area ranging from 320 to 5992 mm², and a total volume of 54–323 ml. There was a good correlation between anteroposterior diameter of the perirectal fat at 4 cm below S1-2 and the left-to-right diameter 7 cm below S1-2, and the total volume. Furthermore, the form of mesorectal tissue differed significantly between male and female subjects. In male subjects, measurements in the anteroposterior dimension accurately reflected the volume of mesorectal tissue, while in women, assessment of both the anteroposterior and the size parameters of the mesorectum from the left to right were required for the best evaluation of the volume of mesorectal tissue. The amount of fat posterior to the rectum was significantly more in men than in women, with or without consideration of length of the pelvis. Finally, the contour of the mesorectal fascia was subject to impression by other nearby visceral organs. There is a great individual variation in the amount of mesorectal fat, and in morphometric parameters between the two sexes. The morphological variations of the mesorectum can be assessed by magnetic resonance imaging using a formula based on two simple measurements of the anteroposterior and left-to-right dimensions.     

Nutcracker and SMA syndromes: What is the normal SMA angle in children?

Objective

The nutcracker and superior mesenteric artery (SMA) syndromes are rare conditions where the left renal vein or duodenum may be compressed by an unusually acute angle between the SMA and aorta, although the normal angle in children is unknown. We measured the SMA angle to define the normal range in children.

Methods

We retrospectively measured SMA angles, left renal vein (LRV) distance, and duodenal distance (DD) in 205 consecutive pediatric abdominal CT. Total and visceral intra-abdominal fat at the level of the umbilicus were also assessed.

Results

Mean SMA angle was 45.6 ± 19.6° (range 10.6–112.9°), mean LRV distance was 8.6 ± 3.9 mm (range 2.0–28.6 mm) and mean DD was 11.3 ± 4.8 mm (range 3.6–35.3 mm). There was a significant but weak correlation between %visceral fat volume (%VF) and SMA angle (R = 0.30; p < 0.001), LRV distance (R = 0.37, p < 0.001) and DD (R = 0.32; p < 0.001).

Conclusion

There is a wide range of SMA angle, LRV and DD in normal children, which correlated weakly with visceral fat volume. Using a definition of SMA angle <25° would diagnose 9.3% of asymptomatic children with nutcracker syndrome, and using a DD definition of <8 mm would diagnose 20% with SMA compression. Our findings suggest exercising caution when attributing these rare syndromes to an absolute SMA angle.     

Prediction of visceral fat area from anthropometric and segmental body composition variables using computed tomography

Abstract This study estimated the area of visceral fat at the L4-L5 level (VFA_L4-5) measured by computed tomography (CT) from anthropometric and segmental percent fat variables. Subjects were 73 adults (50 men and 23 women) aged 24–78 years. Cross-validation was permormed with another 38 adults (25 men and 13 women) aged 21–80 years. The anthropometric variables examined were height, weight, waist circumference, hip circumference, sagittal diameter, and subcutaneous fat thickness (SFT) at 14 sites. SFT and segmental percent fat were measured by ultrasonography and dualenergy X-ray absorptiometry (DXA), respectively. A combination of suitable predictors of VFA_L4-5 was derived by stepwise multiple regression analysis using these variables. A prediction equation was obtained that used seven predictors: sagittal diameter, waist circumference, three subcutaneous thickness variables (subscapula, chest 1 and abdomen), and segmental percent fat at the trunk and left leg (R=0.902, R² =0.813, SEE=17.5 cm²). In a Bland-Altman procedure, systematic error was not found in the original group but was only found in women in the cross-validation group. The percentage of the SEE of the prediction equation for the mean VFA_L4-5 value was 22.5% in the original group and 20.1% in the cross-validation group. Furthermore, the percentages of SD values of the error for the mean VFA_L4-5 value were 21.1% in the original group and 22.2% in the cross-validation group. These values were comparable or superior to those in previous studies. This study provides a useful prediction equation for VFA_L4-5 from anthropometry and segmental body composition variables.